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Old 8th August 2009, 01:50 PM   #1211
udailey is offline udailey  United States
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I cant say as I have any clue and am just asking this out of curiosity. Did you use the BrianGT boards, make your own boards, use P2P, etc?
Uriah
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Old 8th August 2009, 06:13 PM   #1212
pchw is offline pchw  United States
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Checked the FET that has the blown 0.47R to see whether it is still good. It sounded like this FET was passing all the current.
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Old 8th August 2009, 07:41 PM   #1213
toufu is offline toufu  United States
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Quote:
Originally posted by pchw
Checked the FET that has the blown 0.47R to see whether it is still good. It sounded like this FET was passing all the current.
Thanks Fred, the FET was blown...

But now, I got another problem, the FET's on one side are not getting any current at all. One side of FET's are running nice and warm, the other side of FET's are cold. I am trying to check the soldering.
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Old 8th August 2009, 07:45 PM   #1214
toufu is offline toufu  United States
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Quote:
Originally posted by udailey
I cant say as I have any clue and am just asking this out of curiosity. Did you use the BrianGT boards, make your own boards, use P2P, etc?
Uriah
I am using BrainGT's board.
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Old 8th August 2009, 08:39 PM   #1215
pchw is offline pchw  United States
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Quote:
Originally posted by toufu


Thanks Fred, the FET was blown...

But now, I got another problem, the FET's on one side are not getting any current at all. One side of FET's are running nice and warm, the other side of FET's are cold. I am trying to check the soldering.
Hi Jeff

Which side? The current source or the output?
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Old 8th August 2009, 10:10 PM   #1216
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The mis-matched FET's shouldn't cause a melt down providing the part that failed wasn't faulty.

One fet board is a current source, the other is for the output devices, and all connections between the two are routed via the main board. For a start check continuity on all your wiring from the main board to the fet boards is ok - I suffered a major failure on one of my Aleph30's due to a broken gnd connection to the main board so it can be something as simple as that! Also check that there are no shorts to the chassis especially on the FET boards.

If wiring is ok then move on to checking the components on the main board starting with sections around Q5, Q7 and Q4, Q6. You can see from the schematic that the FET boards are an integral part of these circuit blocks, so this is where I would focus my investigations for now.

cheers
Paul
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Old 8th August 2009, 10:24 PM   #1217
toufu is offline toufu  United States
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Thanks for all your help, it was one of the rectifier connection. I resoldered it and I have music for one channel! Sounds good so far.. I am happily soldering the other channel now.

By the way, how important is the matching FET's having an effect on sound? Should I order a set of matching ones if I really want the most out of this amplifier?
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Old 9th August 2009, 05:37 PM   #1218
toufu is offline toufu  United States
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It's alive! Great sound and fantastic bass for my Druids MK4's. I am going to order some matching FET's to see if it can even sound better. Thanks for all your help guys!
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Old 9th August 2009, 06:00 PM   #1219
udailey is offline udailey  United States
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Awesome!
www.tech-diy.com has a very good deal on matched triplet/sextuplets.
Uriah
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Old 14th September 2009, 04:48 PM   #1220
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I'm ready to fire up my MiniA... yes a long time ago I've begun this project.
Now I'm a little bit confused before trying it in "real" conditions.
My PSU is tested Ok, fuses ready too, Amp PCB checked, MosFets are using Kerafol Keratherm Red Isolators.

How do I proceed, I've got some questions :
Do I need a load at the output ?
What are the usual measures to be done ?
Thanks for your advices and help
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