Solved Irem M72 (R-Type) no sprites and rolling screen

[Georgian2]

Hello all,

Here I have on my bench an original R-Type irem M72 PCB. I can't get a lock on the vertical. It just keeps rolling. Is it because of the ~55Hz Hsync? Is it normal?
And all the sprites are missing. There is noc activity on the sprite roms and on a few rams on the middle PCB. Most likely the unobtanium customs are dead?

Thanks a lot for your help.

 

[vsl]

I had a similar problem a long time ago, it turned out to be simple. Somewhere on the board there was a switch that determined the type of eprom used. But I don't remember where it is exactly, look around and hopefully this will solve the problem.

 

[Georgian2]

So far I found that the pin 18 on the IC35 is always HIGH. It is unmarked on the schematics but I traced it to IC66 pin11 VS (vertical sync). Pin7 V16 is floatig! I need to check it. Good progress so far. I'll dump this prom and see if is good.

Also the pin30 on IC35 (!DMAON) is always high. I did replace the PLD that is comming from but didn't change anything. All the inputs on that pld are active.

 

[Georgian2]

The proms is good.
V1 and V16 from IC76 are not good :-(
Pin 62 from the IC76 is floating too :-(( Shorting it to pin 61 or 63 makes the sprites apear on screen! The KNA70H015(11) is dead.
Problem sort of solved.

 

[Georgian2]

Can anybody identify the pin 62 from tthe KNA79H015 schematics? I could divide the V32 by 2 externaly and have the V16 but the other pin is a little harder to do.
https://github.com/furrtek/SiliconRE/blob/master/Nanao/KNA70H015(11)/KNA70H015(11)_schematics.pdf

 

[Georgian2]

I found it. Should be no problem implementig it for an gal pld.

 

[Georgian2]

Implementing the Pin62 in wincupl for an 16v8 did the trick! Now all the sprites are back! Screen is still rolling. I see what I can do with that V16...
Here is the wincupl code if someone ever has the same problem.

Name     PIN62 ;
PartNo   00 ;
Date     16.02.2025 ;
Revision 01 ;
Designer Georgian Borca ;
Company  BrK Empire.NET ;
Assembly None ;
Location  ;
Device   g16v8a ;

/* *************** INPUT PINS *********************/
PIN 2     = H1                        ; /* PIN 38                                */
PIN 3     = H2                        ; /* PIN 39                                */
PIN 4     = H4                        ; /* PIN 40                                */
PIN 5     = H8                        ; /* PIN 41                                */
PIN 6     = H16                       ; /* PIN 42                                */
PIN 7     = H32                       ; /* PIN 43                                */
PIN 8     = H64                       ; /* PIN 44                                */
PIN 9     = H128                      ; /* PIN 45                                */
PIN 12    = H256                      ; /* PIN 46                                */
PIN 13    = H512                      ; /* PIN 47                                */
PIN 14    = S24H                      ; /* PIN 60                                */

/* *************** OUTPUT PINS *********************/
PIN 19    = PIN62                     ; /*                                 */

PIN62 = (H512 & H32 & H16 & H8 & H1 & H2 & H4) &
     (H64 $ S24H)  &
     (H128 $ S24H) &
     (H256 $ !S24H);

 

[Georgian2]

Dividing the V8 by 2 sort of did the trick with the roling image. Now it is stable but every now and then jumps around. I ordered an repro from caius and should be as good as new.
I'm happy with the results, so the job is done here.

 

[Georgian2]

One more update:
Connecting the Pin53 with 21 on the IC76 fixed the rolling screen issue. Anybdy has any ideea what V16 and V16E mean? Is one input and the other output? Too lazy now to put an logic analyser on them...

 

[Retroman839]

Why is Damon ?

 

[Retroman839]

Hey George
What is Damon an acronym for ?

 

[Retroman839]

V16 Vertical sync

V16E

Virtical sync signal
Combined with Earth ?

 

[Georgian2]

Hey George
What is Damon an acronym for ?

You mean NOT DMAON? I have no ideea.