EMUD T7 Radio

Why am I getting clues that the poor radio is the victim of an outright "shotgun" approach to restoration?

After a couple of chassis one may "think" that this technique is valid for what ever radio/phono that comes along.

Clipping and replacing caps in the antenna, RF and oscillator section is a surefire way to disaster and a plea for help.

GL if this radio survives, in the log run evaluate carefully and avoid changes to those mentioned circuits until the radio is tested for faults. Then, use stage isolation techniques and signal injection to determine what passive part has changed value...

YMMV

Chas

I just viewed the new pictures. That looks like an antenna coil for a particular band (VHF) and mode (FM). Check the resistors too because there may have been lightening damage going on there at some point. The coil looks good though. Not uncommon on a radio left attached to an antenna especially back East where I used to live. When a storm was coming up I would go around and disconnect everything if I had time.

73, Rod  WB6FBF

That is unusual for a ceramic to crack, so I would go through that section and do some testing for possible over voltage, bearing in mind they usually crack from that, Or too much stress with the leads having no give due to heat stress and no room to expand or contract. I did notice the very short leads, which maybe of necessity due to frequency. Too long and would affect the circuit but the connections could develop thermal stress, create a cold solder joint then require a larger voltage to compensate. (I'm just rambling on now, so I'll quit)
However, it could be just a common old age breakdown too.

Cliff,
When I checked out the C8 more closely I found the disc to be almost split in half, so out it goes. Thanks for the info on the other parts.

Yes (mmfd) or pF

The crud on c8 would be an indication of a short? I don't think the corrosion is that but wax or flux. But I cannot know since its not in front of me. So test it out of circuit for being good or not.

I did research on the replacement suggestion part numbers c-6 and came up with 2 different voltages, Centralab TCZ-25 of 600v and Sprague 10TCC-Q25 of 1000v, go with 1000v to be on the safe side.

You will notice in the notes whether a capacitor should read in MFD or mmfd if its ceramic. Just to help, If you need verification,  You should look up the part [You must be registered and logged in to see this link.] to compare values, material and voltage along with tolerance online.

Guys--need your comments on the condition of this little board that has the radio dipole antenna leads connected to it. The schematic shows this order from left to right. R6-180 ohms, C8-1500, C7-6, R5-15 ohms, C6-25. I believe the capacitors are pf??  You can see quite a bit of crude on the C8. This will be a major PITA to work [You must be registered and logged in to see this link.] given the tight working quarters. All pics are the same with slight angle and lighting changes. Thanks.

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

Cliff, just got your post--thanks for the information. You and Rod have been a tremendous help with this project.

Thanks Rod--that info is a big help. I have worked on USA and Japanese radios and this is my first German unit. I will post more questions if I get into a bind(most likely)! Thanks again.

Hi,
I was beginning to think that your radio might be German when Cliff said the electrolytic filter cap looked foreign made.  I couldn't think of a (3) section stud mount cap that I had ever seen in a radio made here in the USA. They were usually (1) or (2) section far as I know. Thanks for the clarification. EMUD is a new one to me. I was thinking maybe Grundig or Nordmende.

Those small value clear plastic film caps are probably ok and don't need to be changed. They began to replace mica caps in the 1960s in frequency sensitive areas like the front end (tuner) of receivers and such.

That one plastic cap could be .001uF (1000pF) @ 500V or maybe 100pF @ 500V somewhat hard to tell from the picture.

The ones marked 1.61 @ 125V could be film caps rated 1.61uF @ 125V and probably are ok. You could check them out with an EICO or some other cap checker.

I agree on the small 200pF axial lead cap-it looks German made-probably is still ok too. Hard to read the maker's name on it. German has some different characters from ours.

The large cap above the small clear foil plastic cap could be a film cap too-again it can be checked out with an EICO, etc. checker.

As for the other medium sized dark brown cap with the bulging, separated end near the small 200pF cap-it looks like a paper cap and should be replaced.

Hope this helps.

73, Rod  WB6FBF

It's tougher to resolve parts identification when there not USA products. Although a small fraction made it over here.
Its a dilemma sometimes unless we work on them. However there are foreign Radio Clubs you might seek help from, one of the biggest is Radiomuseum.org

Paper Capacitor on the left (C61?) .02 500V ?

on the right. (C62) SPRAGUE 200 pf 1000V  10% 200pf 1000V ceramic disc capacitor: 10TST20


Tantalum Capacitor? .02 500V?

Same picture

125V- 1.61 mmfd? Since it has a partial line that  probably indicates the outer foil (it usually goes to ground to shield from noise or hum)

This may help A Sam's Photofact link.
  Click Here

I'm giving up because the time is getting late. Try and focus a little bit more , but with you having the chassis in front of you That's better than a camera that doesn't show chassis fully

Hi Guys,

Looking at replacing the caps in my EMUD (German) radio Model T7--circa 1958. I have attached some pics of strange looking 'caps'-some have values on them, others don't. The schematic is vague on some of these. There a a few brown/beige pieces with squiggly brown lines that I can find no info written on them. I have red arrows in the pics to show you the part in question.  Thanks for the help.[You must be registered and logged in to see this image.]