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Old 19th April 2011, 02:09 AM   #21
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I have tried forcing the amp by grounding the tl494 but it will still shut down and nothing gets hot
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Old 19th April 2011, 05:40 PM   #22
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ok jfets q217, q215, q115, q117 are pulling 29 volts at idle the rest are at 24 volts at idle at the gate. ok correct me on the right terminalogy q112, q113, q212 and q213 are the transistors the work with the fets pullin 29 volts and is there a problem with 4 volts difference wait i guess there would be thats what is shutting down the tl494 right? Any suggestions would be greatly apprieated

Last edited by joesch1999; 19th April 2011 at 05:43 PM.
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Old 19th April 2011, 05:49 PM   #23
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All of the outputs are bipolar transistors, not jfets. The B688 and D718 transistors are the outputs. There are 6 outputs per channel.

Bipolar transistors don't have gates. Their terminals are the base, collector and emitter.

The term 'pulling volts' doesn't mean anything. I'm not sure what you mean.
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Old 19th April 2011, 06:00 PM   #24
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I mean there is a 4 (29v) volt difference with the matched bipolar transistors compared to the other bipolars which are only at 24v at idle meaning when the amp is powered up with just remote voltage applied
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Old 19th April 2011, 06:08 PM   #25
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You'll need to be much more specific.

With the black meter probe on one of the non-bridging speaker terminals, which transistors and which leg of those transistors are you referring to for the 29v and the 24v?
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Old 19th April 2011, 06:12 PM   #26
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q217 q215 q115 q117 (29 volts) with remote voltage applied bipolar

q116 q111 q120 q118 q218 q222 q121 q216 bipolar (24 volts)

I am wondering what the transistors connected to each bipolar is the small ones q112 q113 q212 q213 I am pretty sure they are pnps but what do they do?

Last edited by joesch1999; 19th April 2011 at 06:14 PM.
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Old 19th April 2011, 06:19 PM   #27
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You need to write in complete, precise language if you want others to understand what you're trying to convey. For example, what does 'with remote voltage applied bipolar' mean?

The smaller transistors function as drivers, predrivers and as part of the differential amplifiers. They consist of both NPN and PNP bipolar transistors.

Which terminals did you measure the voltage on?
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Old 19th April 2011, 06:21 PM   #28
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Sorry perry was using the battery post

doing it the right way middle leg of the fets there is a ten volt difference
q217, q215, q115 q117 26 volts
the rest are at 36 volts

Remote voltage is with amp powered up at idle with the + and - and the remote hooked up no speakers or nothing hooked to the rcas

black on non bridged speaker termial red on middle leg of the bipolar transistors

Last edited by joesch1999; 19th April 2011 at 06:27 PM.
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Old 19th April 2011, 06:30 PM   #29
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The outputs are bipolar transistors, not FETs.

The outputs should have both positive and negative voltage.

List all 12 FETs and the voltage (including polarity) on the center leg.
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Old 19th April 2011, 06:51 PM   #30
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(q216) d718 (+) 36v
q215 d718 (+) 46v
q121 d718 (+)36v
q222 b688 (-)36 v
q217 b688 (-) 24v
q218 b688 (-) 24v
Q116 d718 (+36)
q115 d718 (+38)
q111 d718 (+37)
B688 q120 (-37)
" q117 (-36)
" Q118(-36)

lol q215 is pulling excessive current
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