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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 1:27 am 
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Do pay attention to the situation. That set is very unlikely to have had polarised filter capacitors: That's why there are no polarities.

Now! This is one of those PSU circuits that for some reason causes issues and should not. The field according to the pdf presented and in both circuits: Is in the "negative" rail. Therefore, if polarised filter caps are use. Both of the positives will be common on B+. One negative goes to the centre tap and the other ground.

I would half expect them to be in one big can with perhaps three wires, and there is a big can. One wire for B+ and two for negatives. There is a diagram showing OP transformer on speaker (very common). Therefore there will be positive going to it via the speaker plug and provided the original wiring has not been tampered with. It is therefore not unreasonable for the common positive of the PSU filters to be connected to that speaker plug terminal, along with a 0.25 mfd cap in another block.

What appears in the schematic as a linear flow, as noted allover the forum, does not represent physically the layout of the "rats nest" that results from it. The layout diagram / drawing does. If unsure you trace from it, albeit that one could be a little better.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 1:30 am 
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Is the 8 uF electrolytic an old, original cap or have you replaced some caps already?

Sorry if this has been covered, but I didn't really want to go back through the last 11 pages of this thread.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 1:33 am 
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Both new caps.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 1:40 am 
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So that would mean negative would go to speaker plug and positive to b plus?


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 1:59 am 
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spsquires wrote:
So that would mean negative would go to speaker plug and positive to b plus?


The schematic shows the negative side of the 8 uF cap connected to ground. One of the speaker connections is also connected to ground. So if that is the one you connect the negative side of the cap to, then that is correct.

The schematic also shows the positive side of the cap connected to The cathode of the rectifier, which is B+. This is correct as well.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 4:19 am 
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10uF goes from cathode (filament of #80) (positive) to the transformer HT centre tap (negative). 8uF also goes from cathode but to ground (chassis). As the field is in negative it goes from centre tap via the speaker plug & returns to ground also via the speaker plug.

With a push pull output I would expect pins to carry ... 1 wire for earth; 1 wire for positive; 2 wires for plates and 1 wire for the floating negative from the centre tap.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 7:47 am 
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In an exchange of PMs, we found the problem:
The schematic shows 2 filters: 10uF and 8uF. Buried in the prose in the service manual, they tell us that the 10uF is implemented with an 8 and a 2 in parallel. They don't tell us WHY this was done.....

There is a huge lesson here:
If you can't find a part on the schematic, then start by finding all the other parts**. This process would have revealed the 2 caps in parallel to get the 10uF shown on the schematic.

**In reality, you would not need to look for every part---Looking where the 10uF was supposed to be, and tracing a few wires, you would discover the 8uF and 2uF caps

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 8:53 am 
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Thanks everyone for your help. I will post later today how it works when I have the electrolytics figured out. But one question since I smoked my last 10 mfd cap and have nothing smaller in high voltage , could I use a 15 mfd 450volt cap?Also i found a used 10 mfd cap and clipped it in the way it should be and now I have no sound at all but all tubes did light up. What damage may I have done by putting positive lead on ground of speaker plug and ground on ground ? Remember I did smoke the cap.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 1:38 pm 
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The highest voltage constantly applied is to the first filter cap and the highest voltage applied to all of "B" is during start up, where in some, sets that can reach almost double the the B+ when the set is running.

Due to failures. I will not run modern caps below 500V (normally 600V) on a 5Y3 / #80, nor Silicon Diodes: Where "B" is 250V. Because of that start up voltage surge and experience: I will say no. Secondly one of the primary causes of new filter caps punching through, or their contents appearing on the outside, often with audible accompaniment, is over voltage. If the cap is B+ to CT, not reversed and there is no load. This is the provenance for me saying no! Use 600V

I did mention that I suspected the filters were liable to be hiding in the big tin can.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 2:34 pm 
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I clipped in 15 MFD cap to cathode of tube 80 pin 1 and negative to speaker plug and get no sound at all but when negative to chassis ground I get a little noise in speaker but touching grid of any tube and get no response.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 2:45 pm 
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Have you confirmed you have B+ voltage at the plate of all tube sockets? All tubes lit and getting filament A.C. voltage?

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 2:50 pm 
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All tubes are lite but have not checked plate voltage yet. Can I do that with tube removed since not much room in bottom of chassis?


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:03 pm 
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"negative to speaker plug"----that is totally ambiguous. You really need to focus on giving unambiguous descriptions of things.

look at the schematic-- For the first filter, the - goes to the HV center-tap. For the second filter, the - goes to chassis ground. The field coil connects between those 2 points. Do you see all of this?? If not, we need to figure out why....

Here's what you need to do to get this set running:
1. Wire it to match the schematic---in the process, plug any gaps in your understanding of how to read schematics.**
2. Bring it up on a Variac or equivalent and verify that the overall voltages and currents are reasonable.
3. Troubleshoot one stage at a time. I prefer starting at the audio output, but do whatever works for you

Again: PLEASE--no more ambiguous descriptions

Answer to an earlier question: The value of the first filter is typically specified on the rectifier data sheet. for a type 80, I think it's around 20 to 30uF. The second filter can be as large as it needs to be.

**As part of this process, read things like my recent thread (linked earlier) and ask questions whereever you don't understand something.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:04 pm 
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spsquires wrote:
All tubes are lite but have not checked plate voltage yet. Can I do that with tube removed since not much room in bottom of chassis?

Tubes should ideally be in the socket.
If the concern is shorting something while poking around, you can power down, attach a clip lead to the plate terminal of the tube and power back up to make the measurement.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:09 pm 
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There is no plate voltage at all with doing one tube out of socket at a time . The only voltage I found was filament and negative 84dcv on both tube 45 grid.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:10 pm 
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spsquires wrote:
All tubes are lite but have not checked plate voltage yet. Can I do that with tube removed since not much room in bottom of chassis?

Plate voltages have no meaning if the tube is removed. You certainly can check the overall B+ level with all tubes pulled (except the rectifier), but it only tells you that a few components are OK.

My method: Watch the B+ during controlled startup and verify that it is reasonable. As soon as the tubes star conducting (maybe around 50 to 70% of input power), check the overall current--and any individual tube currents you can.

Check overall current by measuring the drop across the field coil. Tube currents can be checked wherever there is a DC resistance in series with plate, screen, or cathode

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:12 pm 
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spsquires wrote:
There is no plate voltage at all with doing one tube out of socket at a time . The only voltage I found was filament and negative 84dcv on both tube 45 grid.

No DC voltage on either side of the field coil??

Go back a re-read the last few posts---there are some overlapping conversations. I'm signing off now, so that will help.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:44 pm 
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I just figured out that problem . When I put the IF can back in I pushed down on a resistor and it shorted out. I took the can out and straightened up the resistor and the radio played. Now to figure out what to do to fix it and do other cap block.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 3:52 pm 
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spsquires wrote:
I just figured out that problem . When I put the IF can back in I pushed down on a resistor and it shorted out. I took the can out and straightened up the resistor and the radio played. Now to figure out what to do to fix it and do other cap block.


Ok, that might mean progress.

Maybe you can explain WHICH IF can (1st IF transformer,? 2nd If transformer?) and WHICH resistor (value? connected to what node?) so the rest of us can follow your progress.

Being able to describe to others what you are doing is a key part of helping others to help you.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 4:20 pm 
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It was the 14300 brown and white resistor between cathode of tube 80 and screen grid of tube 235 IF . Also does bypass cap 4423 caps all go to chassis ground?


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