Sansui AU-719 F3098 Board Voltage problem

[Hyperion]

Hi John, It may very well be an open R14. (Also look at my post above re the voltage readings, might be a cracked trace??)

Yes, it has to be something like that - as the voltage readings are so peculiar. It did cross my mind about the power dissipation of R24 (or R16) - but I didn't think any more about it.

 

[Assil]

T

So, maybe we are looking at an open R14 (10Ω) on F-3094 ?

Hi
I have checked R14. It is ok

 

[Assil]

Hi,

Re the voltages that you have measured, can you please confirm the following.

Point G is effectively the base of TR04, and measured 20V initially, and lowers to 13,5V
Point H is the junction of R20, C14 and C16 and measured 0V.
Point F is effectively the base of TR06, and measured 27.7V.

Note that if I am reading the diagram you posted correctly, point H and point F are connected and should be at the same voltage.

Also, the voltage across R 24 looks like it is approx 57.4V, that would result in R24 dissipating approx 0.33W, - it would be getting rather hot, not smoking hot but "burning finger" hot.

my replies

1. Yes G is the base voltage of TR04 measured 20v initially and while maintaining the multimeter it will gradually decrease to 13v approx..
2. No unfortunately it’s a mistake. H reads 27.7V sorry.
3. No F is the collector of TR06. It should have read 0.5V and is now reading 27.7V
4.As strange as it appears .. the multimeter reads 57.4,volts but R24 does not get hots.
The fact of this is confusing since R24 correctly reads 68K

 

[skippy124]

Hi,

Re point 3 in your post above, that was my mistake, I should have stated the collector of TR06.

Can you confirm that R24 (and R23 on the other channel) is 68K - schematic shows R24 ( and R23) are 10K.

 

[Assil]

Hi,

Re point 3 in your post above, that was my mistake, I should have stated the collector of TR06.

Can you confirm that R24 (and R23 on the other channel) is 68K - schematic shows R24 ( and R23) are 10K.

Hi
Sorry for the mistake R24 is 10k and not 68k
Yes R23=R24=10K
R15=R16=68K
Please refer to the photos