Search results

Thanks for looking Lee. The joints are pretty solid they just don’t show up well in the pictures. Joe the copper plate is there insulated from the chassis and wired per your updated ground scheme. Thanks!

I still need to tin the wire ends and dress everything up. Then onto the input wiring. That is provided I don’t mess anything else up on the way.

Maybe these will help.

Where exactly would that be?

Forget that last post. The fuses were not installed. With the fuses in I now read with variac at 120 volts .249 volts on the bias. Bulb is faintl glowing. I’ll see what happens when I reinstall the 4th row. Probably just a brain fart on my part. May not be tonight. Thanks

Symptoms are normal except that I have zero bias voltage when connected to either of the two test points. Bias is reading .032 volts

When connected to the board they show shorted. When disconnected they test good.

Thanks George! There is a schematic. I’m just not smart enough to follow it.

I do have grabbers. I have 15 volts positive and negative on both channels. The voltage regulators seem to be working.

The bias transistors test ok when disconnected from the board. They fail when connected.

These are all new MJ21196G transistors from Joe except the pr-drivers are the original rca 410.

Fuses all check good.

When I checked bias from both test points it was zero. They had been running around .260 with the pots fully CCW. They both would adjust up if you turned the pot.

This is where contact was made. I don’t recall taking the variac beyond 30-35 volts because the DBT stayed bright. I only powered it up for a few seconds. I pulled the outputs from that 4th row and they tested good. The others are still in place.

Time to play “Stump the Experts”. I am working on a 700b I’ve had for a few years. I’ve installed one of Joes rev g boards along with new power supply caps, rectifier, arc fuse holders, input jacks, iec outlet, dc protect board, new wiring, and new resistors on the original backplanes. Now for...

Or termites!

It’s like watching a crime show!

I had quartz installed a couple of years ago. Two seams that are nearly invisible.

Could you tell me what you used to clean the rca jacks?

Looks like the price of donor 400’s is going to go up even more!