Star Trek Pin Problem

SterlingRush

Well-known member
Joined
Feb 20, 2010
Messages
3,738
Reaction score
162
Location
Bremen, Georgia
I'm working on a '78 ST pin for a buddy of mine, just got the AS-2518 -35 MPU board back from repair, and this is all I get when powering on. Just that high hum, nothing activates other than the lighting. Checked all connectors and it has all new fuses. Advice on what it might be and what to check please? Thanks

Edit: Corrected the MPU info, it was a -35 board.



 
Last edited:
Let me start by saying i am no expert. But i think that mpu should be like the as2518 35. So whats with that blinking led...it keeps on blinking? It should have like 7 flashes ?
 
Let me start by saying i am no expert. But i think that mpu should be like the as2518 35. So whats with that blinking led...it keeps on blinking? It should have like 7 flashes ?

According to the original manual, it has the AS-2962-6 mpu listed, but ipdb.org says it uses the 2518-35.

Yes, LED keeps blinking steadily, it's suppose to be 7 blinks, showing that everything is working good.
 
[FONT=verdana,arial,helv,helvetica][SIZE=-1]Repeating flashes (like the game wants to boot and reboot, continuously) can be a few things. A bad 6810 RAM at U7, or a bad socket / broken trace at U7. Look for a [/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]bad socket / broken trace[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1] at U11 PIA especially near pins 35 to 40. L[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]ook for corroded traces or bad chip sockets in [/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]the typical "battery corrosion zone"[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]since U7 and U11 are in [/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]this area[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]. If there is still no seventh (and final) flash, the last thing to check is U14, after the 7th flash, the MPU enables the IRQ line. If the IRQ line is broken, the MPU will restart the boot sequence over and over. Also look at resistor R134 (4.7k), if this is bad it will cause the board to repeat the boot sequence.

If you have a way to test this on the bench, it'll make your life easier.
[/SIZE][/FONT]
 
Thanks guys, I'll pull the board again tomorrow and check those positions out. It was nuetralized and repaired from the battery acid damage, but it doesn't look like U7, U11, & U14 were replaced. I'll take a closer look. It was mentioned to me to reflow all of the header pins on the boards(lamp board, solenoid board, ect..) just to ensure that those were fresh as well. Again, thank you, and will report on my findings.
 
Maybe the romchips are not correctly in their sockets on the mpu board?

Pulled and reseated all rom chips on the MPU board, still same result. Thank you though.



[FONT=verdana,arial,helv,helvetica][SIZE=-1]Repeating flashes (like the game wants to boot and reboot, continuously) can be a few things. A bad 6810 RAM at U7, or a bad socket / broken trace at U7. Look for a [/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]bad socket / broken trace[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1] at U11 PIA especially near pins 35 to 40. L[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]ook for corroded traces or bad chip sockets in [/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]the typical "battery corrosion zone"[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]since U7 and U11 are in [/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]this area[/SIZE][/FONT][FONT=verdana,arial,helv,helvetica][SIZE=-1]. If there is still no seventh (and final) flash, the last thing to check is U14, after the 7th flash, the MPU enables the IRQ line. If the IRQ line is broken, the MPU will restart the boot sequence over and over. Also look at resistor R134 (4.7k), if this is bad it will cause the board to repeat the boot sequence.

If you have a way to test this on the bench, it'll make your life easier.
[/SIZE][/FONT]

I have not had a chance to do this yet, but it is on my list of things to do, thank you.

I did have time to at least run test point checks, here's the results:

Transformer Top/Back Lugs:
Trans 13 / should be 7.8 Vac / reads 7 Vac
Trans 14 / should be 7.8 Vac / reads 7.4 Vac
Trans 15 / should be 12 Vac / reads 11.8 Vac
Trans 16 / should be 12 Vac / reads 11.4 Vac
Trans 17 / should be 7.3 Vac / reads 6.4 Vac
Trans 18 / should be 7.3 Vac / reads 0 Vac

Transformer Top/Front Lugs:
Trans 2 / should be 49 Vac / reads 49.2 Vac
Trans 6 / should be 49 Vac / reads 49.1 Vac
Trans 8 / should be 180 Vac / reads 185.5 Vac
Trans 10 / should be 180 Vac / reads 184.2 Vac

Transformer Bottom/Front Lugs:
Trans 1 / should be 120 Vac / reads 0.6 Vac
Trans 9 / should be 180 Vac / reads 1.3 Vac

Rectifier PS Board:
TP1 / should be +5.4 vdc / reads +2.93 vdc
TP2 / should be + 230 vdc / reads +214 vdc
TP3 / should be +12-14 vdc / reads +13.54 vdc
TP4 / should be +5.7-7.3 AC / reads +6.2 AC
TP5 / should be +43 vdc / reads +43.8 vdc

AS-2518-35 MPU Board:
TP1 / should be +4.9-5.2 vdc / reads +5.18 vdc
TP2 / should be +12-14 vdc / reads +13.75 vdc
TP3 / should be +21.5 vdc / reads +21.8 vdc
TP5 / should be +4.9-5.2 vdc / reads +5.20 vdc

Solenoid Driver Board:
TP1 / should be +4.9-5.2 vdc / reads +5.25 vdc
TP2 / should be +190 vdc / reads +158.5 vdc
TP3 / should be +4.9-5.2 / reads +5.2 vdc
TP4 / should be +230 vdc / reads +238 vdc
TP5 / should be +12-16.5 vdc / reads +13.57 vdc

Lamp Driver Board:
TP1 / should be +4.9-5.2 vdc / reads +4.57 vdc
 
I've also seen a bad or missing 5101 cause constant reboots like that but it could be a number of things.

