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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Mon 04, 2019 3:30 am 
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Per the schematic linked to above, the 200uF capacitor is attached to the same node* as pin 7 of the IF 1U4 and pin 1 of the 3V4.

It is physically located in the same can as three other electrolytic filter capacitors. I checked the rating again, it's actually only rated at 10V if it is original. If you look at its position on the schematic, you will note that if it shorts, it will mean that the entire filament voltage is put across only the 3V4 filament, which would burn it out. I would double check filament continuity on the 3V4, because it has two sections and if one burns out it can still pass an emissions test in a tube tester, but will not work in this radio.

*An electrical node means that it is electrically connected to the same potential, as in it may not be connected directly to one of these pins, but could be connected to a terminal strip near by via a wire, If it is connected through a resistor or capacitor it would not be part of the same node.

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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Mon 04, 2019 3:33 am 
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radiocom wrote:
Where does the 200uf cap connect? B- to .....? this doesnt have a 200 cap.

There is 20uf cap from B- to pin 3 of the 3v4 but I dont think that should be there

Both of these capacitors are on the schematic/parts list. They may have been replaced/misplaced by the previous owner; or slight mistake in tracing the connections. Take your time in sorting this out.

If they are individual capacitors, then they're probably replacements (originals are inside the quad capacitor can).


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Mon 04, 2019 4:38 am 
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I do appreciate everyone's patience and help on this.
I'm not sure though if the 200uf C1D connect to pin 7 of v5 or pin 1 of v3 or does it matter?


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Mon 04, 2019 5:07 am 
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radiocom wrote:
I do appreciate everyone's patience and help on this.
I'm not sure though if the 200uf C1D connect to pin 7 of v5 or pin 1 of v3 or does it matter?

It can connect to pin 7 of V3 or pin 1 of v5. It's all one electrical node.


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Mon 11, 2019 12:53 pm 
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This 6R40 chassis is finally up and running.

Very difficult to align especially the upper bands because the tone was heard at a different position and couldn't move it to where it should be and the tone was verified with a frequency counter.

Main problem is the volume is really low even at full volume. Is this in the 3V4 stage?


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 11:48 am 
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If anyone can help.
The volume on this 6R40 is really low. I peaked the IF 455 to the loudest and put in a new 3V4 but max volume is as if you just turned it on.
Also cleaned the volume pot and switches.

Where should I start?


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 12:24 pm 
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Have you checked DC voltages (supply, and plates of the tubes) after all the fixes?

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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 12:44 pm 
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I will start there and check voltages again.
If not tonite it will be early tomorrow morn.
Thank you.


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 1:08 pm 
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You can bring some of the knowledge gained from your other Zenith and use them here. Things to check (see diagram):

- Plate voltages of each tube (pin 2 of each tube) "blue circle."
- Receck filament string voltage. Place negative lead to B-. One check should give you some clue: pin 7 of 3V4 (8.0V) "blue arrow."
- Check each stage (red arrows): touch 3V4 grid (hear a sound), inject audio signal to volume control, inject 455khz signal into both IF filters and 1L6 (pin 6). Work from right to left. At one of those points, the signal level will drop

Unlike your other radio, this one may actually need paper capacitors replaced. No easy way to tell


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Zenith 2.jpg
Zenith 2.jpg [ 24.28 KiB | Viewed 66 times ]


Last edited by AJJ on Mar Fri 15, 2019 1:15 pm, edited 2 times in total.
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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 1:13 pm 
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paper caps are not replaced yet??---do that first.

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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 1:30 pm 
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Couldn't wait. Voltages on average are 10% high.
Pins 2 and 3. Eg; what should be 95 is 100-101 what should be 85 is 90-92.

There was only 1 paper cap that I replaced unless you are considering the bumblebee bees as paper.


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 1:55 pm 
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paper in oil, maybe? Do some searches here, and I think you will find that most people replace these.

