Troubleshooting an humming WOPL : need help!

Coldsmoke said:
Yes I did - even if I'm not sure of the difference to be expected in terms of sound -but I don't understand when I missed this cruxial information :/ I searched accross the web the la 30 minutes and these 95's look to be hard to find
Click to expand...

Glad you brought it up on the DBT Florian, otherwise you would have let a lot of smoke out of a lot of components :-(
 
Gepetto said:
Hi Florian
I believe you built your backplanes as Full Comp so you missed this vital info on page 1 of the instructions...

Backwall pre-driver and output driver transistors.

  1. 8 each MJ21196 (NPN) and 8 each MJ21195 (PNP) from ON Semiconductor for the Full Comp build version
  2. 12 each MJ21196 (NPN) from ON Semiconductor and 4 each RCA410 (NPN, salvaged from existing devices) for the Quasi Comp build version.
Click to expand...

SO- You built your backplanes, probably as full comp, but have the old transistors that were for quasi comp...

BUT- Did you also build a new control board? That also can be built as a QC or FC circuit! Double check that to make sure!
 
MarkWComer said:
SO- You built your backplanes, probably as full comp, but have the old transistors that were for quasi comp...

BUT- Did you also build a new control board? That also can be built as a QC or FC circuit! Double check that to make sure!
Click to expand...

Florian
That is on the last page (pg17) of the instructions.


  1. Change list for PL14_20 RevD Control Board:
    1. R78L/R and R79L/R are 44.2 ohms, 1/4W, 1%
    2. R35L/R are 1 ohm, 1/4W, 1% with 0.6†lead bend spacing
    3. R34L/R is not populated
    4. D13L/R is not populated
    5. C18L/R is not populated
    6. R62L/R is 2.49K, 1/4W, 1%
 
MarkWComer said:
SO- You built your backplanes, probably as full comp, but have the old transistors that were for quasi comp...

BUT- Did you also build a new control board? That also can be built as a QC or FC circuit! Double check that to make sure!
Click to expand...

In fact, all the required changes are summarized on Page 17 of the instructions Florian. Double check your build against these instructions...


  1. IF AND ONLY IF you are running the PL400 Backplane Board RevA or B in full complementary mode with PL14_20 RevD Control Board, the changes are as follows:
    1. Change list for PL14_20 RevD Control Board:
      1. R78L/R and R79L/R are 44.2 ohms, 1/4W, 1%
      2. R35L/R are 1 ohm, 1/4W, 1% with 0.6†lead bend spacing
      3. R34L/R is not populated
      4. D13L/R is not populated
      5. C18L/R is not populated
      6. R62L/R is 2.49K, 1/4W, 1%
    2. Change list for back wall transistors:
      1. Q11, 13, 15 and 17 are NPN MJ21196
      2. Q12, 14, 16 and 18 are PNP MJ21195
    3. Change list for PL400 Backplane RevB Board:
      1. R6L/R is 1 ohm, 1/4W, 1%
      2. R5L/R is NOT POPULATED
      3. Comp [C] jumpers (20AWG bus wire formed on 0.35†centers) installed as follows:
        1. J14 to J15
        2. J4 to J5
        3. J17 to J18
        4. J1 to J2
        5. J7 to J8
        6. J20 to J21
        7. J10 to J11
        8. J23 to J24
      4. Jumpers (20AWG bus wire formed on 0.9†centers) installed in R42 locations instead of 0.22 or 0.33 ohm resistors
 
Gepetto said:
Must be a CT thing Ron, we have all the CT ones up here in MA :-) Plenty everywhere you turn.
Click to expand...

Seriously Joe, there is none around here and has not been for quite awhile. Do the Walmart's up there have the $1 a 4 pack 100w ones? If so I may drive up there and get a case of them
 
Northwinds said:
Seriously Joe, there is none around here and has not been for quite awhile. Do the Walmart's up there have the $1 a 4 pack 100w ones? If so I may drive up there and get a case of them
Click to expand...

They are not $1 a pack any more Ron, the movement away from them has driven up prices, likely due to lower production volume. But they are still plentiful. I just stocked up recently.
 
ERROR IN THE BOM FOR FC BUILD?

Gepetto said:
    2. Change list for PL400 Backplane RevB Board:
      1. R6L/R is 1 ohm, 1/4W, 1%
      2. R5L/R is NOT POPULATED
Click to expand...

WHOA! Found a boo-boo in the BOM for FC Build- please verify this!

I'm clearly on the FC Build section of the XLSX document, 1Ω says R1, R2, R3, R4, R5.
The parts bag does state R5 (QC only) and R6 (FC only). I built according to the BOM, didn't read the bag notation.
So I have a resistor in the wrong place, correct?
 
5... 4... 3... 2... 1...

Abort! Abort! Abort!

That extra resistor will cause the earths magnetic field to flip
 
MarkWComer said:
WHOA! Found a boo-boo in the BOM for FC Build- please verify this!

I'm clearly on the FC Build section of the XLSX document, 1Ω says R1, R2, R3, R4, R5.
The parts bag does state R5 (QC only) and R6 (FC only). I built according to the BOM, didn't read the bag notation.
So I have a resistor in the wrong place, correct?
Click to expand...

Trust the bag Mark. The BOM lags the bags...

The BOM has thus been updated. Thanks for catching this.
 
Northwinds said:
5... 4... 3... 2... 1...

Abort! Abort! Abort!

That extra resistor will cause the earths magnetic field to flip
Click to expand...

Only if I play a Yoko Ono record at full blast...

Gepetto said:
Trust the bag Mark. The BOM lags the bags...

The BOM has thus been updated. Thanks for catching this.
Click to expand...

Thanks for verifying! Was just going to start the second backplane when I read that.
[BITCH!] Desoldering... [/BITCH!]
 
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MarkWComer said:
Only if I play a Yoko Ono record at full blast...



Thanks for verifying! Was just going to start the second backplane when I read that.
[BITCH!] Desoldering... [/BITCH!]
Click to expand...

I kit to the bags so they are the most accurate documentation on build. The kits are designed to be close to "paint by numbers" so I go to greatest lengths to ensure the bag labels are very accurate.
 
I for one Joe appreciate your efforts.....it has to be.....tedious ....at times...
 
Gepetto said:
I kit to the bags so they are the most accurate documentation on build. The kits are designed to be close to "paint by numbers" so I go to greatest lengths to ensure the bag labels are very accurate.
Click to expand...

laatsch55 said:
I for one Joe appreciate your efforts.....it has to be.....tedious ....at times...
Click to expand...

I second that. I mentioned in the video that my cat could assemble these boards if it weren't for her lack of thumbs. OTOH, if my hands were nothing but thumbs, I'd still be able to do the assembly. Great job on the kits! And people make mistakes- allow yourself to be human.
 
This is how I store mine.....each one stuffed in a styrofoam cup....
 

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