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Upgraded from 10mhz crystal to 12mhz and performance got WORSE?!

Thrillhouse

Thrillhouse

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I have both a 10mhz and 12mhz CPS1 short A boards. I've recently made repro 1941 and Daimakaimura boards for myself, so I opted to upgrade the crystal on the non-DASH board to 12mhz. On either of these games, there would be a light stuttering or slow downs on complex scenes. Both work flawlessly on the factory DASH A boards.

I bought a few 12mhz crystals (from a listing suggested in another thread here) on eBay and swapped in the replacement and.... performance actually got worse on both of these boards. Stuttering is worse than with a 10mhz crystal! I redid the soldering job, and it's pretty clean. The crystal appears to be oriented correctly, using the same marking dot position as the old crystal.

Before I try a different 12mhz crystal or go too much further I just wanted to make sure - am I missing something here?

Here is the part I'm using: https://www.ebay.com/itm/12MHz-Xtal...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
 
Uh... You know about the multi that is coming out right?
*cough* I sold my CPS1 conversions 2 years ago *cough*
 
Don't get the wrong Idea - I simply removed roms from working B boards (one had a good C board, the other had a bad C board), set everything aside in antistatic packaging, and burnt roms for those respective titles. I'm using SheepNova/Lydz generic B-21 C boards. No games were irreversibly destroyed, and I'm not selling or trading them. 2 minutes with a flathead screwdriver and the boards can be restored to factory condition with no indication that anything had been changed, other than maybe tool marks on the underside of the stock ROMs.

They'll probably get converted back to stock once the multi comes out (I'm in line in the high 300's, I think). But - I got impatient and quarantine stir-crazy. I'm not making these repros for money since I used a couple other people's work to make them, namely the GAL for Daimakaimura. The 1941 was pretty straightforward from the MAME ROM.
 
Swapped in a different 12 MHz crystal after verifying that my solder job was ok on the first one. No change. Swapped the original 10MHz crystal back in and performance went back to the "expected" stuttering of a 12MHz game running on 10. Very strange. I might order different 12MHz crystals from elsewhere. Maybe the seller that was recommended changed parts without notice?
 
i have the multi CPS1 from Lydz and i have 2 dash boards (one i used for Daimakaimura conversion , previous was Quiz game - is a long DASH pcb - i tried multi on this and the only slowdown moves are on Area88 ) on the other dash board , the A board who come initialy from Lydz along with multi , all games working great.
 
You may have to change the CPU as well. Boards with 10MHz oscillators come with a CPU rated for 10MHz. You are essentially overclocking the CPU and it may not like it.
 
I've seen some rumblings of a "crystal and CPU" pairing recently, as opposed to the straight crystal swap. Any ideas on an appropriate replacement CPU?
 
Thrillhouse said:
I've seen some rumblings of a "crystal and CPU" pairing recently, as opposed to the straight crystal swap. Any ideas on an appropriate replacement CPU?
Click to expand...
Motorola MC68000P12. The '12' on the end means it is binned for 12MHz clock.
 
Thrillhouse said:
I've seen some rumblings of a "crystal and CPU" pairing recently, as opposed to the straight crystal swap. Any ideas on an appropriate replacement CPU?
Click to expand...
2020-07-21_22-26-52.jpg

Replace these guys.

CPU with an equivalent in 12.5Mhz
http://www.cpu-world.com/CPUs/68000/Hitachi-HD68HC000CP10.html
 
If you can get them to fit, install a socket for the oscillator and a plcc socket for the cpu.
 
I’m going to have to check my board for that cpu. When I did the crystal swap only, I didn’t get any slowdowns at all. actuallt, Hyper Fighting felt right since upgrading.
I wonder if my board already has the 12mhz cpu...I’ll check tonight.
 
Very, very interesting. Thanks, y'all.

I've got a DASH A-board that is currently dead-to-the-world. If I can't get it up and running after doing some troubleshooting, I can see if I can transplant the CPU over. Granted, the reason it's dead to the world could be that CPU so....

Otherwise, best price I can find thus far for a TS68000CFN12 for about $20. Not bad.
 
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