phase linear 400

[gene french]

You had the chance of buying all new stuff from WOAD instead of trying to fix 40 year old junk. THAT was the bad decision. You should be a genius by now.

thanks....

 

[gene french]

I think there is a big difference of Abe losing elections and Edison working the bugs out of an invention than you building a half an amp.

Gene
It is WOAD. You can start the guessing now

not even close???

 

[gene french]

NOPE

thanks....if one doesnt expect much...one suffers a lot less disappointment..

 

[WOPL Sniffer]

thanks....if one doesnt expect much...one suffers a lot less disappointment..

Yer like my dad.... You have a lot of Sayings but they are all lame.

 

[gene french]

they are not my adages...i gave credit where credit was due...i just happen to agree with them...

 

[WOPL Sniffer]

Hey, another one...... Give Credit Where Credit Is Due...........

 

[gene french]

you are writing these down arent you???

 

[WOPL Sniffer]

you are writing these down arent you???

Now THAT, would be my mistake

 

[gene french]

lol....good one!!!!

 

[ABebar]

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

 

[ABebar]

You know Adam that with full comp backplanes installed that you can debug just about any problem with the control board installed BUT with no output devices of any sort installed. The beauty of the full comp configuration

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?

 

[Gepetto]

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?

I actually said it Adam. Are you using your DBT?
Your observed bias voltage will be much reduced because you will now have an additional 150 ohm resistor in series with each 10 ohm bias resistor

 

[ABebar]

I actually said it Adam. Are you using your DBT?

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 frosted glass soft white 75w incandescent.

 

[ABebar]

Sonofabitch. I've been chasing ghosts.

 

[ABebar]

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 as I think Andrew put it.

Adding back in the bottom row and see what we have. I'll run it up to 10vdc rail and make sure I get the same results.

 

[gene french]

Sonofabitch. I've been chasing ghosts.

now...there....look how much you know now than if you had succeeded the first time....experience...experience!!!
congrats....lol
at least your errors were free....a word of advice...DONT PUT IN C8 BACKWARDS....lol

 

[ABebar]

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!

 

[Gepetto]

Sonofabitch. I've been chasing ghosts.

We knew that Adam

 

[Gepetto]

BTW, where are you placing your meter leads when measuring bias?

 

[George S.]

That dull orange glow with a 75 watt bulb is normal and correct. Mine got brighter with each added row on all three builds I've done.
Hoping for your success. I got really freaked out powering up the 700 build after the last row using a 100 watt bulb. Turned it back down and checked everything twice more before finally bringing it all the way up to 120V. Hearing the DCP relay click, good bias, and no smoke was key. Still really freaked me out.
Make sure you turn the bias all the way down before you install the next row, and double double check each transistor in vertical column is same.
Congrats.