power amp repair

Hello! I have problems with a nice Doxa model 40 power amp. It sounded absolutely fantastic and gave me a lot of joy, until it decided to no more. It wouldn't turn on. Opened it up to look for visible faults and there was a blown 6.3a slow fuse. Tried replacing it but it kept happening...

Hi, Wanting some help with a repair of this old NAD3020 amplifier that has blown the left channel. I have hopefully attached the relevant schematic. Soft clipping is off and Pre-out / Nor in connected. When I got it the right channel played fine, but the left had no output and a -10V DC...

Hello! Today I picked up a Kyocera R-851 as part of a lot of audio gear, and I’d like to get it up and running. The guy mentioned that the unit “doesn’t power on, but smokes when you hit the power switch”. Considering the rest of the lot was well worth my money, I figured it was worth a shot...

I am repairing power amps on a JVC FX515VTN. There are 2SD636 NPN Epitaxial Planar transistors used in the bias circuit. The bodies of these transistors have a hard white coating, looks like it could be paint. I am positive the coating is not thermal compound paste. I looked at an Onkyo power...

I appreciate everyone’s input on this forum and I have learned a lot from reading about other people’s issues. I was inspired to take on my first project, of this type, knowing there was a lot of knowledgeable people on the forum. I am restoring an SX950 that I bought new in 1977. It worked...

I was recently offered a Carver TFM-45 for under $100. The right side meter bounces all the time. I do not know what it does while its hooked up to a speaker. When you turn it up and down it changes the speed of the bouncing. I am curious if anyone might know what the problem may be and how hard...

Hello techies I have a clients 250 here. One side is fine and adjusts per spec The other side has over 4.00 DC on it and I've replaced a number of the smaller lytic caps and the first pre-driver transistor. It still has over 4.00 vdc out . The power transistors are ok with the exception that...

SCA-80Q Blown Resistor (5) by Ron Joiner posted Sep 13, 2016 at 10:51 AMSCA-80Q Blown Resistor (4) by Ron Joiner posted Sep 13, 2016 at 10:51 AMThis past spring I resurrected this old integrated amp from the basement. It immediately developed a loud hum. I addressed this by replacing many of the...

I'm considering buying this amp from a local fellow. He told me he burnt a resistor last time he used it (some months ago) and he hasn't gotten around fixing it. I was wandering if someone here could share his/her thoughts regarding the issue and possible causes. I'm not an electrician and no...

I have a Denon DRA-325R receiver (from the late 80s or early 90s) which I have used off and on for many years, and which is currently hooked up to our Blu-ray player for better sound during movies and shows. It still works fine, except that it will sometimes "reset" itself, powering off and then...

I have a Pioneer M-90 power amp which I've owned for over 20 years. I bought it out of the broken pile at a pawn shop and with the help of a knowledgeable tech I was able to bring it back to life. I have had it in to a repair service twice since then and have had extensive work done replacing...