Derek92994's 700 Ser II White Oak conversion

[derek92994]

I did a shitty job of cleaning the topside of the backplanes...

One last thing tonight Darc. Check B+. B- voltages on the test points on the backplanes, minus on ground, plus on the B+, B- test points..

If I power it up again, can I leave the control board unmounted so i can get a better view if something is smoking on the backplane?

 

[laatsch55]

Yep..

 

[derek92994]

Yep..

This time when I powered up, the meters didn't go crazy, and no smoke.

Voltages on both backplanes are between 102.6 - 102.9

 

[derek92994]

Those voltages were pretty much the same between all 4 test points.

 

[derek92994]

I am going back to work tomorrow, unfortunately I don't get home until around this time. I will check each day and do any more tests that are required.

 

[laatsch55]

Hookay. That's good for tonight. While I'm asleep, check the archives for debugging the 14-20 white oak control board. It will show you how to isolate the control board from the backplanes so we can see what's going on.

 

[laatsch55]

It's in the WOPL tips and archive section. 14-20 quick test steps.

 

[laatsch55]

Those voltages were pretty much the same between all 4 test points.

You were getting positive voltage on B+ and negative voltage on B- right?

 

[derek92994]

You were getting positive voltage on B+ and negative voltage on B- right?

One Moment I will re-check

 

[derek92994]

You were getting positive voltage on B+ and negative voltage on B- right?

Yes that is correct. +/-

Just then, first power up, meters go nuts, smoke after about 20 seconds, still can't tell where.
2nd Power up, meters are still, no smoke. Checked voltages.

 

[laatsch55]

Still cant see where the smoke is coming from?

 

[laatsch55]

Hookay. Check the archives. See ya tomorrow..

 

[derek92994]

Lee, I have done quite a bit of searching on the forum, but all I can find is a thread on how to debug the original control board.

 

[derek92994]

Here is some more info:

There are 3 states the amp powers up in:

1. Power up, no relay click, no meter movement
2. Power up, relay clicks, no meter movement
3. Power up, meters peg and bounce, smoke or smell comes from right hand side backplane, but no burnt components. Videos will be posted below of meter activity after power down, and in another video you can hear the meters pegging and bouncing, this is when the smoke or smell occurs.

 

[derek92994]

Video: Meter Behavior approx 30 seconds after power down

 

[derek92994]

Video: Meters pegging after power up, no relay click, and also when the smoke and smell occurs. On this occasion it didn't smoke but the smell was certainly there near the right hand side backplane. No Visible burnt components, could it be an output doing this?

 

[laatsch55]

Start here Darc, you'rer looking for full comp, D board..

https://forums.phxaudiotape.com/thr...ick-test-steps-quasi-comp-and-full-comp.9038/

 

[laatsch55]

Video: Meters pegging after power up, no relay click, and also when the smoke and smell occurs. On this occasion it didn't smoke but the smell was certainly there near the right hand side backplane. No Visible burnt components, could it be an output doing this?

I've never had an output do that, no.

 

[mlucitt]

I wonder if it could be a wire strand or ball of solder under the backplane. Both meters have this behavior on shut down, yes? Most likely a power problem. Maybe pull the B+ fuses (the ones on the upper side), try it again. If it still happens pull the B- fuses (the two lower ones).

If it still happens I would remove the Output Transistors one column at a time and try it. If that has no effect, you will have to remove them all anyway to pull the Backplanes away from the chassis.

BTW, is your chassis bare aluminum? It looks silver in the video.

 

[laatsch55]

That was the prototype White Oak chassis.

1st gen backplanes, outputs are soldered in. Let's do the White Oak debug to separate backplane/ driver board problems and go from there...