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Old 2nd June 2009, 11:51 PM   #1
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Location: Dover,ohio
Default punch 60 dsm getting warm

I had a 60 dsm given to me and it has p80nf55-06 for the ps fets
and they heat up fast.

The bias is turned all the way down after I thought that might cause it.
Are the 68 ohm gate resistors fine with those fets?

The amp works fine other than that.
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Old 3rd June 2009, 06:17 AM   #2
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Do they heat up at idle or only when it's driven hard?

Were they clamped to the heatsink when they were heating up?

It is possible that the gate resistance is too high. These input capacitance of those FETs is significantly higher than the originals (likely IRFZ40s or BUZ11s).
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Old 3rd June 2009, 04:24 PM   #3
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It heats up at idle , fets were clamped .
the 2 caps by the ps fets are getting hot also at idle.
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Old 3rd June 2009, 04:26 PM   #4
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Do you have any resistors between 33 and 47 ohms you could install in place of the 68 ohm resistors?

If so, try it to see if it makes a difference.
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Old 3rd June 2009, 09:55 PM   #5
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replaced them with 47 ohm and seems to be ok .
This amp was a real hack job , parts unsoldered inside the cover , atleast i didn't pay anything for it .

Thanks for the help!
Ben
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Old 3rd June 2009, 10:37 PM   #6
ppia600 is offline ppia600  United States
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Quote:
Originally posted by Perry Babin
Do you have any resistors between 33 and 47 ohms you could install in place of the 68 ohm resistors?

If so, try it to see if it makes a difference.
This /\ guy knows his stuff
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Don't worry... you can always turn the gain down!
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