Tube testers

Cliff,
Some techs would routinely bridge a silicon rectifier across selenium rectifiers as a precaution against future trouble/call backs. You might check all the voltages and see if they look reasonable after you get it going (RCA WT-110A). The change/increase in output voltage can be significant. Some applications might require a series dropping resistor.
73, Rod  WB6FBF

I have done that in the past.
 Just a box with an octal plug to fit the octal socket on a cable, connected to pins 1,2,3,4,5,6,& 7 of the old style septal sockets.
 Specs for the older tubes are often the same as newer ones, just in a different style base.
 IE: 80 is in reality a 5y3. Setup as you would for a 5Y3--- but using the correct pin number settings on the tester. 1 & 4 fil and 2 & 3 plates.  Setting for load and short same as 5Y3. 
 Got sidetracked on my building an adapter to test the foreign ones, with the odd (to us) sockets.

I just Purchased an RCA WT-110a Automatic Tube Tester. Paid close to $150, part of it was $48 just for Shipping.
Opened it up and the meter wouldn't Zero so I adjusted the mechanical zero screw, it didn't work then I tried it again and I could almost get it to zero. so I thought I would tap the meter. Wrong thing to do, now I cannot adjust it so I guess it will have to come apart to see what the problem is. I did test the meter and its working electrically. fortunately Its a 4-1/2" square meter that's 100uA so I should be able to kluge one together using the face-plate if push comes to shove.

Has any one have that Tube tester? If you do, do you have the test card? ( I do have the Master card but not the test card). I haven't seen any info on the test card and I understand its for calibration. I have an inkling that its a blank card. From the comment in the calibration section. Is that right/ Anyone?

I understand that all the pins must be off on the card reader. I could be wrong though.

I have the schematic and parts list but no details on the test card.

I found out the card holes have a matrix of letters on one side and numbers on the adjacent side in which way I'm not sure. Pretty clean but for a little corrosion in the metal parts a tiny bit of internal dust. The corrosion isn't serious and I might get into polishing it out. The cards are quite dirty but there plastic and I tried a little 409 and Alcohol, seemed to help a lot. I think if I'm careful I could use a little plastic polish for a cleaner as long as I stay away from the printed areas.

I will see if I need to change any components due to age. The seller said He did do some but recommended I continue just to make sure I don't have any problems.

This tester looks very well planed as far as design and parts layout, not a jumbled mess of wires and connections.

It has four selenium rectifiers and diodes across them? May just remove the Selenium's
later. It has a Power Transformer and a smaller transformer for just the grid voltages (D.C.)
I am going to enjoy working on this.
Well I guess I'm calling it my time (Today at 2:46 am) to getting some .
_________________________________________
Update. Thursday.
I put the tester on my work bench and opened her back up. The first thing I did was remove the meter. I noticed right off the tiny screws holding the face-plate cover were chewed in the slots. First clue some one had problems. I got my microscope  aimed at the meter movement and noticed a couple of things right off the bat. The fine wires had a coating of corrosion, and the front spring was bent to where the needle couldn't go to zero. The adjustment screw on the face-plate was disengaged from the adjustment lever. The adjustment lever was bent down so the adjustment screw couldn't move the needle. I flattened it and raised it back to a level position. Tried to adjust it but nope didn't work.

Now what to do? I noticed also the front spring was also bent to the point of touching the next loop of the spring. (Definitely was tampered with) I used a pointed skewer stick carefully using the edge of the face-plate to keep my fingers from unnecessary movement. Bent the coil wire back a tiny bit, that seems to help, but not there yet! Now the pointer was sticking, so must have some dirt, I shook the meter and blew puffs of my breath. Still not right so I looked at the needle pointer and it was touching the face-plate. Finally fixed that and went back to the adjustment screw and it still was too far away from the adjustment lever. By poking and prodding I got pointer very close so I finally got the meter to zero when I had the meter at a small upward slant. Blew on the pointer a have free meter movement. So I guess I will use the tester in a small incline position and call it quits for the meter itself. I will stile replace some additional paper caps and test th resistors for value and replace those that are out of tolerance. (There are some 1 per centers). I know have several supplements and schematics and calibration instructions to follow. The only thing is I will have to make a test card. The card system uses a matrix of horizontal letters (A - N) with vertical Numbers (1-9) for hole positions. I do have the data in the supplements.

