phase linear 400

could it be the different values of 470uf capacitor and diodes on left c8 ... the side that works...
and the default 100uf and no diodes on the right c8....the side that dont work...

if at first you dont succeed....then its perfectly ok to cheat...
 
gene french said:
i removed all of the outputs on the right side....
all test good....
can i repopulate one row at a time to see if the dcprotect functions???
with the left side fully populated....
or do i need to remove left side and go up row by row...
how would you check from here....
thanks joe
Click to expand...

The DCP really only cares about output offset which you said was zero on both channels. If true, the DCP should click in
 
i will recheck everything tomorrow...
i will go back to the 4 drivers and 4 outputs one row above the driver...then check the bias and offset and dcp board operation...
if good i will do another row...until i reach the top...
the first time i did this it worked....so i will return to that point...
 
good morning to all...hope all is well...you too sniff ...vsat, you are too kind!!!
i had a dream last night .. where the good lord said if you think yesterday was bad...wait until you see what is in your schedule for today!!!
lol...boy, i cant wait!!!
thanks to all making my phase linesr journey a memorable one!!!
 
Yup, row by row, slow, careful, methodical work. Double check the correct transistor is in place. Check each output case for inadvertent grounding through the silpad. Recognize that the black anodizing is a good insulator, so use a good ground point to check. Make sure the screws aren't touching any back wall components. And recognize that those old back wall sockets do develop shorts to ground. Andrew "The Angry Sailor" fought a intermittent short in his back wall sockets when he upgraded his 700 S1.
 
George S. said:
Yup, row by row, slow, careful, methodical work. Double check the correct transistor is in place. Check each output case for inadvertent grounding through the silpad. Recognize that the black anodizing is a good insulator, so use a good ground point to check. Make sure the screws aren't touching any back wall components. And recognize that those old back wall sockets do develop shorts to ground. Andrew "The Angry Sailor" fought a intermittent short in his back wall sockets when he upgraded his 700 S1.
Click to expand...
Yes that was a pain in the ass! Bias would rise based on the tightness of the output screws on one row.
gene french said:
your will be done...i will be as gentle as i was for a few days after my vascectomy...
Click to expand...

“IM HALF THE MAN I USED TO BE!!!”;)

 
i like em....a first time to hear them...
i will add this to my repertoire....
thank you so much for sharing....
this is a nice group!!!!

me and my 1948 super stinson....
one of my favorites....
continental O470....
was a hoss...
was returning from a flight to mississippi to my home in louisiana when atc called and asked what was a 108-3...i explained it was a stinson with the big tail...
to which he asked what i had under the hood...i asked why...he said i was 25 knots faster than i should be...lol...
i had the big head for days...
...sold it before i moved here...to buy a bellanca ....
a poor mans bonanza....lol
life is so interesting!!!!
 

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i cant believe...
when george of the jungle suggested that anodized aluminum was good insulation...i got to thinkin....(i know sniff...thats dangerous...but i did anyway)
i had removed the fins to clean all of the white cr*p everywhere....so i started checking....the grounding lug on the left side was not grounded to the chassis....the right side was...and i dont really understand why....it has star washers on all sides to bite into the aluminum .... but, evidently it did not...
i scraped an area under the pad to remove anodizing and replaced the star washers and the grounding lug on the 3 position lug terminal...
and now i have continuity from the grounding lug to chassis ground....could this be my problem???
think i will do the right side too...just to be safe...
 
well....all was doing well...
now there is serious dc voltage at the outputs...
took out my throw aways i used for testing...
pegs the meters....
it actually played for a few seconds...just like the first time...
again the left bias adjusted....the right did not....
dont know how the dc protect board did not shut off ??\
fuses not blown...bias transistors tested good...
really at a loss now...
dont understand...
 
I know little to nothing about the original board and back wall. But you have one channel working and one channel not. I'd pull all transistors and recheck them(you are using the diode testing function right?). Then compare voltages on both side of the board at as many points as possible. If all checks good repopulate 1 row, then 2. I think the guys said it'll play with two rows for testing purposes. Lee or Joe or anyone else, please help. Working, later.
 
i have a switch on the dbt...i switched to test and the bulb brightens then dims....about 2 or 3 seconds later you hear the dcp engage....
i then switch to regular power and was watching the bias with one meter and the offset with the other....i thought the offset meter was in the mv scale...but it was not...it was in the v scale...any way....at a loss....dont understand...we just did all of this and all was ok...all of the replacements checked out well...i have paperwork with them...dont get it...
 
i have all of the power transistors out...they all test good...
i have to test the drivers...but, i must take maria to get her nails done...
god forbid those nails dont get done....lol
thank you....
something has to be awry with the driver board...
 
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