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Old 9th November 2012, 08:43 AM   #12651
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light is a bit bad...hopefully you can see
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Old 9th November 2012, 08:59 AM   #12652
Zen Mod is offline Zen Mod  Serbia
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that's present pic ?

already pull them from the amp ?

whatever - desolder mosfets and jfets , check them with Idss test

check all solder points , use magnifier if needed
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Old 9th November 2012, 09:13 AM   #12653
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No, that is a pic just before fitting to heatsink.

What is the easiest multimeter test on the fets? Test impedance between G and S for very high impedance (open cct)?
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Old 9th November 2012, 09:24 AM   #12654
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well , picture of parts still in bags is almost equally useful

except fro measuring dead part - short between pins - DMM alone isn't too much useful for testing them
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Old 9th November 2012, 09:33 AM   #12655
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Quote:
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well , picture of parts still in bags is almost equally useful

Thanks for the interest to help ZM!

If I pull the fets from the boards and test them to be ok I am going to look for the answer in the bottom of a bottle of whiskey.

Last edited by valvesound; 9th November 2012 at 09:36 AM.
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Old 9th November 2012, 09:49 AM   #12656
Zen Mod is offline Zen Mod  Serbia
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you can't do much funnier thing on end of the week

but - do that with some company , and stay at 0,2L per head

for mosfet testing look at Pa's articles on FW

for Jfets - here it is (0 Rs for Idss)

you can use 9V battery instead of 12V drawn
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Old 9th November 2012, 09:51 AM   #12657
fdlsys is offline fdlsys  South Africa
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Quote:
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Guess the culprits will most likely be the mosfets as they are static sensitive.
W, where did you get your JFets from? I presume you didn't measure them before soldering, hmm? Asking because the world is flooded with fakes...
M
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Old 9th November 2012, 10:35 AM   #12658
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Hi Mike!!

I got them from B&M enterprises paid handsomely because I was afraid of the Chinese versions. I believe them to be good originals. But nooo...I did not measure them before installing :-o

I'm sure I must have damaged an output mosfet with static or something...all I can think.

Last edited by valvesound; 9th November 2012 at 10:39 AM.
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Old 9th November 2012, 10:37 AM   #12659
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you can't do much funnier thing on end of the week

but - do that with some company , and stay at 0,2L per head
NO NO...0.2L is not enough volume to achieve resonance!!!!

Last edited by valvesound; 9th November 2012 at 10:40 AM.
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Old 9th November 2012, 11:41 AM   #12660
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NO NO...0.2L is not enough volume to achieve resonance!!!!
Try barrel strength!

Russellc
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