Now will have to find some card stock along with a punch that has a 5/32" hole and at least a 2 " reach into the card. Then I can make the test card, and write the name TEST CARD.
Then if everything else falls into place, turn it on with a variac and slowly let the voltage increase and don't let the smoke genie out.
Then Calibrate and test some tubes afterwards. I am taking all the tidbits from searching the web and compiling a Word document for ease of reference.

Thanks for the info, Rod.

No. 30 Ohms was used for a single 201-A tube while multiple tubes were usually controlled by 6 Ohm rheostats. 300 Ohms is the usual line test rheostat in most tube testers although some of the EMC testers (200, 204, 206, 206A) used 500 or 600 Ohms.

I am pondering, would a filament rheostat from an early battery radio have enough resistance to replace the line control on a t/t?

I am not sure of their ohmage.

The Hickok and Stark Brand tube testers use anything from 200 ohms to 350 ohms, and there ( they're - their ?) rated all at 25 Watts.  Most of if not all are called Rheostat, Because of the wattage and normally only two terminals are used.

I am understanding that potentiometers are usually 2-1/2 watts or smaller.
And trim-pots are very low current.

Any other views?

I have seen that the 400 ohm value is pretty standard from several makers.
Sometimes it is an adjustable ww slider resistor, and sometimes an adjustable ww hi wattage pot.

As a follow up I thought I would add that R10 is referred to in the Jackson 636 literature as a "400 Ohm adjustable" resistor and not as a "400 Ohm pot" as I called it. Not having seen one I can only guess that it is an inexpensive adjustable resistor of some sort. It was used in the line test meter rectifier circuit. In my 636 it was eliminated and the grid of the type 30 tube is tied directly to pin 4. This is somewhat different from other testers where the plate and grid of the rectifier tube are usually tied together at the tube socket. This is done in the Supreme 504-A using a 71A as a rectifier. The 504-B switched to the octal 6X5 rectifier tube (with pins 3 and 5 tied together) although Supreme was known to supply a 6J5 tube in its place. Either one works fine.

Since my last post, I have received a new Amphenol 7 pin socket for the miniature 7 pin X socket and an Amphenol 9 pin socket for upgrading the Jackson 636. These are the large size sockets for tube testers that mount in place of the two "blanks" that came in my 636 tester. I have got them mounted and wired in according to the instructions furnished in the Jackson literature. I have tested several 7 pin heater-cathode type tubes in the new X socket and are very gratified with the results. At present I don't have any test data for 9 pin tubes but should have some data coming in a week or so from a reprint manual/setup chart for the Jackson 634, 636, and 637 models I just ordered.

73, Rod  WB6FBF

Oh,Yes That's the one I compiled (Took several times to assemble) and uploaded. Notice the long listed settings, you will find this started Here on our forum. That was my first attempt to upload to BAMA.edebris.com/manuals.
I have also uploaded other stuff to a couple of other Electronic manual resources. One thing I do now is make sure to Put a watermark saying this is free, so it wont be sold by money grabbers.

