Hello all,
I have a Technics SE-A70 that I'm restoring. I have restored several other pieces, however this is the first piece that I'm having trouble with. I'm learning as I go.
The issues:
The amp was working(ok) but the main caps were leaking. So I did a complete recap. During the reassembly I somehow didn't install a mica insulator for one of the output transistor... This of course caused major problems. What I have done so far to fix it:
Parts replaced:
TH302
TH301
R364
R363
Q501
Q503
Q338
Q502
Q337
Q328-Q326(paired)
Q325-Q327(paired)
The following were all paired:
Q333
Q329
Q335
Q331
Q334
Q336
Q330
Q332
After all those parts were install I used my DBT to power the amp on. Shortly after power on the R364 resistor burned out again... So I have obviously missed something but what is the question? Any help/ideas on were to look will be greatly appreciated.
I have circled the resistor in the pic(pic was prior to recapping).
I have a Technics SE-A70 that I'm restoring. I have restored several other pieces, however this is the first piece that I'm having trouble with. I'm learning as I go.
The issues:
The amp was working(ok) but the main caps were leaking. So I did a complete recap. During the reassembly I somehow didn't install a mica insulator for one of the output transistor... This of course caused major problems. What I have done so far to fix it:
Parts replaced:
TH302
TH301
R364
R363
Q501
Q503
Q338
Q502
Q337
Q328-Q326(paired)
Q325-Q327(paired)
The following were all paired:
Q333
Q329
Q335
Q331
Q334
Q336
Q330
Q332
After all those parts were install I used my DBT to power the amp on. Shortly after power on the R364 resistor burned out again... So I have obviously missed something but what is the question? Any help/ideas on were to look will be greatly appreciated.
I have circled the resistor in the pic(pic was prior to recapping).
Attachments
Last edited:
These didn't come in often, not to say never. I'll have a look at the ServMan tomorrow (print-n-gluejob).
On which one was the mica omitted? Saves considerable time.
Fair enough you admit the blunder, welcome to the club!
On which one was the mica omitted? Saves considerable time.
Fair enough you admit the blunder, welcome to the club!
Further thoughts, an earlier issue on this forum.
Check on the pre drive pcb:
Q318-320, Q322-324, C312-314, R342-344, R350
On the output pcb:
C804-806
In general check all voltages across the circuit as indicated in the ServMan.
Check on the pre drive pcb:
Q318-320, Q322-324, C312-314, R342-344, R350
On the output pcb:
C804-806
In general check all voltages across the circuit as indicated in the ServMan.
Thanks for the additional info. Probably won't have to to work on it until this weekend. I will post the results once I have checked everything.