phase linear 400

[gene french]

i had gone to ent doc in liberia for 3rd time since i lost my voice over 2 years ago...worried a bit...this time they found a mass on my left paralized vocal cord....movie at 11...
he is a private doctor but also worked on the public side...told me he would help so i cpuld use public side ...had appoibtment in local ebias to get appt in main hospital with a letter from him with his diagnosis the very next day at 7am...out of respect for elderly ...i was seen first...got one appt for lab work on 29th....
took a pic of this paperwork and whatsapped it to the ent guy...within 10 minutes i had appt in main hospital for tuesday at 8 am ....i could not believe...but looks like the biopsy will happen quickly....and on the public side...i have to pay into the public fund for medical care to maintain my residency...a bit of good fortune on my part....i had public surgery before for a hernia...doc said it was worst he had seen...double matted both sides of the membrane...took 5.5 hours. .i was very pleased....my gall bladded was private...it was so painful i couldnt/wouldnt wait for public side ..and only private does endoscopy...i bit the bullet on that one...
i always have the option to return stateside as i maintain my medicare ...got some friends / family lining up a doc there if i feel the need after the biopsy...i like options...
trying to keep thibgs organized and flowing!!!
another grandkid story for posterity...
screenshot of the video...

 

[gene french]

this afternoon...my first wopl full comp i built complete with woa cabinet blew rail fuses...probably shorted output transistor...
while checking ... one of my last two stock 400s was not driving...it was driving the 6" mids...hard to notice because the voigts cover the mids too...so both spare wopls are pulling duty now ....if the stock one is even slightly a pain...i will upgrade...
we all knew this day would come with this 50 year old equipment...no clue why the wopl bit the dirt...
i do use them a lot..daily...
and sometimes push hard...but i have never set the preamps more than a smidge above half way...should be safe enough...and npt pushed dac over 85%....

 

[gene french]

preliminary inspection of full compliment wopl...
removed all and labeled by columns...
found two bad 96s and 2 bad 95s in column 1 and 2...
left channel nearest to transformer
right channel checked out...
i do have 2 95s and 2 96s spares new...
will install in rows and follow bring up procedure...
more extensive testing tomorrow...
wonder what got em...i dont have the cleanest power but i do have eaton type 2 whole house protection and a tub full of type 3s on all...
anyway....life goes on...

nothing stuck out visual exam of backplanes or control board...

think i am out of agx5s (stubby ones)
these are now spare amps as i had 2 wopl spares ready for such a condition..will have time to order some....

the system is up...just to repair these!!!

 

[laatsch55]

Check emitter resistors on the backplanes, pico fuses and liw ohm resistors on backplane. Check bias trannies too.....it's not uncommon to have collateral damage after output shorts ..
A lot less than before White Oak.

 

[mlucitt]

Failing MJ21195 and MJ21196 transistors is sorta rare. The specs on these devices are pretty impressive. It will be interesting to see what you discover. I am with Lee, if your Bias Transistor in that channel is original it could be a cause as well as a casualty. I seem to remember if the Bias Transistor shorts, it can take out Output Transistors before the Rail Fuses blow. Are your Bias Transistors original (2N3403)?

 

[gene french]

Failing MJ21195 and MJ21196 transistors is sorta rare. The specs on these devices are pretty impressive. It will be interesting to see what you discover. I am with Lee, if your Bias Transistor in that channel is original it could be a cause as well as a casualty. I seem to remember if the Bias Transistor shorts, it can take out Output Transistors before the Rail Fuses blow. Are your Bias Transistors original (2N3403)?

they are whatever joe supplied in the backplane t...but i dont think they are 3403s...i will follow your suggestion...
thank you

 

[gene french]

Check emitter resistors on the backplanes, pico fuses and liw ohm resistors on backplane. Check bias trannies too.....it's not uncommon to have collateral damage after output shorts ..
A lot less than before White Oak.

the fuses on the back planes checked ok...
i will have to research which are emitter resistors ...
i donk know what liw ohm resistors are...sorry...i will try your advice...once i figure it out!!!
thanks!!!

