Greetings

[DrCharles]

Hello everyone... for years I've had a Cranky Condor pachislo. Bought it cheap because it didn't work (at least one of the reels just quivered and didn't turn). But I'm an electrical engineer (among other things) so I was able to fix it even without a schematic. I suspected that one of the driver transistors for the stepper motor was bad so it was missing a phase. Turned out to be correct and I replaced it with a suitable part.

However - yesterday I turned it on for the first time in a couple of years and none of the Stop buttons will work, so it's not playable I did reseat all the connectors and checked to make sure the buttons themselves were making contact. Now it's possibly the input port on the board itself - hope that's fixable. A service manual, or even just a schematic, sure would make life easier! I'll put in a Tech Support ticket.

Anyway, I just wanted to say hi and share my situation.
Thanks!
Charles

[Drunkenclam]

Without sounding daft. I'm sure you checked the fuse on the stop board.
A lot of pachis have very basic inputs like a child's keyboard that can only handle one note at a time. If a button or spin lever is stuck. It will prevent any other inputs from working. See if you have indicator leds on the main board that react to button presses etc and make note of them. See if any don't give a reaction

[DrCharles]

Thanks. I thought I had checked all fuses but will look for more...

The stop buttons themselves are working (measuring the output voltage) and none are stuck.
All the other functions of the game seem to work (selecting number of lines to play, left hand button with the red light: operating mode which seems to be "insert medals for each play, receive winnings as medals" vs. "accumulate credits", and the Start joystick button). After the spin times out in 30(?) seconds, all three reels stop in quick succession as though the buttons were pushed rapidly.

[Wayne-Ooo]

Post #5 in this Topic.

https://www.pachitalk.com/forums/sho...-no-stop-issue

[DrCharles]

It's fixed That was indeed the problem. Thanks for the helpful suggestion, I didn't know what that board did!

In a bit more detail: the 1 amp fuse was vaporized internally. So I removed the stop board, and on the bench, measured for shorts, opens and normal diode function. Everything looked ok at the test voltage from my DVM.

Next, I carefully applied power (with the fuse jumped) from a current-limited DC power supply (the diode at the bottom of the pic is a half-wave rectifier anyway). As I turned the p/s knob high enough so that the 78L05 regulator would reach its design output (5.08V), the supply current suddenly jumped to the 0.4 amp limit, and I saw a tiny spark from the 1 uF 50V tantalum capacitor that the diode feeds.

Eureka. I replaced it with a 2.2 uF 50V electrolytic and ran the voltage up again. All was well so I put in a new fuse, installed the board and everything now works as designed

For the more technically inclined, the problem with tantalum "teardrops" is their limited ability to tolerate surge currents from rapid voltage rise, as I=C dV/dT. This happens below the rated voltage of the cap!
Tektronix enthusiasts learned this lesson with 7000-series scope plug-ins starting maybe 20 years from the original manufacture dates in the 1970's. Tek used 6V rated tantalums extensively on 5V (TTL) power lines for bypasses. Eventually the caps got tired of the surge at power-on and would short, sometimes spectacularly if enough supply current was available (smoke, epoxy case shrapnel, and actual small flames that would damage the underlying PC board!) At some point, Tek learned of the problem and started putting small (~10 ohm) carbon resistors in series with the cap, to act as a fuse. And they changed to higher voltage rated caps, which also helped.

After looking at the stop board, I see no current limiting at all other than the transformer impedance, and I would guess that there's at least 24 volts across that (50V) cap. A slightly larger aluminum electrolytic will work fine to keep that 78L05 regulator stable. I didn't change the other tantalum, but if the fuse blows again I'll know where to look

Again, thanks for the tip. It seems I'm not the only person who has learned about this failure!

[Drunkenclam]

Some just change all the caps to be on the safe side

[takethecastle57]

DrCharles and biscuits

And Welcome to the addiction

[takethecastle57]

The Electrolytic Caps have a Expiration date of around Ten or Twenty years .

https://en.m.wikipedia.org/wiki/Electrolytic_capacitor

[DrCharles]

The Electrolytic Caps have a Expiration date of around Ten or Twenty years .

https://en.m.wikipedia.org/wiki/Electrolytic_capacitor

I've got plenty of Tektronix, HP and General Radio equipment (and even some Heathkit gear) from the 1960's and 70's that are running on their original electrolytics. Good quality caps will last quite a bit longer than that. I can only recall a handful of failures, one in a cap made in 1962...

Besides, I'm not so sure my expiration date is 20 years from now either

[bjab]

DrCharles, I sent you a message about Cranky Condor

[PacFrank]

Great insights shared