emud: Emud Rekord Senior 60 - I'm lost!

Hi there! This forum is always so helpful and I'm hoping someone can help me again!

Fiftenn years ago I restored an Emud Rekord Senior 60....lovely radio, really sounds wonderful with classical music especially. Full recap, retube (several had shorts), replaced out of spec resistors, etc. About 5 years ago it bit the dust and as I was moving/getting married/had a kid in those last 5 years, I've not had a chance to look at it since. So taking some time to resurrect it now.

When it died... I just turned it on, while warming up there was a bright pulsing flash & pop just behind the glass near the volume pot. I course I immediately turned it off and didn't power it on again until I started working at it recently. I've done necessary switch cleaning, etc. I found one resistor (R38 I believe) had blown in the area behind the volume pot. I replaced that.

The radio will power (lamps and tubes light), but no sound whatsoever. The only inkling of sound I get is a very faint "pop" when switching bands. I did take some measurements on B+ voltages, both high...at V7 (EZ80) checking about 380v instead of 280v, and at V5 (EL84) checking 380v instead of 270v. I've poured over the connections looking for shorts. Aside from liffting resistors, I'm lost on what this could be. Anyone have an idea where I can start? Thank you!

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Hello Mr. Phelps,

I looked at the scheme and I think it's important to know which resistor exactly you changed and which value you used - I'm in doubt with "R38" because there is only little powr to expect there.

If the anode voltage is that high it means there is no current flowing, so I would expect R37 (150 ohms) or R39 ( 1k) went dead. You could check the anode voltage of the other tubes: if there is any it will be R37 if not ot will be R39...

Unfortunately - if it is R39 you have to check also C56 (we call that an "Aü-Killer" because if it has a short the output tranformer can be destroyed) - so hopefully that didn't happen. After the repair I would recommend to connect C56 not to ground but to the output transformer where R39 enters - just because imho nowadays it's cheaper to loose a tube or a resistor and not the transformer if the capacitor goes bad ...

Good luck and regards,

D. Consales

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Regarding C56, it can be a good idea to connect a flame proof resistor of a few kohms in series with it, then the resistor will burn and get open circuit in case of a short in the capacitor. Note that the DC working voltage of this capacitor has to be at least twice the radio's B+ voltage. Y2-approved safety capacitors are also safe to use in this position even if they are just marked with 275 VAC.

Check if the output tube is drawing current by measuring the voltage drop across its cathode resistor R37.  It could also be interesting to measure the heater voltage to see if it is 6.3 VAC as it should or if even that voltage is too high.

And, just to avoid drawing any false conclusions, make sure that your multimeter is within calibration. Many digital multimeters have a tendency to give too high readings when the battery is running out, in some cases even before the low battery symbol is lit.

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Hallo Mr. Forsman,

that would be an option - but also changes it's function whilst the connection to the output transformer has not influence on it's function. For audio frequences it doesn't matter if you go to gnd or to the transformer.

Kind regards,

D.Consales

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Thank you gentlemen for your fast responses! As you can see, I don't have much time to work at this as I have a young family. I did take some time this afternoon and look into your suggestions.

Mr. Cosales, I did infact replace R38 as it was blown out with a 100k Ohm 1/2w resistor. Obviously that's not the culprit.  I did tested the plate of EL84 (showing around 380v) and EABC80 (~28v), which led me to R37 as you suggested. I clipped a leg and it's testing 208ohm so obviously out of tolerance. I'm going to order a replacement and try that, but before I do...would a 1w or 2w be suitable for that replacement? The old one is rather large so I'm speculating it's a 2w but hard to tell.

In my original recap of the radio I had already replaced C56 with an orange drop. Would you still recommend it's replacement?

Thank you gentlemen!!

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I would use a 2W resistor although 1W would also be sufficient. The power at the resistor is about 0,3 watts - but it has to handle that the whole time. so a physically bigger resistor is better imho ...

Regarding C56: not replacing but rewiring, connecting it to the output transformer (where R39 is connected) rather than to gnd.

Regards,

D. Consales

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Hello again gentlemen!

No luck thus far, I replaced R37 and no change. Still nothing, pilot lamps will glow, tubes heaters light, but no functionality. Also no function on magic eye tube. I still get faint pop when switching bands, so the amplifier portion is at least somewhat working. I tried connecting a record player to the phono & tape inputs, and did get very faint signal/sound with that. I'd never tried those inputs before so I have no benchmark to test against.

I'm suspecting C55 maybe the problem (circled in green in photo). I stumbled on this one that I missed in the original recap, and it looks like it may have some electrolytic at the anode end. Thoughts?

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C55 shorts R37 for audio frequency. If its capacity is too low the gain is low(er). But that would not explain the high anode voltage. Also if it where short there would be no negative g1 - so current would be high (and anode voltage low). Did you check the g2 voltage at the EL84 ? Is the EL84 OK ?

Otherwise I have no more ideas now ...

Regards,

D. Consales

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