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Old 7th June 2011, 05:25 PM   #141
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Good advice - Check MOS-FET case temperature with an infra-red non contact thermometer. Only then can you guarantee that you are not cooking the little babies.

I've got mine temporarily biassed at 10A just to check the heatsinking. The heatsinks are hot but the MOS-FETs are even hotter. It is the junction temperature that will kill them, not the heatsink temperature.
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Old 7th June 2011, 05:55 PM   #142
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ok, so if a mosfet pops (like I guess mine did). How would I go about checking that mosfet?

I guess I'll need to replace more than my mosfet. Do the mosfets need to be matched? ( I don't recall I did, just double checking...)
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Old 7th June 2011, 06:11 PM   #143
Itsmee is offline Itsmee  England
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MOSFET testing

The N & P MOSFET's don't need matching

Last edited by Itsmee; 7th June 2011 at 06:14 PM.
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Old 7th June 2011, 06:46 PM   #144
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Great, thanks. I'm pulling it off the board tonight.

Would anyone happen to spare a few parts? (I'll pay for them.) I don't want to bother with digikey.

I'll have a small parts list tonight...
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Old 7th June 2011, 07:47 PM   #145
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Just one point temperature cek with infrared of course is fine but do you trust your infrared termometer?
Unless expensive and calibrated properly they may give you a wrong reading.
Spot size, alignament and the reflection coeficent are all to be taken in consideration.
(nice article in eleKtor mag. 2 months ago made me decide against gettin one.

I got a digital meat thermometer that cost Ģ14 not super accurate but at least I know what I am measuring.

I got few spares (well loads off) what you need and postagge cost may be the issue?
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Old 9th June 2011, 09:56 AM   #146
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If I want to experiment and change some resistance by others of better quality or sonic signature on the pcb F5, what are the most appropriate?, "a difference between prp, caddocks, mills, etc?
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Old 9th June 2011, 11:40 AM   #147
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AlbertoB

If you like I got a load of Holco MF 2W 15ppm

If you send me paid return envelope I be quite happy to give you 4X10R 4X47R and 12X 150R
for you to try out free.

I have a stash of Futabas MCP74 but those are not free.
Send PM if you need to take this further.

For the other values I use RC55Y which IMO sound prety good for the maney

I am thinking about triing Z foils later but Ģ10 each is going to be expensive and maybe just for the imput resistor R9 1K
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Old 9th June 2011, 05:09 PM   #148
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I did some resistor swapping on mine.
Changed the input path resistors to vishay Nudes yes the expensive ones on the 1K as welll as R13 and 14 (47ohm).
Then swapped all the feedback resistors to Caddock MK132s

Yes it sounds better than the stock panny and dales. It takes out some of the high end sterility and gives it more PRaT. Also better midrange as well.
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Old 10th June 2011, 07:02 AM   #149
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Bksabath Thanks for the offer. I will try to Caddock.


Quote:
Changed the input path resistors to vishay Nudes yes the expensive ones on the 1K as welll as R13 and 14 (47ohm).
Then swapped all the feedback resistors to Caddock MK132s

You can, please list the parts for a klutz like me?. example: r14-Caddock ...

THANKS!
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Old 10th June 2011, 03:29 PM   #150
dazed2 is offline dazed2  Canada
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For R9,13 and 14 I swapped in Vishay TX2575 series resistors.

For R1,2,5,6,7,8,10 I swapped in Caddock mk132 series resistors.

I would try the vishays first, listen to the amp, and then add the caddocks.
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