Carvin DCM2000 Circuit Question

wk2w · 27th January 2010, 11:23 AM

I'm trying to fix a problem with the protection circuit on a DCM2000. The circuit can be found at http://www.carvinservice.com/crg/sch...%20rev%20M.pdf .
The concern is with the part of the circuit comprised of D19-21, Q5 and Q6 in the upper right-hand corner of the diagram.
If I'm not mistaken, this is supposed to detect speaker shorts, but I can't see how it is supposed to work. Has anyone seen this before or understand how it works?
Thanks,
Chris

llwhtt · 27th January 2010, 06:19 PM

Why do you think that D19-D22, Q5 and Q6 are for short circuit protection? If you follow the circuitry further you'll see they are all related to thermal protection. Q101, Q102 and associated circuitry are the normal short circuit (overcurrent) protection. D8 and D14 for an OR gate, meaning either the signal from A7 (thermal) OR A6 (overcurrent) will trip the protection. The circuitry that you are looking at monitors the output and in turn changes the fan speed.

Craig

wk2w · 27th January 2010, 06:53 PM

It makes sense now.
Thanks for taking a look and posting the reply, Craig.
Chris

27th January 2010, 11:23 AM	#1
wk2w diyAudio Member Join Date: Jan 2010	Carvin DCM2000 Circuit Question I'm trying to fix a problem with the protection circuit on a DCM2000. The circuit can be found at http://www.carvinservice.com/crg/sch...%20rev%20M.pdf . The concern is with the part of the circuit comprised of D19-21, Q5 and Q6 in the upper right-hand corner of the diagram. If I'm not mistaken, this is supposed to detect speaker shorts, but I can't see how it is supposed to work. Has anyone seen this before or understand how it works? Thanks, Chris

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27th January 2010, 06:19 PM	#2
llwhtt diyAudio Member Join Date: Jun 2008	Why do you think that D19-D22, Q5 and Q6 are for short circuit protection? If you follow the circuitry further you'll see they are all related to thermal protection. Q101, Q102 and associated circuitry are the normal short circuit (overcurrent) protection. D8 and D14 for an OR gate, meaning either the signal from A7 (thermal) OR A6 (overcurrent) will trip the protection. The circuitry that you are looking at monitors the output and in turn changes the fan speed. Craig

27th January 2010, 06:53 PM	#3
wk2w diyAudio Member Join Date: Jan 2010	It makes sense now. Thanks for taking a look and posting the reply, Craig. Chris

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