Right channel dead [resolved]

[Jeroen]

Hi Guys,

After years of duty lately the right channel of my Eros died. It seems the EF 86 doesn't get (enough) power.

I checked all wires and resolderd them, but no luck.

The LED's of the C4s right board are lid, here are the measurements of both channels;

Right channel                                      Left channel
Kreg; 0,05 V                                        Kreg; 1,43 V
Breg; 143 V                                                ; 97 V
OA; 148 V                                                  ; 169 V
IA; 221 V                                                  ; 221 V
OB; 144 V                                                  ; 95 V

I tried to check the transistors as Dan Smalle explained in an earlier topic. They seemed to be ok, but I am not absolutely sure.

Does anyone has an suggestion where to look for?

Thanks for reply's in advance,

Jeroen

 

[Paul Birkeland]

Is the EF86 on that side still glowing?  How about swapping the EF86s from side to side?

 

[Jeroen]

Hi Paul,

I changed tubes, but that didn't matter. I think the EF86 doesn't get (enough) power, it doesn't get warm.

Do you think the C4s board works normal according to the measurments I did?

 

[Paul Birkeland]

If the EF86 isn't glowing, then the shielded twisted pair of wires going to pins 4 and 5 may not be well connected at either end.  An EF86 that doesn't glow won't conduct, and your numbers look like the EF86 isn't really conducting. 

Looking closely at the heaters of the EF86 on that side to be sure they are glowing is the next step in debugging.

 

[Jeroen]

Problem solved.

A couple of pins of the EF86 weren't making contact with the contacts in the socket. I didn't thought this was possible as de pins are gold plated and have a thight fit in the socket.

Enjoying stereo sound again