phase linear 400

[WOPL Sniffer]

Your board is assembled correctly...

Yup, otherwise it wouldn't have worked BEFORE he blew it up.

 

[WOPL Sniffer]

Or was that the other amp?
I'm not going back 100 pages to figure that out

 

[gene french]

with the analog meter....left q7 q8 test good...no c to e either direction....
right q7 q8 test good...but get c to e in one direction....
pretty sure its reading through the diodes we disconnected...
all of the resistors read correct...

 

[gene french]

What do you think is not correct? The BOM snippet you included above is from the Quasi Comp section of the BOM. The first 12 pages document the quasi-comp build and the last 12 pages document the full comp build instructions. You can tell which is which by the header on the page...

View attachment 68345

ok...i just was making sure i did not mess up the assembly...
thats all...

 

[gene french]

Or was that the other amp?
I'm not going back 100 pages to figure that out

all 5 amps were functioning....four still are...
i evidently left a sprig of solder on the faceplate...and buttoned up the wopl...and did damage...installing the metering switch....when i soldered the wires to it...

 

[Gepetto]

with the analog meter....left q7 q8 test good...no c to e either direction....
right q7 q8 test good...but get c to e in one direction....
pretty sure its reading through the diodes we disconnected...
all of the resistors read correct...

HUH, you disconnected the diodes Gene. I can see it in your picture.

I measured a board here just now with everything in circuit with a Fluke DVM in diode mode. C-E on all 4 of these devices is OL in both directions.

If you want to satisfy your curiosity, clip the collector lead of each of the 2 left channel MPS651 and MPS751 and reinstall the diode legs. Test your bias again.

Those transistors are not needed for anything but protection.

 

[gene french]

would hooking back up one diode tell us anything??

 

[Gepetto]

all 5 amps were functioning....four still are...
i evidently left a sprig of solder on the faceplate...and buttoned up the wopl...and did damage...installing the metering switch....when i soldered the wires to it...

And you did not bring it back up on the DBT...

 

[Gepetto]

would hooking back up one diode tell us anything??

Nothing in my book...

 

[WOPL Sniffer]

all 5 amps were functioning....four still are...
i evidently left a sprig of solder on the faceplate...and buttoned up the wopl...and did damage...installing the metering switch....when i soldered the wires to it...

So it DID work in it's early life.

 

[gene french]

And you did not bring it back up on the DBT...

yes i did...

 

[gene french]

once the light dimmed and the dcp board engaged....i clicked over to normal to check the voltages and bias...they report low if left on the dbt

 

[gene french]

So it DID work in it's early life.

maybe close to a month....the first switches i ordered were not double pole....i had to reorder....
maybe closer to six weeks waiting on the others to come....

 

[gene french]

And you did not bring it back up on the DBT...

ah...i understand now....yes, i did...all was fine...i never power on after work without the dbt...but when i put the faceplate back on to bring it back to the den...i carried it by the handles....
the solder evidently fell to the back plane in that position...when i reopened it...i saw about an inch of solder rattling around in the chassis....
sorry, i misunderstood...

 

[Gepetto]

Well get it running again, cut out the bad MPS651 and MPS751 transistors, solder the diode legs back in. Bring it up through the row by row addition of outputs. Enjoy it until you can get some replacements in CR.

Another lengthy process unfortunately...

 

[gene french]

HUH, you disconnected the diodes Gene. I can see it in your picture.

I measured a board here just now with everything in circuit with a Fluke DVM in diode mode. C-E on all 4 of these devices is OL in both directions.

If you want to satisfy your curiosity, clip the collector lead of each of the 2 left channel MPS651 and MPS751 and reinstall the diode legs. Test your bias again.

Those transistors are not needed for anything but protection.

i sure hate to cut the legs...should i just remove them??
or should they be changed??

 

[Gepetto]

i sure hate to cut the legs...should i just remove them??
or should they be changed??

I always cut the legs of components before removal. Save the board, the part is junk.

 

[gene french]

Well get it running again, cut out the bad MPS651 and MPS751 transistors, solder the diode legs back in. Bring it up through the row by row addition of outputs. Enjoy it until you can get some replacements in CR.

Another lengthy process unfortunately...

lololololol
that sure broke the ice ....
i am a pain...i realize that...along with a bunch of other character flaws...

thanks for the support...

 

[gene french]

Well get it running again, cut out the bad MPS651 and MPS751 transistors, solder the diode legs back in. Bring it up through the row by row addition of outputs. Enjoy it until you can get some replacements in CR.

Another lengthy process unfortunately...

yes sir...

 

[gene french]

I always cut the legs of components before removal. Save the board, the part is junk.

yes sir...