Sony TA-E86B Fault

reddish75

Member
2006-08-31 9:57 am
I've come across a fault with my Ta-e86b where as at low volumes the right channel looses all low frequency and the channel goes out of phase with the left channel, pic of the scope traces attached, when the volume is turned up say 5db it corrects itself in volume and almost in phase, the fault? comes into play at volume control out.
 

Attachments

  • DS1Z_QuickPrint1.png
    DS1Z_QuickPrint1.png
    20.1 KB · Views: 63
  • Sony ta-e86 flat amp.png
    Sony ta-e86 flat amp.png
    281.4 KB · Views: 65
Last edited:

llwhtt

Member
2008-06-12 3:43 am
SoCal
The series connection, + to +, is a way to make a Bipolar capacitor. Did you use Bipolar capacitors? The Series/Parallel connection makes for a 10uF Bipolar cap. So the caps were replaced and the problem is still there?

The output relays can cause amplitude problems but not phase problems I wouldn't think.

What is the style of 2SC458? Outhouse looking? Those are on the "shoot on sight" list.
 
Ok, so measuring dc voltage and relating to the schematic in the flat amp it all seems to be correct apart from the collector of Q302 which is 25v not 12.5 which I'm sure is an error. The -10v that is on output one NOT output 2 on the left channel is only evident on the R401 side of the new film capacitor that has been installed. The voltage seems to be coming from the relay side of R506 probing around this area seemed to correct this back down to essentially 0v dc, strange, could the reed relay be intermittently conducting? I don't see how this voltage can appear on the output?
 

Attachments

  • sony 86b output - boost amp.png
    sony 86b output - boost amp.png
    335.1 KB · Views: 33
  • sony 86b relay drive.png
    sony 86b relay drive.png
    213.6 KB · Views: 32
It seems to be ok? The gate when the channels faulty is 10vdc, when not its essentially 0vdv, drain is 29vdc and source is ~0.48v, apart from the 10vdc fault this is the same in both channels I take it this is ok?

Q402 collector is ~0.3vdc and Q403 emitter is ~0.2vdc this is the same in both channels, not sure what to make of this?