Tube testers

First topic message reminder :

This is just to get this topic started. I have 3 tube testers, a Jackson 636, and a couple of B&Ks.
One being a 747 and the other a 707.
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I just replaced a resistor in the Jackson that was way out of tolerance and now I can do a line adjust.
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I would like to make a tube socket strip for the newer B&Ks to test older 4 and 5 pin tube types on. Oh well another project. Has anyone done this?
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On another note there are a number of Web sites that do have free Manual downloads for old tube testers.
If you come across those drop me a PM and possibly add them to our Links.

Well Well, I am getting a TV-7 this Thursday. Only $250. top and bottom case halves are different colors, wired hinges and cobbled handle. It was seen by my Friend Ernie as being very clean inside and it works! So He will deliver it to Me. I trust Him as He is Experienced and a Fellow Ham.

I think when I get it I will start to test my tubes that are in my HP 606 sig. Gen.
The modulation meter only goes to 40% so it may be in the bridge section.

If I can get that job finished then I will move  back to troubleshooting the B&K tube tester. If I can get that one up and running then I may sell it. (I need the experience of troubleshooting first)

Cliff,
Here is data on the transistor:
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Good source for data on most semis.

Remember the 2n404 is a germanium device too.

To be continued as time permits Me.
I have a question for Those who own the Jackson 747B Tube Tester, with Transistor Q2-2N5818 in place and if your tester is working.

Could you please provide a List your actual working Voltages if Possible?
I do have both the Calibration instructions and the Service manual, but as you know not a lot of Information is provided to overhaul and have all the test point voltages available.

Also please  Identify the ACTUAL location of the Zener Diode on the small Circuit card. Notice that All of the Diodes are set down right on top of the Board so the Identifying Symbol Parts ID is covered over.
I would prefer not to have to Remove each Diode to Identify, because the leads are almost too short. And even the Diagram it self is Shaded out to the point where the numbers are so tiny and smeared they cannot be read at all (only guessed at ).

A follow up on this tester, one member ( FrankB ) here was kind enough to give me a scan of His 747 manual. Well I declare, it looks like there is a change,

The schematic I have been using shows two transistors, one being Q2-2N5818, that is an NPN and its collector goes first to R-31 (15 ohms) followed by diode D-10 (1A 600V) then to the Pilot Light PL-1 LED then to the filament transformer tap 3.3VAC. On the same transistor (Q-1) there is a diode D-11 (1A 600V) connected from the base to the emitter, also a resistor R-30 (1K ohm 3W) that goes to the Circuit Breaker CB-1 connected from that base and diode (D11)

NOTE: Keep this in mind-it is very important to look at the revision number of the schematic.

This particular design number is 488-104-9-001 M Model 747B ( note the B signifies it uses a circuit breaker)
The second Transistor Q-2  is a F.E.T. Part # 2N5458 or equivalent which might also work for the 2N 5456 on the other circuit revision, I will see if I have any transistor manuals that detail the specs. of Each and post here... It is used to control signal (I could be wrong here) but it has the same function in both revisions.
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Now in the next Schematic 488-104-9-001 H also Model 747B ( note the B signifies it uses a circuit breaker).

But Here's the difference (D-10s cathode points toward the 3.3VAC transformer tap) first in line then a 2Volt Lamp (not a LED but a filament type bulb) which is connected to the cathode of a different part number transistor also Identified as Q-2. That transistor number is an PNP 2N404. There is also a diode connected between Q-2s emitter and base but the anode is connected to the base and R-30, which is the same resistance and wattage as the previous resistor mentioned (1 Kohms 3W) the emitter connected to the common return of the filament transformer windings, and of course the resistors end goes back to the circuit breaker CB-1 and other wires. of course both circuit breakers mentioned have on the opposite connection a wire going to the filament Heater) Switch S-5 Note: that switch terminal connection lacks a designation number
So with my original installed transistor it too is even different yet.  

Wow that took some time to explain, I will post both schematics below so you can visualize easier.

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Schematic reading TIP: I finally took the time to trace the transformer windings for Just the Filaments. In that process I noticed that the switch ( S-5 Heater ) tab numbers on the schematic  didn't make sense to start with, it then DAWNED on me the position numbers related to Actual Filament Voltages! That should help, when you need to reference the Schematic.

Very Excellent suggestion. Thanks!

The voltages on your tester are not the same as the TV7,10,etc, but should be close enuf to make a test better than a WAG.

