RocNRope No Video - My First Konami Repair

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NivagSwerdna

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OK... so here we go... A few years back I bought a RocNRope from another UKVACer on the basis that it was not working with no video output... Some 5 years later I have got around to having a look at it with a view to using it in the Cocktail I am repairing (at an even slower rate)...

IMG_20230312_145731315 (1).jpg
 
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Connected my test board which has a set of switches (Poor mans test rig) which is now JAMMA and homebrew JAMMA to Konami adapter. Applied 5V to the appropriate bits and pieces.
With a logic probe checked for activity on Konami-1 Pin 42 (A12) and it's pulsing, checked Konami-1 Pin 19 and it's HI so nRESET=1, i.e. running
Checked pin 16 of Konami 082 Custom at B6 and it is pulsing. Pin 16 is nVBLANK used to drive the periodic interrupts.
All good so far..

No monitor connected but attach scope to SYNC...

CaptureRnR_Adapter.png


NewFile1.png

Signal shows nHBLANK Pulses and a long LOW during VBLANK.
NewFile0.png
Interval between nHBLANKS is 15.9kHz... seems good to me and shows most of the video count logic is working.
 
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NivagSwerdna

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R, G and B seem stuck high....

CaptureRnR_ColourPROM.png

Going back to colour PROM...

CaptureRnR_ColourPROM2.png

With logic probe... Pins 10, 11, 12, 13 and 14 pulsing... 15 LOW (nCS)... all outputs high...

Conclusion PROM knackered.
 
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NivagSwerdna

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A 6331 is a 32x8 BiPolar PROM (256 bits)... MAME has a definition for a a17_prom which looks the right size but I would put my device at location A15 rather than A17 but I guess that's close.

Capture_RocNRopeColourPROM.png

It seems to contain rather a lot of zeros... but I think that is probably the correct one. I have a 82S123 replacement board that uses a Flash so will burn one of those and see what happens.
 
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Made up a 6331 replacement. This is my FrankenPROM created to replace a BiPolar PROM in my Galaxian. It's cheaper than a NOS 6331 if you don't factor in the time for fiddly soldering.
IMG_20230313_094313057.jpg
Of the 4M bits in the flash (i.e. 512K bytes) only 32 bytes are actually addressable. (Actually it is bank switched by some solder jumpers on the back you get the choice of 4 images).
i.e. Only 0.006% of the device is used. How about that for overkill. (Still a flash chip is around £2 and the guy I bought my last 6331 from is on holiday)

0000 : 00 07 38 3f c0 77 1d 88 e0 f8 14 ad 13 48 26 ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 CRC32: 22ad2c3e SHA1 Hash: 1c2198b286c75aa9e78d000432795b1ce86ad6b9
Seems to read OK... will Socket the existing one tonight.
 
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cliff_poole

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Nice, great game, very tricky !.

Do you make your replacement parts available for purchase ?. I imagine 82S123 and 82S129 would be very popular. They are used all over the place.
 
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cliff_poole said:
Nice, great game, very tricky !.

Do you make your replacement parts available for purchase ?. I imagine 82S123 and 82S129 would be very popular. They are used all over the place.
Click to expand...
The trouble with my solution is that it needs to be programmed before soldering, so it's really a one time type process. Also I use PCB edge pins which are very hard to come by. The design is pretty trivial...

CapturePROMSchematic.png
 
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