Weird coil issues on Sega Star Wars Trilogy

[Andy B]

Working on a Star Wars Trilogy for a mate.

Some coils are not working in diagnostics mode but they have power to them, fire when I connect to ground and fire when I send a signal to the transistors from the test points on the I/O board (which the manual says you can do to test them) so that means the transistors are good? I also have continuity all the way back to the pins in the I/O board.

So I am guessing the issues are upstream right? Potentially the chips at U1 and U2? Is it possible to test these with a multimeter?

The ones that are not firing in diagnostics are a combination of low and high power, specifically:

High Power:
#2 Auto Launch YEL/VIO BRN/RED

Low Power:
#18 X-wing motor relay BRN VIO/RED
#22 4 bank drop downs target 3 down BRN BLK/RED
#26 Tie Fighter Shake BRN BLK/RED
~F8 Flash Pop Bumpers x4 ORG BLK/GREY

I also have 2 which are not firing in diagnostics or when I send signal via test point on I/O board but are firing when I ground them so I suspect dodgy transistors for those 2 (though I just replaced one of them - maybe I did a crap job of soldering it in!).

Thanks in anticipation

Andy

 

[Andy B]

Update - the 2 that were not firing with the test point tests are now working after I soldered in new transistors but they are still not working in diagnostics.

So now all coils are working from transistor to coil but still the problems with 4 of them not working in game or diagnostics (and I’ve checked the switches that trigger them and all are good).

And, this is the confusing thing - one of the low powered coils (#22) which wasn’t working in diagnostics before now is. Hmm…

 

[CHRIS B PINBALLS]

Is there any acid damage to the cpu
You would need a logic probe to test the chips

 

[Andy B]

I think that must be it.

The batteries had crusty green crud around the terminals so I removed the battery holder and fitted a remote one tonight but I couldn’t see any obvious leakage on to the board.

I’ll have a closer look tomorrow.

Wipe down with vinegar soaked cotton wool bud then water?

 

[Chilpin]

I had a similar problem one time in the past. One of the 7402 or 7408 was bad.

 

[Pick Holder]

If it is battery leakage then on many occasions it damages these boards beyond economical repair. Fingers crossed.

 

[Andy B]

If it is battery leakage then on many occasions it damages these boards beyond economical repair. Fingers crossed.

Well it looks like it could be this

I’ll give it a good clean up all round but looks like my mate’s gonna have to Chuck £300 at a Rotten Dog replacement.

Won’t tell him today - it’s his birthday

 

[Andy B]

 

[Andy B]

 

[Andy B]

 

[Moonraker]

No wonder you have problems but it's repairable. I've repaired far worse. U201 and U213 need closer photos to see if they're affected. U213 is a PAL chip so that causes it's own dilemma. Connector CN1 is also looking a bit funky.

 

[Andy B]

1st pass with vinegar, water and alcohol.

201 looks good but think I need to have another go at 213. Socket for CPU looks a lot better. I would take it out but there are lots of tiny tracks on the back of the board that I’d probably damage.

 

[Andy B]

 

[Andy B]

 

[Andy B]

Looks like I did more harm than good with that clean, now the game just keeps resetting.

Checked for 5v to main board just in case and no problems there.

I’ll have a go at swapping out the CPU socket and main rom but then call it a day if it doesn’t work and tell him a replacement board is needed.

If anyone knows where I can get a programmed eprom from please drop me a PM.

Thanks

Andy

 

[Moonraker]

You need to get the traces back to copper and replace the socket for U210 and the one to the right. C282 should be replaced.

https://www.pinwiki.com/wiki/index....hite_Star_Repair#Repairing_Alkaline_Corrosion