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Hi!

Welcome to my DIY audio forum.

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Per-Anders Sjöström

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#61
Headphone amplifiers / Re: QRV-08 gain reduction
Last post by Hodgin - September 11, 2019, 03:42:45 PM
Do 330 ohms impact anything else besides the gain?
#62
Power supplies / Re: SSR03-15V LM431 Volt too l...
Last post by eloes51 - September 08, 2019, 05:16:26 PM
Hi,

Thanks for the tip.

I did not think that the AGND have no mass !!!
#63
Power supplies / Re: SSR03-15V LM431 Volt too l...
Last post by peranders - September 08, 2019, 04:14:04 PM
Are the sense inputs connected? Have you tin drops on J1-4?
#64
Power supplies / SSR03-15V LM431 Volt too low
Last post by eloes51 - September 08, 2019, 11:42:53 AM
Hi,

SSR03 board with OP, the rest soldered itself.
Plus volts 13.4V, minus volts 10.4V.
OP From PIN6 + V -6.5V
OP from -V + 3.5V.

All components checked twice.
Maybe components defective?

Please help!! :-(
#65
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - June 13, 2019, 09:11:47 PM
Hi,
E29 is fine. Have a look at a thermal photo of the amp. Does it look fine?

What can I measure to confirm that it is working properly now, amd how do I adjust the pots correctly?

Thank you again, it would have been really great to get this amp working properly.

#66
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - May 28, 2019, 12:30:36 PM
Ok, it could be something close to it that is heating up, but I will have a look.

#67
Headphone amplifiers / Re: QRV-08 power up
Last post by peranders - May 28, 2019, 07:01:10 AM
R29 should be 470 kohm. Impossible to get it heated for any value more or less. Check the resistance and the voltage across it.
#68
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - May 27, 2019, 11:12:08 PM
With new rectifiers, the psu seems ok. I soldered the amp section in, and it does not shut down like before. It makes a mechanical 50hz humming sound, and e29 lights up with the thermal camera.

What should I measure next to make sure it is ok? I sort of assume that this is a temporary thing until the new rectifiers brake down.
#69
Headphone amplifiers / Re: QRV-08 power up
Last post by peranders - May 22, 2019, 07:39:30 PM
Switch over to "diode" on your DVM and measure the diodes in the rectifier bridges. If you read near zero, the you probably have broken diodes => change the parts.
#70
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - May 21, 2019, 11:03:53 PM
I have measured all the electrolytics in the psu, and all the resistors. When still on the pcb, they all measure the same.

When I watch the amp power up with a termal camera, the only thing really different is the rectifiers. The two in the middle (the two failing ones) gets really hot. When I measure resistance across these, I get almost a short between the ac and the positive on the two failing ones, but the working ones show several megaohms.

Should I simply order new ones, or do you think these are only symptoms for another error?


Thank you for following me through this so far!