Sony STR-DE835

wondernutz · 31st May 2010, 09:16 PM

I have a Sony STR-DE835 today I was messing with some speakers and shorted th speaker leads It blew the power supply fuses so I replaced them with new ones found two burnt transistors MN2488 and MP1620 so I took them out of the surround channel since they were the same now its not blowing fuses anymore but it displays protection. does anyone know if its the missing transistors from the surrround channel thats causing this amp to go into protect mode or is there somthing I am missing thanks in advance.

bob91343 · 1st June 2010, 12:14 AM

I have one of these with the same problem. Maybe we can fix ours together.

I found some shorted transistors and everything seemed okay otherwise so I replaced them. It started working okay but before I could close it up the new transistors popped. I checked everything I could but so far have had no success with it. So it's in the closet until I decide to work on it again.

wondernutz · 1st June 2010, 12:26 AM

do you know if all the transistors need to be installed to make these amps come out of protect mode I orderd new transistors but will take time to get here

bob91343 · 1st June 2010, 02:42 AM

The unit has several channels and I'm sure you only have to repair the failed one. Once that's working, it will come out of protection. If you don't have the runaway problem I had, all will be well. Anyway the thing is in the closet, and has been there, for a few years now. I have plenty of stereo receivers, Sony, Yamaha, JVC, Kenwood, Sansui, Onkyo, maybe more.

What transistors did you order, from whom, and what will you pay for them? If you order on line, the shipping kills you.

wondernutz · 1st June 2010, 03:30 AM

Quote:

Originally Posted by bob91343

The unit has several channels and I'm sure you only have to repair the failed one. Once that's working, it will come out of protection. If you don't have the runaway problem I had, all will be well. Anyway the thing is in the closet, and has been there, for a few years now. I have plenty of stereo receivers, Sony, Yamaha, JVC, Kenwood, Sansui, Onkyo, maybe more.

What transistors did you order, from whom, and what will you pay for them? If you order on line, the shipping kills you.

I got them on ebay free shipping for 10 bucks

bob91343 · 1st June 2010, 05:00 AM

Can you give me a link? I might spring for a set myself.

wondernutz · 05:20 AM

Quote:

Originally Posted by bob91343

Can you give me a link? I might spring for a set myself.

http://cgi.ebay.com/1-x-MP1620-1-x-M...#ht_1573wt_920

bob91343 · 1st June 2010, 06:39 AM

Thanks! I hadn't heard of that distributor.

Let me know what luck you have installing them.

wondernutz · 5th June 2010, 12:08 AM

OK so I got my transistors today installed them and i am still having the same problem so I started tracing and found a funny resistor burnt out its a MPC725 .22K+.22KOHM does anyone know of a sub or have one for sale thanks Bob

bob91343 · 5th June 2010, 12:51 AM

Where in the circuit is this resistor?

It's troubleshooting the hard way by scanning the unit looking for overheated parts. A much better approach would be to measure voltages and trace signals and measure components. And of course replacing a bad part may cause other failures if you still have bad parts.

31st May 2010, 09:16 PM	#1
wondernutz diyAudio Member Join Date: Apr 2010	Sony STR-DE835 I have a Sony STR-DE835 today I was messing with some speakers and shorted th speaker leads It blew the power supply fuses so I replaced them with new ones found two burnt transistors MN2488 and MP1620 so I took them out of the surround channel since they were the same now its not blowing fuses anymore but it displays protection. does anyone know if its the missing transistors from the surrround channel thats causing this amp to go into protect mode or is there somthing I am missing thanks in advance.

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1st June 2010, 12:14 AM	#2
bob91343 diyAudio Member Join Date: Mar 2010	I have one of these with the same problem. Maybe we can fix ours together. I found some shorted transistors and everything seemed okay otherwise so I replaced them. It started working okay but before I could close it up the new transistors popped. I checked everything I could but so far have had no success with it. So it's in the closet until I decide to work on it again.

1st June 2010, 12:26 AM	#3
wondernutz diyAudio Member Join Date: Apr 2010	do you know if all the transistors need to be installed to make these amps come out of protect mode I orderd new transistors but will take time to get here

1st June 2010, 02:42 AM	#4
bob91343 diyAudio Member Join Date: Mar 2010	The unit has several channels and I'm sure you only have to repair the failed one. Once that's working, it will come out of protection. If you don't have the runaway problem I had, all will be well. Anyway the thing is in the closet, and has been there, for a few years now. I have plenty of stereo receivers, Sony, Yamaha, JVC, Kenwood, Sansui, Onkyo, maybe more. What transistors did you order, from whom, and what will you pay for them? If you order on line, the shipping kills you.

1st June 2010, 05:00 AM	#6
bob91343 diyAudio Member Join Date: Mar 2010	Can you give me a link? I might spring for a set myself.

1st June 2010, 06:39 AM	#8
bob91343 diyAudio Member Join Date: Mar 2010	Thanks! I hadn't heard of that distributor. Let me know what luck you have installing them.

5th June 2010, 12:08 AM	#9
wondernutz diyAudio Member Join Date: Apr 2010	OK so I got my transistors today installed them and i am still having the same problem so I started tracing and found a funny resistor burnt out its a MPC725 .22K+.22KOHM does anyone know of a sub or have one for sale thanks Bob

5th June 2010, 12:51 AM	#10
bob91343 diyAudio Member Join Date: Mar 2010	Where in the circuit is this resistor? It's troubleshooting the hard way by scanning the unit looking for overheated parts. A much better approach would be to measure voltages and trace signals and measure components. And of course replacing a bad part may cause other failures if you still have bad parts.

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