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Old 13th August 2004, 04:22 PM   #1
rkc7 is offline rkc7  United States
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Question Another broken Sony receiver... won't turn on

Ok.... so I have a Sony receiver. That's the problem right? STR-DE595. Anyway, I purchased it in order to repair and resell, but the problem seems more complicated than anticipated. It won't turn on at all... no protector mode, etc. The power supply fuse isn't blown, all transistors seem good, transformer is putting out voltages that seem correct (when I manually turn on the AC supply relay). So, I plug it in, and press the power button... nothing. I've tried looking at a bunch of different things, and nothing apparent seems wrong. I'm considering removing all of the relays and testing them individually, but my impression is that relays typically don't go bad. Anyway, any help on what could be the problem or what else I should check would be really helpful. Thanks.
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Old 14th August 2004, 09:18 AM   #2
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Default A potential cause of your problem

When I was in the repair business I ran into a number of problems like you describe. Iím not familiar with your particular unit but most of the newer equipment such as this is controlled by microprocessor mounted on the front panel circuit board. This processor may not be getting power or is being held in a reset condition. This will cause the symptoms you describe and the receiver remains off. If your unit has such a processor you may need a circuit diagram to help follow the power and reset paths. You could have a failed processor, but it would be wise to check all of its supply and control voltages before replacing it.
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Old 14th August 2004, 02:37 PM   #3
anatech is offline anatech  Canada
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Hi rkc7,
It sounds like the AC detect circuit may not be working. Look for a approx. 1 uF capacitor feed by a single diode. These tend to go open and hopefully will be an easy fix.
Like alaskanaudio, I am not familiar with this exact receiver, but the circuits should be common to most, in form. If you have a 'scope, look for a big ripple waveform on a small cap that goes to ground. If you see a half wave rectified waveform, it's open for sure.
-Chris
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Old 14th August 2004, 03:18 PM   #4
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Default sony

Make sure no buttons on the front panel are pushed in
if a switch is activated when powering up micro may not work.
check connectors going to the display board and check for 5 v
check for cracks on display board or main board.


JEFF
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Old 14th August 2004, 04:53 PM   #5
Rimband is offline Rimband  United States
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Default Re: Another broken Sony receiver... won't turn on

Quote:
Originally posted by rkc7
Ok.... so I have a Sony receiver. That's the problem right? STR-DE595. Anyway, I purchased it in order to repair and resell, but the problem seems more complicated than anticipated. It won't turn on at all... no protector mode, etc. The power supply fuse isn't blown, all transistors seem good, transformer is putting out voltages that seem correct (when I manually turn on the AC supply relay). So, I plug it in, and press the power button... nothing. I've tried looking at a bunch of different things, and nothing apparent seems wrong. I'm considering removing all of the relays and testing them individually, but my impression is that relays typically don't go bad. Anyway, any help on what could be the problem or what else I should check would be really helpful. Thanks.

Hello rkc7, I have a service manual for that receiver in PDF format, I can upload it to you if needed. It is about 6 MB in size. While you're at it, check the standby transformer, those are known for opening up the primary, which will cause a dead receiver.

If your mailbox can handle a 6MB file, please let me know at rimband@hotmail.com (not my DSL account). I'll E-mail you through my DSL account and upload the manual for you!

Joe
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Old 15th August 2004, 05:03 AM   #6
rkc7 is offline rkc7  United States
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Wow, thanks for all of the advice. Unfortunately, I don't have a scope, just an advanced multimeter that can measure the normal current, voltage, resistance, etc... with diode check, transistor check, and caps up to 200uf. I would be very happy to receive the service manual. You can send the file to skimaniac3@spymac.com, that should have much more than enough space. I'm going to try looking at everything mentioned, and I'll report back. Thanks!
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Old 18th August 2004, 01:44 AM   #7
rkc7 is offline rkc7  United States
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Doh! I have a new problem... my receiver isn't STR-DE595. That's what the auction said, that's what the box said, but that's not what the receiver says. It's actually a STR-K502P... a cheaper, older receiver. Anyway, anyone have a service manual for this model?
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Old 24th August 2004, 02:52 PM   #8
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OK... I found a service manual and have done some testing. Capacitors I've tested so far have been good. But I tested the standby transformer and here's what I found:

2 pole side: 11ohms between poles
3 pole side:
between 1,3: 900ohm
between 1,2: open
between 2,3: open

Take a look at the diagram. Pole 1 is the bottom, 2 is middle, 3 is top. Thanks.
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File Type: jpg diagram.jpg (78.4 KB, 169 views)
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Old 24th August 2004, 11:55 PM   #9
anatech is offline anatech  Canada
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Question Voltage?

That in itself is okay. What's the voltage on the secondary?
-Chris
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Old 25th August 2004, 12:35 AM   #10
rkc7 is offline rkc7  United States
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Attached is a diagram of the measured voltages from the transformer. The bracket that has two voltages were measured with the red lead connected to the pole nearest the voltage.
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