Gorgar: Can someone please help with the location of a broken wire?

[JD]

Thanks Boots.

The boards were both tested yesterday MPU and solenoid driver. All worked fine on Ken Skybeu's tester. Many thanks for the diagram. Is there any point in going further with the chips if both boards were tested and functioned fine?

J.D.

Hmmm definately something hiding there.
The connectors must be ok of the coil fires when you earth the driver transistor.
Are the IC's I mentioned socketed?
If so you could do a quick swap out to 100% eliminate them.
Perhaps something got zapped when you were testing before you changed the coil diode.
It wont hurt to check the chips with a multimeter, that will only take 5-10 minutes.
If the switch signals getting to the boards, I would definately change the chips, like I said cheap and easy and if its not necessary at least the new chips will be socketed for any future problems.

Thanks for your help Boots.

I changed the diode before I put the re-tested boards in so as all tested, I am assuming OK nothing has happened to undermine this. I am out of my depth if not and would give back to Skybeau to sort but I think all is OK on both MPU and solenoid driver board.


Cheers

J.D.
 

[Retropin]

Let me have a look at my sys6 notes... from memory the special solenoids are the bumpers.

Im glad that the drops dont reset during test mode because it means that your problem isnt too much of a head scratch.

Basically you have nothing happening from CPU TO the solenoid.

It will either be a decoder, PIA or predriver transistor... also board interconnect.

Ill get back later... but no doubt it will be sorted by then by someone else.

But in all honesty... unless the 3 drops have their own pin designated at the 40 pin board interconnect ( please check this on game schematics) and this is not making true, then you have a board issue whether they tested good or not

[Retropin]

OK,

Have schematics in front of me.. and we can ignore the CPU.. our problem lies on the driver.

I looked on IPDB and GORGAR manual is not available so i cant be too specific as to what IC drives the solenoid and what transistor etc... but f you have the manual and it says SOLENOID 8 is 3 drop target etc.. then post this info as we can really narrow it down.

[Boots]

OK,

Have schematics in front of me.. and we can ignore the CPU.. our problem lies on the driver.

I looked on IPDB and GORGAR manual is not available so i cant be too specific as to what IC drives the solenoid and what transistor etc... but f you have the manual and it says SOLENOID 8 is 3 drop target etc.. then post this info as we can really narrow it down.

The pdf manual I have says that the "GOR" reset coil is solenoid 4.

[JD]

OK,

Have schematics in front of me.. and we can ignore the CPU.. our problem lies on the driver.

I looked on IPDB and GORGAR manual is not available so i cant be too specific as to what IC drives the solenoid and what transistor etc... but f you have the manual and it says SOLENOID 8 is 3 drop target etc.. then post this info as we can really narrow it down.

The pdf manual I have says that the "GOR" reset coil is solenoid 4.

Yes it is thanks Boots.
Gavin, I will send one to your email.

J.D.

[Skybeaux]

 J.D brought the boards back to me to test after the faulty diode.
Both pre-driver and tip102 tested good on the bench , i then put them on the test bench and all solenoids fired as they should...also all switch columns and rows are working properly.
The test bench has never lied to me so far , but that doesn't mean it can't happen.
Before that when he first brought the boards to me with the blown transistor , i replaced the pre-driver , driver transistor , and the 7408 chip and put it in a socket.

If you want J.D i can lend you another pair of boards ,Driver and Cpu and that way if you put them in you can be sure where the problem lies.

[Boots]

J.D brought the boards back to me to test after the faulty diode.
Both pre-driver and tip102 tested good on the bench , i then put them on the test bench and all solenoids fired as they should...also all switch columns and rows are working properly.
The test bench has never lied to me so far , but that doesn't mean it can't happen.
Before that when he first brought the boards to me with the blown transistor , i replaced the pre-driver , driver transistor , and the 7408 chip and put it in a socket.

If you want J.D i can lend you another pair of boards ,Driver and Cpu and that way if you put them in you can be sure where the problem lies.

Could the 7402 chip be faulty?
This chip is closer in circuit to the coil than the 7408 chip, so if the 7408 chip was no good I would expect this chip to be stuffed too.
My Timewarp had a similar problem where all the other coils on the 7402 chip worked fine but one didn't, changed the chip and away it went.

[Skybeaux]

The old 7408 chip was ok , i just changed it in case it was stressed out.

The transistor is Q21 , goes back to IC1 ,7408 and then to the 6821
I was sure the 7402's only controlled the special solenoids.
Either way , every solenoid transistor on the board ,standard and special all fired properly on the test bench.