OK thanks, I know that B&K and the Military had made up the same thing to cover older tubes, but unfortunately they are rare and rather costly. I did look at a couple of supplies for ceramic tube bases and each base socket is usually less than $3 each. So if you cant find a cheap Junker tube tester (by the way that is an excellent Idea) then making your own test strip might be the way to go.

The only problem depending on the good tube tester, would be voltages, because some older tubes from what I understand could be several Hundred Volts, so the tester wouldn't be able to use correct Higher voltages like the Military or Hickok brands. You know DC VS AC on the plates and Dynamic VS Static testing.

One tube tester I have always wanted is the TV7 but the TV2 would do in a pinch LOL.
I have seen how many meters the TV2 has and you would need at least 15 minutes to setup each tube before testing. But of course that would be the Rolls Royce of Testers, pssst I under stand over on the other side of the Pond Their preferred tester is the AVO.

I am slowly working through my B&K 747 because of screwy readings and voltages. I am blowing up the schematic so I can read the tiny print and make a color chart of transformer leads and voltages that aren't printed out. The service manual has some. Of course I have already replaced two transistors and that really screwed things up as far as meter readings. So I will check by removing leads on caps to test and replace and resistors too. It's a real challenge.

The old 4,5,6 & 7 pin tubes with 2 large pins. 01A, 26, 57,, etc.

I need some clarification! What is a septal based tube?

I have tried to find a definition on several tube sites and dictionaries, but alas have come up short.

OK, Now you demolished the tube tester to make the test panel for the Septal base tubes,
you have a bunch of junk leftover.

Power cord, transformer, pilot lite, voltage selector switch, etc.

Now leave the selector switch hooked up to the power transformer.
Get a nice chassis box and mount this in the box, putting in a pwr switch, primary fuse, and pilot light. Add some binding posts or banana jacks and you have a nice adj. filament supply for many of those odd voltage TV tubes you wanted to use for something.
NOW-
Make up a bridge rect. and filter assy ( Figure the filter caps for 150VDC) and mount to the output of the fil voltage selector switch using another switch, and adding in a DC voltmeter.
Add output jacks, a bleeder, and you have a nice low current supply, with selectable output voltages.
Good for use as a bias supply, low voltage DC for B+ etc.

OK, so sitting here today and reading the post on making a adaptor panel to test the Septal base tubes- and it hit me!
Its so bloody simple  

Take an old junk tube tester that has the sockets you need in it. A dead one preferred. (You can usually get them at the hamfairs pretty cheap. Many times because the case has fallen apart. Forget the case- just need the front panel sockets to be in good shape.)

Cut out the panel section containing the needed socket types with a hacksaw, and mount to a casing, wood, metal or whatever.

(The sockets will be parallel wired on almost all testers.)

Add an 11 pin plug on the end of the wiring harness feeding the sockets and the plate/grid caps;(Standard relay plug) and make an extension cable for it using an 11 pin relay socket. Off the socket you put on an octal plug, and 2 plate/ grid cap conn to connect to the tube testers P & G caps.

Sounds harder to do than it is.

I have been trying to test some tubes for my newly acquired HP 606 Signal generator. I tested three tubes as a start, and every one was very low. I figured something was wrong with the tester.

So I started to look at the Calibration instructions and ran into a problem when trying to adjust a calibration POT. in the second step.
So my voltage reading was between 37 and 50 volts, whereas it should be around 2.5 volts.

Time to do some investigation. Opened the case and removed the unit, turned over and looked for the obvious burned parts, which I could not find.
That's good. Downloaded the Users Manual, Service manual and schematic.

The parts list is incomplete in that the company noted to look on the schematic for part values.

So checking the parts one by one,   I found that there were some discrepancies. Both Transistor(s) were the wrong part numbers.  

The Q1 is a 2N5456 FET. Which I will remove and test. OH-OH It is a 2N5458 Will have to check that out too! Not even close to the original part Number- I know what happened with that one the printing is so small the numbers could have been mis-read, Its also a  NPN AUDIO TO VHF FREQUENCY DRIVER SWITCH

The Q2 is supposed to be a 2N5818 (Q2 is an NPN Silicon.)
,however, whilst the one in its place is a 2SB370. ( it was a PNP Germanium .)
I did test Q2 but have no definite conclusion as to why it was a replacement. Strange replacement to say the least.

I will post further as things develop and post a few pictures.

