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WH2O bi directional motor board faulty - HELP!!!!

newdos

newdos

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Newdos
OK so a recap here and now put up as a separate post as no answers on this yet

Motor works ok - tested with battery, 12v dc led is on motor board. I have grounded pins 1 then 1&2 together and nothing. I have metered pin 1 & 2 and when motor isn't(or shouldn't be) running both are at 13v When I test the motor one way one pin drops to 0v and when I reverse it both drop to 0v but not a tweet outta bigfoot.

So I guess it is the motor board. As it doesn't go either way is it more likely to be the LM339 than a tranny ??? or as the enable line going low doesn't make it run and that doesn't seem to rely on the LM339 (if i'm reading the drawing right) is it something else like Q3??? Any other points I can meter out on the board ?
All help appreciated

Cheers Kev
 
Addendum - forgot to say board looks mint - no leaky caps or any signs of being repaired before.
 
Walk away from the machine!!!!!!!!

First question is - was the machine bought working or are you trying to fix it? Just seams strange that everything is dying at once.
 
Supposedly bought as working, but to be fair to the guy he isn't techy minded and I like a challenge!!! Parts four soundboard ordered so that will be fixed soon and other than a display on it's way out once I have the motor board fixed it is basically working a 100%. The real work then begins when I fully shop it and re-decal etc Plus I have another playfield coming for it as well so should come up minty ish with a bit of luck!!

So back to this motor board any ideas ???

Cheers Kev
 
You need to scope it out. I don't have a diagram to refer to but is the motor signal actually arriving at the motor control board from the CPU? If so, and it's going to a buffer, is the buffer output latching? What about if you fire the transistor manually? To simply say "it doesn't work" doesn't give us a lot to go on! If you have a schematic, can you post the relevant section on here?
 
Starter for 10 grizz I will meter the diode out on the board. Hoping the legend might chip in :)

cheers kev
 
All diodes meter out ok, so what's next. The switching ground signals are arriving ok at the motor board from the power board. As Andy pointed out if you manually ground these inputs the motor should start spinning one way and grounding both it should reverse so the problem is deffo on the motor board. The schematic for it is in the wh2o manual on ipdb.

Hope this helps

Kev
 
I'd be suspecting Q5 - TIP102 or the LM339. You need a scope to measure the outputs or (although it's not a very elegant method) simply change the components given that they're just a quid each.
 
Schematic for all you guys
 

Attachments

  • motor board schematic.docx
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Few logical sections to look at lets get the easy stuff out of the way first.

Obviously you've checked for dry joints around the inductors and for continiuty between the q2 emitter and J2/1 and q4 and J2/4. Any large heavy component inside a pinball machine is going to vibrate around.

I agree that Q5/D5 should be checked. It's going to be impossible to fully check them in circuit as the tip102 is in reality going to be two serial diodes in the other direction :p Just replace them.

Get your oscilliscope/meter out and check pins 1 and 2 of the lm339 relative to ground. Pin 2 should go low if driver is high and pin 1 high if the driver is low (might have that the wrong way round but one should be high when the other is low). Basically they shouldn't be the same. If they are either the lm339 is foobared or there is something seriously wrong at the output darlington part. Toggling the driving high/lo should flip these over. Ie what was high goes low and what was low goes high. Noting that the logic is based on +12vdc and is comparied to 1/2 12vdc by r4/r5 combo.

Do the above but metering J2/1 and J2/4. Once you have this data you should be able to know where the first (never assume it's one) fault is. IE buggered LM339 or something wrong in either out of the darlington output stages.


Personally, I'd do the lm339 test first, then the J2/1 etc as it'll take 2 minutes and 99% of all diagnostics will have been done without any soldering. Even if it's just a buggers D5 or Q5 at least you'll know everything else is working!
 
Well this is weird!!! this is now fixed so I have finally have a fully working whitewater albeit a bit battered and in need of some TLC.

Took the board to work for the electronic tech to test for me as I couldn't find anything wrong - neither could they and showed me it working on the bench!!

However he took a couple of the trannys out to test and found they were fine and refitted them to the board. On putting it back in the wh20 all works perfectly - how weird is that. One can only assume it was a very odd dry joint of some kind!!!

Cheers Kev
 
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