Juanbanzai
Active Member
Good morning.
I'm in the process of recapping my 2245 - taking one board at a time - and I've run across an issue I want to ask the experts about. This unit was in really sad shape when I got it, but it WAS working. The power switch needed to be replaced before any additional rebuilding could be done, and of course, the pots and switches needed to be cleaned as well. The only odd thing I noticed - which lead me to believe the unit was NOT working, was the protection relay took almost 10 seconds or more to close.
I replaced all the caps on P800 in addition to H808, a C945 NPN transistor, which was swapped with a C1845. The original Omron relay was replaced as well. When I was satisfied that everything was replaced correctly, I powered the unit up. Immediately, the relay closed. I got sound out of the amp, but according to the service manual, there's supposed to be a 3-5 second delay on the closing of the relay.
Thinking that the C1845 might have been the problem for the quick relay, I swapped it back with the original C945 which I tested as still being good. When the unit was powered back up, again the relay closed immediately, then opened back up. No further testing was done until I started checking all the components on the board.
I found that H809 and H810 were bad... which would explain a lot since the protection circuit is based on those three transistors. I'm curious why the protection circuit worked in the first place, albeit not according to spec. I probably should have checked all three of the transistors at the start, but H808 was included in the rebuild kit I purchased and I was following the component replacement recommendations of the kit.
I'm waiting on replacement C1213 transistors for H809 and H810 so no further work will continue until they arrive. But I'm wondering if there's anything I should be looking at specifically as to why H809 and H810 failed but H808 is still intact.
Thanks for any assistance.
Aaron
I'm in the process of recapping my 2245 - taking one board at a time - and I've run across an issue I want to ask the experts about. This unit was in really sad shape when I got it, but it WAS working. The power switch needed to be replaced before any additional rebuilding could be done, and of course, the pots and switches needed to be cleaned as well. The only odd thing I noticed - which lead me to believe the unit was NOT working, was the protection relay took almost 10 seconds or more to close.
I replaced all the caps on P800 in addition to H808, a C945 NPN transistor, which was swapped with a C1845. The original Omron relay was replaced as well. When I was satisfied that everything was replaced correctly, I powered the unit up. Immediately, the relay closed. I got sound out of the amp, but according to the service manual, there's supposed to be a 3-5 second delay on the closing of the relay.
Thinking that the C1845 might have been the problem for the quick relay, I swapped it back with the original C945 which I tested as still being good. When the unit was powered back up, again the relay closed immediately, then opened back up. No further testing was done until I started checking all the components on the board.
I found that H809 and H810 were bad... which would explain a lot since the protection circuit is based on those three transistors. I'm curious why the protection circuit worked in the first place, albeit not according to spec. I probably should have checked all three of the transistors at the start, but H808 was included in the rebuild kit I purchased and I was following the component replacement recommendations of the kit.
I'm waiting on replacement C1213 transistors for H809 and H810 so no further work will continue until they arrive. But I'm wondering if there's anything I should be looking at specifically as to why H809 and H810 failed but H808 is still intact.
Thanks for any assistance.
Aaron