Found some info on the web:
from old postings back in 2011 on ARF.
I consolidated them to make for easier reading.
Spell check used to correct most errors.

B&K 747 Tube Tester-Calibration step problem

Author Message
ss1965  I have a B&K 747 tube tester & went to do a calibration following the direction's in the instruction manual for the tube tester.  All adjustments work great except setting the bias voltage. After replacing electrolytic cap's & checking the resistor's & diode's for the bias circuit and transformer voltage and all checking o.k. I have the voltage down to -38 volts from - 44 volts, according to the instruction manual it should be 2.5 volt's!! I am new at doing my own electronics' repair but determined to fix this...
I will appreciate suggestion's on this problem!! Thanks' Steve
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jcmjmp   Make sure that your ground connections are nice and solid around the bias circuit. A lot of the connections to ground on these things aren't the best it seems.
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jcmjmp    Another thing to check out is the actual resistance values. On my tester (707),some of the resistors were out by 20% in some cases. The carbon comp resistors are particularly prone to drift up in value over time.
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ss1965     Thank you! I did not think to check the ground connections because the other adjustment worked o.k.!! but I will check that possibility!!
All the resistor's checked close to value's listed on the schematic..I removed each one from the circuit to test them & real surprised that with the age of them they have been good so far...
I guess maybe best approach would be to actually clean the ground at the first tube socket since that is were the measurement for the bias voltage is taken and go from there...
Once again Thank you for the help!!
Steve
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Alan Douglas   It sure sounds as if the bottom of the voltage divider is open.
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ss1965    Like I mentioned I am just starting to try get into electronics' at least do more than just read about electronics'! Could you give me some idea's how to go about checking voltage divider? I am pretty much learning by doing & asking lot's of question's...so I would appreciate all input... Thanks'!
Steve
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jcmjmp  
Do you have a copy of the schematic?
A voltage divider is basically two resistors in series and voltage is taken between the two, referenced to ground.
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dsbk  
 There is a 470 ohm bias-string resistor on the end of the lever switches that goes open on the 747. Use same of higher wattage rating. B&K went to lower wattage resistors at that time, they don't tolerate setup mistakes and shorts as well.
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ss1965
I do have the schematic for the 747
I will look for the two resistor's for the voltage divider, hopefully I will recognize it?(hee hee)
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ss1965  Thanks' dsbk!
I will locate the resistor and check it!
So far I have checked the resistor's on the p.c. board that is in the bias circuit & they were good! changed the electrolytics on the board plus changed diode 8 and 9 because they each had a spot that visually had sign's they had been hot. Even though they checked good on digital meter??
Steve
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dsbk     Going over that PCB with a iron is mandatory. Many bad connections are found there. Look at everything with a lens.
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ss1965   Hello everyone! I am still working on the 747 tube tester as time permit's.
I have taken every component off the p.c. board and tested all are good! getting 120 volts from the transformer.. schematic say's 110 volt's. checked every solder joint, all resistor's checked with in spec... the variable resistor for the bias adjustment I have had of the board twice and checked with ohm meter & is o.k.!! and have not found any shorts but the bias voltage is still way high! using a variac to make sure I have 110 volt's from a.c. power..I still get 38 volt's at lowest setting from variable bias resistor & calibration instruction's say 2.5 volt's d.c.??
And still all other calibration adjust in just fine!!!
This is driving me NUT'S!!
How important is the bias voltage for correctly testing tube's??
Should I add a resistor from the transformer to get the bias down to the 2.5 volt's??
I will welcome all advice!!
Steve
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Alan Douglas   It's been years since I looked inside my 747, but, there ought to be a string of resistors across the bias source, used as a voltage divider. The resistors may be scattered around various tube sockets, but in the end, they're all in series across the bias supply. There has to be zero volts at one end and full voltage at the other. Find that string, measure the voltages, and you'll find the broken connection or switch contact that's the source of the problem.
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dsbk   The 470 ohm on the end of the switch bank goes open often. Bias makes its way back to common thru the signal ballast.
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ss1965    Thanks' Allen & dsbk!
I have replaced the 470 ohm resistor already from a suggestion to check it from one of the earlier post's...there is a wire directly from transformer soldered to variable bias pot on the p.c. board...unhooking the wire and checking voltage from the transformer is close proper out put voltage...but voltage just high at the first tube socket where it should be low?? I have checked all resistor's on the schematic and every thing on the board there is two wire wound resistor's off the board I am going to check still and that will make every resistor in the unit checked...
