P&M Coin Keno: this one won't be easy!

[SolidSilver]

Just acquired this machine today: only 50 bucks, but 350 miles RT.
This will be my "challenge" for the summer
It's a dedicated Keno machine, pre-touchscreen with a light-pen.
Very very well built, clearly a quality product; and quite clean inside, not abused
Unfortunately, P&M Coin machines are rare, and there's virtually no support or spare parts around.

Funny thing, it has exactly the same issue as several Fortune and IGT Keno machines on this forum:
a clear, sharp, bright screen with scrambled images: looks like the machine is trying to output
2 or 3 different screens at the same time. I will try to track down those others on the old site,
to see if/how they fixed theirs.

In the meantime, does anyone know how to reset a P&M Coin machine? Or recognize this problem?

(My grand daughter says I need a can of SprayFix...)

[SolidSilver]

More pics

[jay]

It looks like one of the graphic chips is bad.
Is there any consistency between what is displayed well and what isn't.

[SolidSilver]

Jay, since I have no clue what is supposed to be displayed, it's difficult to determine what's wrong
Looks to me like it's showing multiple screens. I see things like credits, payoffs, and Insert Coins, typical of a "start"
screen; but I also see much of the "pick your numbers" screen, and some stuff that looks like Arabic!
But everything is displayed clearly and sharply. I'm a mechanical engineer, but I would guess the screen is showing
what it's being sent, and that what it's being sent is correct; but the machine's brain is somewhat scrambled so it
is sending out confusion. At my age, I can totally relate!

[Paul]

You can start by checking the battery to see if
it has the correct voltage and then try to force a reset.

Post a picture of the main board and some one may see
some thing to help you get it going.

[UNIMAN]

When I picked up an old Universal video poker machine it had a scrambled screen, a RAM clear cleaned it up. Maybe it needs a RAM clear???

Added; I found this 7 year old post on another site, the guy has/had a video poker P&M manual!     http://forums.arcade-museum.com/showthread.php?t=42276

[SolidSilver]

Those would be my first guesses also: battery & RAM clear.
Pulling the board was the first problem, as someone had removed the board extraction ears
and there's no room for enough fingertip bite to pull it out. (Well, maybe I just have fat weak fingers... )
I wound up putting pins in the ear holes, then used a pair of micro ViseGrips to grab the pins & jerk the board out.

Funny thing: no battery! It's got a Dallas DS1220Y-150 Nonvolatile RAM module. The freakin' battery is built in,
and has a 10-year lifespan, for a 25-yr-old machine.
Removed said module, waited 5 minutes, reinserted. That should quality as a RAM reset (?)
Zip, zilch, bupkis: no change. I've ordered another one with full battery charge just for giggles, but with serious doubts.

In the meantime, here is a pic of the board, and the NonVol RAM with three of the TWELVE [!!] EPROMS this thing has.
It is Z80-based. There is no reset switch on the board itself, and neither of the internal control panel buttons help either.
Board is marked Copyright 1984 Nevada Video Inc, GPB Assy 455205. I wonder if they still exist...
System comes up not-ready, ie: no lit user buttons, inserted coin is diverted to the payout tray.
But the change switch & light work fine: Wowie Zowie! (BFD)

There's gotta be a way to get this thing into a TEST mode. Crossing my fingers that some NLG member who
owns a P&M Coin anything can help: I'll bet my Bippy the same board & system was used in every P&M video game.

[Paul]

The Dallas Chip (  Dallas DS1220Y-150 Nonvolatile RAM module)
has a Lithium battery in it and is most likely dead.
I would start by replacing it and go from there.

[SolidSilver]

Yup, as noted, new one already on order.
I doubt that it's the problem, though: a simple loss of RAM
would usually initiate an error message or test screen, not
scramble the image. Still, it's worth a shot: first things first!

[Buzz]

Jim  I have a P&M Coin Poker machine and like yours it has a scrambled screen. But unlike yours it has only one button, I think it's the service button. Operates by touch screen. The BV actually takes bills but either the touch screen isn't working or with the scrambled screen I'm touching the wrong spot. As I recall the MPU is extra large. I bought this thing 4 or 5 years ago for I think $25  no one seemed to have a manual so out to my 40 foot junk trailer it went.It and about 60 more machines are in that trailer and no way am I going to try and get it out of there.

[SolidSilver]

Buzz, sounds like the trailer of my lust dreams: I love the wierdos.
Any chance I could wander through it some day? 

More to the point, some research has paid off: I discovered that P&M Coin was a DBA
of Nevada Video, who did the actual design work & manufacturing. Same GenMgr for 14 years,
from '82 to '95. Turns out most all Nevada Video and P&M Coin and a few other small-name machines share the same Z80
guts built by NV. So, a manual for any of them would be helpful for all.

And interesting that most P&M machines, and many other early Keno machines have
the same scrambled screen problem. There's a connection there...

[SolidSilver]

Well, Crapski, Comrade!
Received the Dallas 1220 RAM, slapped that little hummer in, flipped the Go switch, and....
ZIT/CRACKLE/POP!!! followed by that unmistakable perfume Essence of Burning Phenolic.
And of course weird flashes & bright lines on the screen, barely noticed as I leaped for the Kill Switch.

