I'll test all caps around the crimescene and begin to order parts.
Thanks a lot for all the advice. I learned a lot and it's been fun to follow the process.
It might take some time for the parts to arrive here on the Island but i 'll let you know how it went after soldering.
Happy Easter everyone!
Thanks a lot for all the advice. I learned a lot and it's been fun to follow the process.
It might take some time for the parts to arrive here on the Island but i 'll let you know how it went after soldering.
Happy Easter everyone!
Offcourse
Last week i finally received the rest of the parts I order ed. One has to be patient here😄 next week i am starting to solder. Here's hoping it will succeed ☺️
Last week i finally received the rest of the parts I order ed. One has to be patient here😄 next week i am starting to solder. Here's hoping it will succeed ☺️
Allas!
Well, finally the update.
After 6 weeks of waiting I received the rest of the parts I orderered.
I replaced the transistors Tr 409 and Tr 410 (pnp 2sa663y and the npn 2sc793y) with pnp mj21193g and npn mj21194g.
I also replaced the 3,3 ohm resistor R418 which was phisically broken.
I am sorry to say that this did n't solve the problem. When i turn on the power switch the relay kicks in immediately, no noise from the speakers.
Well, finally the update.
After 6 weeks of waiting I received the rest of the parts I orderered.
I replaced the transistors Tr 409 and Tr 410 (pnp 2sa663y and the npn 2sc793y) with pnp mj21193g and npn mj21194g.
I also replaced the 3,3 ohm resistor R418 which was phisically broken.
I am sorry to say that this did n't solve the problem. When i turn on the power switch the relay kicks in immediately, no noise from the speakers.
Quick update
I replaced the transistors 408 409 410 with
MJE253G MJ21194G MJ21193G
I replaced the 3,3 ohm resistor R 418 which wad phisically broken.
The result is that the speaker relay doesn't engage anymore but still no sound. I guess I'll start checking the caps and resistors on the board again.
Any thoughts would be highly appreciated!
I replaced the transistors 408 409 410 with
MJE253G MJ21194G MJ21193G
I replaced the 3,3 ohm resistor R 418 which wad phisically broken.
The result is that the speaker relay doesn't engage anymore but still no sound. I guess I'll start checking the caps and resistors on the board again.
Any thoughts would be highly appreciated!
Hi, how is that possible, the transistors i replaced are compatible with the original ones I think
Hi, the SU-3500 is a good amp. here's a little suggestion.
Study the schematic thoroughly.
Don't do it in a hurry, take it easy.
Check for bad joints, sometimes it looks good but actually a bad connection.
For your SU-3500:
1) check tp0 to ground for continuity.
2) check tp1 to ground , around -40v.
3) check tp2 to ground , around +40v
disconnect pre out and main in ( there will be no sound signal to the main amp).
input cd signal to the aux input, (make sure the selector is right selected)
check the pre out with multimeter with AC mV range.
turn the volumn up and down, if you can read output AC volt then the preamp is OK.
Power amp part
check F2, F3 for continuity, and it should 0v to ground or around a few mv.
check the metal case of the output transistors to ground should be around +-37.5v.
you can check the voltages according to the schematic.
take it with great care, one short circuit means disaster.
Study the schematic thoroughly.
Don't do it in a hurry, take it easy.
Check for bad joints, sometimes it looks good but actually a bad connection.
For your SU-3500:
1) check tp0 to ground for continuity.
2) check tp1 to ground , around -40v.
3) check tp2 to ground , around +40v
disconnect pre out and main in ( there will be no sound signal to the main amp).
input cd signal to the aux input, (make sure the selector is right selected)
check the pre out with multimeter with AC mV range.
turn the volumn up and down, if you can read output AC volt then the preamp is OK.
Power amp part
check F2, F3 for continuity, and it should 0v to ground or around a few mv.
check the metal case of the output transistors to ground should be around +-37.5v.
you can check the voltages according to the schematic.
take it with great care, one short circuit means disaster.
A little more from one of our members
A good visual check is always good first.
Dry joints, unsoldered joints, bad connectors, dodgy pots, bad relay etc.
Bad zeners, old caps.
A good visual check is always good first.
Dry joints, unsoldered joints, bad connectors, dodgy pots, bad relay etc.
Bad zeners, old caps.