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I switch between backplane and control board, but they both agree 1:1, so I typically use the TP1 on the backplane.

Looks good with bottom row in. Bias is at 0.255v full CCW on the pot. Came up to 0.350 just past halfway point. Holding steady. Broken WOPL400 may be off the market. Time to crack a beer and celebrate prematurely!

I pulled the driver transistors and brought her up slowly. Bias voltage ran up along with rail voltage, until magically when rail voltage reached 10vdc bias clicked down to 0.05vdc. It held there all the way to 120vac. I may not have a problem after all. My problem may have been pussyfooting...

Sonofabitch. I've been chasing ghosts.

Always. Variac -> DBT -> WOPL400. I haven't had any real illumination since the rectifier polarity issue was resolved a few weeks back. Only the slightest glow since at 120VAC input - and even then I have to shield the light from ambient to see the orangeish glow. Unfortunately it's a...

Are you implying that I can pull the driver transistors and not worry about the bias runaway because nothing expensive will blow? Then I could run it up to 100 or 120VAC input and see if the bais settles in or continues to climb with the rail voltage?

This is fun and all, but can we get back to solving my failure :-)

There may be something to that. The first time I brought it up with the driver transistors installed and the control board wired in, I don't remember what voltage I was monitoring on bring up. I could have been looking at rail voltage or offset and then didn't check bias until voltage was...

White Oak Audio Design

You probably already know my status. I started tearing into the stock chassis on January 22. Had the stock wiring and boards out and the filthy chassis cleaned up on February 6. Started wiring on February 11. Tried to power on for the first time on March 26. Hit a roadblock on April 9 and...

I was enjoying myself and listening to a new Clapton Crossroads 2019 vinyl box set that just showed up today. It sounds great. I highly recommend it. I was thinking I found enough questionable solder joints to feel fairly confident that I addressed the problem. Apparently it's somewhere else.

Both channels + and - I have not tried jumpering out the bias transistor. Does the fact that it's both channels point in any direction?

Here's how it lies. Bottom row of drivers in place and control board mounted.

Honestly, I'll never give up. I'll eventually get it. But I may be giving up for tonight.

I tore the whole thing apart down to the chassis. Cleaned up all of the solder joints. Checked all connections. Brought it up backplane only - all good. Added bottom driver transistors and brought it up - all good. Mounted and wired in the control board and just put the slightest voltage on and...

Ugh. I give up. Anyone want a broken WOPL400?

I don't know what they are, but those speakers look awesome. That Phase Linear 200 is basically why I'm here in this forum now. When I was a kid, my dad had that 200 and a Harman Kardon Citation 11 preamp pushing some Infinity 12" 3-ways. The bass was so punchy and tight. It took me decades to...

Costa Rica I believe.

You can't be poor... You live in a tropical paradise! Even if you are low on cash, you're still well off.

I had a set of Pioneer CS-99a's with the FB drivers in my garage setup at my last house. I had remodeled my kitchen and mounted all of the old cabinets in the garage with the Pioneers as the focal point. I rented the house out and left the garage setup as-is thinking that would be a good feature...