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mosfet replacements please help!!!

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young simba sounds View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote young simba sounds Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2017 at 8:13pm
between the resistor is the two brown little ceramic capacitors thats the last thing, i have one that has gone, any info on what would be the best as there is no indication on them? 

Edited by young simba sounds - 16 May 2017 at 8:17pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote young simba sounds Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2017 at 8:15pm
between the resistor is the two brown little ceramic capacitors thats the last thing, i have one that has gone, any info on what would be the best as there is no indication on them? also this is a pic of the board in repair 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2017 at 8:16pm
Originally posted by young simba sounds young simba sounds wrote:

thanks everybody, also would anybody no a close value to the small ceramic capacitor next to the mosfet?

the little orangy brown ones have no numbers or any values on them at all??

If the capacitor is connected between drain & Gate of each FET then i assume these are being used to minimize the amplifier from oscillating & i would say around 10pf (250v).WinkWink

That PCB board looks like the top MOSFET output module of a PSL amplifier ???. Check Gate voltage protection diodes / Zeners as well.Wink


Edited by simonp1100 - 16 May 2017 at 8:22pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote young simba sounds Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2017 at 8:18pm
perfect, this is more a project for me so will get them ordered thanks again for quick replys!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2017 at 9:55pm
Do yourself a favor and buy one of these little doodads - http://www.ebay.co.uk/itm/New-All-in-1-Component-Tester-Transistor-Diode-Triode-Capacitance-ESR-Meter-0W77-/201493269992?hash=item2ee9ef4de8

I promise you will find it more then useful enough to warrant the price tag for applications of unknown components.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 16 May 2017 at 10:42pm
good sounding amps when working properly.
K. Edwards Electronics Engineers

North Staffordshire

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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2017 at 12:18am
DALBANI !!!

Have had a huge problem with them in the past with counterfeit parts.

Buyer Beware.


Edited by _djk_ - 17 May 2017 at 1:28am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote young simba sounds Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2017 at 8:16am
odc04r i will do, i just havnet really thought about getting into amp prepair im very very novice, dont no much but do no a couple little basics, been lurking on this forum for years and years learning and takng in points. after further looking at this amp on the secondary board all the fets are unmatched anyway ShockedShocked so looks like either somebody has been in there before (could be within 20 years) as they are old now as i doubt they was made that way, this is more of a practice amp for me anyway so if it goes wrong it does
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Post Options Post Options   Thanks (0) Thanks(0)   Quote young simba sounds Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2017 at 8:22am
thanks for heads up djk!!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2017 at 9:40am
Originally posted by young simba sounds young simba sounds wrote:

odc04r i will do, i just havnet really thought about getting into amp prepair im very very novice, dont no much but do no a couple little basics, been lurking on this forum for years and years learning and takng in points. after further looking at this amp on the secondary board all the fets are unmatched anyway ShockedShocked so looks like either somebody has been in there before (could be within 20 years) as they are old now as i doubt they was made that way, this is more of a practice amp for me anyway so if it goes wrong it does


That's why I recommended that gadget :) Like a budgie it is very cheap for the help it can provide.

Maybe it would be worth drawing out the schematic and simulating it, then seeing what other FETs might work well in it? I have no idea if they exist but I bet you could get somewhere close and you'd learn an awful lot. Plus simulation is free and quite powerful for the audio frequency range if your device models aren't hopeless.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote young simba sounds Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2017 at 9:45am
yeah thanks again, we all have to start learning somewhere, everything i am good at apart from circuits and amplifiers, its the last part of audio im yet to learn so now is time to start i think SmileSmileWink i have orderd all parts so far ill keep you updated when all come to see if the amp fires properly, (it did fire when i aquired it) but ive only just realised these parts had gone, i heard amps will still run without some fets anyway??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VentureSound Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2017 at 1:38pm
Originally posted by _djk_ _djk_ wrote:

DALBANI !!!

Have had a huge problem with them in the past with counterfeit parts.

Buyer Beware.

+1 
Beware Dalbani. Quite well known for selling fake parts. 
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