A Couple of Color Problem Repair Logs: Boomer Rang'r and Bomb Jack

DarrenF

Well-known member
Joined
Jan 7, 2011
Messages
5,855
Reaction score
526
Location
Florida
A Couple of Color Problem Repair Logs: Boomer Rang'r and Bomb Jack

Boomer Rang'r (Data East)
---------------------
Problem: no sync

Diagnosis: common on-line pinout is wrong; sync is on D, green on E, vid gnd common with other GND pins.

Solution: re-wired test rig

Problem: no green signal

Diagnosis: during careful inspection, a broken (gouged) trace was found on the back of the PCB.

Solution: soldered fine-gauge wire across break.

Result: PCB now works fine.

Bomb Jack (Tehkan)
-------------------
Problem: Video reddish tinted all over.

Diagnosis: scoping video output; red video signal is always high (except during vblanks).

Further investigation: following schems backwards from R output, it comes almost directly from a color palette RAM (as opposed to a color PROM, which is more common). The signals on the data lines of this RAM looked different than those for the Green or Blue outputs. Piggybacking a new RAM clears up the problem. [Interestingly, the power-on self-test does check RAM, but apparently not this RAM, as it did not report any problems at bootup.]

Solution: Replaced 2114 RAM @ 6A

Result: PCB now works fine.

PS--also added an NVRAM and installed the JROK high-score save EPROM. Works well, just need to play it a few more times to knock the rest of JROK's initials off of there...

PPS-- YOU ARE LUCY!
 
Last edited:
Back
Top Bottom