Hi!

I have a problem with my HK again... :-(
It turns OFF sometimes. No messages, just orange led. It turns OFF quietly like it just stopped to Play. It happens even if AMP board is disconnected so it seems like it has nothing to do with output transistors. It seems I can force it if a volume is louder and when parts are starting to Heat more. I can hear something like a quiet boiling sound coming from power supply board but I can not detect which part exactly. I have measured capacitors capacity around that area and they seem ok.

Re: harman kardon avr 3700





I really think they're the same. You don't have to worry about parts from China. At least you know you're buying originals 🙂 It would be Weird if you bought it from USA or Germany. Here is a link to AVR370 service manual if you didn't found it. Try to compare parts arround IC91....

Re: harman kardon avr 3700



You think IC91 is different between AVR370/AVR3700?
As much as I know, some jumpers are, or not used depending on 100V/240V and some main capacitors may be different.
IC91 in my AVR370 has marks:

D22203
OB2358AP
L...

Re: harman kardon avr 3700

Sorry.. 2sd transistors are about 55Hfe and 2sb are about 150Hfe

Re: harman kardon avr 3700

Ok. After all measurements i made... All power supply board voltages seems to be ok. +/-5V is about 5.1, +/-12V is 11.84, 50V that leads to AMP board is 51.3V.
After all, it seems like a problem with AMP board because, if I disconnect 3pin 50V power connectot to the AMP board, AVR works fine and I can not force it to Shut Down. I disconnected output transistors and measured some resistances and Hfe with some cheap multimeter. 2sd transistors are mostly about 150Hfe, but three of them are about 100Hfe. 2sb transistors are about 55Hfe, but two of...

Re: harman kardon avr 3700

Ok. It's really frustrating. I will take measures as much as I can. I allready checked some capacitors and it seems they're ok. If someone have some suggestions about What and how to measure, it would be great.

Re: New Members - please post your introductions here

Thank you all for making this forum. It helps a lot. I'll try to help you too.

Re: harman kardon avr 3700

Just to describe my problem...
My AVR370 just turns OFF randomly. Only orange standby led stays on. Sometimes it happens ten times in a row and sometimes once in a two days. It seems like it was ok when I resoldered joints on a power supply board, but after a few days it happened again. Then I resoldered joints on an amp board, but no use...
It happens even with no speakers ar any other cable except power cable connected.
Now I'm thinking about removing a jumper :-)
Any advice? Sorry about my English...

Re: harman kardon avr 3700

Hi!
Thank you all. Badcaps forum is great. It helped me a lot.
I just wonder, does your AVR still works with that broken jumper? I'm trying to fix my AVR370. It has the same issues. Maybe breaking a jumper would help ? :-)
Thanks!