Thank you for the pictures of the Jackson 103/636 models. They were a help in identifying R1 to R10 in the circuit. I found some info including a schematic for the 636 on BAMA. I didn't know they had anything on it. Maybe it is a fairly new listing there. I managed to identify all of the resistors except R10 as my 636 has a factory change in the type 30 rectifier tube circuit that eliminates it (R10: a 400 Ohm pot). The schematic has a listing of all the resistor values although they are a bit hard to read. I eventually figured them all out. R6 is the critical calibration resistor. It is listed as approximately 83K Ohms and is in the plate circuit of the rectifier tube. This resistor is composed of two sections. One is a nominal 70K Ohm 1/2 W axial lead carbon composition type (Violet-Black-Orange). The other section is about 13K Ohms and is wirewound. The wirewound section is wound directly on the carbon composition resistor body and connected in series. Together they make up the 83K Ohms specified. This combo had increased to about 91K Ohms affecting the setting of the proper primary tap (no line rheostat in this model). This was enough of a change to lead to a setting up of an excessively high filament voltage on the tube being tested. I have been aware of this for some time with the 636 but hadn't looked into it. I replaced R6 with a new 82K Ohm 1W film type. The line test now reads in the center of the meter scale with this new resistor in place(with the primary tap adjusted to give 6.3 actual Volts at the tube socket). I used a 6.3V 0.3 Amp load in the octal socket for evaluation purposes (a 6J7 tube). The actual filament voltage delivered to a given tube type will vary somewhat. I don't think it is really that critical in evaluating most tubes. Far as I know, I haven't seen any calibration procedure given in the various tube tester manuals on how to go about setting up and doing a line calibration. Usually they just make some mention of what resistors affect the calibration.

Hope this helps.

73, Rod  WB6FBF

And here is another veiw. Look at the two small resistors on the top right. could be them.[You must be registered and logged in to see this image.]

Heres a PM that Rod Clay sent me.
I felt it was importaint enough for all to see.

Subject:	JACKSON 636 TUBE TESTER Line Test Resistor Replacement	[You must be registered and logged in to see this link.]
Hi Cliff, I saw your posts on tube testers this morning. I have a question about your Jackson model 636 tube tester. What was the value/wattage of the resistor you replaced that affects the line test calibration? Reason I ask is because I have a Jackson 636 here as well  and would like to check on that. I previously replaced the line test calibration resistor (82K Ohm) in a EMC model 206 as well as 3 or 4 related resisters (220K 2W, 75K 1W, 27K 1W) each in the Supreme 504-A, 504-B tube testers I have here.  Rod  WB6FBF

REPLY:
So, since the Jackson 103 is a spitting image of the 636, I will post this picture I found on the web.

[You must be registered and logged in to see this image.]

Look at the resistor underneath the two power resistors. (note the ink pen pointing to it) I think it was way out of tolerance. I believe its one of the resistors in the meter balance bridge. So measure that and see. If its not try the other resistors in the bridge circuit.

This link is no longer recognized.



Heres a link for the Jackson 115 --->    Manual and Schematic of Jackson 115 Tube Tester PDF

On the old Cramolin package I have, (80's vintage) it says that if you can see it on the contacts, you used too much.
 They made a Cramolin Red and Gold in spray cans.
The Red & Blue were in bottles- back in the 80's- Came as a set.

  Edit: I was told the Gold contained gold, which is why it was about 10 bux more than the red.

I always applied CRAMOLIN with a toothpick, one difference is most rotary switches in military, has either gold or silver, gold was used mainly in circuit card connectors, and a lot of electronics plugs. But if the plugs were for power, then silver was the mainstay.

Gold had a threefold use, good conductivity, corrosion resistance, and because of its malibility ( or softness ) it was a a good lubricant between metal sliding contacts.

There were, or still are different colors of CRAMOLIN. One was specifically for gold, another for silver, I knew of two, red and green. I even have a butane size spray container, called gold mist, it is specifically for computer circuit card connector edges.

If you apply too much CRAMOLIN you can use a q-tip swab to absorb the excess, and it will still leave a microscopic film that is sufficient for applications. Then you can use the same swab for applying to other switches and contacts.

Remember- EASY on the Cramolin. Too much causes problems.

Tarnish can also be removed with a stick type typewriter eraser, or a "Pink Pearl" eraser- gently!

 For the really adventurous, an ultrasonic cleaner works well, with Dawn brand dish detergent. DO NOT use the Harbor Freight  ultrasonic cleaner cleaner on anything aluminum.