I will look for voltage divider again dsbk! if I ever figure this out it will probably be something simple! but hard for a newbie like me!
Thanks' again!! I will be on here & let you know if me or tube tester is winning!
Steve
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ss1965   Sorry
I meant I will check for voltage divider suggestion Allen!! I mixed you and dsbk up!!
Steve
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dsbk    ss1965, are you pressing one of the Test buttons while doing your string voltage measurements?
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ss1965   No instruction's said to put voltage meter between pin's 1 & 7 (pin 7 being ground) and adjust bias voltage to 2.5 volt's dc.. but voltage is 38 volt's at lowest setting on pot....i have not checked switch contacts closely but I will...recheck more component's not to many left to check though :)I've been unhooking about every thing an checking trying to find a bad something to fix this tester.. Steve
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ss1965   sorry last post not complete!! meant pin's 1& 7 at 1st tube socket...
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Retired Radio Man  Try the adjustment with test button 1 depressed as suggested by dsbk. The 707 requires this. There may be a goof in the 747 manual. RRM
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It's worth a try! you could be right pressing the button may have been left out of instruction's... Thanks' for the response &suggestion retired radio man... Steve
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dsbk    "Press test button 1" is an item in the procedure. Does your instruction not say that? It should. Look in the back of your owners' manual. No wonder...
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ss1965   I am sorry but I gave you people wrong information! yes I have pressed test button #1 when I was setting bias voltage...and as I said with pot at lowest point it's at 38 volt's.... I answered totally wrong earlier do not know where my thought's were at!!!!
And I am using original owner's manual following calibration procedure...
Steve
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dsbk     OK, when a "Test" button is pressed it measures like this on a calibrated tester (you won't get print voltages):
Point "Z" white bus -19.5vdc, then thru 2.4K to blue bus -7.5 Vdc, then thru 1K to green bus -2.5vdc, then to ballast .07vdc. on a gray/violet wire. These are print colors, occasionally B&K may have used a different color in the build.
The bias string has its' source of -volts at point "Z" (hi bias) and the - of your 10 mfd bias filter is also tied to that point. The + side of that cap is at the ballast point (lo bias).
When testing, the AC drive signal comes from the ballast, and the ballast acts as the return to common for the dc bias voltage divider. The AC signal level is unaffected by the divider and will be 1.5vac everywhere on the string.
You can use a jumper to connect the lo bias (gray/violet) to chassis, and see if the divider is working to give different -dc levels. Do not push any buttons with jumper in place.
You will occasionally find a no-solder on a socket or switch with these testers. A lens helps.
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ss1965   Thank you so much for detailed explanation dsbk! that help's a lot
I will check what you described...I will be working on it this weekend I hope for the last time!! hee hee!
i have to unhook a diode from the circuit and check it out it show's a voltage both direction's it's by Transistor Q2 (2n404) then I will have checked each component singly...
Then I will follow your direction's...and hopefully cure this thing!!!
Thank you very much for your help!!
I will post later this weekend on if the tester or me is winning the battle....
have a great labor day weekend... Steve
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dsbk   That FET Q1 often goes bad too. NTE457. Good luck.
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ss1965   I have to check voltage's that you posted still..... and I understand your instruction's.... but looking at the schematic (more like staring at it) I am not seeing any of the resistor's in the bias showing where they are going to ground!!the schematic is showing ground at the transformer & following the schematic the only ground shown is at c-6 & c-7 electrolytics, but none of the resistor's from the transformer through the bias circuit to the buss is shown being grounded like a voltage divider...how is bias referenced to ground?
My schematic is the original factory schematic ..but dose not show any grounded resistor's???
Steve
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dsbk   Feed at the high bias end. Return to chassis through the signal ballast at the lo bias end.
The 10mfd filter is across those two points. The string is floating when not making a tube test.
Voltages are divided only when a "Test" button is pushed and the lo end gets connected to the ballast. The same -dc will appear at every point on the divider when a "Test" button is NOT pushed. That is why you can use a jumper to chassis at the lo end, thereby freeing your hands for diagnostics. Don't push a button with the jumper in place.
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Retired Radio Man   The 707 has a 10 meg resistor that is in series with the bias divider. It is part of the gas test circuitry. This resistor is shorted and the low end of the divider connected when a Gm. test button is pressed. The schematic I have for the 747 shows a 3.3 meg and an 18 meg in the same general position. Both of these have to be shorted and the low end connected for the bias to be correct. Open switch contacts in either place will cause the bias to be way off and unadjustable. My schematic doesn't have numbers for the switches but the shorting set is part of the Hi Bias line and the low end set part of the Lo Bias line that goes back to the 1.5 volt signal source. RRM
