phase linear 400

well, well....no disasters....marvin did not show up nor called....i am sure he is sorely disappointed...lol
some progress....changed the 5k adjustable bias pots....changed 2 1304s and 2 1305s....need to get more...i am out...the 4 transistors were as sniff described on some of his rebuilds...the legs were just dust...or would totally snap off if touched...this machine was stored in a nasty humid place...
tech spray and alcohol are doing a pretty good job of cleaning up...
checked every transistor and diode on the board....no corroded traces...no obvious resistor malfunctions...wires were long on the trace side...trimmed them all up...scraped a bit on the resin from the solder....toothbrushed it....looking much better....
cleaned and cleaned and cleaned....rechecked the outputs i had set aside....one was bad....rechecked the drivers...all is good...
the input jacks did not have the insulator washers with the lip on it...they used electricians tape on the inside...the washers were on the outside but were cracked....i have them hanging in free air...for now...i will get a few more when i order from mr. joe...should have my list ready by then...
installed the row of drivers and one row of xpl909s....checked collectors to chassis ... no shorts...did not overtighten the outputs on the sil pads...
plugged it into the dbt....and let her rip...
light went bright then dimmed as normal....cant adjust the bias lower than 430 mv...if i remember right...i had a similar issue on some of the other units that i went through....i think when more outputs go in it will adjust...i just dont remember....will go back and read a bit...
did not check the offset...wasnt too worried...was more worried about runaway bias...after this i just shut her down for tomorrow...
first thing tomorrow i will check the offset...then reinstall one row at a time....
was a great day for me...i have learned a lot since november a year ago when i started the sx1080 rebuild...
i have learned to be more methodical....and check and recheck until i am POSITIVE i have it right...
its paying off...i ordered a recap kit for the board....
thanks to all that have helped me out this past year....a great bunch of guys...
and a nicely run forum....i am thankful to be here...
take care and good night...
gene
 
gene french said:
well, well....no
light went bright then dimmed as normal....cant adjust the bias lower than 430
gene
Click to expand...
Looks good Gene
you should be able to adjust it, did you test the pots before you put them in? Could try the heat gun test and see if it changes the Bias voltage.
 
MusicSteve said:
Looks good Gene
you should be able to adjust it, did you test the pots before you put them in? Could try the heat gun test and see if it changes the Bias voltage.
Click to expand...
yes, i did check the pots....went from around 100 ohms to over 4500 ohms....within specs i would think....
i did not spend too much time with that problem...as i was tired...and i am sure now nothing is shorted any more...
this amp is rough...
 
WOPL Sniffer said:
I see the problem...... It's got too many fins. :)
Click to expand...
this is actually my second 8 fin....i bought one from rob...joe put me on to that one...along with a parts 4 fin...
i bought a new chassis from joe...made 4 more fins and converted the parts 4 fin into a wopl...
recapped the 8 fin...upgraded and recapped the first pl400 i bought ... a 4 fin off of ebay....
the 8 fin is pulling the woofers...the 4 fin is pulling the mids....the sx1080 is doing tweeter duty....all as per georges suggestion a 4 x 8 dsp....
and mr. joes wopl is powering the voigts...it is doing the heavy lifting...
the easy way to go...everything runs so cool....it really does sound good...
not sure what i am gonna do with the new to me 8 fin...i have enough preamps and stuff...and a spare tv in the dining room...but would entail another set of speakers....oh well...
 
just checked offset...
left channel is .0000
right channel is rail voltage.. 70+ v using dbt...
no blown fuses...
will recheck q5 q8 q9 and drivers and outputs..
is that a good place to start???
i can use l/r comparison....luckily...
 
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