Zenith Model 6-S-128 repairs

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Hello members!!  I bought my first fixer upper and it plays with a loud hum so I figured I would start to recap it beginning with the wet electrolytic capacitor. I was hoping someone could explain to me how to replace these two 10-10 mfd 450V electrolytic capacitors.  The original 16 mfd 450V wet electrolytic capacitor was left in place for aesthetics but the wires were cut and replaced with one or both of these Mallorys by somebody else. I have a 16 mfd 450V axial Ecap to replace it with.  If anybody could help me with understanding this I would really appreciate it. Also, in the schematic, if you could point out the wires that I labeled in the photo it would really help me to better read and understand the schematic.  Thanks to anyone willing to help!!!!
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75W / 120V = I
Use 120 that's the normal line voltage now.
I + 10% overload =

.6875A round up to .75A

Since it's a tubed power supply go for slow blow fuse 250V rating

Fantastic Cliff.  I think I'll do the fuse and wait on the X2 and Y2.  How many amps do you think Cliff? Current consumption is 75 watts.  
75 watts/112 line volts =.6 amps
.6 amps X 135% overload = .9 amps.  So would a 1 amp fuse work?

1. It's a question of priorities, if you have a lot of spikes or power outages, or fluctuating voltage, then yes.

2. I would definitely insert a fuse and holder for any transformer powered set. Better than looking
For a replacement transformer.

Radios need protection in both cases, and if you put being safe, that's  good insurance in guareenting long life for you collection, and if you sell that's a plus to the buyers.

OK got it!!! I have two other questions for you Cliff.  1) Should I install X2 and Y2 safety capacitors?
2) Should I place a fuse on one of the hot leads heading into the transformer?

Yes yup, take the two negatives and twist togather and use a sleeve to cover the bare wire than solder to the center lug. Then use sleeves over the (+) leads and solder to connections as per schematic.

Thanks again Cliff for all of your help!!!  Any feedback on how to tie the two different Ecaps together would be greatly appreciated.  I have a 2 uF axial and an 8 uF axial and just the two lead wires to work with. Should they be side by side so that the negative and positive leads of each cap tie together?

Yes  The connections that you described all exist. Positive to R4-R9 and Negative to Tab 2. Hopefully this makes more sense.
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The old cap with two wires doesn't make sense. I could see 3 wires (2 being positive and one wire negative, being the negatives being tied togather internally then tied to the external negative wire on the cap, because it would go to the center lug which is the negative)

The caps you are going to use must have smaller cap ( 2 mfd ) wired to the (+) lead that connects the lead between R-4 and R-9. And it's negative lead to the center lug of that lug strip where you put the negative wire from tab 2.

The larger cap ( 8 mfd ) also has its negative lead to the same center lug as the smaller cap. However it's ( + ) lead goes to tab ( 6 ). Directly or through another wire.   ( there are so many wires that it would be hard to detail all the tie points, R-7, speaker field on the left side of schematic, the primary of the audio output transformer and more.) 
But that should set things straight as far as the cap wiring.

You should check all resistors, and replace all paper caps, the mica caps should stay normally.

OK the 8-2 dual cap is going to be replaced by an 8 and a 2 tied together.  There was only two wires in the old cap.The dark one (black) comes from Tab 2 Candohm and the light one comes from the Power tube which I've labeled. Is this correct?
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Where's your dual caps? C25? 2mfd and 8 mfd?

Thanks so much again Cliff.  Ok I think I have it as you've described. How does it look?
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(((Rather than call the candohm position 1 or position 2, redefine as tabs, as there are 6 tabs and 5 resistors in the candohm. )))) 
Makes it easier if connections are designated by numbers.

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The tie point for both  C-25, 10 mfd. (?). By the way, in my riders, one value of C25 is (2) two mfd. that should have its positive lead connected between R4 & R9. Usually the first cap is smaller in value.


That Cap(s) (negative ) leads should connect at the middle lug as your top picture shows -where the twisted bare wires on that one cap were. Just to make it easier!






Along with the negative lead from the candohm. Which should be the lug on the candohm 250 ohm and 56-ohm common lead. Tab 2



The other C-25 value is 8 mfd. ( the 10 mfd is ok for only this side being Up to +/- 20 to 50% tolerance )

The 16 mfd. cap + connection goes between R9 and speaker field coil. The negative lead goes to the rectifier hi voltage transformer center tap wire. 
............

So ( Tab 1 ) is what the HV rectifier center-tap and C 21 ( - ) negative lead should be wired to.
The pictures help but I cannot see each surrounding wire in focus and its exact connection.  Therefore these more detailed instructions should help. I had to refer to my manuals to see the clearer schematic. 
So first tab then 250 ohm then 2nd tab then 56 ohm, then 3rd tab, etc.
Hope this helps you.

Thanks again Cliff!!  So these two pictures show my next step. I've removed both Ecaps and labeled the wiring correctly based on my understanding of what you've told me.  I haven't soldered anything yet.   Does this look correct to you?
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Check polarities, and use a dim bulb tester to be safe.

Thank you Cliff!!!

The hanging metal clip (grounding collar) goes to the connection for the negative twisted wires that have no connection.

C21 (+ ) wire goes between R9 and field coil
And C25 (+)goes between R 9 and R 4.

Hello members!!  I bought my first fixer upper and it plays with a loud hum so I figured I would start to recap it beginning with the wet electrolytic capacitor. I was hoping someone could explain to me how to replace these two 10-10 mfd 450V electrolytic capacitors.  The original 16 mfd 450V wet electrolytic capacitor was left in place for aesthetics but the wires were cut and replaced with one or both of these Mallorys by somebody else. I have a 16 mfd 450V axial Ecap to replace it with.  If anybody could help me with understanding this I would really appreciate it. Also, in the schematic, if you could point out the wires that I labeled in the photo it would really help me to better read and understand the schematic.  Thanks to anyone willing to help!!!!
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