[Retropin]

Yes- 7402 only control special solenoids not standard.

Ive been back through the thread... and before we go any further i think we need to be sure that the wire that had fallen off this drop target was put in correctly.
Once this has been done and we are all sure its done right, then we need to look at the driver board cct for solenoid 4.
Skybeau's work is well known for its quality but it is possible that something happened AFTER the check.

I say .. wire first and then go from there.

Need a pic of the resoldered wire JD!

[Boots]

The old 7408 chip was ok , i just changed it in case it was stressed out.

The transistor is Q21 , goes back to IC1 ,7408 and then to the 6821
I was sure the 7402's only controlled the special solenoids.
Either way , every solenoid transistor on the board ,standard and special all fired properly on the test bench.

Yep your right, I was looking at the right hand side of the schematic "switched soldenoids"
Weird how when the transistor is grounded the coil fires???
Got to be something we are not seeing here

[JD]

Thanks Gents,

Here is a photo of the GOR cards with the wires re joined.

[JD]

Many thanks to all who have contributed here. I really appreciate your help.
Just to explain, the orange wire from the switch behind the drop targets broke at the drop targets as it was too short and when I removed the targets to change the burnt solenoid, it broke which was why I asked the original question. The wire as per Peter's photo, was soldered into the same position which joins wires to targets 1 and 3 also. I replaced the wire down to target 2 and also the joiner wires to targets 1 and 3 just to make sure the connections were good. The original wire was orange hence my replacements are orange.

Over to you Gurus.

J.D.


 

[Retropin]

Ok - kids are in bed.. youngest had a bottle and making gurgling noises and im ready with my schematic.

I looked at the 2 pics of the drops and it looks like its wired OK so long as lug with 2 green wires links to 2 lugs over ( picture blurs out when expanded for this).

So, assuming that this is all good we need to look at where it comes to driver board.

GOR drops is solenoid 4... and is controlled through PIA4 and seeing as we only have one solenoid not working, its a good bet that this chip is OK.

Really before we go anywhere we need to ascertain that the switch for the GOR rest is reading closed... this is switch #22... its this switch that when closed allows path to ground through transistors etc.
If you put your multimeter onto CONTINUITY test and one lead to WHITE/BLUE wire and other to GREEN/ORANGE then you should read closure with all 3 drops down.. if not.. dont go any  further.. this is your fault ( do this with game off).. there might be a diode across this switch.. so if it does not read closed first time then swap leads round... 2 non reads is a definate fault.

Now i cant see where this switch closure comes int the board as my copy is really crappy on this part.. but we can test the output drive.

First test to do is with game on, get your DMM and set to 20VDC put black lead to ground and test the inputs to the 7408 AND gate chip... we need to look at input at pins 1 & 2 on IC1.

You should have the same readings on both pins 1 & 2.. if not you have an input fault... the output on this is pin3 and should read the same as pins 1 & 2. If not, this chip is faulty and needs replacing.

Now turn game off again and set DMM to resistance  1K ohm and put leads across resistor  R38.. should read around 560ohms. ( resistors in circuit can be a bit hit and miss if in parallel with anything but you should be good with this one)
Now test R39 ( i think.. my diag is pretty crap and im struggling to read some of it)... should read 68Ohm
Now to R40.. should be 270 Ohm.

All test good?? Ok

Move onto the pre driver.. we know the TIP102 is good as solenoid fires when tab is grounded.

Ok - game off again and set DMM to resistance X1

There are 3 legs on the predriver.

Put leads on outer 2 legs and take a reading, then swap the leads around and you should get the same reading... both should be high resistance as this is between Emitter and Collector.. there should be no connection between these two legs.
Now put leads onto middle leg and one outer and take reading.. swap leads over .. one should be high resistance and other low.

Now do this with the last outer leg and centre.. once again.. one reading high and one low.


If all the above is good then just to make sure.... turn game on ( in game mode) and put DMM to 20VDC again... put black lead to ground and put red lead to pin 5 on PIA 4... if it reads lower than 2.5V then its not enough for a logic signal and the PIA is faulty.

If we find nothing here then the output side of this is all OK and we need to look at the input... and for that i need another print off.. which means i need to buy some ink - LOL


OK - let us know the results!

[Retropin]

Sorry - pre driver is Q20

[JD]

Thanks Gavin,

I will give it a go / test tonight.


Appreciate your help.

J.D.