phase linear 400

[gene french]

great...mr laatsch....they were in circuit and only comparing left to right....all right resistors were equal..about 1.5 ohm if i remember right ....left side had 3 that were way off...and 3 that matched...

one 3meg one OL, and one 500k...i will retest out of circuit tomorrow!!! i have several .5 ohm to test with. .
mr. mark...
swapping dcp worked ...swapping relays still allowed swapped in dcp to trigger...
upin removing the affected dcp...i found the problem....see the pic..

 

[gene french]

great...mr laatsch....they were in circuit and only comparing left to right....all right resistors were equal..about 1.5 ohm if i remember right ....left side had 3 that were way off...and 3 that matched...

one 3meg one OL, and one 500k...i will retest out of circuit tomorrow!!! i have several .5 ohm to test with. .
mr. mark...
swapping dcp worked ...swapping relays still allowed swapped in dcp to trigger...
upin removing the affected dcp...i found the problem....see the pic..

forgot the pic..lolol

 

[laatsch55]

3 mega and 500 k are considered "open".

 

[gene french]

3 mega and 500 k are considered "open".

the OL is infinity which i would consider open too....
what about the 1 ohm resistor measuring 82 ohms??
open as well...i am sure i have that one in my inventory...
thank you so much!!!!

 

[Gepetto]

forgot the pic..lolol

I would say that is a problem

 

[gene french]

I would say that is a problem

lololol

 

[gene french]

i am sure you recognize it...
that is the middle part exposed on the long single rowed chip on botyom of mr. dons board...

 

[gene french]

well...after further scrounging...i found 6 .33 3watt emitter resisters..had plenty of 1 ohm 1/4 watt resistors...pulled backplane...put in new stuff...reassembled ....dbt dimmed as normal ..
left and right offset both at .001v...
left and right bias at .350v...
both sides played music...used disposable speakers as i have no dcp board...
dead soldiers...
2 95s
2 96s
3 .33 ohm 3w emitter resisters
1 1 ohm 1/4 watt resistor...
2 x5 fuses...

any ideas about what happened???
and why??

thanks so much to mr. laatsch...and mr
mark for pitching in to help...

mr. laatsch...you hit the nail on the head...
liw ohm resistors and emitter resistors as you predicted...(the liw part was sarcasm)...lolol

i have confidence in the repair...but am aware there could be some output transistor cripples....
i will order spares and spare x5 fuses...i did find a few more ..think i have 2 left...

need that long single rowed pinned ic for the dcp...
all else checked ok...

thanks to all!!!

 

[Gepetto]

well...after further scrounging...i found 6 .33 3watt emitter resisters..had plenty of 1 ohm 1/4 watt resistors...pulled backplane...put in new stuff...reassembled ....dbt dimmed as normal ..
left and right offset both at .001v...
left and right bias at .350v...
both sides played music...used disposable speakers as i have no dcp board...
dead soldiers...
2 95s
2 96s
3 .33 ohm 3w emitter resisters
1 1 ohm 1/4 watt resistor...
2 x5 fuses...

any ideas about what happened???
and why??

thanks so much to mr. laatsch...and mr
mark for pitching in to help...

mr. laatsch...you hit the nail on the head...
liw ohm resistors and emitter resistors as you predicted...(the liw part was sarcasm)...lolol

i have confidence in the repair...but am aware there could be some output transistor cripples....
i will order spares and spare x5 fuses...i did find a few more ..think i have 2 left...

need that long single rowed pinned ic for the dcp...
all else checked ok...

thanks to all!!!

Depends on how the 2 -95s and 2 -96s failed Gene. Please advise on each device what you measured from C-E, short or open.

One device failure can start the chain of events that occurred OR the failure on the DCP could have started the chain of events (not sure why the detection IC would pop its lid like that).

We need to send in CSI Miami.

 

[laatsch55]

Gene, when I blow up.400's like that, it's usually toomuch throttle.
The detection IC is a new one. Haven't seen that one before..

 

[gene french]

3 are shorted in all configs
1 is shorted in one config...not shorted b to e...reads 233 in diode mode ...
b to c or e to c shorted...
didnt lookup pinout..too lazy...lol
i think the transistors that fully shorted got the emitter resistirs...and partially shorted did not...
whatever happened...it blew both x5 fuses even though no damage on right side...my first response was to change fuses...left blew...rite did not ...then i started digging deeper...
i still have the stock one to look at...did not blow fuses...just dont play...if not a slam dunk...will upgrade...waiting to see for a parts run...

 

[gene french]

Depends on how the 2 -95s and 2 -96s failed Gene. Please advise on each device what you measured from C-E, short or open.

One device failure can start the chain of events that occurred OR the failure on the DCP could have started the chain of events (not sure why the detection IC would pop its lid like that).

We need to send in CSI Miami.

horatio and wolfe are on standby...awaiting further evidence!!!

 

[gene french]

Gene, when I blow up.400's like that, it's usually toomuch throttle.
The detection IC is a new one. Haven't seen that one before..

well...i have been pushin...

maybe pushin too hard...

 

[gene french]

there are still wonderfully nice people left in this world ..... and some fine examples are members here...thanks for accepting me!!!
thanks for the kindness and generousity!!!

 

[J!m]

There’s an equal number of people like me…

Have to keep things balanced.

 

[gene french]

There’s an equal number of people like me…

Have to keep things balanced.

lololol

 

[wattsabundant]

Were the failed transistors outputs, drivers or both? It's normal (?) to have NPN and PNP outputs fail when any one output fails. Repeated fuse replacement takes out more parts on the control board. Drivers sometimes fail. Note these observations are based on the experience of stock P/L amps. I've not seen a properly built W/O upgrade fail.

An open bias transistor, or broken lead, turns all of the outputs full on and the ensuing battle often results in all outputs and drivers fail.

 

[gene french]

2 mj...95 and 2 mj...96 output transistors
3 .33 ohm emitter resistors
1 1 ohm 1/4 watt resistors
and a blown ic on tje dcp board
the amp is back up and running...
all damage limited to left channel back plane...
nothing showed physical signs of damage...
thanks!!!

 

[gene french]

very interested to know what/why...not smart enough to figure it out myself...lol

 

[wattsabundant]

The emitter resistors are a surprise. The only time I recall them fail is when I found foil wrapped around the fuses. It suggests the fuses were slow to open. The blown chip is a surprise also.

During development of the board, I pulled two of the 3 outputs in one channel and ran the amp until the one output failed. I ran the test about 10 times and never once did the relay or the chip fail.