Whitestar- switch rows 4,5 &amp; 7 locked on.....

About a month ago I picked up an Austin Powers, and was having fun with it until a week ago when this happened.

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Somehow without reason that I can determine switch rows 4,5 & 7 are locked on. Cannot start a game, but can cycle through menus. Switches on all other rows appear to work fine. Both the CPU, and the I/O Driver boards are rottendog made in 2019. I pulled both boards for closer examination, and didn't see anything obviously wrong.

I'm having a hard time figuring this out.

Any ideas?

Thank you-

-Paul

#2 3 years ago

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Pablito350

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Afternoon bump

#3 3 years ago

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Roamin

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Bumped!

First thing to know, did you pull the connector associated with the switch matrix to test if the issue is on the board itself, or really in the matrix and its wiring? If the issue is present without the connector plugged, then we'll focus on the board..

#4 3 years ago

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Pablito350

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It's still present with the connectors unplugged (except the plug for the coin door switches).

I believe it's on the board.

-Paul

#5 3 years ago

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Roamin

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I can't find the rottendog mpuws schematic anywhere. All I managed to find is a close up picture ,but I can't tell the part number of U205 and u204? From what I read the rottendog boards use the same components and part number as the original boards, so U205 would be a 74hc245. On the original schematic for a whitestar board, CN7 is connected to 2 x LM339 labeled U400 and U401. I can't find those on the picture I have of the board. U205 pins 12,14 and 15 could be measured to see if they are stuck either high or low (probably low). Compare them with the state on pins 11,13,16,17,18 that are still working good. Also check pins 5, 6 and 8 of U205 as this is the output of the chip.

So the LM339 if it exists on that board as to be tested , and U205 also.

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#6 3 years ago

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Pablito350

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Excellent! I'll check those pins shortly.

Thank you!

-Paul

#7 3 years ago

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Pablito350

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Quoted from Roamin:
U205 pins 12,14 and 15 could be measured to see if they are stuck either high or low (probably low). Compare them with the state on pins 11,13,16,17,18 that are still working good. Also check pins 5, 6 and 8 of U205 as this is the output of the chip.

On U205 here's what I got:
Pin# / Value
12 / L
13 / -nothing-
16 / H
17 / H
18 / H

5 / Pulse
6 / Pulse
8 / Pulse

-Paul

Post last edited 3 years ago: “recorded pin values upside down”

#8 3 years ago

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Pablito350

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Just a couple of pics of the board.

18 (resized).jpg
19.jpg

-Paul

#9 3 years ago

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Roamin

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What about pin 14 and 15? Are they low as well? 13 really has nothing? That's using a probe or voltmeter?

With the game powered off, check continuity between ground and pin 12, 14 and 15. Any of them shorted?

#10 3 years ago

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Pablito350

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Quoted from Roamin:
What about pin 14 and 15? Are they low as well? 13 really has nothing? That's using a probe or voltmeter?
With the game powered off, check continuity between ground and pin 12, 14 and 15. Any of them shorted?

I'm using a logic probe.

Pins 13 & 14 have nothing. No reading from the probe.
Pin 15 reads Low

With the game off pin 12 has continuity to ground. 14 and 15 do not.

#11 3 years ago

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Roamin

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Just to make sure you made those measurements with CN7 disconnected? If the game is off , CN7 disconnected and pin 12 has continuity to ground, it seems U205 is broken. I would desolder it, measure continuity again pin 12 to ground on both the board then on the chip. If the short is still there with u205 removed, then it has to be the in-line resistor just below CN7, but I've never seen one of those go bad.

It really seems like the 74ls245 is bad. I would install a socket if I remove the chip.

#12 3 years ago

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Pablito350

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Quoted from Roamin:Just to make sure you made those measurements with CN7 disconnected? If the game is off , CN7 disconnected and pin 12 has continuity to ground, it seems U205 is broken. I would desolder it, measure continuity again pin 12 to ground on both the board then on the chip. If the short is still there with u205 removed, then it has to be the in-line resistor just below CN7, but I've never seen one of those go bad.
It really seems like the 74ls245 is bad. I would install a socket if I remove the chip.

The readings I posted above were with CN7 still connected. I just removed CN7, and went through the pins again with no change. Pin 12 still has continuity to ground.

The in-line resistor below CN7 doesn't show any visual clues that it is bad. It looks new with no discoloring, corrosion, or any tarnishing anywhere.

Unfortunately I don't have any chips or sockets on hand to swap so I'll have to get an order in.

The chip says it's a 74ALS245AN. Is that any different than the 74ls245?

Thanks again for all your help!

-Paul

#13 3 years ago

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Roamin

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Most 74xLS245xx will work, the differences between different markings is subtle.. Before you go ahead and order , you can at least desolder it and check for that short again between pin 12 and ground. It should no longer be shorted when you measure on the board. If you measure on the chip between pin 10 (ground) and pin 12 , the short should be there.

#14 3 years ago

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Pablito350

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Got it. I'll desolder the chip after work tomorrow, and post the results.

Thank you!

-Paul

#15 3 years ago

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Pablito350

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I removed the chip, and there's no continuity between the hole for pin 12 and ground. So it appears that the board is OK.

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I really beefed removing the chip so unfortunately I couldn't verify continuity between pins 10 and 12.

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With this info is it safe to assume that the chip was the problem?

Thank you

-Paul

#16 3 years ago

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Roamin

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That sounds correct. If there no longer is a short on board with the chip removed it should be good. It just needs a socket and a new chip! Just a few bucks and it should be readily available if you have a decent electronics store in your area, otherwise there are plenty of sources online.

#17 3 years ago

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Roamin

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The chip is broken in half but pin 10 and 12 are in the same block.. It might have been possible to test for the short even then. I assume by now the chip is in the trash though

#18 3 years ago

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Pablito350

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Quoted from Roamin:
The chip is broken in half but pin 10 and 12 are in the same block.. It might have been possible to test for the short even then. I assume by now the chip is in the trash though

Oh I tried testing it. (I didn't post a pic of the split on the underside of the chip... it runs between pin 10 and the edge of the chip thus lopping it off from every pin on the opposite side of it.)

(..... and I still have it) lol

-Paul

1 week later

#19 3 years ago

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Pablito350

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