So I was recruited to repair an Option Audio OAX2000 amplifier.
It had killed its power supply mosfets, and somehow ONE of its TO220 package diodes.
I replaced all the mosfets, and all the diodes, and as a result, one bank of mosfets decided to run constantly on.
SO I replaced the 8 drive transistors, and the TL494, and we're all good.
Or so I thought.
After running for half an hour at very low volume, something smelt hot, I soon realised it was the output inductor, sitting at 90 degrees Celsius
I swapped out the paralleled 10uf, 100volt non polarised electrolytic capacitors, for some polyester ones borrow from another amp, but this made no difference...
Ideas? Thanks!
It had killed its power supply mosfets, and somehow ONE of its TO220 package diodes.
I replaced all the mosfets, and all the diodes, and as a result, one bank of mosfets decided to run constantly on.
SO I replaced the 8 drive transistors, and the TL494, and we're all good.
Or so I thought.
After running for half an hour at very low volume, something smelt hot, I soon realised it was the output inductor, sitting at 90 degrees Celsius
I swapped out the paralleled 10uf, 100volt non polarised electrolytic capacitors, for some polyester ones borrow from another amp, but this made no difference...
Ideas? Thanks!
Last edited:
Those tend to run hot but 90c is very high. I'd suspect a shorted turn. It's most common where the terminal winding comes over the top of the rest of the windings.
Twist/push/pull the inductor while closely watching the idle current. If the idle current changes when twisting, it's likely shorted.
Twist/push/pull the inductor while closely watching the idle current. If the idle current changes when twisting, it's likely shorted.
I've a USBLASTER USB3003 that use two SINUS LIVE SLA1500 board, internally linked.
I've the same "issue".
At this point, i don't think that is an issue.
The two inductors come hot in 10-15min producing a clear audio output.
despite this, the amp work correctly and not have a high current draw.
I've the same "issue".
At this point, i don't think that is an issue.
The two inductors come hot in 10-15min producing a clear audio output.
despite this, the amp work correctly and not have a high current draw.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.