nashou
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Tech in Training.....
Posts: 1,239 
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Post by nashou on Mar 30, 2016 22:58:47 GMT -5
SO I removed the good amps, checked all the way from the base of the B688 to the D718, ut I wasn't sure if it was base to base or base to collector, so i decided to test one of the B688's yep NPN BEC....tested the D718 NPN BEC umm wait a freaking second!!!! The 2sb688 is suppose to be a PNP !!!!!!!! WTF!!!! Freaking Chinese crap ass freaking no good sumsofabitchencrochmunchers!!!! No wonders!!!!! I hope that was it. Now I am going to check all the parts I got, some were from Jersey. ugh.  Lesson learned and note to self: CHECK ALL PARTS FROM UNKNOWN SUPPLIERS BEFORE USING !!!!!!!  Nashou |
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nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
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Post by nashou on Mar 31, 2016 20:09:05 GMT -5
The guys at Audiokarma gave me the idea to use 470 1 watt resitors across the Base and Emitter for testing voltages. I didn't have a 470 ohm 1 watt but I did have a bunch of 1k 1/2 watt so i put two in parallel and used that.
I first measure the voltages I could see listed on the PCB, the +/- 25 v and the 12 v those where there. I then moved to the underside to measure the output transistor pins.
BASE on all were from 5-6 vdc
Collector were all close to 50vdc
Emitters were all in the millivolts if i remember correctly.
the best part was NO SMOKE !!!!!
SO hopefully I'll get the new transistors by the week end or early next week. I also need new emitter resistors
and some bulbs. Just not sure about the 4 trimpots in her. I assume they are
for the idle current and the DC offset .
Two had 68k on them but the other two are nudie types( no plastic covering ) , no place to stamp them.
Thanks so far for the help Mac.
Nashou
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Post by mastertech on Mar 31, 2016 21:04:19 GMT -5
Yeah, hopefully it was that effed up output was the problem.
Just measure across the main coil of the pot and that is the value.
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nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
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Post by nashou on Mar 31, 2016 22:44:31 GMT -5
Yeah, hopefully it was that effed up output was the problem. Just measure across the main coil of the pot and that is the value. The variable resistor right? I guess it have to be removed to do so correctly . Nashou |
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nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
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Post by nashou on Apr 3, 2016 20:15:51 GMT -5
Well she sounds wonderful !!!!! Just tested one input so far but I have no reason to think that any other won't work. I think this one is a keeper for sure. love how she looks and sounds so far.
A little video for you guys.
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Post by mastertech on Apr 4, 2016 16:45:14 GMT -5
Good job. Nice to see it running again.  |
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Post by fuxtor on May 14, 2016 23:27:39 GMT -5
Wow, nice save! Looks and I bet sounds great... I am curious as to why couldn't 1/2 watt resistors be substituted anywhere on the board ( aside from fusubles) ??
As far as I understand it, going for bigger wattage only guarantees better results assuming they physically fit?? Mac??
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