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Roadshow Dozer Blade problem and possible solutions ?

  • Thread starter Thread starter ColinD
  • Start date Start date
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ColinD

Hi, Just signed up.. I'm ColinD from Jamma+

Just trying to sort a Roadshow pinball out.... and its giving me the usual dozer blade issues that come up and get talked about....

Ok, here what I can gather and understand......

You have a motor, which drives a cam that raises and lowers the dozer blade..... motor only drives one way....

The cam has a blade that interrupts two opto sensors, so that the cpu knows when the dozer is up , down or in between....


So... the cpu says.... raise the dozer, it might check that its already up via the up opto, but if not, turns the motor on, waits for the up opto to be interrupted by the blade on the cam.... saying its now UP.... and then turns the motor off....

Same in reverse.... CPU says... Lower the dozer, another check maybe if down, if not motor goes on, and then waits for the down opto to be interrupted.... and then turns the motor off......

Now... from Diagnotics , this seems to work fine.... Motor drives, Dozer goes up and down, and the opto's register ok....

But... It does not work properly during the game ?? (Yes... everything is enabled in the menus and factory reset etc)

Now I hear that there is a replacement opto board available.... which is going to cost about £50+taxes delivered from the USA.... and its supposed to work much better ??

I'm reluctant to buy this... as if it aint broken... why fix it ??? Can anyone shed any light on this please ? - Is it a software bug or something that doesn't take into account a bit of wear and tear etc ???

I'm thinking that there may be either some interference generated that causes false feedback and causes this to fail...

If I can't fix this, I might design a little add on board that goes between the optos and motor drive, and takes care of the issue automatically.... simulating the whole assembly, giving the right feedback to the cpu... and doing its own thing while de-bouncing the opto's etc.... but that's a last measure.... would be simple enough to implement though with a PIC microcontroller , a few components and a few lines of code !!!

So... whats the score with this then please ??

Thanks, Colin
 
No that's all fine....Eddy is very happy.... Bill goes to sleep , opens up his mouth.... but no Dozer Blade up action !! - This seems a common problem.....
 
Sorry... Ted goes to sleep !! LOL (God knows where Bill came from !!)
 
I've looked into this.... its a common problem... but the threads seem to go quiet.... the solution seems to be install the new design of opto board.. but like I say... mine seems to be working !!

Now I've just had a thought....... could be dry joints or an intermittent connection........ as both opto's are closed when the blade in midway.... so any breaking of the circuit would register that its reached the derired position !!
 
Always worth trying to reflow the solder on the opto's if there nothing else obvious, can't make it any worse (unless you go a bit mad with the soldering iron) :thumb:
 
Yes.... I concur with that thanks...... Think I just needed to think 'aloud'..... Looking at the replacement board, they have extra's like led's and looks like some surface mount transistors to buffer the signals....

Existing opto's could get weak... led's do fade and wear out over time....

So... Now.... whats can I replace them with that will fit ?? - a Standard opto off the shelf from RS ??? - Any prefered part numbers ??
 
It says in the parts list...... P/N 5490-13341-00 - opto intergrated w/tab - 10mA..... I'm assuming the 10mA is the LED drive current.....
 
Thanks... Have just found it on pinballheaven.co.uk too..... I hate part numbers... would be easier to say what it actually is.... lol !!!
 
I've reflowed the opto board, cleaned the optp's and tested for operation on the bench....

Refitted, did the Dozer Test , that works as expected and as before.... showing opto's and driving the motor..... remember this works !!

Now.... Stopped it in the closed position, re-enabled Ted, saved it, exited and switched off the machine....for luck....

Switched back on again, fed some balls in to the locks and the dozer now works perfectly :-)

So... there must have been some kind of intermittent connection (maybe even the plug) or the opto's were just a little dirty....

Super stuff.... Thanks for your help and advice guys....

Cheers, Colin
 
Ps.... to test the board on the bench, I gave it 12v off a bench psu, and 0v... also fed 0v to the column select.... and 2 pull up resistors on the rows... 2.2k in this case (to be safe) wired to 12v..... you measure the voltage on the rows and see it going from 12v (when interrupted) to just over 1v when closed (no interruption)... after cleaning, it went down to about 850mv..... (these voltages are with the 2.2k resistors though , so it will vary with what values you use) - I think the game uses 1K ones...

Cheers, Colin
 
Need to sort the eyes out now... Suffering from a very nasty infection here.....

eyes.JPG


and some nasty metal fatigue.... Red has been welded up..... on both sides but Ted has 2 hair line cracks either side (where the metal has been formed in the press) ..... I'm thinking I could use some metal loaded epoxy here... and not bother to remove and have it welded up or fir a repair bracket.....

welded.JPG
 
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