Intermittent PS problem on Yamaha HTR-5250 - diyAudio
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Old 28th June 2008, 12:12 AM   #1
jtholle is offline jtholle  United States
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Join Date: Jun 2008
Default Intermittent PS problem on Yamaha HTR-5250

Hello,

Like many, I'm new to this forum and DIY audio in general. I have a Yamaha HTR-5250 that I'm having problems with. I took it to a local shop, but they said they don't work on Yamaha equipment anymore. I figured I might try to take a look at it myself before I toss it. Maybe I can learn something.

Here is the problem. Once I power on the unit and listen to music from anywhere from 30 seconds to 10 minutes, the protection circuit engages and it shuts off.

I did find the service manual online and was able to look at the service code associated with the protection. It indicates PS PRT 20%. This would seem to indicate that that problem is in the power supply. 100% is supposed to correlate with 5V so it seems that somewhere in the PS I'm getting only 1V.

I have a DMM and oscilloscope and have been working through the service manual checking the DC and AC voltages. Everything is fine when I'm checking. It seems to be some intermittent problem.

I did reset the DSP to default and that didn't seem to help.

I also tested the DC at the output of the regulated power supply all the voltages seem to check out fine.

the +/- 25V were about +/-23.8V: I figured that was okay
the +10V was around +11V
+/- 5 were right on

( newbie question: what is the difference between the +5 and the +5D)

For the 30 seconds to 10 minutes that it does play, everything seems to work fine..Everything sounds and works as it should.

One more thing. Two times I can remember when it came out of standby, I did hear some crackling and a sort of high pitched whine that happened just before the protection kicked in. I'm not sure if I heard this on both channels or just one.

Does anyone have any ideas on how I can test this intermittent problem or any ideas on further testing I could do?

Thanks,

Jeromy
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Old 28th June 2008, 04:04 AM   #2
PM650 is offline PM650  United States
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Join Date: Jul 2005
Location: Tennessee
You will need to cause the receiver to go into protection to find which rail is the problem. Also, check the voltages at points other than the source (i.e. at the boards they're powering). I noticed in the 5230 SM that there are two +12v supplies, you may wish to check the remaining +/-12v supplies.

Also, since you did not mention this and I don't know if you already know, the PS value should be between 23-38. The +5D source is strictly for the digital circuitry (likewise, the other supplies not labeled with a D will be used only in analog sections).
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