Taking the Plunge Into the WOPL 400-II Pool

I always match the gain or forward current transfer (hFE, = Ic divided by Ib in Amps for a bipolar transistor, sometimes called "beta") of my MJ21195/96 devices.
I do this while standing on my left foot and sticking my tongue out to the right side. HAS to be the right side or the readings will be off.
Know what I mean...
 
LOL! Pics or it didn't happen, as they say!

Ok - then I will roll the dice and hope for the best.

Thanks again, guys
 
e30m3mon said:
Ok - then I will roll the dice and hope for the best.
Click to expand...
You have modern manufacturing methods like CNC machinery and extreme improvements in materials consistency on your side.
I used to check the gain from Joe's transistors. Results were like 72, 72, 72, 73, 72, 72, 72, 73, 72, you get the picture. I don't bother to check them anymore and the amplifiers just work.
 
I do remember you and i matching TIS -97's on the stockers...
 
A quick update ... When BMW lowers the chassis onto the driveline, they call it "The Marriage". I would call this the WOPL equivalent.

First row of transistors were tested on the bare backboard and no issues. I got the rest into place today and will turn up the variac with the control board attached. Crossing my fingers for no bad stuff ...
 

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From the looks of your work I'm gonna go out on a limb and say you're gonna be fine...
 
At the RCAs, consider removing the copper grounding plate and isolating them from chassis ground with fiber washers.
 
George S. said:
At the RCAs, consider removing the copper grounding plate and isolating them from chassis ground with fiber washers.
Click to expand...

It looks stock George so that should already be the case.

Al, clip that bus wire off of the copper input plate that used to go to output binding postsl.
 
Al, your RCAs should "float" above chassis ground. Joe designed these to have only 1 ground point, the "star" ground, which is the short wire I see on your photo coming off the copper storage cap buss bar that goes to the stud. Like Joe says clip that wire off the RCA copper plate if you hadn't already done so and make sure those RCA jacks are insulated from chassis ground.
It's going to sound great, good work!
 
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Seriously, I am happy to be here in this group. You guys are the best - I appreciate all your (collective) support!

Thanks George - I had exchanged email with Don, as I noted his instruction (and the co$t associated with losing those fiber washers!) regarding the space. I had replaced the RCAs several years ago, one at a time, to ensure that I maintained that gap. As I was soldering the wires to the PL14_20, I pulled the ground wire back and cut it after taking the above picture. A close-up is attached below...mind the gap, as they say!

I finally got around this afternoon to bringing up the row of drivers with the PL14_20, and then the first row of outputs. I'm letting the B voltages get down to a fraction of a volt before going back to the third row. All output voltages sitting pretty at 0.000v and the bias voltage was 0.2xxv

I'll post an update when I get through the next two rows and adjust the bias....fingers crossed.
Al
 

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I cut the original white wire back to the solder blob on the copper plate (note that stub). I then spliced/soldered/shrink-wrapped a length of new white wire (from Joe's kit) and ran that back to the star point/copper bus between the PS caps. You can see that wire laying in the corner of the chassis. The small piece of bare solid wire was previously tied to the right speaker (-) terminal. I ran two new (gray) 16ga wires back to the star point, which will be connected to Don's DCP board to provide the speaker (-) terminal connections. I believe that is the correct way to do the input and output grounds over there...otherwise, please advise. Thanks Mark.

Having played Boris Karloff a few times with the variac this afternoon, bringing up and down the voltages while laying out the rows of transistors, I'm happy to say everything went off without a hitch! A tribute to Joe's meticulous design which made for a easy assembly and confidence. Kudos to Joe for putting up with my questions! Not sure where the "sweet spot" for bias settings should be, but 0.366v is within the recommended range, so I went with that. Note at idle the amp draws about 0.3A, and 29W standby.

I'm getting my class ready to take the EPA 608 in a couple weeks, so I won't be able to get the WA DCP board hooked up tonight.

