phase linear 400

George S.

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Vertical row #3 from the transformer, 3rd socket up, is that lower screw touching the diode lead? Close enough to arc? This is only potential issue I see. Your control board is totally different from the board that came in my 400 S1 8 fin (Joe's box of chocolates). Also, your bias transistor wires are twisted. All of the bias wires on my three amps were straight. To reduce stress and breakage of the transistor legs I suppose. Hope you find the issue. after transistor swap1.jpg
 

gene french

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well, i had the dcprotect board wired wrong...
the directions in the 400 relay install pdf had the white wire in j1-1
1651623440768.png
flicker had the gray wire in j1-1
so, that would explain the dc on the outputs....
1651623487272.png

i did not do enough research before i installed it...i should have checked both places....
and i thought how difficult can this be....i took too much for granted....
anyway...
i have removed all transistors including the drivers....all tested good...
i marked them and put the left channel drivers on the right channel and the right driver on the left channel...
with a row of 909s above this...which i was advised this was enough to start checking....
no change....
can set bias on the left channel and can not set the right channel...
and the dc protect does not engage...
so the offset of course shows zero....
i even tried without the screws just to be sure i was not shorting thru a sil pad or with a screw...
no difference...
i guess there has to be something on the driver board holding it down....
i checked the voltages on the dcp board
using chassis ground...for the negative lead on the dvm

j1 1 is -79v dc
j1 3 is 0
j2 1 is 64v dc
j2 3 is 0
j3 1 65v dc
j3 2 is 0
j3 3 is 60v ac...

i am pretty sure j1 1 is not what it is supposed to be....

what a bucket of worms this has turned out to be...lol
such is life...

thanks in advance for any advice....
 

Gepetto

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well, i had the dcprotect board wired wrong...
the directions in the 400 relay install pdf had the white wire in j1-1
View attachment 65282
flicker had the gray wire in j1-1
so, that would explain the dc on the outputs....
View attachment 65283

i did not do enough research before i installed it...i should have checked both places....
and i thought how difficult can this be....i took too much for granted....
anyway...
i have removed all transistors including the drivers....all tested good...
i marked them and put the left channel drivers on the right channel and the right driver on the left channel...
with a row of 909s above this...which i was advised this was enough to start checking....
no change....
can set bias on the left channel and can not set the right channel...
and the dc protect does not engage...
so the offset of course shows zero....
i even tried without the screws just to be sure i was not shorting thru a sil pad or with a screw...
no difference...
i guess there has to be something on the driver board holding it down....
i checked the voltages on the dcp board
using chassis ground...for the negative lead on the dvm

j1 1 is -79v dc
j1 3 is 0
j2 1 is 64v dc
j2 3 is 0
j3 1 65v dc
j3 2 is 0
j3 3 is 60v ac...

i am pretty sure j1 1 is not what it is supposed to be....

what a bucket of worms this has turned out to be...lol
such is life...

thanks in advance for any advice....
Left channel pegged at B-
Right channel pegged at B+

What a fine mess you have now Olly...
 

gene french

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Buying a WOPL or trying to piece another together?
piece one together, of course...
Vertical row #3 from the transformer, 3rd socket up, is that lower screw touching the diode lead? Close enough to arc? This is only potential issue I see. Your control board is totally different from the board that came in my 400 S1 8 fin (Joe's box of chocolates). Also, your bias transistor wires are twisted. All of the bias wires on my three amps were straight. To reduce stress and breakage of the transistor legs I suppose. Hope you find the issue. View attachment 65284
no sir .... there is plenty of clearance....and i did go back and recheck the 4 diodes and the bias transistors on the back wall....
i have looked all day today for something like that...to no avail...
i believe there is something amiss on the driver board...
you can see in this picture the dcprotect board is wired wrong...i have since changed it...
now....the relay is not engaging....and probably rightfully so...it had dc on the output....
pin one should be the gray wire in j1 and j2...with both whites in the third position according to flicker...
i explained what happened in a previous post....
thanks for hanging in there with me...
not everybody will....cant say that i blame them...lol
 

gene french

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You might want to cut down some of the component leads that stick out, IMO the leads are to long and could bend over and cause a Short.
i have been cutting them down....they were at least twice that long originally....as i progress i have been trimming...and i will continue...
thank you for looking....i appreciate !!!
 

gene french

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guayabo de bagaces, guanacaste, costa rica....
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music...the healer of souls...
OLD COLD joints are a problem, and not just for us old guys. Our equipment suffers too. Hope that removes your gremlins.
i cant seem to find anything wrong....so far just the solder joint....tested left channel vs right channel...so far all matches....
no shorts...no opens...but, still looking...i am afraid to turn it back one....lol....
thanks again for your attention...and advice!!!!
 
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