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Resistor #62 smokin'

PostPosted: Tue Oct 11, 2005 2:17 pm
by kudos
No shorts that i have found anywhere. R62 will smoke when powered up any suggestions? :shock:

PostPosted: Wed Oct 12, 2005 6:56 am
by tpryan
R62 is smoking but not R63? Is R66 hot? Are you absolutely sure you have Q15 and Q16 installed correctly?

Let's see.

PostPosted: Wed Oct 12, 2005 1:54 pm
by kudos
R63 is fine R62 is not. What happened so you can hear it all was I had some solder shorting the transistors did not hurt them but lit those two led's like a Christmas tree. So i have fixed that but what happens is the PS03 led's do not power on but R63 will smoke then stop smoke then stop etc.. Could it be that I fried R63 the first go around? The reason I do not think so is that from r62 to r63 there is no resitance. When I pull the molex connector from the C84 the PS03 powers up fine. So something on the pre in that area is funky. I built one before it and was fine and sounds incredable by the way! So I guess I am wondering could I have damaged anything on the first go around when I had that short? I will keep looking.

PostPosted: Wed Oct 12, 2005 2:25 pm
by tpryan
I suspect you may have a shorted Q15 and probably some more solder bridges. If your DMM has a diode test feature, measure the BC, BE, and CE voltages at Q15 on your good C84 and compare them to the bad one. If you don't have a diode tester, measure the resistances instead. If this doesn't make sense, read this first. Let us know what you find.

Yep You were right!!

PostPosted: Wed Oct 12, 2005 4:48 pm
by kudos
:D Yes it is Q15 and Q16 when I first had a solder bridge that is what happened. I will have to get two more. This should fix the problem according to the readings I am getting! Thanks again Tim and again these preamps are quiet and very neutral! Awesome response times and awesome preamps!!

PostPosted: Thu Oct 13, 2005 8:05 am
by tpryan
If you're sure the transistors are bad, it's much easier to get them off the board by snipping the leads at the transistor body and removing each lead individually. Clear the holes with a solder sucker or wick and you'll be good to go.