No doubt the monitor problem is unrelated to the RAM; equally no doubt it was stupid of me
to have not checked out/cleaned up everything in a new-to-me machine before
firing it up multiple times. Now I see lots of dirty crap on the monitor boards that I had not noticed in the
anxiety of getting a new toy to play. DUMB!

Oh, well, this machine was intended to be my summertime project; it will certainly be that.
Looks like I'm sidetracked into rejuvenating the monitor as a first task. It's an RGB Display Inc Model 1401 (vertical, .31mm).
Turns out there are differences in 1401 monitors, like analog & digital versions; and according to the
factory guy's best recollection,  all 1401 monitors are 15 kHz, except P&M which are 24 kHz!

Naturally no one including Zanen has a cap kit, but I think I have a schemo on the way.
Yippee! This will clearly not be an easy boring toy!

[UNIMAN]

Bummer! One step forward, two steps back.
Was hoping to see you get an old classic back to life. Never easy.
Good Luck!!

[SolidSilver]

No sweat, Uniman: two steps back just gets me room for a run at it.
We will bring her back to life.

[SolidSilver]

Well, now it turns out Zanen does have a CapKit for this thing! While waiting for it to arrive,
closely inspected the main board, to zero in on the original problem before I stupidly zapped the monitor.
Coupla' things, as noted on the attached pic:

1. There's a pair of 2N5064 transistors in sockets, always a sign of expected problems.
And stretching between one of them and a neighboring 2N2222A is a smoky area on the board.
I think I will replace all 3 components, just to be sure.

2. There's a C203YY transistor, one of many, with a broken leg. Looks like it was bent over,
then straightened up.  Another definite replacement.

And, there are two chips near the edge of the board, a 74S08N and a 74LS157. Both look like
they've been water-stained or moisture-shorted. I'll wait on these to see if the other fixes help.

Anybody electronic-ey out there know if any of these visually-bad components could be related to scrambled video?

[Op-Bell]

I've started to reply a couple of times in this thread, then killed it because I'm just guessing. But by this time I figure my guesses might be better than nothing.

When this machine was designed, RAM was very expensive, so it has no video memory as we know it. All the graphics are pre-formed in the EPROMs. Only the P0-P1-P2 EPROMs contain code, the rest of them contain graphics.

I guess the row at the top contain the fixed background that never changes.

I guess that the EPROMs marked SCAN produce the line and frame syncs and blanking

I guess that the ADDRESS and BLOCK EPROMs contain pointers to variable video data, like numbers and words, that are stored in the FORMAT EPROMs.

You can experiment by pulling them out of their sockets, one at a time, and seeing what effect it has on the display.

All these EPROMs are 30 years old, and the specs only guarantee them to hold data for 10 years, though when the spec was written nobody actually knew how long the data would last. It is likely that they're losing a few bits by now.

[SolidSilver]

Op-Bell, you are probably right on all points. While I see at least one, possibly 4, damaged components,
EPROMS are a definite source of similar problems. And since I can't get anything else on the screen, it would
not surprise me to have multiple things wrong.
EPROM sockets alone are historical problems on old machines; and this board has only single-sided contacts.
Just pulling EPROMS and cleaning the sockets have fixed many an unworking machine.
[Although I must say I have never experienced eprom failure in any machine including industrial controllers
built in the '70s]

So, much as I hate introducing multiple simultaneous factors, I intend to re-cap the monitor and the board;
replace the noted components, and pull/clean the EPROMS & sockets, before turning it on again.
Maybe by that time a knowledgeable P&M owner/tech will have told me how to reset the li'l hummer.

[Op-Bell]

If the EPROMs are losing data, it may be possible to read out the original contents at a lower supply voltage than 5V. The storage mechanism in EPROMs is sensitive to supply voltage, and what may read as erased bits at 5V will often read correctly at 4V or 3.5V. You need a fairly sophisticated EPROM reader to do this, though. Once you recover the original data you can then either program it into new ones, or reprogram the ones you have - though doing this means you lose forever any chance to read the original again, in case you didn't get it right the first time.

[SolidSilver]

Op-Bell, I did not know that; I learn something on this site every day!
('Course, I'm a mechanical engineer, and don't really believe in e-lectronics  )

Do you know anyone who would perform such a copying service? Maybe a MAME-type?
Even if my machine pops up running like a champ, I'd still be more comfy with a download;
and no way I'm the only guy on this site that would be seriously interested.

[Op-Bell]

Op-Bell, I did not know that; I learn something on this site every day!
('Course, I'm a mechanical engineer, and don't really believe in e-lectronics  )

Do you know anyone who would perform such a copying service? Maybe a MAME-type?
Even if my machine pops up running like a champ, I'd still be more comfy with a download;
and no way I'm the only guy on this site that would be seriously interested.

I know a thing or two about EPROMs, since at one point in my career I designed EPROM programmers. So I could perform such a service. But right now this has caught my eye (pic). Your picture isn't hi-res enough to make a good inspection, but check real carefully around where that thin wire is patched on and make sure there's no flux or corrosion that could be leaking to adjacent tracks.