Larry's Phase Linear 700B

[laatsch55]

DC offset 10 mv right channel, 1 mv left channel. Got er whipped. Going to bed,

 

[laatsch55]

The problem was a bad mica insulator under an output. Wasn't a dead short, but enough to pass voltage.........sheesh, nothing wrong with the original board. Doug, the "B" you send back will get that board.

 

[mlucitt]

Lee, how did you find that bad mica? Makes me want to go and check all my micas with a megohm meter. Oh wait, that might not be good for the xistors... I'll just fluke it.

Mark

 

[Gepetto]

Glad you found it Lee, an elusive one. At least your 6V input test weeded out the weak soldier.

 

[laatsch55]

Weak by disaster standards, very robust by factory standards.

 

[laatsch55]

Joe, a board tester would need all 4 drivers and a row of outputs correct??

 

[laatsch55]

Time to warm up the AP and watch level increments VERY CLOSELY......

 

[fitz43]

The problem was a bad mica insulator under an output. Wasn't a dead short, but enough to pass voltage.........sheesh, nothing wrong with the original board. Doug, the "B" you send back will get that board.

ok, thanks.

 

[Gepetto]

No you can build a simplified tester with one predriver and one output only on each of the positive and negative halves and a restricted load value. Remember that you are testing the control board, not the final output stages that are mounted on the chassis. This simplifies the task greatly Lee. It is what I use for production.

 

[laatsch55]

And test 1/2 the board at a time??

 

[Gepetto]

That is the simplest way Lee, yes.

 

[laatsch55]

Hookay, thanks Joe.

 

[jbeckva]

Well, you can always send 'em to me. I have my old Navy HATS station out in the garage, and I'll make an Atlas TPS to test em.. something like this here..

000010 DISPLAY, RESULT, "%%" $
20 DISPLAY, RESULT, "ENTER PIU PIN TO BE CHECKED - "; $
30 WAIT FOR, MANUAL DATA, 'PIN' $
35 DISPLAY, RESULT, "ENTER PIN TO USE FOR MEASUREMENT - "; $
36 WAIT FOR, MANUAL DATA, 'MPINR' $
40 CALCULATE, @PIPIN@='PIN' $
45 CALCULATE, @P1@='MPINR' $
50 CALCULATE, 'PADDR'='PIN'+ 53 $
51 CALCULATE, 'MPADDR'='MPINR'+ 53 $
55 APPLY, DC SIGNAL, VOLTAGE 5, CNX HI PIPIN $
56 PERFORM, '/OBIT','PADDR', 57, 0 $
57 VERIFY, (VOLTAGE),DC SIGNAL, LT 1, CNX HI P1 $
58 GO TO, STEP 4000 IF NOGO $
60 LOOP, THRU STEP 100 WITH 'IB'= 1 TO 3 $
65 PERFORM, '/OBIT','PADDR','IB'+ 48, 1 $
66 PERFORM, '/OBIT','MPADDR','IB'+ 48, 1 $
70 VERIFY, (VOLTAGE),DC SIGNAL, GT 4, CNX HI P1 $
71 GO TO, STEP 75 IF GO $
72 DISPLAY, RESULT, "IBUSS ";'IB';" IS OPEN!" $
75 DISPLAY, RESULT, "IBUSS";'IB';"IS GOOD" $
76 PERFORM, '/OBIT','PADDR','IB'+ 48, 0 $
77 VERIFY, (VOLTAGE),DC SIGNAL, LT 1, CNX HI P1 $
78 GO TO, STEP 90 IF GO $
79 DISPLAY, RESULT, "IBUSS ";'IB';" IS SHORTED!" $
90 PERFORM, '/OBIT','MPADDR','IB'+ 48, 0 $
C000100 END OF LOOP $

(yeah.. lol.. if one of 'em hasn't turned to scrap in a DRMO yard.. plus running 3 phase 208V to power it.. hmmmmmm... next project.. )

 

[laatsch55]

Is all that necessary?? Or you could get an AP> Course it doesn't diagnose only measures.

 

[laatsch55]

I'll say one thing for sure Joe, when ya get done wiring an entire output section to 4 sockets it looks pretty damn busy there.

 

[jbeckva]

Is all that necessary?? Or you could get an AP> Course it doesn't diagnose only measures.

Heh.. of course it isn't.. but it sure would be COOL..

 

[laatsch55]

Ah yes Jer. the cool factor. the Series I should be there the 29th. I'll get ya tracking number when I get it.



On another notew, some interesting THD& N figures. Just got a call, gotta hit the field. Almost abig problem. Will be big if it isn't handled quickly. Later folks.

 

[Gepetto]

You have a 60 Hz wiring crosstalk problem going on on both channels and something pretty out of whack on the other Lee.

 

[mlucitt]

Bad cap somewhere or maybe two wires uncomfortably close to each other. It would be fun to expand the band around 60Hz and play with the wires to see if that makes a difference. I need an AP.

Mark

 

[laatsch55]

Yeah the low end just ain't right!!!