 

[gene french]

they are whatever joe supplied in the backplane t...but i dont think they are 3403s...i will follow your suggestion...
thank you

bom shows the bias transistors supplied were 2n5088...which i do think if have spares if necessary....
i had to go look it up...my memory is not as sharp as it used to be...
thanks again...

 

[gene french]

Check emitter resistors on the backplanes, pico fuses and liw ohm resistors on backplane. Check bias trannies too.....it's not uncommon to have collateral damage after output shorts ..
A lot less than before White Oak.

i see nothing listed on either bom about pico fuses or values...
can you help me a bit more and explain what i am suggested to check in reference to pico fuses...
i appreciate your interest in my problem...thanks

 

[laatsch55]

Pico fuses are green, resistors looking types. Do your backplanes have glass fuses?
Lie= low value resistors..

 

[laatsch55]

Emitter resistors are the two watt, .33 ohm, I per output...

 

[gene french]

Pico fuses are green, resistors looking types. Do your backplanes have glass fuses?
Lie= low value resistors..

i do have glass fuses 2 per backplane.. ..
i will check the resistors!!!
thanks!!!!

 

[gene french]

Emitter resistors are the two watt, .33 ohm, I per output...

thank you!!!

 

[gene french]

bulb dim...
no more blown fuses...
meters light...
dcp will not engage...even with l/r yellow wires disconnected
rail voltage + and - 82v
pl20 voltage + and - 15v

left offset .046
left bias.. -.039
right offset .001
right bias .350

bias transistors did not show open or shorted...
checked in circuit...both side had same readings on dvm check...

 

[mlucitt]

Gene,
You have a Left Channel issue, no? Bad Left Channel Bias voltage could point to the Bias Transistor supply circuitry (2N5088 are the good ones).
Can you change the Left Channel Bias Voltage by operating R2L Bias Potentiometer?

Next I would ring out D1L-D4L, part of the Bias Feedback Circuit. Then I would check D13L, the Current Limiting Gate. If those are OK, I would look at Q6L, the Left Channel Pre-driver.

Lack of the DCP operation is odd. It should latch-in when Rail Voltage +80VDC, Ground, and an AC Line Input of at least 25V are present at the inputs of the DCP Connector.

Oh, I have a hundred AGX5 fuses, can I send you some?

Mark

 

[gene french]

dcp board
rail voltage present on j3 pin 1 82v
ac voltage present on j3 pin 3 60v

 

[gene french]

my discoveries...following pointer given...
i check left side (bad) against right side (good)
all diodes check good...
all resistors match except...
of the 6 .33ohm resistors per side..
right side all read 1.5 to 1.6 ohm in circuit
left side in circuit only 3 match right side

r35 reads 3.2M
r34 reads 480k
r32 read OL totally open

r7 right side reads 1.3 ohm
r7 left side reads 82 ohm
again all in circuit...

i will go measure your suggestions mr. mark and report back!!!

thanks a bunch!!!

 

[gene french]

mr. mark...
bias pot movement makes no significant difference...
d1 - d4....check ok
d13...also good...
q6 measured good...
left measurements matched right measurements...

i have no clue why dcp wont trigger...
i can rob another unit to test...
trying to test as much as i can...to find out what i need...
so far all damage limited to left back plane...
i have no .33 ohm resistors...
thank you!!!

 

[gene french]

bypassing dcp...right channel plays music...
left channel kinda makes an ascending whistling sound ...
maybe whatever fried the 4 outputs...may have damaged dcp...or vice versa...i have no clue why ..

i do have .5ohm emitter resistors left from the sx1080...is that close enough in value to test??
or better no...

i will rob another dcp and hook up j3 only to see if mine is damaged as i suspect....and i can swap relay to chwck that...

ideas??

 

[laatsch55]

.5's will do to test...emitter resistor values were out of circuiut?