Should I do it or Not??? Tech question


I accidentally shorted out the speaker cables connected to my Creek 5350(not SE version). There are 2 fuses that I replaced(same rating of course) but it keeps on blowing up every time I turn on the power. I contacted Creek Audio and told them about the problem. Here is their reply:

"The fuses inside the 5350 are in series with the power supply. They are there to protect the power supply in the event that there is a fault with the amplifier that would cause it to draw unlimited current. Shorting the output has unfortunately blown the power transistors on that channel. They fail as a short, which is why the fuses have blown. I'm sorry to say you have been unlucky, but will need to have the power transistors replaced."

I replied back telling them that I can replace the power transistor myself(I already bought the parts) and this is their reply.

"Dear Sir,

This is not the type of repair that can be carried out by the public so I would advise that you contact the distributor for help in getting the unit fixed.

Without seeing the amplifier I would not be able to say if it was just the output transistors and even if it was, you will need to be able to power the unit up on a stabilized power supply before adjusting the BIAS current to avoid damaging the amplifier again."

Here is my question to the tech savvy out there. Should I go ahead and replace the power transistor? I don't know what "you will need to be able to power the unit up on a stabilized power supply before adjusting the BIAS current" involves, plus I don't have any of that equipment other than a volt meter. What are the chances that it'll blow up again if I skip those steps and just replace the power transistor? This amp is probably worth $300 now, if I send it in for service, it will probably cost me $200 plus shipping it back and forth, so I'm willing to gamble on it if my chances are good.

royy

Showing 2 responses by tobias

Yes, as Unsound says, you are in over your head. If you don't know what bias current is or how to adjust it, then after the repair the amp will sound horrible and may even oscillate ( and damage your speakers )--even if you do solder the new parts in correctly.

Royy, have the repair done by a competent technician or sell the amp as is, but don't take any chances with what's still not broken. It's too bad, but things like this do happen and they cost money to fix. I blew the outputs on the same NAD amp not once but twice, doing exactly what you did.
No, your bias trimpot setting will not necessarily be the same for the new output device as it was for the old one.

Transistors, like tubes, vary from sample to sample. That is why the better gear includes matched pieces.