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Taito Speed Race Resto (I hope)


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The wheels board which I believe is very similar uses a 4.75MHz as best I can see. I also saw @taito post where he was looking for one for his game which used a 14.314MHz crystal

 

https://www.aussiearcade.com/forum/a...for-speed-race

 

It looks like these are really not available any more so my repair activities are at a stand still :-(

 

Extract from the Wheels schematic:

[ATTACH=JSON]{"alt":"Click image for larger version Name:\tScreen Shot 2021-06-15 at 3.12.39 pm.png Views:\t0 Size:\t96.0 KB ID:\t2214519","data-align":"none","data-attachmentid":"2214519","data-size":"medium"}[/ATTACH]

 

Someone will have one maybe used but still working. Also you used to be able to get custom crystals cut so look into that too.

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Ax, maybe look into cleaning the board before you start working on it. It will be hard getting logic probe signals with all that crud on all the I.C legs.

 

Yep - had a go at cleaning some of the paint of the chips today and it does show some of the chip markings but most have been scratched out.

 

What would you use to clean the chip legs @Gemini2544 ?

 

20210615_164206.thumb.jpg.c249cafd27098cf5e18d8e503be9c4d0.jpg

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Hi, well done spotting the missing crystal!

 

- Without it the crystal oscillator will not run and there would be virtually no activity on the PCB at all including no video or sync as just about all signals on the PCB would be derived in some way from the master clock frequency.

 

I read the previous thread about the crystal frequency, it seems the original 14.314 MHz is not readily available but 14.31818 is relatively common - I have to say that the latter frequency is so close, within 0.03% of the original I don't believe there would be any noticeable difference to the operation of the circuit and doubt any tearing or rolling of the graphics would have been due to that difference. If the main clock frequency is just that tiny bit higher all parts of the circuit should be affected equally...

 

So if you can't source the original frequency crystal but are able to obtain the 14.31818 I'd definitely try that one. It will hopefully get the board running with some output for starters. It should also be possible to 'pull' the oscillator frequency back down by adding a small capacitance and checking with a frequency counter but I really doubt it would be necessary at all.

 

The 0.1 uF greencap is easily obtained from Jaycar, Element14 or pretty well any component supplier. They might be marked 0.1 like the original or they might be labelled 104 which is 1 0 0000 picoFarad, the same as 100 nanoFarad or 0.1 microFarad. That one may just be acting as a noise filter on the PCB and not urgently required but worth installing a new one in any case.

 

Regards, John

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Hi, any output on the screen is a good start!

 

I suspect the board has other issues besides the exact crystal frequency but at least there's some activity there now.

 

Regards, John

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Question Has anyone used an IC clamp in conjunction with one of these Chinese logic chip identifier/tester's to a) identify logic chips and b) test them?

 

The point being to identify and test an IC without needing to remove from the PCB.

 

2050885572_ScreenShot2021-06-22at5_54_21pm.png.56d23935c1bb9eed877fc0998a52d07a.png

1747129805_ScreenShot2021-06-22at5_53_41pm.thumb.png.0cd9440e0b7fabc27ac34c88edc43aa7.png

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  • 2 weeks later...

Trying to determine the chip type in circuit will not work.

 

The ic is not in isolation with connections to pullups. caps and other components that will trip up the chip identifier.

 

You are not able to power up just the chip as the power rail is common and the chip identifier will be trying to power the while unit (which it cannot). If you tried to do it with power applied (and the chip identifier does not blow up) the other chips are powered up they will be driving the pins on the chip you are trying to determine preventing the chip identifier from being able to test the chip pins to identify the type of ic.

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  • 3 weeks later...

An update...

 

I managed to score on Gumtree a full working machine similar to mine so I now have 2 projects (thanks @wiredoug).

 

Although the new one is fully working, the original cabinet is much better so have decided to concentrate on firstly getting one fully working / restored cab happening and to that end I have been busy sanding, painting, etc.

 

Will post some pics soon.

 

Have also made some new artwork and am having some new cabinet side decals made. They are pretty close to the original.

 

Mockup-side-2_Small.thumb.jpg.9937ea552e59bde3bd411a5239d0b129.jpg

Mockup-side-2_Small.thumb.jpg.d93349a04f06438ada71f03da84c37b7.jpg

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  • 4 weeks later...
  • Super Moderator
On 23/08/2021 at 4:21 PM, AxedBandit said:

For future reference I have managed to identify 99.9% of the chips on this board. Here it it for anyone who needs it in the future.

PCB.jpg

That is the sort of post that AA is all about.  Great share.

Dave

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  • 1 month later...

All decals are now on and steering wheel is back from being leather covered to match the gear shifter I bought.

Also received back the shifter cover from the electroplater today so now just waiting on the PCB repair to be complete and then we are all done.

 

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