Avionixx AXT800.2

spooney

Member
2006-12-01 4:41 am
I have this amp here with blown outputs and power supply fets.The outputs (W34NB20) are easy enough to find but I am having some trouble sourcing the STP80NE0's in the power supply.Does anyone know of a viable substitute for this part or a place it can be found?Also the gate resistors in the power supply are totally fried beyond recognition.Does anyone maybe know what the value of these resistors might be?
 
How many outputs were shorted? And where did you find them cause everywhere I looked here in the US says the exact part is discontinued.

I ask cause this design is a text book Tripath design and after doing a bunch of these. I am use to a few things.

First off for the supply to toast out like it did it was either not fused, or mis-fused badly. Also The power supply toasted when the outputs shorted, but when they did the drivers inside the tripath IC also most likely went south also. A good IR replacement for the supply is the IRF3205. typical gate resistors are 30 ohms for the original 80 amp mosfet.

Tripath stopped production of all these early D class divers and if your lucky you might find one floating around at 41Hz website < Maybe.

And the replacement ( TA2500) although labeled as a universal replacement requires a bunch of tweaking to get get to work without turning off for no reason.

Most amp makers like Clarion, PG, and others that bought into this design all have stopped supporting it. Clarion says sorry no parts available for their older T class amp. Some makers with any reputation are replacing these with newer designed amps for a flat fee to maintain customer loyalty.

I own two of the early PG Tantrum 1200's that were built with the exact same parts. Your chip is either a TA 0103 or a TA 0102 for lower powered amps like the Clarion., and both are fun to locate nowadays, I wish you luck and if you do find them please link me up. I could use a few myself.

As for testing the amp you will need to repair the power supply minimally ( leaving out all but just enough fets to just run the amp at idle) and then after getting it turn on read the gate drive signals with the bad outputs removed of course. I have seen 1 in 10 with good Tripath chips after such a blow out as you describe.. I wish you much luck, and I hope some of this info helps you to do the right thing...:)
 

spooney

Member
2006-12-01 4:41 am
the outputs I found were at mouser.I think two of the four in the output section are toasted but I am not positive as I haven't pulled them from the amp yet.The part number at mouser is STW34NB20.If this is not the correct part please let me know.I will order the power supply fets and gate resistors and cross my fingers and hope for that 1 in 10 chance. I wish I had looked a little deeper into these things before I purchased this amp.Is there any serviceable parts inside the cover of that tripath chip or is it just a large IC?
 
There is nothing serviceable under the plastic cover of the Tripath board. The small IC would be impossible to get a hold of and the FET drivers are permanently sealed.

http://i32.tinypic.com/4zutza.jpg

What Tripath IC is it? Here are a couple TA0102A for sale on ebay (not cheap)....

http://cgi.ebay.co.uk/TRIPATH-TA010...VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247

BTW, I have 10 used STW34NB20 you are welcome to have. They were removed from a working Tripath amp. Actually, I can send you some HUF75337P3 75A 55v 0.014 power supply FETs too. This way you will have everything you need to try and fix the amp (minus a new tripath IC) without spending a dime. If it works, then you could upgrade the supply FETs if you feel it's necessary.
 

spooney

Member
2006-12-01 4:41 am
I installed two power supply fets and new outputs today.The amp powered up no problem.One channel appears to have straight rail voltage coming out of it and the other appeared to function correctly but when I hooked a speaker up to it the fuse blew instantly although it was a very small fuse(3 amp).Is the rail voltage I'm seeing on the one channel a symptom of a bad tripath IC?