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Old 28th January 2013, 06:42 PM   #51
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Hi KatieandDad,

I measured all the components on both amps. They both measured OK so I got confused. I was expecting to find defective transistors at least. But all seems to be ok using the diode test..... I'm not saying that this test is 100% conclusive, but both the left and right amp measure exactly the same on all components.

So I browsed the internet and found this:

How to Measure DC Offset: 5 steps - wikiHow

Don't know for sure yet, but it would explain the shabby sound on only one channel. My speaker protection unit could have been cutting off the left amp while stil running the right amp. But if the DC offset is very high, that could result in crackling sound couln't it?

I'll try the methode described in that article tomorrow :-) I'll let you know how it turnes out.

Kind regards,
Sjoerd Smits
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Old 28th January 2013, 07:24 PM   #52
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Quote:
Originally Posted by SjoerdSmits View Post
Hi Wintermute,

Yep, get it now! Learning all the time!

Didn't know what you were trying to say with C or CRC.... :-)
Thanks!
Yes I realized that once Katie and Dad nailed it down Easy to forget sometimes that some of the stuff we now take for granted we would have said "whats a CRC" ourselves when starting out!

Tony.
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Old 29th January 2013, 04:27 PM   #53
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Hi Tony,

You are so right! But hey, I'm a guy and I'm supposed to be cocky offcourse :-)

I was so confused that I didn't "see" your question the way it was intended. I apologize for that!

Thanks for the lesson :-)

Regards,
Sjoerd
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Old 29th January 2013, 04:29 PM   #54
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PS: Tonight I'll set the DC offset while connected to an empty input... Hope to get better results!

Thanks again all!
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Old 14th July 2014, 09:23 AM   #55
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Hi There again!

I have a strange problem. It seems that my power supply is having trouble but I can't seem to find what it is. here's what happened:

I accidently swapped pos and neg of the amplifiers. This resulted in a "boom" ofcourse. So I replaced the amps and the diodes on the PSU.

Somehow the new amps do not work. I measured 10VAC on the secondary side of the PSU and the expected 35VCD on the same side. How is this possible? And can this be the reason the amps will not work?

Please help! I'm going out of my mind :-)

Kind regards, Sjoerd
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Old 14th July 2014, 09:34 AM   #56
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disconnect the amplifier.

Power up the transformer Alone using a mains bulb tester.

Measure the AC voltage
post your results.
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Old 14th July 2014, 09:38 AM   #57
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Hi Andrew,

2 x 25VAC out of the toroid. I guess the toroid is ok. I swapped it to be sure...
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Old 14th July 2014, 09:44 AM   #58
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Now add on the bridge rectifier.
Measure the AC at the ~~ connections and measure the "apparent DC" at the +- connections.
report.
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Old 14th July 2014, 09:47 AM   #59
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Hi Andrew,

Ac both 25VSC

DC Both 35VDC

Note that DC measurement is on the output of the PSU.
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Old 14th July 2014, 09:48 AM   #60
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Now add on the smoothing capacitors.
and measure the AC and DC voltages.
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