More than happy to act as a sidewalk superintendent. 
The best way to clean the switches, without washing is use a squirt bottle with isopropyl 90% and an acid brush, then dowse again. This time rotate each switch in turn and observe each finger to make sure you can see the contacts each move up and down. This will indicate the switch fingers have positive mechanical contact. 

Also note the spacing in between each set of finger contacts. All must either touch each other or have the same non-contact space between each. If so then it has to be less than the thickness of the rotating center contacts. 

If you find a contact that is having intermittent operation, make sure it doesn't have a loose rivet on the finger. Also do a continuity check on the fingers and wires to final destination point.

Next do a visual inspection to find cracks on electrical contacts and the center rings. If the rings have a black tarnish, that's OK, as silver tarnish is still a good conductor, I personally would burnish that away, just to see if there were hidden faults.

A q-tip will be an acceptable method, as it cleans, it picks up tarnish residue, that will itself aid the burnishing process. Silver cleaner liquid such as Tarnex is a good choice if you want to go fast. However it is important to thoroughly rinse and flush the wafers because of the salts in the cleaner.

I would use CRAMOLIN for all fingers and contact rings. The fingers will add the CRAMOLIN to fingers on the rotating fingers.

Another burnisher would be toothpicks or a strip of copy paper used as a belt between each set of fingers, or take the strip of paper and roll it into cone, and use the tip of cone to burnish.

The wafers themselves must also be inspected for mechanical faults.

The same things must be done to the push button switches.

I have a TV-7U that needs the contacts cleaned on the push buttons. It probably needs more too. Been a while since I used it. Gonna have to ask around locally to see if anyone works on these.

I'll be keeping tabs on how you're doing. Maybe there are a few things I might be able to do myself here. Be prepared to be bugged with a few questions if I do.

I finally printed the PDF files for the TV-7. Friend and member FrankB said if he can, he will swing up to my place, and help get my TV-7 up and running. Not that it doesn't work, but the voltages I measured, we're not in specs.

I have printed each file, and they have both sides of the page printed on. That sure makes a difference in the size of the manuals. Now I am going make side notes for referencing parts location and tests needed that are either missing, or never mentioned in the manuals. 

I am also going to make a parts list of each component, and will look up by mil spec each tolerance. These are not listed in the manuals part list, except by military designated numbers, and stock number.

The first thing to do is remove the tester from the case, then get the proper meter for testing each voltage. It has to be a 1Kohm per/volt meter, to load the circuit(s) properly. Then get the proper test resistors as required for calibration.

I now have the following manuals to help.
Folder # 1
A.  TM11-5083 (T016-35TV7-6)
B.  TB 11-6625-274-12/1 (changes No. 1 May 31,1962) (original also dated Jan 17,1962)
Folder # 2
C.  TM 11-6625-274-12 (14 June,1960)
D.  TM 11-6625-274-35 (30 June,1960) (Field and Depot Maintenance Manual)
(Air Force - T.O. 33AA21-5-32 changed of 15 March, 1962)
E.  TM 11-6625-274-24P (Nov. 1979)

One of the problems, with most Digital Meters is that they cannot measure a combined voltage.
What I'm trying to say is you can have a D.C. Voltage and an A.C. Voltage on the same circuit.

Using a V.T.V.M. You have a probe that you can measure both component voltages separately.

One of the things I would suspect first off is either something is dragging the voltage down, such as a capacitor going bad, or a bad resistor. Next thing is to make sure there are no crossed wires, or miswiring. I would start at the source, THE TRANSFORMER voltages. Make sure they are correct and not under load. When you take other voltages they must be taken according to the manual with all switches in the number 1 position, have you done that?

