Lw3 vuk coil locked help needed

(Topic ID: 217271)

Lw3 vuk coil locked help needed


By Chochi_ca

6 months ago



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  • 72 posts
  • 5 Pinsiders participating
  • Latest reply 85 days ago by wayout440
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There are 72 posts in this topic. You are on page 2 of 2.
#51 4 months ago

Replaced my 7408 chip. Still not gettin enough voltage on my high/low inputs for the vuk gate?

#52 4 months ago
Quoted from Chochi_ca:

Replaced my 7408 chip. Still not gettin enough voltage on my high/low inputs for the vuk gate?

Do you mean high/low inputs to the 7408? If so, check the outputs of 5F 6821 PIA, that is all there is before the 7408. If that's not what you mean, I am not clear about your question.

2 weeks later
#53 4 months ago

So back at it again. I replaced the 5f 6821 pia. But while I was desoldering the old chip I burnt away the trace points for pin 38 and pin 2. I can’t c the traces on the board to c where they go? Can someone please tell me what points they go to from there. I am unable to read the print. Now upon start up my machine does not boot properly.

#54 4 months ago
Quoted from Chochi_ca:

So back at it again. I replaced the 5f 6821 pia. But while I was desoldering the old chip I burnt away the trace points for pin 38 and pin 2. I can’t c the traces on the board to c where they go? Can someone please tell me what points they go to from there. I am unable to read the print. Now upon start up my machine does not boot properly.

Ugh. Looking at the schematics, you should be able to jumper pin 5f pin 38 to 6821 11D pin 38, both of these are IRQA low signals. Looks like pin 2 is not used, so you should be ok with leaving that be.

#55 4 months ago

K I jumped that along with a couple others that had no continuity. I was able to understand the numbering and trace the rest. But is pin23(cs2) run? That’s the only trace I can’t can’t read where it goes?

#56 4 months ago

Sorry and pin 19..... ugh.

#57 4 months ago

Pin 23 signal name "2100" runs from LS139 8E pin 5 (CPU sheet 1 of 4, right side of page about halfway down)
Pin 19 signal name "EN" runs to 7402 12B pin 8 (CPU sheet 1 of 4, signal enters about halfway down on the left, ends up about the middle of the page)

#58 4 months ago

K both those were good. But now my machine boots up and 5v and pia light stay lit. Does not boot. I placed a jumper btw pin 38 5f and pin 38 11d also. Is this correct? So pins 37 and 38 have continuity on both chips? Irqa and irqb.

#59 4 months ago

Yes, pins 37 & 38 of both PIAs should have continuity to each other, and all four pins (37 & 38 of each PIA) should have continuity to LS08 7E pin 9.

#60 4 months ago

Those points all test good. I have checked all points btw both pias and there good. What would cause my machine not to boot? Only the 5v and pia leds stay solid on boot up? Apreciate all the help. Maybe I should order a new rottendog mpu board? Damn it didnt wanna shell out the price of a new board.

#61 4 months ago

The machine booted properly before the replacement of 5f pia

#62 4 months ago

*most likely* something went wrong with the replacement.
Check and solder all vias on both top and bottom. Make sure there are no shorts between IC legs unless there are intentional traces between them.

Was this a new IC? Not something used that could be questionable. Keep in mind that new IC can be DOA ( a slim chance, but it happens). ICs can also be damaged by ESD, excessive heat from soldering, or mechanical stresses to the legs.

If it wasn't any of those, then the failure is coincidence, and you'll have to troubleshoot it as a new problem.

1 week later
#63 4 months ago

So one last attempt. Can someone please tell me what pins on the 5f 6821 chip that are not directly on that numbered print where they are coming from or goin? I’m not grasping how to read 1-12f e line?(though it would mean print 1.... 12f location on that print?) all similar pins that read like that to. If this fails I’m gonna buy a new rottendog mpu

#64 4 months ago
Quoted from Chochi_ca:

So one last attempt. Can someone please tell me what pins on the 5f 6821 chip that are not directly on that numbered print where they are coming from or goin? I’m not grasping how to read 1-12f e line?(though it would mean print 1.... 12f location on that print?) all similar pins that read like that to. If this fails I’m gonna buy a new rottendog mpu

The "1" on the 1 -12f designation refers to CPU schematic sheet number 1 (there are 4 pages to the CPU schematic, this would mean page 1 of 4). The "12f" refers to the coordinates on the page to find that signal (follow the numbers across and the letter down). Signal "E" comes from LS244 IC 6D, pin 3 located in the middle of page one.

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#65 4 months ago

K I was able to read most of it. Thanx for the detailed description. Just two pins I can’t read. Reset pin 34. I don’t c any reference to “reset” at 1-12a? And pin r/w pin 21. 1-12g?

#66 4 months ago

I think I figured it out. Pin 34 goes to r106? Listed as 1 12f and it supposed to b 1-12a? And pin 21 r/w goes to 6d pin 18?

#67 3 months ago

All reset low signals (that's what the long line over the word reset means) come from the same place, they all come from the reset generator/power monitor IC: IC1 PST518. This signal will be high during game operation, if it is stuck low permanently the system will not run. Same thing if it is toggling (bouncing). This signal feeds main processor and all the PIAs.

#68 3 months ago

Ok all pins test good for continuity. When I boot my machine my gi lights up. Maggie calls out “back in action” then nothin. Only the pia and the 5v lights come on and stay on. No blanking led. Reading the pinwiki guide it states the eprom at 5c is bad? I did have battery leakage when I bought the machine. I cleaned it up but never neutralized. Could the damage from the battery leakage b time delayed? Should I try and order a new eprom?

#69 3 months ago

possibly....depending on the severity of corrosion, battery leakage not only has to
be neutralized, but also affected components removed, traces sanded to bare copper, and new components installed, any non-continuous traces must be repaired. Battery alkaline damage is a cancer of printed circuit boards.

#70 3 months ago

Here r some pics of my board. I don’t c any corrosion ? I also noticed my eprom chip doesn’t have a sticker covering the lens? Does that matter? It hasn’t had one since I picked the machine up 6 months ago.

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1 month later
#71 85 days ago

Update! My machine is working now. Installed a new rottendog mpu board. Fixed my locked vuk. But still had some other issues. Found the solder flux I was using must b conductive? After cleaning away the leftover flux with alcohol and carbon deposits from board burning its playing flawless now. Expensive lesson learned.... ouch. Thanx for app the advice in the post.

#72 85 days ago
Quoted from Chochi_ca:

Update! My machine is working now. Installed a new rottendog mpu board. Fixed my locked vuk. But still had some other issues. Found the solder flux I was using must b conductive? After cleaning away the leftover flux with alcohol and carbon deposits from board burning its playing flawless now. Expensive lesson learned.... ouch. Thanx for app the advice in the post.

Congrats on getting it going
Which flux/solder were you using? Typically we don't see problems from flux except for very high frequency circuits where water soluble flux was used, not cleaned properly, and has sit for some time on the board.

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There are 72 posts in this topic. You are on page 2 of 2.

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