LW3 home, pictures attached diagnostic underway

[max242]

OK, fuse replaced. Next found no power to the power supply board on the yellow & yellow/white wire pairs. Per diagram I should have 6.3 VAC on each pair. It appears to me I have a bad secondary on my Transformer part # 010-5003-00. By the look of the butt connectors vs the original molex plug, this has been messed with before. Anyone want to confirm? Is this common? Also where would be the best place to buy one? Searched by part number online, a few sites show discontinued. Where is the best source? Or does anyone have one to sell? - Thanks - Max

[ralphwiggum]

Not super common for a transformer to go belly up. Are you sure the butt connectors are tight? If you remove and test, are you still getting zeroes?

[max242]

Ralph - You were correct, rookie mistake on my part what a DA. Voltage good, meter operator error. lol. I re-did the connections anyways.

After verifying that, I have found:
1) F7 fuse pops right away on power up.
2) On PS board - Display J2 voltages all in VDC.. Red 5.2, Blue 11.06, Vio/Yel 29.19, Blk 0, Gry/Yel 0. 3 of 5 voltages are incorrect per diagram.
3) Next search on power supply board and found CN8 has burnt connections.
4) Wires between PPB board and PS board are good, connector is shot on PS board side.
5) I do have 6.75 vac out of all pins on CN8 but a couple are burnt, see pictures.

With the voltage issues on J2 and the wrecked pins on CN8 looks like I may need a Power supply though. If a replacement is needed, who would be the best source? But I am not sure what caused the short yet and am hesitant to just poof a new board. Unless someone knows that the power supply is the root cause?

Also a connector for CN8. I have never replaced a connector, any tips or special tools I need?

Also thoughts from anyone on next steps....

This is fun

Thanks Max

[ralphwiggum]

I wouldnt jump right to a new power supply, your issues appear pretty minor. If you like figuring stuff out, this Data East repair bible will be a great tool-

http://techniek.flipperwinkel.nl/desega/index1.htm

If you dont want to work through things, Rottendog power supplies have been used for many years without issue in this particular application.

[max242]

Ralph, thanks for the link. I read about the connector and pin replacement. Looks like pins and connectors may be a way to go. Not afraid of soldering. Did look at the Rottendog boards, price is not out of line. I feel I still need to diagnose the board regarding the voltage issues though 1st.

Thanks - Max

[ralphwiggum]

Cool, if you like to dig, lets get started. F7 is your high voltage section for your display.

Here is,how you can test it-
http://pinwiki.com/wiki/index.php?title ... MD_display

[max242]

Following PiniWiki I found:

VDC at C8 on DMD board and CN5. VSP 28.82, VCM 11.96, VCC 5.01, VRW .517, VSN 0.

VDC for Diodes (banded side) - D5 30.41, D7 19.85, D10 -.006, D11 -.005.

Left terminal of F7 94.6 VAC.
Right terminal F7, continuity to ground.
CN1 unplugged F7 doesn't pop
CN5 unplugged with CN1 plugged in F7 pops

I pulled the board to inspect the backside.
1) CN8 terminals and plug will need to be replaced and traces repaired.
2) RY1 terminals are in bad shape, guessing it should be replaced.
3) Image for grounding plate behind Power Supply shows traces of overheating for other components.
4) Back side of PS board shows rippling on the coating for the traces.

Please let me know what you think

Thanks Max

[max242]

I would like assistance with determining the individual components on the board that need replacing if you would recommend that step 1st.

[ralphwiggum]

Okay, so I finally got a little time to look at your post.... Lets break it down a little further.

Put the .5 fuse back in, and then connect everything back on the power supply board. Go to the DMD, and completely unplug it from all of the connectors. This includes the connectors on the DMD itself, and the driver board going to the DMD.

Does the fuse pop when these are disconnected?

At first glance at your readings, it looks like your HV section on your driverboard is toast. BUT, I want to confirm your DMD itself isn't taking out the fuse.

[max242]

I only tested it with the CN5 unplugged and yes fuse pops. I didn't pull all harnesses from the DMD. I will do that, re-test fuse and report back. It may be a few days, I am out of town for a bit.

Thanks Max

[max242]

Ralph, I got back and finally had time to test tonight. With all connectors plugged in to power supply board and all connectors unplugged from DMD including ribbon cables, fuse popped. Thanks for your help - Max

[ralphwiggum]

Your HV section is toast on your power supply. It may not be the worst thing to get a repro board, and then get your original fixed to have a working spare.

If you have a lot of confidence in your soldering/desoldering, it isnt an overly difficult repair, but there are a lot of individual components you will need to test.

[max242]

I like the idea of buying a repro board and then diagnosing the original board in my spare time. Will be ordering this week. I will need to replace the burnt plug & pins as well. Is there a preferred vendor you all use for Data East? - Thanks Max

[ralphwiggum]

Rottendog can be hit or miss for repro boards, but their DE power supply boards have been tried and true for many years.

[max242]

Power supply board, display Molex plug & pins ordered. Now comes the careful fun.