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Old 8th January 2010, 01:04 AM   #11
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yes. I put the exact outputs back in there,went and picked them up at MCM today, as i had to get a new set of diodes to fix a memphis that had 4 shorted diodes.

Last edited by mbates14; 8th January 2010 at 01:06 AM.
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Old 8th January 2010, 01:07 AM   #12
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Have you checked the driver transistors for leakage?

Are you sure that the outputs are in the correct locations (sorry to ask but I've seen it happen many times)?
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Old 8th January 2010, 01:09 AM   #13
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the drivers were shorted. I had to replace those, and replace the outputs, yes the outputs are in the right spots because i followed the rail traces to the adjacent channel.

Last edited by mbates14; 8th January 2010 at 01:26 AM.
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Old 8th January 2010, 01:14 AM   #14
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Pull QA8 and check it for leakage, shorts and confirm that both the base-collector and base-emitter junctions are intact.
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Old 8th January 2010, 01:27 AM   #15
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Alongside the drivers being shorted, there was a top blown off of one transistor, so that made a total of 3 transistors excluding the outputs that had to be replaced. All the rest of them test fine, even against the other channels. within spec.

Unfortuantely, which could be the cause of my entire problem, i didnt have the exact drivers on hand either. :-(

Could be my whole problem, as i pulled these drivers from another board that worked but had shorted power supply turns.

The original drivers were:

2SA1023
2SC1027

Transistor that blew its top off was:

QA8, 2SC3198.

Replaced the drivers with:
2SB1238
2SD1859

replaced QA8 with a 2SC945.

This is all that I had on hand. anything wrong with these figures so far? thanks.

There was also a handfull of resistors that were open or burned, so i replaced those as well. both 2.2ohms and the 220ohms bridging between the two were all blown open. I checked all other resistors and diodes they are all fine
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Old 8th January 2010, 01:32 AM   #16
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another issue i ran into, is i couldnt find any data on those particular drivers, hence one of the main reasons i chose to use the 2sB/2sD.
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Old 8th January 2010, 01:56 AM   #17
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I don't see anything wrong with the subs you used.

Are either of the 1N4148 diodes that are connected from the base of the drivers to the rails leaking or shorted?

You'll have to desolder at least one terminal on each one to determine if they're leaking (meter set to ohms).
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Old 8th January 2010, 02:09 AM   #18
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no idea yet. but id say its possible considering that QA8 was completley blown apart which is what, the bias drive? i dont have schematic so i have no idea. the diodes arnt shorted though, however that dont mean they arnt leaky.
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Old 8th January 2010, 02:14 AM   #19
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http://www.bcae1.com/temp/unknownaudiobahn01.swf

This may be close to what you have. It's from a smaller 2 channel amp.
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Old 8th January 2010, 02:32 AM   #20
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darnit. gotta have flash to view a schematic. lol whats this world comming to
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