I would start by connecting only J4 to the MPU. If it boots you know you've got a problem elsewhere. Seems unlikely in this case but you might as well isolate the MPU as much as possible.

You could pull the 5101. If you get only two flashes then nothing you know the 5101 or something related to it (socket, address decoding logic, etc...) is bad. Of course, I've seen a missing 5101 cause constant reboots so YMMV. If that doesn't work you could try pulling the 6810. If you then get only one flash you know there is a problem with the 6810 or possibly even both RAMs. Ultimately you're going to have limited troubleshooting options with original game code, assuming you actually have a RAM or ROM problem.

If none of that points to the problem it's time to pull it out and test it on a bench. Preferably with a test ROM. It's also possible that there is a problem unrelated to the MPU like bad power.
 
Update on this old thread. Ended up repairing the Solenoid Driver board, he opted for a new Alltek MPU & lamp board.

The game's up and running, but it's still having problems with the control lights. Some are on, most are off or barely light. I took a reading from the lamp board, getting +3.XX at the +5DC test point, trace it back to the power rectifier board, getting the same reading at the +5DC test point 1(I think) there as well. Pulled the fuse, checked the DC at the fuse clip, still in the +3.XX realm. All other TP's were fine.

I have checked continuity from rectifier board to lamp board, I've checked everything I possibly could under the playfield from the lamp sockets back to the lamp board. Checked for cold solder & continuity all the way back.

I have yet to redo the connectors for the lamp board. The original board had some slight acid damage for the old MPU dripping down. That might not be it, but it will ensure new connections to the new board.

So with everything I've checked, does it seem like the problem is back at the rectifier board or even before that? I don't have the machine handy, just wanting to gather what info I can before going to look at it again. Thanks
 
Yo Lance, replace those connectors, they suck. Also, do the ground and 5v mods to the driver board for good measure.
 
One other thing you can try is to disconnect all but the 5volt power to the board and see if it boots. It will eliminate all other boards and interactions. If the LED still blinks then you can be sure the problem is isolated to the MPU alone.
 
Also, the lighting pin on the rectifier board is as issue, orange wire on connector J3, it usually tarnishes bad, re pin this with new trifurcon pin...
 
Update on this pin: Spent hours yesterday, redoing all four connectors for the light board, since he was using a new replacement Alltek light board. Also, replaced the 3 connectors on the ps rectifier board, I am proud to say it's all up and running now. I still need to do the 5V mod to the driver board, and plan on doing that sometime next weekend.

This pin has made it's journey from being completely dead, to fully functional, and taught me a lot along the way. This was the first pin I really dove into, and learned how to approach the pin, and came away with some great experience from it. And a lot of my information came from this site, or from links posted by other members here. So to all of you who are a part of KLOV, thank you for this great community.
 
Rise from the dead, ol' thread of mine :D


So, doing some maintenance on this machine again, and am now having reset issues every 1-2 minutes. Machine was running fine, just doing a tune up, repinned and replaced every connector(that was done from the previous post), for all of the boards in the back back. Just to bring you up to date, the owner now has the MPU, Light Board, and SDB Alltek replacements, and has been running fine.

OK, so the only change that has been made from working to rebooting status, is redoing the pins and connectors in the back box, to all of the boards. I am lead to believe either I have a pin that does not have a clean crimp, or one connector has one wire out of place. I was very careful as I repinned and moved wires to the new connectors, but one connector I am questioning. I say that, as I had a moment where I removed the pin, and then had to think of which slot I pulled it from.

So anyone that has a Bally Star Trek(or similar machine), I am asking for verification please. On the MPU, top right J2 15 pin connector: Is the first(top) slot empty, or the second slot? I want to say slot 1 is empty, and 2/3/4/5 are populated? I tried determining this from the schematics, but am not 100% sure of what I think it says.

Thank you for your assistance.
 
OK, went through all of the connectors I redid, replaced a couple pins that were questionable. Still same result. In test mode, the machine acts as it should, no rebooting. In game mode, I get about two minutes tops, then it reboots. Need to find time to diagnose some more.
 
Solution to above, had to rebuild the rectifier board. When doing so, I learned a very valuable lesson, and want to share the information for others. If you rebuild or replace the rectifier board, use caution when soldering the ISO wires back on. Before finding out the rectifier was bad, I swapped ISO's to rule it out. In doing so, I had to resolder the wires to the ISO. There is one tap on the ISO, where it looks like the manual says it's tap 11 at a glance. This is not the case, and will send 113AC volts through all of your GI lighting!!! It is suppose to be 7.3AC volts, coming off of tap 17. The manual has this tap number faded/not printed clearly, even the PDF online shows this faded out.

With that said, it was a cheap lesson learned. Thankfully that tap and Rectifier board connection, goes straight through to the GI lighting. The only damage/loss was every single GI bulb had to be replaced(coin door, playfield, back box). Connectors, bulb holders, ect... were all fine.

Thankfully, this was only about a $10 lesson, but hoping this saves someone in the future.

To recap my post/problems above, check your DC measurements at your boards, and work them back towards the rectifier board. I discovered the Solenoid Driver board and MPU were not getting their +43DC volts from the Rectifier board, causing the reset issue. Since I rebuilt the Rectifier, I did not pinpoint the exact failure, but there's only a few possibilities between the ISO to TP5 on the Rectifier board. The path leaves tap 17 from the ISO, hits the 5A fuse at F4, then through Bridge Rectifier 3(BR3), before hitting TP5. My money's on BR3 went bad, or cold solder joint at the handful of locations along this path. Fuse was still good, so I'm 98% sure BR3 went bad. I say that, as BR3 tested fine out of circuit, but I'm thinking it was failing under any load put through it.
 
Back
Top Bottom