I'm going to reassemble it for now and enjoy for a while.
I've recapped the powerboard with some cheap caps at first to try and figure out the problem.
I'll be ordering some decent replacement caps, new zeners,1N4148's, maybe recap the preamp and EQ too in the near future.
This whole adventure...
IT'S ALIVE
Oh man this is great! No more protection problems.
Thank you this is really amazing.
SO stupid I didn't check the resistors well enough @kevzep
Thank you so much @Hyperion for taking a look.
I'm quite happy right now :)
My wife's going to be disappointed the big sansui SP3500...
Haha this is stupid.
You're right. they are 330 ohm.
I'm quite ashamed not seeing this.
Not sure about the R47. I didn't change them and the schematic says 2.2 ohm.
I wil solder them out and check again.
So.
I've measured the voltages again this morning after the last reply.
+ and - 50,8v supply
Zenerdiodes
Left channel
ZD01 21,82v
ZD02 -23,16v
Right channel
ZD01 22,45v
ZD02 -23,09v
They changed a little. Didn't do anything to it :-/
Right and left:
I used the diode test on my multimeter for the VD1212. As I said I'm not a skilled technician so everytime I suspect a component I search the web how to check it.
Before I started ressurecting this amp I hardly knew anything about transistors and diodes. I only knew how to follow schematics...
Yes. Output resistors R44 and R45 have been replaced together wit the output transistors.
I've checked every resistor on the boards (maybe even four times :)) and replaced everything that seemed dodgy.
Do you think the difference in voltage at the zenerdiodes could activate protection circuit?
I really would like to get this fixed. I really like the sound through the sansui SP3500 speakers.
Don't know how to quote so I'll @ for reply :)
@slimecity : the problem occurs in both channels
@Hyperion : The fuse resistors seem to be changed already, they look like ordinary brown colored...
Thanks for the reply.
I bridged the switch and even tried the poweramp with a different preamp. It still goes in protection with speakers.
I can't find the cause of why it works with headphones but not with speakers. 64 ohm <-> 8 ohm.
Hi,
I'm from Belgium. I've been reading through this forum for a while trying to revive my sansui AU-517.
I've already found some great tips here but now it seems I'm stuck.
The amp was given to me a few years ago, including a sansui turntable and sansui speakers.
I worked great for a few...