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Black IcE
03-05-2015, 01:48 AM
I have a Truxton board that just displays the following when it is turned on...

http://i61.tinypic.com/34g5wxx.jpg

I've been searching for Truxton repair logs but I haven't found much. Any suggestions would be appreciated. Thanks for looking.

Atro
03-05-2015, 02:35 AM
It looks like it's stuck in watchdog.

I'd start to look for pulses on the Motorola reset pin ( don't remember which on is ).
My Fixeight board had the same issue, but it turned out to be a little something that was bridging the CPU reset pin with something else.
After a few blows and cleaning, it works like a charm.

Can be a bad ram/IC also.

Xian Xi
03-05-2015, 04:44 AM
Addressing looks all jacked, check the work ram if they're still good and verify the program rom(s).

bustedstr8
03-06-2015, 12:00 AM
For no boot games I usually follow something like this...

Check voltages
Clean the board and reseat the eproms, like said a little piece of metallic dirt can get wedged in a QFP or something and cause problems
Press test a few areas while powering on and look for changes
Inspect the board for damaged traces, cracked solder joints....etc
Check clock, halt and power on reset of the CPU
Verify program roms
Check control signals of program roms and main work ram
Check addressing and data of program roms, main work ram and CPU
Throw the board at a wall and mix a nice drink

Black IcE
03-06-2015, 01:07 AM
For no boot games I usually follow something like this...

Throw the board at a wall and mix a nice drink

I might try this as my first step.
In all seriousness though, I will go to town with my inspection and report back what I find. Thanks for the input everyone.

Black IcE
04-23-2015, 10:01 PM
I haven't gotten a logic probe yet to do more in depth troubleshooting but after cleaning and running the board, I noticed that one of the ram chips was getting very hot. The chip is a Sanyo LC3517AL-12. Looks like I will be trying to track down one of those chips and try swapping it out.

Xian Xi
04-23-2015, 10:02 PM
Does this PCB have an HK-1000 near the jamma edge?

Black IcE
04-23-2015, 10:07 PM
So far, I don't see one. I don't know what one looks like but I understand it is a 48 pin custom toaplan chip ?

The only custom Toaplan chip I can find so far is a M70H005 (7Z2001).

The other thing I noticed is that if I touch the legs of the hot ram chip, I can change the screen colors and pattern.

There is one other chip next to the ram chip that is a larger surface mount 150ish leg chip (FCU-2) that gets hot but not as hot as the ram chip.

Also verified the program roms, #9, 10, and 11

Kid Panda
04-23-2015, 11:11 PM
How hot is the ram getting? Like blistering hot?

Black IcE
04-23-2015, 11:16 PM
It takes it a minute to get really hot but it gets up there. Hot enough I wouldn't want to touch it.

Opethian
04-24-2015, 12:24 AM
check both NEC branded chips and RAM.

Xian Xi
04-24-2015, 06:00 AM
So far, I don't see one. I don't know what one looks like but I understand it is a 48 pin custom toaplan chip ?

The only custom Toaplan chip I can find so far is a M70H005 (7Z2001).

The other thing I noticed is that if I touch the legs of the hot ram chip, I can change the screen colors and pattern.

There is one other chip next to the ram chip that is a larger surface mount 150ish leg chip (FCU-2) that gets hot but not as hot as the ram chip.

Also verified the program roms, #9, 10, and 11

Check the connection from work RAM to CPU, one ram would be the upper bits and one the lower.

ebinsugewa
04-26-2015, 08:58 AM
Random tangential question - I have a big stack of boards I need to pore over at this level. Schematics are readily available for the classic games I work on, but I seem to have difficulty finding them for newer games. Is there a list of places you guys search or do they just not exist? I know I can ohm stuff out and follow traces but I'm lazy :keke:

Kid Panda
04-26-2015, 11:12 AM
Random tangential question - I have a big stack of boards I need to pore over at this level. Schematics are readily available for the classic games I work on, but I seem to have difficulty finding them for newer games. Is there a list of places you guys search or do they just not exist? I know I can ohm stuff out and follow traces but I'm lazy :keke:

The only company I am aware of that continued to offer schematics after the start of the Jamma years was Atari. Everyone else started either
A: creating custom chip designs
B: used of the shelf components but scratched off what they were ontop of the chip
These things were mostly to keep bootleggers at bay for a bit.

Black IcE
05-17-2015, 11:26 PM
Just updating the status of the repair. I just ordered a logic probe from Amazon and it should be here Wednesday. I will finally be able to test the ram chips and processor to see what is going on. Thanks for everyone's input and hopefully I'll have more info later this week. No shooter deserves going unrepaired...

Black IcE
09-26-2015, 09:47 PM
After poking around with the logic probe for a while (assuming I'm using it right), I found a ram chip that isn't showing any activity compared to the other ram chips. It is a Sanyo LC3517AL-12 but the only reasonably priced possible replacements I can find are LC3517AL-15 on ebay. Could the slightly slower 150 ms chips work in place of the 120 ms ? I imagine it would NOT work, but I just thought I would get a second opinion.

EDIT: After typing this, I found some LC3517AL-10 chips for sale in Germany. I imagine I can use chips FASTER then 120ms, but not slower ?

bustedstr8
09-27-2015, 01:36 PM
You can use any standard type 2K x 8 ram 120ns or faster.

http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?langId=-1&storeId=10001&catalogId=10001&position=1&refineType=1&sub_attr_name=Density&refineValue=16KBit&refine=1&history=gbb7wq5q%7CsubCategoryName~ICs%2B%2526%2BS emiconductors%2B%252F%2BMemory%2B%252F%2BSRAM%5Eca tegory~105090%5EcategoryName~cat_1050%5EprodPage~1 5%5Epage~SEARCH%252BNAV