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Old 3rd November 2012, 08:50 AM   #1
icewall is offline icewall  Sweden
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Default Broken A 30

A couple of years ago I build me two Aleph 30, based on boards from chip amp. The miniA but with 6 output devices for use with my Orion setup, top channels. They have been playing great until some weeks ago when one of the channels gave up No heat and not much of sound unfortunately! Measuring is not my strong side but after changing q3 on the faulty channel all of my channels where playing happily until the same q3 broke again the other night!
Something else has to bee wrong, right, besides the brokenq3? Could someone please point me in the right direction where to start looking?
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Old 3rd November 2012, 09:16 AM   #2
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You have the correct channel and compare measurement.

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Old 3rd November 2012, 01:05 PM   #3
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Correct me if wrong original poster, but I think your question is more basic. Is your query more like "yes I have a correct channel, I dont know what to measure to compare?" If so, I find myself in the same boat if one of my channels failed. I am watching this one and am all ears!

Russellc
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Old 3rd November 2012, 01:16 PM   #4
icewall is offline icewall  Sweden
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@Russelic Yes, exactly what I meant! Couldn't have put it better myself! Thanks
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Old 3rd November 2012, 02:10 PM   #5
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Start by looking at this: pdf by Algar_emi

Also, post, post, post pictures. There might be something that can be found by looking at pictures of your pcb, parts, layout, etc.

Steve
Attached Files
File Type: pdf Aleph30by Algar_emi.pdf (29.9 KB, 69 views)
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Old 3rd November 2012, 02:16 PM   #6
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Quote:
Originally Posted by HIPCHECK View Post
Start by looking at this: pdf by Algar_emi

Also, post, post, post pictures. There might be something that can be found by looking at pictures of your pcb, parts, layout, etc.

Steve
Excellent post! I forgot about it. All I could do without it is look for toasted/discolored parts! If I recall correctly this pic also shows a number of nice things to add, pots to zero off set and a few other things. Thanks for reminding me of it! Helpful for most any Aleph.

Russellc
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Old 3rd November 2012, 02:26 PM   #7
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pm me and I can send a few other files if interested.
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Old 3rd November 2012, 05:19 PM   #8
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I would replace Z5 zenner which sets the current through Q3. And check for bad solder joint around it.
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Old 6th November 2012, 03:29 PM   #9
icewall is offline icewall  Sweden
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Thanks for all your input! I'll put it to use as soon as I get home from vacation! Have checked out the PDF and z 5 was one of my suspects initially!
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Old 11th November 2012, 01:25 PM   #10
icewall is offline icewall  Sweden
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So, back from holiday, started measuring. Finds that after R112 where there's supposed to be +15V Click the image to open in full size. I have same voltage as from V+, 24,5. This can't be right, right? I don't get the 4V that I have on the current source - compared with working channel I think my mystery is solved or can something else have broken bescause of this?
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