Tron erratic spinner repair

kstillin

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Well, I made a deal to sell my Tron. After the guy left, I was getting it ready for a later pickup and found that the spinner was erratic.

Tron's hand would jump from place to place and not follow the smooth spinner movement.
Test mode showed large gaps in the count display when the spinner was moving.

Being a packrat, I pulled out another CP and it did the same thing.
Being a packrat, I pulled out another I/O board and it worked fine (but that I/O board had no sound).
Being a packrat, I pulled out a manual, which was very difficult to read I'll add.

The schematic showed a set of 74LS244's bringing the spinner inputs, button/joy inputs, and DIP switch inputs to a common bus. The processor picks the right chips when reading the various inputs.

I noticed that all the signals from the spinner were routed through a single chip at E2. Suspected this since all the button inputs worked fine.

Lo and behold, I had some 20pin sockets and more amazingly, a few 74LS244 chips. Socketed it, slipped in the chip, and returned to the storage building to test it out.

Works fine.

I'll add this- after I brought the board home, I checked some old posts, both here and on Google archived RGVAC feeds. Dozens of posts where people complained about the same thing, but were directed to suspect voltages, optics, and connections on the spinner itself. Several people had luck with that.

Had I not had the spare parts, I would have probably started there too, but taken a LONG time to get back to the PCB.

Anyway..
 
Tron spinner issue you posted about

I saw the post, and see you had success in getting it to function properly. I didn't understand what you did though. I have a Tron that has an erratic movement on the spinner when I move it as well. I'm not familiar with circuitry on the boards though. can I just replace that 74LS244 chip thingy you mentioned? and if this is an awkward question, I truly apologize but I sent the board to CDJump to be repaired about 2 years ago, and I recently got the parts to repair the Tron itself. i put the board in and it's a spinner jumper. I don't have spare chips or a programmer either, so I may need those too. I can look, but I'm not sure if programming needs to be done with it is all. thanks for any info you can give me. -Ken
 
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I know these replies are to an OLD post, but it's apparently a common problem.


I just remembered I had some old MCR weird boards not quite like Tron, but it has quite a few of the 74LS244 chips on it... can i de-solder one of those and try it or should i just try and re-solder the pins on the one that's there currently?
 
I know these replies are to an OLD post, but it's apparently a common problem.


I just remembered I had some old MCR weird boards not quite like Tron, but it has quite a few of the 74LS244 chips on it... can i de-solder one of those and try it or should i just try and re-solder the pins on the one that's there currently?

You can do this but that part is not real costly and you may damage the part you are trying to remove. The local parts guy has new 1's and they are under a $ each. I try to get a tube or more each order. Here is the part you are looking for.

https://www.twistywristarcade.com/search?orderby=position&orderway=desc&search_query=74ls244
 
I have an erratic spinner but when I had my boards with CDJump he tested it and it worked fine... which leads me to think I have a problem with the encoder board or the connectors... I checked the connectors and they "seem" fine, but what do I know... I guess it would be best to simply repin the connectors first and go from there?

BTW... I checked the encoder board for obvious cold solder joints and didn't find any...
 
+5 measures fine at the encoder...

:(

Am I down to a jacked encoder chip?

It turn smoothly for about 60% of the turn then erratic as hell for the other 40% or so...
 
Wish I would have found this post last year.

I've done everything but replace this chip. Spinner is smooth most of the time, but every once in a while it jumps.

Going to socket and replace this chip.

Thanks for bringing this post back to life!

-John
 
If you're going to replace it, go all out.

Don't just resolder the pins, and don't substitute an old chip.
New chip. I like to install a socket when replacing chips, but that's a preference thing.

Oh- I never played it too much, but I miss the Tron anyway!
 
It could be your 74ls491 chip it a 10 bit counter..


Is that on the encoder? I ask because CDJump tested the boardset when he had it and had no issues...

Anyway, I repinned the molex connector today just in case... no help.

I am picking up a 2nd encoder from ArcUnderground tomorrow... if I have the same problem with that one then I guess it'll come down to the connector going to the encoder or the connector going to the PCB...

BTW ... what is the optimum voltage for Tron? I have it a 5.05 right now... though I had the problem when it was as high as 5.15...
 
OK... ArcUnderground here was so cool as to offer up his extra spinner encoder board. I picked it up today. I installed it. Unfortunately I have the very same issue.

It seems to be MAYBE a hair better... 70% of the spin it works great... then at certain "spots" it jumps. It's pretty consistent where it jumps and to what number... it'll go from 22-23 or so to 120ish then back to 25 and on... if I back up a hair it will again go down from 25 to 120 then back to 23, 22, etc... There are a couple of these "spots" during the circle that it will jump like this...

(1) CDJump checked the inputs of the PCB when he had it and confirmed they are working properly ... so it's not the PCB.

(2) I re-pinned the molex connector ... so it's not the molex.

(3) I am getting proper +5 voltages at the encoder.