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dsbk    Thanks RRM, I glossed-over that, and you are right, it may have been a source of confusion.
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ss1965    I have not a chance to check any voltage's to spend any time with the 747 but will since this is a long weekend for me. Following the post you gentlemen have sent( I appreciate your help very much)
1)I need to clip a jumper from the + side of the 10 mfd. cap to chassis for ground. And with out pressing any buttons...have volt meter from chassis ground check voltages at blue buss/ green buss /& at gray / violet wire. And if voltage divider is working voltage's will be at or lower than -7.5 v at blue buss &-2.5 v & .07 v at gray/violet wire...
Am I correct?? I am wanting to make sure I am correct so I do not check voltages incorrectly and mess up 747..worse...
Thank you guy's for help & patience!!
Steve
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dsbk    That sounds right, but as RRM said above, you still have other resistors in circuit that would be jumped-out when using the test button. This is just a fast diagnostic step to see if the divider is working with the jumper.
You may have to look at switch contacts or elsewhere if that test works, and the button test still does not give division.
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mescalero   When evaluating switch contacts, I prefer to do it "live."
This allows me to better determine contact resistance under load. So, instead of powering down and using an Ohm meter, I will put a Volt meter across the contacts, either AC or DC (depending upon circuit properties) and measure the voltage across contacts when the switch is supposed to be opened and closed. Hypothetically, and depending on circuit properties, there should be two dramatically different readings. However, the voltage reading across contacts in the closed state should typically be very, very close to zero.
This works for relay contacts too.
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ss1965    Hello everyone! I wanted to give you an update on my battle with the tube tester..
I have checked the voltage's to see if the voltage divider is working as was described in the earlier post's.
With jump wire from + side of 10 mfd. cap to ground..
-009.5mv at blue buss...(7.5v)
-003.0mv at green buss(2.5v)
-000.0mv at the gray/violet wire (lo bias)(.07v)
I guess I need to follow the gray/violet wire back and see what I can find at other end?
Steve
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dsbk    OK - you are getting close then. You have your meter and the print (and a nice chopstick is always good). If I told you anything wrong you will figure it out.
I'll look at the print again over the weekend if you need more help, or someone else will chime-in.
Good luck, ds
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ss1965    dsbk! You have been a big help!!! plus retired radio guy, and all the other's that have taken time to add a post! I am farther than i was to the source of the problem..
I have all ready replaced to 10 mfd. cap. I had the 470 ohm resistor lose checked both with meter and both were good. The low bias wire gray/violet is attached on the buss where cap & resistor are soldered to it..I resoldered the connection's when I had checked the cap & resistor...so solder joint is o.k. but I am going to have recheck it again....but I must be getting close...( I hope)
I will be looking at it over the weekend...
Steve
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ss1965  Just rechecked the 470 ohm resistor & 10 mfd cap & rehooked jumper to ground still no voltage at the low bias gray/violet wire...the 3.3m R 12 & 18m. R13 resistor's are good...
If I understand schematic there is a green /white wire between the R 12 & R 13 resistor to a closed switch? IF I understood correctly earlier post there should be a switch with closed contact's to make low bias show voltage? Am I correct on this thinking?
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ss1965   P So far the test button contact's are checking O.K. with continuity meter...a few more to check & then I don't know what to come up with?? :?
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ss1965     One more up date! Contact's on test buttons seem o.k. the 3.3meg & 18 meg resistor's are as shown in schematic...I discovered the two #55 light socket's show continuity between the center contact & socket housing with light bulb's removed! to me that is not very good...any opinion's?
Steve
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dsbk    That's OK. Looking at the print you will see the lamps come off a transformer winding through a 10 ohm pot and 16 ohm resistors. If they are glowing with equal brightness and change when you adjust the pot, you can move on. That circuit is always producing the grid drive signal and you should see it at point EE and to your test1 and test2 switches on normally-open contacts.
You are using your dc scale for the bias readings - right?
Concentrate on what should be switched in and out. Make sure the resistor string from D8/C6 to point EE is complete and correct values. If you lift the bk/wt off of point EE, you can read the entire signal string with your ohm meter if the unit is unplugged and you press test1 or test2. This way you can read ohms from -Vdc source to the point EE conductor. Lifting the end off EE will get the return off of chassis so you can see through the string sequentially resistor-by-resistor if need be.
Check D7 for approx. +16vdc. If you still have problems pull the FET Q1 or replace it and measure again bias. A bad FET could be dragging you down.
No time to look at the print right now - I'm having generator madness service calls this month, and glad to get them.
ds
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dsbk    For internet searches I'll post the conclusion here, which the OP put into a new thread.
The problem was Q1. Tester repaired.
ds

