blast from left channel when powering off

[dan]

never mind. it was just a coincidence. just gonna live with it for now. if i ever find a solution, i will post it for anyone else.

 

[Hajidub]

never mind. it was just a coincidence. just gonna live with it for now. if i ever find a solution, i will post it for anyone else.

Recap it yourself, or send it off to someone for repair. Simple soldering skills will bring this back to life!

 

[dan]

figured it out. the hum on ac and the left channel blast on dc. i noticed tapping on the unit would induce the hum on ac. took the back off, with a bic pen, i started tapping around everywhere. i noticed tapping on the main PCB around the the power amps would cause the hum. i narrowed it down to the area and then i simply touched the solder points with the pic pen. pin 18 on the left power amp is the culprit. causes hum on both channels even with the volume all the way down while on ac and causes the left channel blast while on dc. all you gotta do is touch it with the finest touch with a plastic pen which rules out other solder joints.

 

[hopey]

Good pickup. It must have been due to the lower voltage on DC and voltage drop across the amp pin versus the higher voltage on AC.

How many people replace caps and fix the problem but it was never the caps in the first place.?

 

[Superduper]

Are you saying you "fixed" it, or are you saying you think you found the problem because you hear a hum when you touch one of the amp chip leads?

 

[dan]

Are you saying you "fixed" it, or are you saying you think you found the problem because you hear a hum when you touch one of the amp chip leads?

pretty sure i fixed it. it was a bad solder joint. no more blast or hum. any vibration or flex in the board in that area would start the hum. pressing down on that joint would stop the hum because it would close the gap. putting sideways force on the lead from the chip would open the gap and start the hum. i repeated it over and over.

 

[Fatdog]

 

[dan]

i know. it also cured some minor left channel hum i had on the phono input when i turned up the volume all the way with nothing playing.

 

[docs]

Glad you fixed it, thanks for sharing the fix.

 

[ralrein1]

Nice job finding the problem. Frequently persistence pays off. Now its time to celebrate, crank it up!!!

 

[Transistorized]

Made my day.

Dan...I'd be rockin' that thing for the rest of the year and dare it to malfunction

 

[Hajidub]

NICE! Dare it to malfunction? Thanks Transistorized, beer clean up aisle 3!