Bottlehead Forum

Bottlehead Kits => Eros Phono => Topic started by: Jeroen on April 28, 2018, 11:16:48 PM

Title: Right channel dead [resolved]
Post by: Jeroen on April 28, 2018, 11:16:48 PM

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
 

Title: Re: Right channel dead
Post by: Paul Birkeland on April 29, 2018, 03:56:59 AM

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

Title: Re: Right channel dead
Post by: Jeroen on April 29, 2018, 06:42:37 AM

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?

Title: Re: Right channel dead
Post by: Paul Birkeland on April 29, 2018, 07:06:30 AM

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.

Title: Re: Right channel dead
Post by: Jeroen on May 10, 2018, 10:52:24 PM

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