# audiobahn a4801t and a1300hct



## cheebs (Apr 3, 2009)

i have these two audiobahn amps i was given for freeeeeee. but of course somethings wrong with them. are they worth saving? i took a look and i saw a few burnt mofets on each. should i try and replace those before trying to send it out to get fixed. a few dollars for a few fets i could do. wheres the best place to find the fets? on one or two i can't see the numbers. is there another way to find what they are?


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## sq_assasin (Nov 10, 2008)

cheebs said:


> are they worth saving?


IMO, no.


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## sqshoestring (Jun 19, 2007)

I've fixed quite a few, some are just blown on the sink some not. Is it the power supply (around the transformer) or the outputs? The PS they will all be the same except for the rectifiers, or were in AB amps I worked on. The outputs in class AB will have two types the same deal in each channel. One kind on positive rail and another on negative rail. The class AB the outputs are a larger case transistor than the mosfets in the PS, they didn't use mosfet outputs. I have an A8000T I think, pretty sure it has IRFZ44 in the PS I can go look if you want. Mouser or digikey is a good place, should be <$2 each. They are a cheaper amp and they do blow up, but for all I know they were running them at 1 ohm I have no idea.....just fixed them and bailed. I been too busy in the summer to play with amps though. If the are lower power they are not worth much, I got well over 100 last time I sold a 8000 (2x200rms iirc) but was last year. If you put the parts in, start it up on one 10A fuse and they usually will not blow the new parts if you have them clamped to the sink.


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## cheebs (Apr 3, 2009)

sq_assasin said:


> IMO, no.


wow so harsh. you don' think they would be worth 20$ in fets?


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## Volenti (Feb 17, 2010)

I'd check the output transistors before you go and replace the powersupply fets, plenty of the cheap amps I've fixed have had the power supply fets explode _because_ the output devices have failed to a dead short, and then they play a fun game of power chicken, see who explodes first


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## sqshoestring (Jun 19, 2007)

Go to bcae1.com and read the amp repair page if you have not, lots of good info.

Right you have to test the outputs if you do a PS, that is often why they let go.


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## kevinb84 (Jun 17, 2010)

im in a similar situation and cant afford a new amp at the moment. my a2200hcq blew the power fets so i ordered replacements and got them put in. when i hooked up the power and ground it imediately blew the amp fuses. it didnt do this before i switched out the fets. now i test the rectifier (what i think is the rectifier circuit) and it seems these are bad. they seem to be obsolete parts tho now and i cant seem to find a cross reference to the part # F15U20DN and F15U20DP any ideas on what would be comperable to this.

none of the output fets are bad they all test good.


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## Volenti (Feb 17, 2010)

kevinb84 said:


> im in a similar situation and cant afford a new amp at the moment. my a2200hcq blew the power fets so i ordered replacements and got them put in. when i hooked up the power and ground it imediately blew the amp fuses. it didnt do this before i switched out the fets. now i test the rectifier (what i think is the rectifier circuit) and it seems these are bad. they seem to be obsolete parts tho now and i cant seem to find a cross reference to the part # F15U20DN and F15U20DP any ideas on what would be comperable to this.
> 
> none of the output fets are bad they all test good.


Maximum Reverse Recovery Time is the critical spec for these rectifiers (appears to be 40ns in this case) along with peak forwards voltage, peak forwards current and average forwards current search for "ULTRA FAST RECOVERY POWER RECTIFIER" check the datasheet and make sure it's 40ns or lower.


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## kevinb84 (Jun 17, 2010)

Volenti said:


> Maximum Reverse Recovery Time is the critical spec for these rectifiers (appears to be 40ns in this case) along with peak forwards voltage, peak forwards current and average forwards current search for "ULTRA FAST RECOVERY POWER RECTIFIER" check the datasheet and make sure it's 40ns or lower.


awesome, thanks for the help!!!


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