Only one thing left to contemplate....Cylon meters. I bought caps with the plan to replace all those 40 year old dogs - but the meters worked fine last time I had this amp plugged in roughtly 20 years ago.
Somebody talk me out of buying Joe's Cylon board package - or tell me why I shouldn't bother re-capping mine.
Many thanks!
Al
 

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Al, I call the white wire the "White Wire of Death". Some on the forum will disagree (and that's OK), but I was taught never to connect the grounds of the inputs to the grounds of the outputs. Your inputs are properly grounded when you run the two wires (signal and shield - from the RCA jack nomenclature) to Joe's Control Board. You don't need that potential ground loop caused by the white wire circling back to the star ground.
These are the nine wires that I connect to the Star ground:
1. Left Speaker Ground
2. Right Speaker Ground
3. Chassis Ground
4. Faceplate Lighting or Cylon Meter Ground
5. DCP Relay Board Ground
6. Left Backplane Ground 1 (if installed)
7. Left Backplane Ground 2 (if installed)
8. Right Backplane Ground 1 (if installed)
9. Right Backplane Ground 2 (if installed)
 
Can't do that, them caps are OLD......385 is nominal on bias....no reason NOT to have it there...it's too easy to make it stay...
 
mlucitt said:
Al, I call the white wire the "White Wire of Death". Some on the forum will disagree (and that's OK), but I was taught never to connect the grounds of the inputs to the grounds of the outputs. Your inputs are properly grounded when you run the two wires (signal and shield - from the RCA jack nomenclature) to Joe's Control Board. You don't need that potential ground loop caused by the white wire circling back to the star ground.
These are the nine wires that I connect to the Star ground:
1. Left Speaker Ground
2. Right Speaker Ground
3. Chassis Ground
4. Faceplate Lighting or Cylon Meter Ground
5. DCP Relay Board Ground
6. Left Backplane Ground 1 (if installed)
7. Left Backplane Ground 2 (if installed)
8. Right Backplane Ground 1 (if installed)
9. Right Backplane Ground 2 (if installed)
Click to expand...


Excellent point on the grounds, Mark, and I see how this could open the path for ground loops. I was following the procedure in the DCP installation instructions (Step 23 specifically), which apparently doesn't account for installations with a WOA PL14_20 control board. Might be an opportunity for a revision? I do have all 9 ground points above as described, so that's cool.

"23: The white wire will connect the input jack ground wire to the power supply common. Strip 1/4” of insulation off one end of the white wire. Use a pocket knife to scrape away any oxidation on the bare ground wire on the input jacks. Solder the white wire to the ground lead. Some rosin flux may be required for a good connection. Run the white wire in parallel with the input wires and along the bottom of the driver board. Cut it to length and connect it to the copper buss bar on the power supply caps. Save the remaining piece of white wire. It can be soldered to the copper bar or the terminal lug can be installed under the screw on the cap and the wire soldered to the lug"
 
Al, maybe this photo (it's not the best) will help. I remove that copper plate and use the ground tabs that come with new jacks. If you don't have the tabs, then leave the plate as your "ground tabs". PXL_20210210_135845454.jpg
 
laatsch55 said:
Can't do that, them caps are OLD......385 is nominal on bias....no reason NOT to have it there...it's too easy to make it stay...
Click to expand...

Thanks Lee - I have the old Cylon boards disconnected at this point. I had found some threads regarding issues with the original Cylons while educating (and convincing) myself to go fully-complimentary with new WOA backplane boards. I believe they are susceptible to latch-up and potentially other shortcomings....but I can't put my finger on all the details at this time. So that was why I would either re-cap them OR just bite tue bullet and go for Joe's updated boards. Do you or any others have more info why I should replace the original Cylons? And trust me - I am a WOA fan-boy at this point!

I have a good friend locally who has a 400-II that I've been working hard to convince him to ditch ambitions of buying new Carver monoblock tube amps and do a complete WOA restoration instead....
 
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