EDOT lamp sequencer schematic/ parts list

p1899m

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Trying to troubleshoot this lamp sequencer board and have looked at the manuals online at a few sources but none seem to have a schematic or even parts list for the lamp sequencer board. Actually none I've located have any schematics for any of the boards.

So far I've tested continuity to the lights themselves and all is good. I also verified in test mode I get a pulse to the resistors. Beyond this I don't know where to go. Sounds like replacing the MPN22222A's might be worth a try but if I'm testing what I'm pretty sure are diodes correctly then I got a lot of bad diodes too. So a parts list and schematic would be helpful if anyone has a source for them.
 
Trying to troubleshoot this lamp sequencer board and have looked at the manuals online at a few sources but none seem to have a schematic or even parts list for the lamp sequencer board. Actually none I've located have any schematics for any of the boards.

So far I've tested continuity to the lights themselves and all is good. I also verified in test mode I get a pulse to the resistors. Beyond this I don't know where to go. Sounds like replacing the MPN22222A's might be worth a try but if I'm testing what I'm pretty sure are diodes correctly then I got a lot of bad diodes too. So a parts list and schematic would be helpful if anyone has a source for them.

Can you post a pic of what you speak of, please.

Look at this, it has some good info about testing the lamp sequencer for the Disks of Tron.

http://users.rcn.com/jenison/mars/pages/DoT/

here is another one

http://forums.arcade-museum.com/showthread.php?t=67155
 
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There are assembly drawings and schematics of all boards in the Parts & Op manual (but not in the circulating PDF). I probably won't be able to get to it until friday night, but I can do 300 DPI scans if still needed by then.

Anyone want to sell me their EDOT?
 
Still unsure but my original thought was that everything circled in blue and red were diodes. I'm now thinking maybe just those circled in red are diodes. Circled in green are the MPN22222A transistors . (most people say they are MPS22222A but mine read MPN)

lampsequencerEDOT.jpg
 
The 4 circled in blue at the top of the picture, the ones in blue to the left and right of NE556N, the one to the left of the 74HC374 and the two to its right are all the same caps (0.01 uF 50v ceramic). The ones to the right of the big metal axial cap are all the same caps (100pF 50V ceramic). The transistors are all MPS 2222A. The ones in red are all the same diodes, 1N4148.
 
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Red and blue are diodes and green are transistors. It looks like something cooked some of the diodes just by looking at them.

well if both red and blue are diodes then I will stand by my original statement that I have a lot of bad diodes. I base this on the nine I tested where only one looked to possibly be good. All but one had no continuity when metered either direction so they were totally open. Pretty sure diodes should test open when metered one direction and should show some level of continuity when metered the other , right?
 
well if both red and blue are diodes then I will stand by my original statement that I have a lot of bad diodes. I base this on the nine I tested where only one looked to possibly be good. All but one had no continuity when metered either direction so they were totally open. Pretty sure diodes should test open when metered one direction and should show some level of continuity when metered the other , right?

that was some bad info on my part and deleted the post:
Aside from the ic chips, there is not much expense for parts on that board.
 
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The 4 circled in blue at the top of the picture, the ones in blue to the left and right of NE556N, the one to the left of the 74HC374 and the two to its right are all the same caps (0.01 uF 50v ceramic). The ones to the right of the big metal axial cap are all the same caps (100pF 50V ceramic). The transistors are all MPS 2222A. The ones in red are all the same diodes, 1N4148.

What he said.

Something Really bad happend to that board for that many parts to go up like that. I would bet the chips are fried also. :(
 
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The 4 circled in blue at the top of the picture, the ones in blue to the left and right of NE556N, the one to the left of the 74HC374 and the two to its right are all the same caps (0.01 uF 50v ceramic). The ones to the right of the big metal axial cap are all the same caps (100pF 50V ceramic). The transistors are all MPS 2222A.


Ok so everything in blue are capacitors and the 4 in red are diodes. If this is the case then it's possible I actually don't have bad diodes. Have to double check which of the diodes I actually tested. I know the one that tested "good" was a diode.
 
that was some bad info on my part and deleted the post:
Aside from the ic chips, there is not much expense for parts on that board.

Yeah I'll probably buy a few parts, replace a few things and see what happens. It would be nice to actually know what went bad though. For future reference if nothing else.


Thanks, i86time

as well as kb0jjn

for your responses.
 
In the MCR power supply thread ELutz posted about how the tantalum caps can go bad, and you can test them- might want to look at those. According to the schematic, J2 pins 4 & 5 provide 12V to the lamps, pin 6 is the regulated +12V and pins 1 & 2 are ground. Might want to test that to make sure the proper voltages are being output.
 
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In the MCR power supply thread ELutz posted about how the tantalum caps can go bad, and you can test them- might want to look at those. According to the schematic, J2 pins 4 & 5 provide 12V to the lamps, pin 6 is the regulated +12V and pins 1 & 2 are ground. Might want to test that to make sure the proper voltages are being output.

+1

a short or voltages were applied to the wrong pins. Caps usually filter voltages for the chips (in this case) and if caps are bad then chips are possibly bad. :(

Usually if a Tantalum cap goes bad it shorts out...very bad.
 
Vader's post in the resto forum reminded me of something. On my EDOT, only lamps 2 & 3 lit up. I figured it was the MPS2222's. So went ahead and did a typical NPN transistor test (outlined here: http://www.stickycarpet.com/pinx/test.html). Oddly, all tested good. After going back and forth testing every other component on the board, I finally did the first transistor test on the first page kb0jjn linked to in the 2nd post of this thread (hooking it up in circuit). With a digital multimeter, the 2 good transistors had a small voltage drop, but the 3 bad showed a huge spike, sometimes followed by an open loop notice. Testing in circuit seems to be the definitive way.
 
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