(4) The behavior is consistent for the most part between two encoders. What is left? Connector to the encoder and the connector to the PCB... right? Should I re-pin those (what a pain in the ass)? Do I even have the right pins for those... likely not.

I checked voltages on the PCB at the two caps on the supersound PCB. It was down to 4.8ish even though the switcher was at 5.09... so I upped the voltage to where the caps were reading 5.05-5.06 or so... it SEEMED to help a little (wishful thinking?)...

Someone told me he had to really crank the voltages up to get his spinner to work properly. What is the max voltage you'd recommend I run the PCB at? Could this still be a voltage issue? Between this nagging issue and the Mario Bros flaking out on me I am really pulling my hair out these last couple days.

:D
 
OK... I took good look at the harness and saw that it was hacked at some point. Someone evidently hacked a new connector in rather than re-pin it... he hacked a different Tron connector in as about 12" from the connector the harness was soldered to a hacked off portion... I checked all the solder joints and they were solid... but it WAS taped all together like crap. So I taped each solder joint independently... I also ordered a connector/pins from Bob...

Anyway... the GOOD news is that there is an improvement. A huge improvement... but it's still not perfect..

Going one direction (counter-clockwise) it is PERFECT... the numbers in the test drop by 2 each tiny turn of the knob...

Going the OTHER direction (cockwise) it's not so perfect. It seems SMOOTHER the faster I go... but if I move it very slowly it seems to go up in increments of 8 rather than 2 like the other direction. Now, the huge jumps from 22 to 120 are gone... which is great...

Any idea what color wire(s) I should be looking at for this particular issue? Do one set of wire deal with one direction and another set the other?

PS: Sorry to hijack this thread... :(
 
Is that on the encoder? I ask because CDJump tested the boardset when he had it and had no issues...

Anyway, I repinned the molex connector today just in case... no help.

I am picking up a 2nd encoder from ArcUnderground tomorrow... if I have the same problem with that one then I guess it'll come down to the connector going to the encoder or the connector going to the PCB...

BTW ... what is the optimum voltage for Tron? I have it a 5.05 right now... though I had the problem when it was as high as 5.15...

Hey what is the 12 volts like on your spinner like?
http://gl.tter.org/spinnerhack/schematic.gif
I am using the above as reference material.
 
Both +5 and +12 are fine (5.1ish and 12.8ish)....

EDIT: I noticed that pins 12 and 13 are +5... I only tested 13... time to go check 12...

EDIT #2: Naw... voltages are more than solid on both pins. Actually, at 5.0vdc on the PCB I am at 5.21 on the encoder... but the counter-clockwise motion actually stabilizes A LITTLE bumping the PCB voltage to 5.05 or so putting the encoder over 5.3vdc... I just dont' want to push the PCB any more... and I am guessing it's not too good for the encoder PCB to have over 5.3VDC pumping in to it. I DID drop the voltage on the PCB to 4.85VDC putting the encoder at 5.11 or so and it seemed a little worse than the above two voltages... all voltages though present counter clockwise as smooth and clockwise not so much so... at 5.21 and less on the encoder going clockwise actually started jumping backwards a hair (though not nearly as crazy as it was originally)...
 
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I recommend that you do not increase the power supply voltage any more than 5.1V max. More is not better. IMHO, that is an act of desperation that likely will only lead to severe damage of other ICs. It's not worth the risk.

To determine if the wiring harness is a source of problems, you can use a continuity meter (ohmmeter on beep setting) to check for continuity from one end (at the encoder board) of each data bit path to the other end (at J4 port on sound board). Keep in mind that you can connect the meter at components on each board so that the measurement includes the header pins and harness terminals. If all of the data lines are okay, then you can move forward and check the input port circuitry.

The encoder input port circuitry is on the sound board and it is not all that complex. In all likelihood, if you replace the 74LS244 chip at location E2 then your encoder problems will be solved. Of course, a physically broken resistor or cap related to any of the 7 data bits on the input side of the chip could cause the failure that you are seeing. Fortunately, resistors and caps are easy to test using a simple ohmmeter. If you do not have a scope or logic analyzer available, it would be very hard to actively troubleshoot the input buffer chip E2 (74LS244). In this case, simply replacing this inexpensive and commonly available chip is a simple enough repair.

As an aid to troubleshooting, I very quickly put together a simple set of instructions within a pdf file that can be downloaded here...

http://www.biltronix.com/pdf_files/Omega_Race_sound_board_encoder_port_info.pdf


Granted, it doesn't include the second encoder port component locations but the principles are obviously the same. The schematics pdf that I have is not clear so it's quite difficult to read. I hope I got everything correct in the pdf. The spinner/encoder board provides 8 data bit outputs but the game is only wired for 7 of those bits, D0 through D6.

I also noticed on the encoder board schematic that R111 is incorrectly shown connected in series with R109 and that the output pf the comparator is tied to +5V. This is a gross and obvious error. R111 should be shown as a pull-up for the comparator output, similar to R102.

Good luck, I hope that you can solve your spinner problem.


Bill B.
 
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