Pole Position : no acceleration .. Gas pedal not responding

Smart Bomb

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Pole Position : no acceleration .. Gas pedal not responding

The gas pedal on my pp no longer works. It was working perfect and i get nothing...so rev up sound..nothing...car wont move.

In self test no number increase when i press gas...everything else works.

I am getting 5 volts to it.

Manual states its either a bad A-D converter on the CPU PCB or a mechanical problem...as of now i see no mechanical problem.

And what/where/location is the A-D converter?
 
Pot is good...and I just reflowed 8J...and checked for broken traces...and checked legs continuity...still nothing..its like the gas never existed.
 
Oops..i did 8j...not 8k....dang...i have to do it again..dang it....I dont kno why i was thinking j.
 
Oops..i did 8j...not 8k....dang...i have to do it again..dang it....I dont kno why i was thinking j.

Use your logic probe and check the output of 8K pin 11 (Or if it's easier check pins 6 of 8J). This should change when you press on the gas pedal.

If you're not getting anything, then 8K might be bad, but not necessarily. There are a lot of components in that area just for gas. R108, R107, R102, R101, R99, CR7, CR8, CR9, CR10, C14, C12, C10, C11, C13, C15 and 8K all sit in front of the DAC at 8J.

It's easier to start from the DAC and work backwards. If you are getting something from 8K, then 8J might be bad.

Look on Page 15 of the Schematics, that's where the Gas pedal is handled.
 
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Use your logic probe and check the output of 8K pin 11 (Or if it's easier check pins 6 of 8J). This should change when you press on the gas pedal.

If you're not getting anything, then 8K might be bad, but not necessarily. There are a lot of components in that area just for gas. R108, R107, R102, R101, R99, CR7, CR8, CR9, CR10, C14, C12, C10, C11, C13, C15 and 8K all sit in front of the DAC at 8J.

It's easier to start from the DAC and work backwards. If you are getting something from 8K, then 8J might be bad.

Look on Page 15 of the Schematics, that's where the Gas pedal is handled.

I just checked voltages to each chip: leg 20 on 8j and legs 12 and 14 of 8k and all are solid at 5.03

I logic probed both pins you suggested and both are a solid steady low...when impress gas pedal both pins stay at low....zero fluctuation.

And it is not a wiring issue just to get that out of the way..i have continuity from pedal to wiring harness and i am getting 5 volts at pedal/pot.
 
Use your logic probe and check the output of 8K pin 11 (Or if it's easier check pins 6 of 8J). This should change when you press on the gas pedal.

If you're not getting anything, then 8K might be bad, but not necessarily. There are a lot of components in that area just for gas. R108, R107, R102, R101, R99, CR7, CR8, CR9, CR10, C14, C12, C10, C11, C13, C15 and 8K all sit in front of the DAC at 8J.

It's easier to start from the DAC and work backwards. If you are getting something from 8K, then 8J might be bad.

Look on Page 15 of the Schematics, that's where the Gas pedal is handled.

Actually i am getting 4.66 to wiring soldered to the pot..i put my leads on the tabs of the pot..and im getting 4.66...i wonder if thats the problem?..i put black lead on middle tab...and red lead on red tab..i get 4.66...am i testing this correctly?
 
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It's pointing that way for sure.

Smart Bomb, if you have a spare 4066, I would replace it and see if that fixes your issue.

I have a spare parts ms pac...there is a 4066 on that....would this one work? Pic attached.

Or is that a 14066?....i will look up the ms pac bom
 

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Yes, sorry was looking at the wrong part. The MC14066B is the same type of chip.

Looking at the specs, it should work...

4066 Datasheet:
http://www.datasheetcatalog.com/datasheets_pdf/4/0/6/6/4066.shtml

MC14066B Datasheet:
http://www.onsemi.com/pub/Collateral/MC14066B-D.PDF

Looks like the MC part has a higher voltage range, but the switch voltage looks the same.
 
Yes, sorry was looking at the wrong part. The MC14066B is the same type of chip.

Looking at the specs, it should work...

4066 Datasheet:
http://www.datasheetcatalog.com/datasheets_pdf/4/0/6/6/4066.shtml

MC14066B Datasheet:
http://www.onsemi.com/pub/Collateral/MC14066B-D.PDF

Looks like the MC part has a higher voltage range, but the switch voltage looks the same.


Well that didn't work. I took the 4066 off the ms pac pcb and installed it in place of 8k on pp board (and i did socket it). Completely unchanged...zero gas.

A few things:

1- i do not know if that 4066 from ms pac is working. The ms pac board is a salvage board i use for parts...the parts ive used off it in the past worked on other games so i can only assume the 4066 is good...but again..i never seen the ms pac board working.

2 - i tried a different method, for the first time, for removing the soldered chips...on the solder side i used a heat gun to heat up,the chip area..held the heat gun about an inch or two from the board...while on parts side i clamped down on the chip ends with a chip removing tool...i then slightly tugged on the chip as it heated below until it slipped right out...i did the same on the pp board to remove 8k. Once removed i used a desoldering gun with a .08 tip and cleaned the holes..slipped the socketed chip in then soldered it in....i loaded it into the cabinet and the game booted right up...but still no gas. My concern was the heat from the heat gun would possibly damage components close to 8k area because it does get really hot in the whole area...but the game lit right up so i will assume there was no heat damage to close components....and there was zero discoloration on solder side from the heat...zero burned looking area....so that was a success i feel as far as procedure goes and will do it in the future from now on.

3 - I did not logic probe anything on 8j or 8k. I was too discouraged to go further so i shut it all down until i get new ideas/suggestions what to do next...maybe replace 8J next?

4 - i picked up a 5k volume pot from radio shack thinking that may work in place of existing pot...after i replaced 8k i had zero gas with the new pot....so i figured maybe that new pot wouldnt work because its for volume? ??..i dunno..seems like it would work, right? Anyway, i then removed the new pot and reinstalled the original pot thinking with the "new" 8k the original pot may be needed in the game...zero luck..no gas.

So maybe now i will order a new 4066 for 8k and may as well buy a new chip for 8j.
 
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I dont know what the value is but I do know that you need to have that pot at its "home" position before you power the game up. if its not right the pedal wont work.

For instance. I have a 5k pot from a Raw Thrills game on my PP test harness. If its not set correctly I wont have any gas when I power the game up. If I do its very little or full blast.
 
so heres what I would do next.

Make sure that you are getting the pots sweep signal on the white with a green striped wire at pin F on the CPU edge connector.

If its good there make sure you have continuity to R108 then from R108 to pin 3 on 8K. If thats good check pin 4 of 8K to pin 6 of 8J.

But... 6H is a custom and they are known to have corrosion on their legs and even missing legs. Have you messed with it yet?
 
so heres what I would do next.

Make sure that you are getting the pots sweep signal on the white with a green striped wire at pin F on the CPU edge connector.

If its good there make sure you have continuity to R108 then from R108 to pin 3 on 8K. If thats good check pin 4 of 8K to pin 6 of 8J.

But... 6H is a custom and they are known to have corrosion on their legs and even missing legs. Have you messed with it yet?

I do have continuity from pedal to "F" but did not check for fluctuations when pot is engaged.

I will check r108 suggestions tomorrow.

6h is good as far as i know.
 
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