700/1 “Tim” WOPL driver board

[AngrySailor]

The diodes around those, the low voltage test points in the middle od the board. Rail fuses ok?

I annihilated the rail fuse on the right channel + rail when I slipped with the probe. The fuses are all ok now that’s when I smoked the bias resistors. I’m not real close to being up yet either, still got some reassembling to do.

 

[AngrySailor]

For the really tough rosin----acetone. Dont get it on electrolytics.

Nice, I’ll give that a try.

 

[laatsch55]

K...

 

[AngrySailor]

K...

Getting some strange diode reading but I bet that’s because they’re in circuit?

 

[laatsch55]

Strange?

 

[AngrySailor]

Fug... I forgot to solder the negative rail supply wire before I put the back plane in... this gonna be tight...

 

[AngrySailor]

Strange?

Everything checks 600mv one direction on diode test, some have reading with the leads reversed. Linda’s board tests the same, Tim’s tests same side to side.

 

[laatsch55]

K....

 

[AngrySailor]

Ok I think I’m ready to try a bring up. Got stuff taped off like the 6v supply and the meter wiring. No DCP installed rn, speaker outputs taped off, RCA 401’s and one row of XPL909’s installed. Going to plug in the DBT and variac for this one... wish me luck!

 

[AngrySailor]

Right channel kept the bulb on, pulled the 410’s and the first row of 909’s. One of the drivers tested wonky swapped that out. I got drivers and one row of XPL909’s in now. Passes DBT, bias 260mv pot at minimum and responds to increasing. Time for another row!

 

[AngrySailor]

All outputs in, both channels pass DBT, bias same both sides pots down, pots in same orientation for ~350mV each side.

 

[George S.]

Cool, your getting really good at that!

 

[AngrySailor]

Cool, your getting really good at that!

Practice makes perfect guess I’m getting lots! Hopefully got it licked. Might take a break for a bit maybe the night. Gotta put the DCP back in and connect the meters and light board too. Made a real brain fart there forgetting the negative rail supply, also got the wrong bias resistors... see how long these hold up!

 

[laatsch55]

You might be surprised....check offset too, when ya get the DCP back in...or you can check it now..

 

[George S.]

If you have extra resistors you could parallel them for the time being.

 

[laatsch55]

If he had a couple 20 ohm....yeah...

 

[AngrySailor]

You might be surprised....check offset too, when ya get the DCP back in...or you can check it now..

Bias 350mv with no DBT, both channels <5mV offset. 4.2&4.4mV

 

[laatsch55]

EXCELLENT!!!!!!!!

 

[AngrySailor]

EXCELLENT!!!!!!!!

I’ll finish assembly tomorrow. Having a celebratory beverage at a friends place working on tractor fenders.

 

[laatsch55]

As well you should, when messing with the original backplanes that's a win bud!!