Arne-Tom
New Member
I`m currently working on a Pioneer m-90 which belongs to a friend. It was in need of a complete service and also from time to time the left channel makes cracking noises. Sometimes it works fine for an hour, sometimes the cracking noise appears right after startup. It's only for one or two seconds and then it works fine again.
Here's what happened so far:
- replaced all electrolytics
- reflowed every single solder joint (they were looking awful)
- cleaned the 4 big relais
- took apart all switches etc and cleaned/polished the contacts
- cleaned off thermal paste and applied fresh paste
- cleaned off the brown goo
- tried triggering the cracking noise with ice spray...no success
- tried triggering the noise by carefully "knocking" the components with a wooden stick...nothing
- checked all the purple 11E2 diodes with a dca55...all are reading fine, checked the diodes between the main caps...all fine
When turning the amp on it takes unusually long for it to switch from protect to "ok"...about 25 seconds.
Since the cracking noise only appears for such a short time it's almost impossible to locate...at least for me it is.
Any help is appreciated!
Thank you!!
Arne
Here's what happened so far:
- replaced all electrolytics
- reflowed every single solder joint (they were looking awful)
- cleaned the 4 big relais
- took apart all switches etc and cleaned/polished the contacts
- cleaned off thermal paste and applied fresh paste
- cleaned off the brown goo
- tried triggering the cracking noise with ice spray...no success
- tried triggering the noise by carefully "knocking" the components with a wooden stick...nothing
- checked all the purple 11E2 diodes with a dca55...all are reading fine, checked the diodes between the main caps...all fine
When turning the amp on it takes unusually long for it to switch from protect to "ok"...about 25 seconds.
Since the cracking noise only appears for such a short time it's almost impossible to locate...at least for me it is.
Any help is appreciated!
Thank you!!
Arne