I just got my first tube tester I've ever owned. I used to bring my suspect or unknown tubes over to a friends house to use his dad's Mighty Mite, back in the day.
Finally got my own--a Superior Instruments TW-11.

Thanks Alan, That is an Awesome Tester!

Wow, quite amazing thorough stuff here...

I don't get back here as much as I probably should, but when I do there is certainly a mountain of info for me to digest..
Regs to all,
Dave

Thanks for that detailed description.

Cliff,
Making an adaptor strip for the oldies is real ez.

The hard part is finding a good chassis or box to make it on, and for gosh sakes, do NOT use wafer type sockets. They will not last.

(If you want to drive down, I have a full set of chassis punches and a nibbler that would speed up the process.)

Just punch the holes in whatever pattern you wish on the chassis you choose. Be sure to leave space between them for ease of wiring and estethic looks.

Center punch and then either drill out or punch the holes for the sockets. Then mount the sockets.

Add either a pin or banana jack for the grid cap and one for the plate caps. Be sure to color code them so you do not get them mixed up when connecting. If possible find some colored test lead wire for this besides using identically colored jacks and plugs. Make up and color code the pin/ banana plug wires for the grid and plate connectors. You may be able to salvage the plate and grid caps from an old radio & TV chassis or a defunct tube tester.

BE SURE TO USE ACTUAL TEST LEAD WIRE FOR THE GRID & PLATE CAPS. BE SURE THEY HAVE INSULATORS ON THEM.

There can be lethal voltages on them, and this new "wiring insulation" can sometimes break down at quite low voltages. Somes 300V or less. I reccommend using 600V wiring for the cabling and all pin interconnections.

Next, wire up all the sockets with the pins in parallel, by this I mean: Pin 1 to pin 1 on each socket, Pin 2 to pin 2, etc. BE SURE TO COLOR CODE YOUR WIRES! Use the RMA code to make things easier too. This will help keep you from making an "OOPS!" and make trouble shooting and making the connecting cable quite easy.

Go as far with this as is applicable. If you are using the old Septal tube sockets, some will be from 4-7 pins. If you can, find one of the old sockets that used the center for testing pilot lights also. (That feature can be handy ).

Then make a connecting cable from your chassis to the tube tester you are using. You can find an 11 pin socket and plug- Relays still use these sockets and salvage the plug from an old relay or from an old Motorola or GE "coffin case" radio. (You DID save all the parts from those when you scrapped them out 20 yrs back, didn't you?). Mount the 11 pin socket on the side of the adaptor chassis. The tube tester side will use an 8 pin octal plug, either salvaged from a tube or one from a supplier. They still make these plugs, but they can be hard to find. (Try Electronic Resourcing Olympia WA 360-943-1071)

Now I know you will have an extra pin left over on the octal socket and plug, as the most pins on the Septal base sockets is 7. (Septal= 7 Hmmmm.......).
Seriously, this will allow you to wire in a socket for some sort of other tube you might like to test that DOES use all 8 pins on its base.

Then make a wiring harness from the adaptor chassis to the tube tester. Be sure to leave the wiring for the Plate & Grid leads longer than the ones to the octal socket.
Wire one end of the cable up to the 11 pin plug and the other end goes to the 8 pin plug. The other 2 pins will go to connectors that will plug into the grid and plate connectors on the tube tester. Still keeping them color coded is a very good idea.

Plug the 11 pin into the chassis and the 8 pin into the octal socket on the tube tester in and you are ready to test tubes.

WARNING: READ THE USERS MANUAL YOU GOT WITH THE TUBE TESTER. This will generally tell you which lever of button connects to which pin/ element of the tube.