My rule: If I don't know what it is, it gets replaced. (I do NOT do this with tuned circuits---see how it works first)

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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 4:22 pm 
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radiocom wrote:
Couldn't wait. Voltages on average are 10% high.
Pins 2 and 3. Eg; what should be 95 is 100-101 what should be 85 is 90-92.

There was only 1 paper cap that I replaced unless you are considering the bumblebee bees as paper.

10% or even 15% off from the schematic value is fine.

"Bumblebee" capacitors are paper. It just looks different because of the outer casing. The way many old paper capacitors deteriorate is that moisture in air gets in there causing them to be leaky. "Bumblee" capacitors are not different because the seal is not completely tight.

One may get lucky sometimes where the radio circuit is robust enough that it can tolerate some "not-so-bad" capacitors; or the radio was stored in a very dry place. With luck, a radio could come back to life by just replacing one or two random paper capacitor; in some other cases it won't play until all are replaced. You can't tell, even with resistance/voltage measurements. Even if radio may still be sort of working, it won't be 100% unless bad old capacitors are out of there.

From: https://www.radiomuseum.org/forum/repla ... itors.html


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Sams Zenith 600 series.jpg
Sams Zenith 600 series.jpg [ 48.94 KiB | Viewed 53 times ]
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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 5:20 pm 
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Thanks AJJ ..... Does anyone know of a set of replacement caps available? a set with all the values?

Looking at the parts list there are 38 caps to replace.

I would imagine that someone has put a kit together. Hayseed has a kit but doesn't seem to have enough.
Or, I'll just have to go through the list


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 5:40 pm 
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Also, capacitor suggestions. metal film, poly, ceramic or does it matter?


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 5:46 pm 
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Not all the capacitors, just the paper ones; larger tubular ones. For the "bumblebees," you would need to spend a little time to read the color code.

I think there are about 15; I don't have this radio, so you would have to do an actual inventory yourself, or someone here has a list. There's a diagram and parts list in Sam's service data.

Most people get their capacitors from Sal's, Digikey, Mouser, JustRadio... Sal is a forum member here, so he might be able to answer some specific questions.

Any modern capacitor type would do. Most of us use film type. Exact color/shape doesn't matter. Some folks prefer larger yellow ones with longer leads, others like the small one. Just make sure each has sufficient voltage rating (if you get something like 630V rating for all of them, then it's good and you won't have to worry).

Because C39 is on AC power cord; C40 connects between power and chassis; get that special type that's marked "X2" for C39 and "Y2" for C40. Value of C40 can be lower (like 0.01 or 0.015mfd). Both are for lowering power line noise (if there's any); radio should work ok even if they're removed.

Here's a screen shot. Don't trust my highlighting, do a physical inventory.


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Last edited by AJJ on Mar Fri 15, 2019 7:38 pm, edited 11 times in total.
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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 5:49 pm 
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See these threads here about replacing capacitors:

viewtopic.php?f=6&t=348497
viewtopic.php?f=6&t=354840


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 6:00 pm 
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Reinforcing....
Any film cap is fine.....I go to Sal's or JustRadios and buy the cheapest---or occasionally the smallest.

JustRadios used to make up kits for specific radios, but I don't think they still do it.

If you're going to do more than one radio, go to one of the above and buy an assortment (they call it a "kit", but it's generic.)

For just one radio, Sal will have the lowest shipping and no minimum order.

Don't bother with the mica or ceramic caps unless a problem shows up. The "problem types"--in order of badness:
1. electrolytics
2. anything with paper in it
3. occasional mica or ceramic (I think there's a certain type of Zenith ceramic that is "replace on sight"
4. relatively rare---an older film cap--eg in some German sets.

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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 6:26 pm 
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In case you haven't found it yet, this might be helpful:

https://antiqueradio.org/recap.htm


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 Post subject: Re: Transoceanic R600 6r40 Rectifier and 50a1
PostPosted: Mar Fri 15, 2019 8:26 pm 
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Thanks AJJ.... I was trying to place an order at Sal's ( tuberadios.com ) but email returned not deliverable.

capacitors@tuberadios.com


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