Dampfradioforum

hi everyone
I have repair a grundig K2musiktruhe(same machine with 1070).I hope , you will help me. the radio now playing but not perfect.I have replaced all paper capacitor, but there are 280VDC on pin 9 in EABC80 tube.

Hi,

At first i'll place the Schematic:

https://nvhrbiblio.nl/schema/Grundig_1070.pdf

Pin 9 is the Anode of the Triode System and they should be around 70V

You should measure the Resistors R30 and R31, These two Resistors are conected to the Anode of the EABC80 and going to Aode Voltage. I think during the Change you have bridget them (Maybe soldered a capacitor to the wrong connector).
They should have a Resistance around 440k Ohms.

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

hi,I measumend thats resistors and 220K resistance, just now

Both of them 220k?

To be honest, i'm not sure if the R30 is a 220K, because in the schematic stands 220A, but that could be a Print mistake. can you look which Value is printed on the Resistor?

Can you measure the Voltage directly behind the Rectifier and on Pin 9 of the EL84? At the Rectifier there should be 280V and on the G2 from the EL84 I think around 270V

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

the rectifier(+) is 295VDC
EL84 pin 9 is 274VDC

That sounds ok

But that means, that the Resistors don't have Resistance, because you have the same Voltage at both sides of the Resistors . Pin 9 EL84 is on Anode Voltage like the Resistors to Pin 9 of EABC80.

Please measure the Resistance between this two Points (pin 9 EL to pin 9 EABC)

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

0.46M ohm between pin9 EL84 to pin9 EABC80

Okay, that's weird…

Try to disconnect the Capacitor from Pin 9 EABC and measure the Voltage again, Maybe measure the Voltage of the Resistors.

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

is it 10 nano farad

Yes, just dissolder this capacitor and make sure it wont get Connection to enything else while the Radio is on. Then Measure the Voltage again.

I don't think this would be the Problem, but you never know. Often the Problems are just so simpel that you search Hours at the wrong Point.

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

I disconnected 10 nanof cap. and measuremend voltage on pin9 (eabc80) 265VDC

ok and there is Nothing else connected then the resistors?

can you measure the voltage from the other side of the resistors? This than this should be 274V like on pin 9 of he EL84

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

other side of resistors???

Yeah, you have measured at the Pin9 of the EABC, there is 265V. Now pleas measure the Voltage at the other end of the resistors, there should be 274V

_________________
Wer sich nicht schonmal am Lötkolben verbrannt hat, der hat noch nie richtig gelötet.

it is 272VDC