Wait- You don't have the information on which pin to hook up for these tubes, you say?
Well, get a copy of Lud Sibley's TUBE LORE.
It will help you find the equivelant for the old tubes that they list in the tube roll charts, if you do a bit of research. Also spending some time with the old tube manuals can help with this too. After a bit of practice, you should be able to make up your own chart or pin hookups and tube readings.

Basically thats all there is to making the adaptor. You can also make one for the newer tubes for your old tester too. Same procedure, but more difficult on the hookups, as some of the newer ones are 12 Pin compactrons. I have not gotten around to making the newer adaptor setup, but the biggest challange will be finding the connectors and picking which pins to use. You might also have to build a switching setup on the adaptor, or carefully drill out another tube pin hole on the sockets, ala Coletronics style adaptor. Tube data for the newer tubes is much easier to compile, as Tube Lore has the equivalent listings for the sections of the newer tubes referring back to the older types.

This may take a few evenings to build depending on your skill and soldering levels.
If you can't solder well, I'd advise anyone not to try this. The reliability and accuracy of this will depend largely on your soldering skills.

This can be a great opportunity to use up a lot of the stuff in a well stocked junkbox.
(I saved a lot of 600V rated chassis wiring, and do not reccomment using any wiring rated less than 600V in this project.)

Please- if using salvaged tube sockets, take time to look them over carefully.
Check for broken off or damaged/ spread/ loose pins, corrossion, and animal feces/urine /spray on them. Mouse poop/urine and cat urine do not make for a reliable project nor does it smell good- especially when you are soldering.

DO NOT'S:

DO NOT use a "fly cutter" to make the holes. (I have the scars to prove this out )

DO NOT use "wafer type" sockets. They are not real mechanically sound and will tend to fall apart fairly soon.

DO NOT use the so called "liquid solders" to connect the wires. (Yes, I have actually seen this before in equipment that was brought to me for repair).

Disclaimer for anyone contemplating building this project:

I take absolutely no responsibility for anyone building the above described equipment.
Its up to you use safe construction practices and the correct parts and equipment for the job. You are an adult with- presumeably- with common sense and experience. I am NOT your mommie.

very good explanation and visual.

Hi Cliff, anyone is welcome they only have to shout, here is some info on the Mullard High Speed Valve Tester, please see link below....regards....Alan.

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I have no need for the manuals, but you might be a good resource for our forum for them. Thanks!

Hi Cliff, re..I would like to see your testers and the model numbers of the AVOs and Mullard. It would be nice also if you have the instruction manuals.

I have web printed manual for my ancient two panel Avo tester circa 1936-1938. I have manual for the Mullard High Speed Valve Tester. for the 177 again web printed manual. if there is any manual i have that you wish a copy please just shout out. The model numbers for the Avo,s are Avo 40. Avo 7. Avo 8. Avo 40 Admiralty-ex Navy. I will put pics on and manuals which i have.....regards....Alan.

Here is a link showing one of my tube testers, its an American Services unit, from WW2, another lovely piece of working equipment, with cold cathode rectifier, i have a downloaded manual for this tester, here is a link below showing a tester just the same as mine....Regards.....Alan.

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I would like to see your testers and the model numbers of the AVOs and Mullard. It would be nice also if you have the instruction manuals.


I have a Jackson but cannot find a manual, so I went to YouTube and followed and wrote down the instructions that a fellow was using to operate it, I had to repeat the video several times to get the wording correct.

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Hi, i have 4 tube testers, my large home brew, which has served me well, a two panel Avo Tube Tester, a Mullard High Speed Tester, and a lovely 1-177-B made by Supreme Inc, Greenwood Mass. i use the Supreme with a step down Transformer eg 240 volt down to 110 volts, regards.....Alan.

Hi Cliff,

I'll have to look at this site further. I have a TV-7U that needs a bit of help. The momentary push button you press for the tests are dirty I think. When I push down on mine, the meter movement jumps back and forth. Especially when you wiggle the push button around.

Bob

This Web page is in German, but google translates it for you, what is especially interesting is the way to rewind the METER coil.
If you go back there is a large section of different home designed tube testers, I like the one on testing Eye tubes with a pocket tester, self contained.
Click Here

Folks, the Jackson 637 has no info for testing the above tubes.
Does anyone know of a close equivalent that would be listed?
I've found the following info for similarity between EL34 and 6CA7on an Eic0 667 tester, but I reckon there must be a closer tube??
6L6:Plate = 180V                                  6CA7: Plate = 180v
    Screen = 90V                                          Screen = 90v  
    Grid = plus 25V                                       Grid = plus 14v
   "Meter 100" = 45mA                               "Meter 100" = 45mA

I'm scared if I just use the 6L6 setting the overvoltage on the grid will kill the tube..

