Jul 162016
 

Got this orginal Hellfire PCB (by Toaplan) for a repair:

DSCN3844

After some initial problem due dirty sockets of program ROMs and oxidized JAMMA edge connector which caused missing boots, I was greeted by this scenario:

Sprites were wrong, garbled and stretched all over the screen.This part of graphics is generated by the custom ASIC ‘FCU’ :

FCU_ASIC

I did a reflow of it but this didn’t lead to any improvement.Probing around I found a 6116 SRAM with some data lines stuck low:

DSCN3847

Chip failed once tested out-of-circuit:

6116@2W_failed

But still no big improvements.Testing TTLs with my logic comparator I found a 74ALS169 counter @3N with bad outputs:

DSCN3849

Its output pin 15 was almost shorted to VCC (only 7.9 Ohm measured)

DSCN3850

Once removed, the chip failed miserably :

74ALS169@3N_reworking

 

Finally the sprites were correctly drawn but blocky :

DSCN3853

I noticed that, if I pressed down the ROM 9 @4E, sprites were 100% restored:

DSCN3856

Removing the EPROM revealed oxidation on socket pins:

RSCN3858

So I replaced it:

DSCN3860

Installing a new socket fixed game completely.

 Posted by at 6:28 pm

  2 Responses to “Hellfire repair log #2”

  1. Hi,

    Great repair. You guys allways impress me with your fixes.
    Also, that Logic Comparator looks homemade 😉 Is there a writeup on how to make such a ting. I would love to build one for my own repairs 🙂

    Regards
    Jan