(Topic ID: 92254)

Gottlieb Sys. 1 Driver Board issue


By Zolzar

4 years ago



Topic Stats

  • 20 posts
  • 8 Pinsiders participating
  • Latest reply 4 years ago by barakandl
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#1 4 years ago

I am working on a Gottlieb Genie with all original boards. I have done all of the ground mods including the ones for the driver board that tie together all of the grounds. Other than the problem below the game is working.

The problem I am having is that the solenoid output #8 is not firing. The problem is that the r39 resistor is getting cooked when the drop target bank attempts to reset. This also takes out the pre-diver for #8. The coils fire just fine when grounding the metal tab. The only thing I can think of is that I possibly mixed up a wire when re-pinnig but it's unlined as I did do one wire at a time.

Any ideas?

Thanks,

John

#2 4 years ago

First make sure that the coil isn't shorted, and that it's diode isn't shorted either.
Clip one wire and measure resistance across the lugs. Then swap the leads and measure again...just for the hell of it. Resistance should be above about 2.5 ohms.

Solenoid 8 is driven by the big 2N3055 on the driver board, right?

--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#3 4 years ago

To add to what Chris said, be sure to check the wiring of the coil. Is the correct wire going to the banded side of the diode on that coil?

#4 4 years ago
Quoted from KenLayton:

Is the correct wire going to the banded side of the diode on that coil?

...because if it's not, you'll blow the diode and the drive transistor immediately. Ouch.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#5 4 years ago

I will check the wiring. When I got the machine the two cooled that operate the large drop target bank were completely melted down and open. I replaced them but could have made a mistake when installing the replacement coils.

Yes. This bank is driven by the 2N3055 which is predriven by a MPS-U45. What's burning up is the 9ohm 1/2 watt resistor on the collector leg (5vdc) of the U45.

Now that I've sort of talked myself through it I'm also going to check the voltage on the collector of U45.

#6 4 years ago

Was the coil working ok before you did the ground mods and repinned connectors?

#7 4 years ago

It is hard to say if they worked correctly or not. I can say they did not fire under test 13 before the re-pin. However once I reseated the game ROM the pin came to life.

#8 4 years ago

As a fun side note. I am about to go downstairs and deal with a sys1 game that locked on that same solenoid circuit until the point the coil burned out big time, yet the driver circuit actually survived. At least under minimal load it survived. We'll see when i put a coil back in.

#9 4 years ago

I had to work a little late tonight so play time was limited. I disconnected the coils and booted up the game. Everything went well and the driver transistors and the resistor did not get hot. I checked both coils and their diodes independently and they all test good. At this point it appears to be a wiring problem. Does anybody have a idea what wires go where on the large bank reset coils for a Genie?

On a side note I did buy this pin as a project.:...and a project it has become! There is plenty of evidence of prior repairs both amatuer and professional. One of the coils has been replaced but with a machine this age it's anyone's guess as to what and when things were done.

John

#10 4 years ago

Also as with most old Gottliebs, its a good idea to put an inline fuse just before any large coils. Mount them under the playfield near the coil. 2.5ASB will do fine. Fuses are a LOT cheaper than coils.

#11 4 years ago

Excellent idea. The small drop target bank has a fuse but not the large one. Seems odd but that's what it is. I did dig up a schematic with the color codes. I'll hopefully have some time tomorrow to trace and verify the wiring.

#12 4 years ago
Quoted from Patofnaud:

Also as with most old Gottliebs, its a good idea to put an inline fuse just before any large coils. Mount them under the playfield near the coil. 2.5ASB will do fine. Fuses are a LOT cheaper than coils.

I think the under PF fuse for all the solenoids except flips is 2amp slow.

#13 4 years ago
Quoted from Zolzar:

The coils fire just fine when grounding the metal tab.

Useful info...this means that the coils, diodes and wiring correct !

Whats wrong ? )
If I understand correctly what problem is, I suppose that is bad 2N3055 and/or MPS-U45
(Assuming that the correct (1Kohm ?) resistor on MPS-U emiter ..."shorted" or similarly,
aka "ground-moded" )

Greetings from Croatia

#14 4 years ago

I stand corrected after looking at the schematic. Both banks are protected by a 2 amp fuse. I did trplace all of the fused with the correct values.

I have replaced the U45 and associated resistor twice. I have not replace the 3055 so I should do that eve though it tested good with the DMM.

John

#15 4 years ago
Quoted from Zolzar:

I checked both coils and their diodes independently and they all test good.

What was the resistance of each coil?

You could also have a ground short somewhere on the sol 8 output wire from the driver PCB connector. Measure this wire at the connector to gnd and see if there is a short.

#16 4 years ago

One coil was 10ohms and the other was 9.5ohms. They are A-18102 coils. The forward voltage on the diodes tested at around .560. I did remove the diodes for testing just to be sure.

#17 4 years ago
Quoted from pdman:

You could also have a ground short somewhere on the sol 8 output wire from the driver PCB connector. Measure this wire at the connector to gnd and see if there is a short.

Did you do this?

#18 4 years ago

SOLVED.

I checked all of the wiring tonight. Everything was correct. I once again pulled the driver board and tested the 2N3055. No good. Was testing .4 on one leg but 1.3 on another. Definitely bad. What drives me crazy is I know I tested it previously and it was fine. That's why I started this topic.
The only TO-3 package transistor I had laying around was a 2N6057 and based on the spec sheets it is close enough. Basically I'm in business with the drop target reset circuit. I still have some switches that need attention but that shouldn't be too difficult.

Thanks to all of you who participated in helping me get through this problem!

John

#19 4 years ago

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