Thoughts anyone??
DAve

Thx Cliff, tons of handy info there!
I'm suspecting the "obstruction" idea as I was able to get the needle to settle further left by horizontally rotating the whole device back and forward - as the needle swung back left it got a little further each time.
It's not right back to zero, but it's much much closer now.
I tested a heap of tubes this arvo and it seems to be going OK.
BTW, there's only 2 caps inside - see my different topic.
I haven't changed them yet - they both read in spec on my DMM, BUT the replacement 0.1uf is an awful lot smaller than the paper/wax one and I'm deeply suspicious of that. It's about 1/4 the size.
The 1uf is probably a bit over half the size so I'm happier using it.
I'm going to install a pilot light- either LED with a small bridge and resistor, or simply a 110v ac neon - but the latter takes up more real estate and it's crammed inside..
Thx again for the good info,
Cheers from Down Under, DB

Zero Adjusting the Meter
First adjustment is mechanical zeroing. This is normally done while the tester is flat on the bench.
..."Observe the pointer position, then turn the zero adjust screw on the face of the meter until the pointer rests directly over the 0 volts division to the right of the infinity mark on the meter scale. (This is a mechanical adjustment for meter movement zero), use a small screwdriver to adjust the screw first one way then the other to position the pointer to ZERO volts. Rotate the zero adjuster a sufficient amount to introduce mechanical freedom or "PLAY" but insufficient to disturb the position of the indicating pointer. This procedure will avoid disturbances to the Zero setting, by subsequent changes in temperature, humidity, vibration and other environmental conditions."

This previous statement was copied from the Simpson 260 manual, but is a good method to use.
--------------------------------------
Now using the OHM meter function:
Now you would adjust the electrical Zeroing Potentiometer Before each use. An ohm/volt meter operation must be "zero adjusted." This compensates for fluctuations (usually declines) in the internal battery and is in series with the internal battery. If you don't zero adjust, you will get an incorrect reading. To zero adjust a meter, hold the two leads together firmly with one hand and turn the "zero adjust knob" (which is left of the center push buttons labeled ranges),with the other hand until the meter reads exactly zero OHMS. If the leads are touching, the resistance between them should be zero. Now your meter will give a correct reading no matter what the interior battery voltage is. If you can't zero adjust a meter, you need a new battery. Zero adjusting must be done again if you have changed the range or scale controls since the last zero adjustment.

Some meters have mechanical stops so the pointer can only travel within the scale of the meter. These can be adjusted slightly so the pointer can move to both ends of the scales before stopping the pointer.

If the pointer hangs up at any position, this may be caused by metal filings or dust that has found its way into the meter movement.
Can you provide a copy of your schematic?

The only other adjustment is adjusting the line adjustment knob. Use a Voltmeter (not the built in one) to monitor the house line voltage, then turn your tube tester on and let it set for about 10 minutes to warm up the internal tubes and stabilise. Use the line adjust to set the tube tester meter to show the same reading in volts as your external voltmeter.

You should be then set to use your tester. If you cannot get correct readings then you may have to start by replacing filter caps and tubes inside the tester. And checking for dirty switch contacts.


By the way note this, as its of paramount importance.
PLATE: This control adjusts the meter to the proper condition for the tube type to be tested. This knob has been carefully adjusted at the factory – do not loosen set screw.

Hi folks,
finally got the schematic for the Jackson 637 tester.
Long story short: powers, lights 12ax7 filament, but can't get meter movement - it's sitting far left, just off the scale. It flickers 0.5mm-ish on power on-off.
Measures 170ohm (0-500uA and 200ohm specs).
Tried a quick 1.2v battery across terminals- now it works fine BUT,,
it returns left NOT to zero but sits about 1/3 way up the scale.
It reads line control, displays 12ax7 readings seemingly accurately, and the multimeter function displays 9.2vdc of a 9v battery accurately..
but when returning to zero it doesn't drop down to far left, in fact when the battery 9v battery is disconnected the needle drops short of full zero left and stops and slightly bounces as if it's hitting a physical obstruction??

Have I killed it, any ideas as to what I've done and more importantly, solutions??
Many thanks, Dave