Resurrected a Customized WOPL 400

scottonnob said:
Just for clarification, by infinite resistance, I assume you mean just make sure it's an open circuit with the DMM. Also, when you say disconnect the single wire to the left board, I'm assuming you mean the ground that goes to the buss bar. However, I'm a bit confused as to what, specifically, is meant by chassis ground. Where is it? I also don't understand transformer 'cases'. What is meant by cases? I thought my transformer was a single unit without what would be typically specified by 'cases'. Sorry to be such a dim bulb, but I'd rather humble myself and get clarification than muscle through and screw something up.
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Transistor cases.

With the connections to the control board all taped off so they do not short out to anything (both the bottom row of 10 wires and 3 bias connection wires per channel).
Install the bottom row of transistors starting from the transformer, NPN, PNP, NPN, PNP.
Remove the one wire to the upper left backplane 6-32 screw by removing the securing nut and floating this wire in the air.
Install rail fuses.
Check for infinite resistance between chassis ground and the transistor cases. If not debug. (you will get a reading between DC ground bus bar and these cases, you meter will be charging up the bulk caps)
Connect a ~10K resistor between the output and ground test point on each backplane.

Bring up on DBT and Variac to 60VAC in on the AC input. Make sure all is good and no smoke is coming out. Measure that you have B+ and B- voltages present at the respective test points and B- at PAD12 and B+ at PAD 11 on each back plane board.

Check that you have 0V at the output test point.
Take the Variac all the way up and repeat.

Next, before doing anything else, power the amp down and fully DISCHARGE the bulk caps using a 1K 2W resistor (any value close to 1K will do) down to a level below 1V.

Then you are good to proceed to the next assembly step if this is all good.
 
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Ahh, that's quite different, isn't it. Okay, sorry for being careless in my reading. You know how it is, you read something incorrectly one time and your brain will keep misreading it until something breaks the cycle.
 
Yeah, I found that guy's video series some time ago. He's fantastic. And I've followed along with his journey. But now that you reminded me of it, I'm going to go watch chapter 6. Thanks for the help.
 
scottonnob said:
Ahh, that's quite different, isn't it. Okay, sorry for being careless in my reading. You know how it is, you read something incorrectly one time and your brain will keep misreading it until something breaks the cycle.
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The site flipped a few things around in the document Scott. Very weird, like autocomplete at work.
 
Mark isn't nerdy or whatever, he's just good at talking like you were sitting there with him and a really good instructor. There are some others like him on You Tube, if they aren't fighting getting their channels yanked and other stuff...that makes their viewers rather upset because it's not like they are ripping off VEVO's music videos or pirating advance album copies via videos like some others who can be varying degrees of ID10TS.

There is a pretty large audience of people trying to learn how to fix and preserve vintage gear on YT.
 
I checked out that guy's video on the power-up process. Very clear. I'm going to go find the resistors tomorrow. Right now, NASCAR is finally sending the field off in Texas. Five hour rain-delay. Time to get a pizza delivered. Plus, I was just invoiced and then PayPal-ed for both your board and for Don's relay. Might have all the parts by the end of next week.
 
Okay, I finally found more time to tinker. Also, both the control board and the relay arrived, so I'm all set. The only thing is, I need to wait for a couple items in the mail. First, I had to order one of the capacitors for the relay. Second, I ordered a needle-thin tip for my soldering iron. The control board is pretty crowed, and a thinner tip will make things easier and cleaner.

I did install most of the resistors. The soldering is okay, but there are a couple connections that will have to be cleaned up. The solder joints are contacting other pads. That may be alright, given the two places where it happened. But I'll post close-up photos of the joints, in that, it may be alright that they are contacting the pads next door. They are so close together I think they're on the same path. I'll look at the schematic and see what I can learn.


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The backplane boards are installed and everything is ready for the next step — putting juice to the first row of transistors. I'm just waiting until I finish building a DBT. I need to find a DPDT switch to produce the type of unit I have in mind, and they didn't have any at the local hardware store. Also, I'm switching out all the fasteners, in favor of button head socket screws throughout. I just like the way they look. Silly, I know. Oh, and I'm waiting for fuses to arrive, as well. I have a drawer full of 'em, but none the right rating. I'm in a rural area and the only Radio Shack doesn't even carry parts any longer, so it's Mouser.

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Also, I finished the faceplate. Although it's not really visible in the photos, it's jet-black, sanded with 2000 grit, and then hand-rubbed. It's like a mirror. What appear to be imperfections in the photos are really just weird light glitches and fingerprints. Now it goes to my friend to get the graphics painted on by hand.

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Looks great Scottonob......pictures, pictures and more pictures.

everyone here love pictures

:toothy5:
 
Alright, the control board is populated. . .

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. . . except for one thing. As I was cleaning up the bench, I found this little diode underneath some tools.

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And here's the thing, all the pictures of finished boards I've found online are of a different vintage than mine. So I don't have anything to compare to. I suspect that the diode goes to D82 or D83. But there are several positions left empty, depending on whether it's quasi or not, so I'm just not sure. Can anyone help me out with this? Are you able to see the picture of the board well enough to see the empty spaces?


The Mouser parts order for the relay arrived. So now I can fiddle with that as well. I also had them ship me a bunch of fuses, just in case.

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But mostly, I'm just getting ready to bring up the first row of transistors. I had to wait until I built a dim-bulb-tester (that always sounds like an I.Q. test to me), which I'll finally assemble tonight. I tried to find a household-type DPDT switch, so as to be able to take the bulb out of circuit, but the only ones I saw were ridiculously expensive. So I'm just going to use a DPDT toggle switch and then cut something on the sheer to fit on the faceplate and hold the toggle switch.

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Was the diode a 1N4148?? If so , joe usually puts an extra one in. From your pic I did not see a place where it would go in full comp mode....
 
Hmmm.. I see several issues. Yeah, as Lee said, usually there is a spare in4148 or two. But D82 and D83 should be IN4004's (black, and bigger).

The other thing I see off the bat is Q7L/R appears to either be missing or you have them in Q1L/R's spot (Q1L/R is not populated according to Joe's latest BOM).

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laatsch55 said:
Was the diode a 1N4148?? If so , joe usually puts an extra one in. From your pic I did not see a place where it would go in full comp mode....
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The problem is, I don't know which bag it came from, and they're all thrown out now.
 
Okay, I don't have a bag for Q7, LR. And, as far as misplaced, I do have bags for Q1- NPN MJE15032, as well as Q1, L and R- MPSA92.
 
I will double and triple check the shop, but all the components were left in their box until I started soldering.
 
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