xtant 3300c

[nath339]

im attempting to repair two xtant 3300 c amplfiers
one the power supply supply fets have gone
one the output fets have gone

the output devices on both amps are the same
the problem i have is the power supply fets are differant in each amp and i dont know which one is correct

the amp with the blown outputs is using irfz44 fets for the power supply and this amp does power up
the other amp which will not even power up is using
smp50n06
both amps appear to be the same revision

could someone please tell me which ones are correct before i attempt to repair

thanks
nath

[Perry Babin]

Generally, you can determine if the parts are original by looking at the solder connections. Assuming that one set of parts are the originals, the parts have similar specs so either should work in the amp.

[nath339]

thank you very much kind sir

[nath339]

right have moved onto the second amp
which has blown outputs

at first i thought they were the same but after carefull checking there are a couple which have been changed

heres what ive found

ive found three outputs which originally look like they were
buz20 have been replaced with irf530
is this a suitable match or are these not suitable ?

ive also found three buz271 which have been replaced with irf9z34
again is this a suitable match or could this have been what lead to the failure in the first place

one last question what on the datasheets am i looking for to tell me if one transistor is suitable to be replaced with another

[Perry Babin]

Those are generally good replacements. The 9z34 is rated for less current so it may not be quite as reliable if the amp is driven hard.

In a linear audio amp (not class D), the most important specs are voltage and current. It must be able to withstand the total rail to rail voltage. It also must be able to withstand the current output. If the current rating is equal to or greater than the originals, it should be a good replacement.