Make yourself a voltage chart of the transformer taps, and put down expected vs. actual. Then do the same for listed test points.
Look and make sure someone hasn't miswired the switches, tube pins, even the push buttons.
The voltages must be taken without any button pressed. ( from the manual)

Well I hope you had a wonderful Thanksgiving..
Anyway...I received the resistors and installed them....and no change.
Observations: Variac set to 117Vac (verified with Fluke)/ Test socket in Pos 1 connected pins 1 to Pos, Pin2 to Neg/ Pressed TEST1 required is 1.5Vac /  received is 1.15Vac.
Cleaned R20 (10 Ohm pot) Pot tested (center to end leg) 10.2 High and .1 low; the other end tested 10.4 high and .1 low.
Power supply lead on the pot tested: (connected to pot) 6.3Vac / 9.4Vac (desoldered/isolated) these are with no Variac...direct wall voltage.
Could the pot value be too high (10 ohms)

I did note that there is a difference in the TV-7/U vs TV-7D.

The R134 is TIED TO TERMINAL 37 of T101 a 40K value, and it can be adjusted, 
And in series with that is R124
the older versions were 245K, the newer D model is 225K.
The 117VAC feeds those two resistors in series then goes to 2 resistors R123 and R125, this is the start of the meter bridge. The meter is tied to the bottom of those resistors then connected to CR101. Those two diodes makeup CR101, and finish the circuit back to terminal 19 of secondary 117VAC
That looks like the area I will concentrate on first.

On the Jackson, the center socket is a 5 pin, used for early photo tubes in projection equipment.

Cliff,
 I have started that project, except I need it for European "oddball" types (Like Rimlock) and such.
Still trying to find all the sockets I need, before I start the panel layout.

The older tubes should be pretty easy. Just wire all the appropriate pins in series.
I think I'd use an octal plug (An octal base from a 6 or 12 SN7 works great. It has all 8 pins) to connect to the main tester with. A separate conn. for grid and plate pins, switched so it can be connected to the appropriate pin connection, mounted on the panel. A couple of rotary 7 position S.P. switches should do it. Maybe remove the end stop to make it easier too.
I'd make the grid & plate caps connect to the panel switches via banana plugs and jacks, of different colors.

Something wasn't right on my testing tubes on the TV-7/D.
I finally got the manuals as PDF files from on line. The 12, 24,  35, plus the tube settings to where I can read them.

One of my Ham buddy's loaned me a nice large D.C. 1Kohm per volt meter.
I started to test per printed instructions, and found all the readings were low enough to be out of tolerance. Testing the filaments, all low, testing the B+ Low, testing the bias, low, so I will now have to start looking for problems.

I suspect one of three issues, internal tubes need to be replaced, bad CR 101, or R124, is out of tolerance. I suspect the last item, it's a 275Kohm 1W resistor that is feeding the bridge meter circuit.
I will also test the transformer voltages and resistances.

Most meter circuits are actually a bridge circuit with the meter setup electrically in the center. The bridge is designed to be in balance at the start, so when a voltage is applied from a circuit, such as the plate, it unbalances the bridge circuit and that is then displace on the meter. It is a little different than a simple volt meter.

That would be great!

I really appreciate the advice....
I'll update as soon as the resistors arrive
Thanks again, Have a great week

Soldering the bulbs in place is a waste of time, the only reason to do that is for field use, where there is a lot of jostling and banging the tester around a lot.

The neons need to be the exact # type, because of break over voltage requirements.
Only use the Fuke for required VTVM Measurements. Use your analog Triplett for all the othe measurements, because of its recognized load on the circuits. Think of it this way, it was set up to be used by radio repairers, that had limited test equipment resources.

The design Engineers took this into consideration, so if they were called for troubleshooting questions, they would have a common base within which to start with ( in effect a standard on which they could depend on).
That way when the voltages were not in specification, at least they knew the meter wasn't drawing too much or too little current ( IR DROP)

Also: I installed a neon into the test socket...not sure how 'smart' that is i.e. how critical that bulb is.
The bulb was sold as a replacement for that. 
I have been using the Fluke but if it is more advisable I still have several chrono Tripplets that work fine if they are better suited....pls let me know.
Tom