TU8200 - weird problem

sunil

Member
Paid Member
2003-05-15 7:56 am
Bangalore, INDIA
Hi, wondering if someone can help solve a problem with the TU-8200 (earlier version).

About a year back I tried the 6P3S-e and while they sounded fine, the amp clearly was not pleased. Everything got really hot and ended up with weird buzzing noise. I replaced the mosfets Q1-Q4 and some of the problem went away.

Now, I have the strangest problem - even with the amp switched OFF I hear a slight buzz. The speakers are Altec with a fair bit of efficiency, but none of my other DIY amps have a similar problem. The buzz remains when playing music and gets louder with the volume control turned up. When switched off, the buzz is at a constant level and the volume control has no change. Any ideas would be really helpful, this thing is driving me NUTS.

Since THAT experiment I've stuck with G.E 6L6GC (tested on another amp). The only way to get rid of the buzz is unplugging the mains cord.

thanks,
Sunil
 

sunil

Member
Paid Member
2003-05-15 7:56 am
Bangalore, INDIA
Thanks Victor, was hoping you'd pitch in :). I checked the voltages some time back and they looked ok. I'll do them again in a week.

By glass diodes, do you mean ZD1 /2 /3 /4 ? My manual has a print date of 2014 and ZD1&2 show as BZX79C12 and ZD3&4 are IN5929B. Is that right ?

Any pointers to the check point number would be super helpful ? My list has 29 points.

regards,
Sunil