nelsress begins his WOPL 400 project

laatsch55 · Mar 1, 2015

The Br to the caps is not wired correctly. Look on the side of the BR. The green wire closest to the side of the chassis on the BR goes to the minus,-, cap terminal. The other green wire closest to the inside of the chassis on the BR goes to the plus,+, terminal of the top cap.....

nelsress · Mar 1, 2015

Got it

laatsch55 said:

That's what I thought based on the way the green wires were already "trained" but I misread the instructions and thought it was telling me to land them both on one screw. Thanks Lee, I'll change that straight away. So to paraphrase, the green wire closest to the cap that has nothing attached to the rear lead gets landed on that currently empty lug. Right?

laatsch55 · Mar 1, 2015

If you look on the side of the BR there are +, & - signs indicating what polarity the DC voltages are at that terminal.....

nelsress · Mar 1, 2015

Gotcha

laatsch55 said:

Will check the side of the BR for the (+) and (-) designations and move it accordingly, thanks Lee. I did not see the markings on the BR when it was hanging there and didn't think to look either. I'll try to be more observant going forward. :thumbright:

laatsch55 · Mar 1, 2015

It's all good Nelson!!

Gepetto · Mar 1, 2015

nelsress said:

I appreciate the suggestions Joe, Lee and Doug, thanks. What I ended up doing was running the 10-24 tap about 3/4 of the way in and backed it out. It didn't seem like it was taking much of the aluminum out, it went so easily and when I backed out the tap, a couple little shavings came back out with the tap. Then I threaded the rod into the hole and when it stopped, well short of the distance the screw was in, I turned it with a nut driver over the two nuts and went the rest of the way, stopping 1/16" or so from the depth the screw had been in.

The instructions say to attach the two black wires with ring lugs coming from the transformer to the rearward cap screw. The black wires coming out of the transformer were attached to lugs on the bridge rectifier as were the green wires with the ring lugs so those are the ones I attached. Is that correct? I had to extend the white wire from the transformer to the copper bus so it would reach the end of the new, longer resistors without being bent fairly drastically in the middle.

The upper capacitor's rearward connection point is supposed to get the red wires with ring lugs and the photos on the instructions show the old point to point wiring on the back wall, not the backplane boards so I'm not sure what wires go to that spot yet.

I installed the bottom row of transistors with silpads starting from the transformer and going away from it in this order-95-96-95-96 and snugged them down. Now I may have missed it or perhaps it comes in a later step but I didn't see anything about soldering the transistor leads. Do these solder cups have some sort of contact inside them that eliminates the need to solder them or am I just getting ahead of myself and I'll be told to solder them farther along in the assembly?

Attached are some more photos so you can see what I've done up to this point. Thanks guys!

View attachment 19603 View attachment 19604 View attachment 19605 View attachment 19606 View attachment 19607 View attachment 19608 View attachment 19609

DO NOT SOLDER THE TRANSISTOR LEADS IN NELSON!! The socket cups are precision gold plated sockets. They make a slip fit contact like the old Keystone sockets on the backplane did but are high quality contacts instead of what was there in the original amp.

nelsress · Mar 1, 2015

Gepetto said:

Thanks Joe, that's pretty cool, I never heard of those kinds of sockets and obviously wasn't aware that the originals were like that!

nelsress · Mar 2, 2015

Okay, I moved the green wire with the ring lug coming from the (+) side of the BR, from the negative of the lower cap to the positive of the upper cap. I read over the capacitor instructions several times and because of the fact that I'm inexperienced and I'm doing a full comp with new backplane boards and the photos are showing replacing the caps in a PL 400 with the old wiring on the backplane, I'm still not sure if there are more wires that are supposed to go on the PS capacitors or not. I'm also not sure where the red wires coming out of the left side of the power transformer are supposed to go.

I'm going to move on to the PL14_20 connections, the new LED board installation and the DC protect circuit connections in the mean time.

laatsch55 · Mar 2, 2015

The 2 red wires are the 6 volt AC secondary for the light board.

nelsress · Mar 2, 2015

Super!

laatsch55 said:

Thanks Lee! I have yet to look at the light board yet, will be getting to that soon!

laatsch55 · Mar 2, 2015

I don't usually mess with that until it's been brought up and running...

nelsress · Mar 2, 2015

That makes sense

laatsch55 said:

Would you also wait on the DC protect circuit?

laatsch55 · Mar 2, 2015

No...
That wiring is integral with operation...
So it would be after the backplanes and before the driver board.

nelsress · Mar 2, 2015

laatsch55 said:

Thanks, then that's how I'll do it!

Gepetto · Mar 2, 2015

nelsress said:

Okay, I moved the green wire with the ring lug coming from the (+) side of the BR, from the negative of the lower cap to the positive of the upper cap. I read over the capacitor instructions several times and because of the fact that I'm inexperienced and I'm doing a full comp with new backplane boards and the photos are showing replacing the caps in a PL 400 with the old wiring on the backplane, I'm still not sure if there are more wires that are supposed to go on the PS capacitors or not. I'm also not sure where the red wires coming out of the left side of the power transformer are supposed to go.

I'm going to move on to the PL14_20 connections, the new LED board installation and the DC protect circuit connections in the mean time.

Did you bring up the backplanes only before the control board was installed?

nelsress · Mar 2, 2015

Gepetto said:

Hi Joe,
I haven't yet brought up the backplanes, no, but I haven't installed the control board yet either. Thanks!

Gepetto · Mar 2, 2015

nelsress said:

Well you can do a safe bring up of the backplanes without the control board in place with only one transistor installed in the bottom row of the amp. It is a good checkout procedure before you go to far.

That allows you to ensure that you have all the proper voltages and confirm your wiring is correct before proceeding further.

You have to masking tape off all the loose wires that are intended to go to the control board to keep them from shorting to each other. You can then bring up on the DBT/Variac. You should have all the B+ and B- voltages, zero volts on the output test point and no blown fuses. Once you have achieved that, you have a good platform to move forward.

Also, before doing that, temporarily remove the single chassis ground wire (the lug to the upper connection on the left channel backplane board). After you remove that wire, you should confirm that the collector cans of the 4 transistors you installed read infinity with your ohm meter when measured from chassis metal to collector cans.

These are a few of the tricks you can employ to ensure a successful bring up.

nelsress · Mar 2, 2015

Thanks Joe, I only installed the bottom row of transistors because I remembered reading about bringing it up configured like that but mistakenly thought the control board had to be installed before doing it. Thanks for speaking up! I'll go ahead and disconnect the ground wire from the chassis lug, mask off all the wires that go to the control board and test the transistor collector can to chassis readings. I've got variacs and I built a DBT a while back but was never sure whether it's working properly or not so I'll go with the variac.

Great to have you and Lee here checking in with me, I appreciate it a lot.

laatsch55 · Mar 2, 2015

Don't forget to mask off the bias transistor wires also.......the ones that go to the control board

nelsress · Mar 3, 2015

laatsch55 said:

Roger that Lee, will do. Thanks.

nelsress begins his WOPL 400 project

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