Grundig TM819A help needed

[Tedzed1]

Thanks everyone, have got some 0.22 poly caps and suitable resistors, will give that a try, now to find out why I have no sound output or record level, this unit only has four valves, EF804, ECC81, EL42, and a EM71 magic eye, but the EF804 has been substituted with an ECC86, could this be a problem?

[fido]

You should use X2 capacitors if the relays are switching mains:
http://uk.farnell.com/jsp/search/product...KU=9717293

[AlanBeckett]

EF804 is a Pentode. ECC86 is a very special/peculiar Double Triode.
http://www.r-type.org/exhib/aaa0172.htm
Alan

[DODGERN]

From what you report, the HT voltage looks to be O.K. as your magic eye lights up. The fact that you can hear clicks from the speaker may indicate that the amplifier is also working.
It might be an idea to check at the front end to see if the Bias Oscillator is working.

Roger.

[Steve_P]

As has already been stated, that is the wrong valve. It can't possibly ever have worked like that! Put the correct valve in and see what happens! It might even work...

Cheers,

Steve P.

[Tedzed1]

Hello Steve P, the valve socket has been changed at some point, wonder if someone used the deck for spares, as when I got it, it had no belts, possibly stuck the ECC86 in to fill a hole, and as I have not got an EF804, may have to alter the pin-out on the valve base, as I have a few EF86 spare.

[Paula A]

Off the top of my head an EF80 might be a better alternative. or even a 184 (should be stacks of them about.. I built a 24 valve guitar amp with them back in my tv scrapping days) The 804 is just a low noise special quality version of the 80 or 84 (telefunken industrial valve). Generally the EF8x series are completely interchangable in audio applications.. as are the ECC8x series.

http://www.radiomuseum.org/tubes/tube_ef804.html

http://www.radiomuseum.org/tubes/tube_ef80.html

http://www.radiomuseum.org/tubes/tube_ef86.html

Check the pinout.. They ALL differ.. and the wrong one can be bad news.. I just think the 80 would make a better match interelectrode capacitances wise..

Grundig are another company who tended to use "IC" valve base pins as spare tags.. which was fine when only used with the precise replacement. (as in the Wem Westminster vs EL84 from anybody but Mullard

[Tedzed1]

Thanks for the help so far everyone, rewired the valve socket, and now have life, sound is at a good level, but alas have got an incredible hum, it only appears on playback, but not on fast forward or rewind, it will vary with the volume control, but sounds similar to a 50Htz mains hum, at a good volume, the speakers are bouncing, but whatever is on the tape, plays at a decent volume.

[DODGERN]

That's good news.
Looks like it's time to change some more caps Paul.
The audio circuits are probably muted when not in the 'play' position, hence no hum in FF/RW mode.

Roger.

[Tedzed1]

Thanks Roger, got to order some more caps, so will take a few welcome days rest from it, the X2 caps for the relays arrived today, the big smoothing can seems ok, i changed it for two separate equivalents, which made no difference, all the waxies have been replaced, but it has about 7 more electrolytics dotted around the chassis that have not been changed, do you think these could be the cause of the hum?