phase linear 400

[gene french]

this is from the bom with the wopl documentation....
12 emitter resistors at .33 ohm....6 per channel....
and 22 one ohm resistors....11 per side....
i ordered extra....
lol

 

[gene french]

good morning....seems i am the proud new owner of a fluke 77IV.....

 

[e30m3mon]

good morning....seems i am the proud new owner of a fluke 77IV.....

Congrats! I've had an 88V automotive DMM with all the attachments for about 10 years. Great tool, got it off ebay in like-new condition for half new retail price. May it serve you well for years to come.

 

[MusicSteve]

good morning....seems i am the proud new owner of a fluke 77IV.....

Congrats! did it come w meter leads?

 

[gene french]

Congrats! did it come w meter leads?

it does...or at least there was a picture of leads with it!!
i bought a set of various leads with various tips...i think i am covered in any case!!!
good morning music man!!!

 

[Gepetto]

And don't skimp on test leads. Pomona are expensive but very good...

 

[laatsch55]

And your priority leads should be a set of Pomona mini-grabbers..

 

[gene french]

duly noted !!!!
thanks!!!

 

[Gepetto]

No Chineez crap...

 

[Gepetto]

if you are missing your bias reading, it has zero to do with open emitter and base resistors, those should be fixed but are not the cause of zero bias.

If you are convinced that your bias transistor is good, then the next step is to check out the other resistors (fuses) in the circuit. R37L (22), R41L (22), R38L (1), R21L (56), R32L (56)

Seems like you took out all the fuse resistors on the backplane so now you have to check the fuse resistors on the control board.

 

[gene french]

i checked every component on the left back plane...comparing it to the right...when questionable, i removed one leg...and confirmed...
the bias is constant at 14mv...adjustment doesnt affect much...see the photo a page or two ago...you can see ...
right channel bias set as per documentation...
all i checked on control board was +- 15v...
the components you listed are on backplane or control???
i will refer back to docs to get my bearings...
thank you...

 

[Gepetto]

i checked every component on the left back plane...comparing it to the right...when questionable, i removed one leg...and confirmed...
the bias is constant at 14mv...adjustment doesnt affect much...see the photo a page or two ago...you can see ...
right channel bias set as per documentation...
all i checked on control board was +- 15v...
the components you listed are on backplane or control???
i will refer back to docs to get my bearings...
thank you...

If you are convinced that your bias transistor is good, then the next step is to check out the other resistors (fuses) in the circuit. R37L (22), R41L (22), R38L (1), R21L (56), R32L (56)

Seems like you took out all the fuse resistors on the backplane so now you have to check the fuse resistors on the control board.

 

[gene french]

i was trying to locate the bom for the control board....which i do not have in the 34 document files you sent when i purchased the wopl....
i do have the bom for the back planes....and since those resistor numbers are not on the back plane bom...
they must be on the control board....
if you could send the bom for the control board....that would be nice...
thanks

 

[Gepetto]

i was trying to locate the bom for the control board....which i do not have in the 34 document files you sent when i purchased the wopl....
i do have the bom for the back planes....and since those resistor numbers are not on the back plane bom...
they must be on the control board....
if you could send the bom for the control board....that would be nice...
thanks

I will resend but the BOM is in the large tranche of documents you received...

 

[gene french]

found it...

 

[gene french]

If you are convinced that your bias transistor is good, then the next step is to check out the other resistors (fuses) in the circuit. R37L (22), R41L (22), R38L (1), R21L (56), R32L (56)

Seems like you took out all the fuse resistors on the backplane so now you have to check the fuse resistors on the control board.

all 5 values tested the correct resistance....
i see nothing looking bad on the control board as with the back plane which had a black soot mark under r3...only two emitter resistors tested to spec, one being open and the other 3 showed very high resistance......and r1 and r3....

 

[Gepetto]

You will get very low bias readings if you do not install the bottom row of transistors. Have you installed the bottom row?

If no, install them and recheck.

If yes, measure the voltage at the collector and emitter of the bias transistor at the control board connection points with your DVM black lead connected to the single point ground.

 

[gene french]

You will get very low bias readings if you do not install the bottom row of transistors. Have you installed the bottom row?

If no, install them and recheck.

If yes, measure the voltage at the collector and emitter of the bias transistor at the control board connection points with your DVM black lead connected to the single point ground.

i took all left outputs out to unsolder the bad resistors...at one time i had bottom row installed..
is it safe to power up without resistors??
i will do as you tell me...

 

[Gepetto]

i took all left outputs out to unsolder the bad resistors...at one time i had bottom row installed..
is it safe to power up without resistors??
i will do as you tell me...

As long as both 10 ohm bias resistors on the backplane and both of the 150 ohm base-emitter resistors are good, that is all you need to power up the backplanes with the bottom row transistors in. You have a schematic, you will understand by looking at this why you won't get a proper bias reading until the bottom row transistors are installed.

 

[gene french]

ok...i will study..
i will not reinstall blown resistors...
i will confirm 10 and 150 ohm resistors on back plane are good...and install bottom row...then check bias ...