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Sega whitestar cpu 5v ground short?

To quote Jim...

The E means external clock input (not extra instructions) and the B means 2mhz max operation. The crystal used on the circuit will be 4x this speed so 8mhz in the case of pinball boards. The P at the end means Plastic case.

The reason you cant use a 68B09 is because of the external clock needs. the pinout between the 68B09 and the 68B09E are slightly different. The 68B09's pinout is more traditional and similar to the popular earlier 6802 ic, where it has an internal frequency gen and you just as a crystal externally with 2 caps. The chip then outputs the E and Q lines. On the 68B09E however you input the clock signal into the chip via the E and Q lines therefore creating the incompatibility between the 2 variants.

The B letter in the middle is part of a standard approach by many manufacturers and different cpus to signify max clock speed, so you ofter see letters A,B,C etc to note increasing frequency speeds. (Z80, 6502 for example)
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Paul said:
To quote Jim...
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Thanks Paul I'm trying to digest all that info! So the fried board had 68B09EP chips and my spares are 68B09P so no E so they need to have the E for external clock?

Thanks Ronnie
 
Paul said:
IBasically if the original is an "E" varient, the replacement needs to be, since the "E" specifies external clock, yes.
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Ok thanks Paul, I will need to find a pair of these as the 2 here are fried!
 
So I swapped all the chips over from JP board to donor board, both cpu chips, sound chip roms etc and I getting 1 led on cpu lit. and blanking led on driver board blinking along with the relay clicking and PF light blinking also, I checked 5v it's 4,968 swapped out ram still the same? Not swapped out the other 5116 ram?

Thanks Ronnie
 
But you don't get display or sound and can't start a game? And you have swapped all socketed chips from the donor board to the one you repaired? Seems the board is running at least which is a start.
 
drhex said:
But you don't get display or sound and can't start a game? And you have swapped all socketed chips from the donor board to the one you repaired? Seems the board is running at least which is a start.
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It's not the one I repaired it's another board we got with no corrosion, the pin wiki says it's not booting if the blanking led on driver is flashing and pf lights also flashing constant on off every second or so, this new board has all the chips fitted from the working board, I checked reset pin 37 on cpu and it is held high?

Just to confirm this is not the fried board

Thanks Ronnie
 
I'm a bit stuck now with this board, it's not booting only thing I can think is the pal chip at U213 but it has no signs of corrosion, it was only 2 pins on the ram socket that were green, what I will try is probing the pal chip to see it's activity and compare it to the working board.

I do have a logic probe and a scope but not the brain to work out what I should be seeing from the chematics lol.

Thanks Ronnie
 
Just tried the above, on the working board pins 6 and 7 are pulsing but on the non booting board pins 6 and 7 are stuck high this is the pal at U213 Now this might be because it has not booted and if it did there might be activity but it's all I have to go on at the moment.

Looking at the schematic pin 6 is vma and pin 7 is r/w so might not be active until the board has booted?

Thanks Ronnie

Edit the track to pin 18 ramcs is open at the via! Hope that's the issue


IMG_4461.webp
 
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If chip select doesn‘t work it will be unhappy. That is an inverted signal so no signal will enable RAM all the time - probably not good for reading the code from the EPROM…
 
drhex said:
If chip select doesn‘t work it will be unhappy. That is an inverted signal so no signal will enable RAM all the time - probably not good for reading the code from the EPROM…
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Thanks drhex, I repared the track and also found another track to the ls138 open! I repaired both of them but the board still does not boot and pins 6 and 7 still high

So I removed the pal chip and tried to verify it with a known working file it failed, So another question can I programme the JED file onto a GAL chip without any issues or must it be a PAL chip?

Thanks Ronnie
 
If pin 6 and 7 do absolutely nothing even with the chip out I would continue looking for these signals first (they originate at pin 32 and 36 of the CPU. Also scope the address/data lines to see if anything gets set there. As long as it is pin and level compatible you should be able to burn the PAL otherwise.
 
www.alldatasheet.com

PAL16V8 PDF

Part #: PAL16V8. Description: EE CMOS 20 PIN UNIVERSAL PROGRAMMABLE ARRAY LOGIC. File Size: 3248.15 Kbytes. Manufacturer: Advanced Micro Devices.
www.alldatasheet.com
 
Also, if you identified signal breaks already, you should make sure that the basic signals needed like clock, address lines etc have continuity. If you have two broken, there probably are more.
 
Thank you, I could not find any other open tracks but just been over it again it all seems good with meter and bright light under pcb

I checked the cpu address and data lines with scope on bench with only 5v supply I'm getting activity on them all so nothing looks stuck, with the pal removed pins 6 and 7 are showing high with some low going pulses.

I think I will make the new pal chip and test again in the pinball and see what happens.

Thanks Ronnie
 
Well my programmer is not playing ball! it either hangs while trying to burn the file or comes up with error over current detected, I have tried a Lattice gal16V8c and a pal16L8NC, nothing is ever easy!
 
Not any further forward one thing I noted with board on the bench if I have the pal chip fitted the bottom led quickly goes out after powering, if pal not fitted the led stays lit?

Still not managing to programme a pal or gal with my programmer! This is closest I get, seems to programme and verify then blank check? Very annoying

Thanks Ronnie

IMG_4469.webp
 
drhex said:
What happens when you try to read the original GAL? If that fails can you read another one? I have a GALEP 5, happy to program a few for you if that helps.
There is a connections table here https://pinwiki.com/wiki/index.php/Sega/Stern_White_Star_Repair#MPU_boot_issues - did you check all of those?
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Thanks drhex, yes I can read it fine but it fails the compare when I load the file I downloaded in the buffer. If you could programme these for me both Ste and me would be very grateful. I have still to go through the conection table but wanted to rule out the pal chip first

Thanks Ronnie

P.s I have 4 spare chips and the one that came from the board
 
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