phase linear 400

gene french said:
what is the minimum i can power on with....just the bottom two rows on left side???
Click to expand...
On the WOPLs, we start with bottom row, check bias, then next row, check bias, next row, etc. On a original quasi backplane, I don't know. I don't see how it would be any different. I may be wrong.
 
Gene, the guy I bought the amp that board came out of said he used it as a guitar amp and the amp worked fine. But, I never even plugged it in before stripping it.
 
There is a way to bypass the bias transistors with a diode to simplify troubleshooting, but you'll have to search the forum on how to do it. Never done it myself, but it's been mentioned many times.
Long day today and again tomorrow. Later. Don't smoke more parts, sometimes it's good to step back away from it, think and sleep on it, tomorrows another day. Perhaps there's good info in the WOAD Tech Docs that'll help.
 
George S. said:
There is a way to bypass the bias transistors with a diode to simplify troubleshooting, but you'll have to search the forum on how to do it. Never done it myself, but it's been mentioned many times.
Long day today and again tomorrow. Later. Don't smoke more parts, sometimes it's good to step back away from it, think and sleep on it, tomorrows another day. Perhaps there's good info in the WOAD Tech Docs that'll help.
Click to expand...

You put a jumper between C-E of the bias transistor, it takes the bias to zero.
 
George S. said:
There is a way to bypass the bias transistors with a diode to simplify troubleshooting, but you'll have to search the forum on how to do it. Never done it myself, but it's been mentioned many times.
Long day today and again tomorrow. Later. Don't smoke more parts, sometimes it's good to step back away from it, think and sleep on it, tomorrows another day. Perhaps there's good info in the WOAD Tech Docs that'll help.
Click to expand...
already watchin the tube..lol...youre a good guy...
thank you...
 
Gene, your dealing with a bunch of unknowns with all those old parts, so try this. Remove the top 3 rows of outputs leaving only one bottom output in each column. Test for stabile bias and DC on the speaker jacks. If unsuccessful, add no more outputs until you find the issue. If successful add another row, and retest.
This is part of "the bringing up procedure" in the docs. I didn't do this in my latest S1 upgrade thread because I had a working amp prior to the upgrades which didn't involve the outputs
Best practice is bring it up row by row and check for issues with each row.
I'm thinking your going to find a leaky output or shorting socket like Andrew had on his 700 S1. He said the DC would rise as he tightened a screw, a bad socket.
Read the tech docs about populating the outputs and bringing up a WOPL.
 
George S. said:
Gene, your dealing with a bunch of unknowns with all those old parts, so try this. Remove the top 3 rows of outputs leaving only one bottom output in each column. Test for stabile bias and DC on the speaker jacks. If unsuccessful, add no more outputs until you find the issue. If successful add another row, and retest.
This is part of "the bringing up procedure" in the docs. I didn't do this in my latest S1 upgrade thread because I had a working amp prior to the upgrades which didn't involve the outputs
Best practice is bring it up row by row and check for issues with each row.
I'm thinking your going to find a leaky output or shorting socket like Andrew had on his 700 S1. He said the DC would rise as he tightened a screw, a bad socket.
Read the tech docs about populating the outputs and bringing up a WOPL.
Click to expand...
yes sir....will do...
joe said one row will surfise to start...which is the row of driver transistors
 
set both offsets to zero...
set both bias to 350...
left channel bias pot no longer at the stop...
has two way adjustment from the present position...
will proceed to add one row of 909s
this test was done with only the bottom row of driver transistors...
as per joe and george...
 
second row in....
no dc on outputs....
left offset and right offset set to 0...was off a bit...but well within tolerances
right bias set to 350mv
left bias set to 320mv when pot runs out of adjustment....
i think i will change left and right 909s...to see if it follows the transistors ...
 
gene french said:
second row in....
no dc on outputs....
left offset and right offset set to 0...was off a bit...but well within tolerances
right bias set to 350mv
left bias set to 320mv when pot runs out of adjustment....
i think i will change left and right 909s...to see if it follows the transistors ...
Click to expand...
Try swapping in a different set of outputs first in that second row.
 
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