Bally ProVideo (By Belbenchtech)

[SAT (aka GANDHI)]

Some notes from a Bally ProVideo seminar...


V5000 and V5,500 MPU boards are the same, except for the reset switch.

Check the battery, no battery disconnect jumper...if storing desolder one side of the battery.

Denomination is set with DIP switches, set denomination then clear RAM (Full clear) to lock in denomination change.

Z80 processor (8 bit bus) U25.
EPROMs U10 (main), U11 (personality)...when converting games make sure you have ALL the EPROMs needed for the conversion.

RAMs (Game) U12 (S-RAM) & U13 (scratch pad)...power down & scratch pad looses all data.

Video RAM; U4...assembles info & sends to monitor.

Color RAM; U46...sends info to digital to analog convertors, to transistors, RGB drive, Horizontal, & Vertical use analog signal.

CRT control; U15...scan rates, horizontal, & vertical syncs are derived from here.

Sound controlled by U72...all sound generation.
     *NOTE*DIP switch next to sound chip...if DIP switches aren't being read correctly the problem might be the sound chip(8 bit port runs through it).

If no data is coming from data buffer, check U86A pin 12 BEFORE you change U47.

If the board is "dead"
1) Check power (5V to 5.15V)
2) Check clock (Y2 12MHz osc.) check w/o-scope U38 pin 3 (5V-12MHz).  Check pin 6, U25 for system clock.  U40A pin 12 normally (1) high output.
3) Check Resets;
    A) Push button
    B) Watchdog
    C) Static
    D) Power-up
    E) Low voltage
4) Halt & wait; "dead" bd. U25 pin 18, always (1) high, U25 pin 24, short random (0) low pulses...No bus activity-wait all data freezes either hi or low-will have a scrambled screen...both should be (1) hi.  Should be 5V always.
5) Interrupts (inputs); U25 pins 16 & 17 (even pulses on Wait or interrupt lines are NOT normal).
6) Page 1 & 2 (U109 pins 8& 9, or U60 pins 16 & 19 should be plusing.

200K+ memory on board done with paging (divided into 4 pages) done through U109 pins 8 & 9 (page 1 & 2)

All outputs are Direct Current (no AC outputs).

-12V used only in serial data (U80, U81, U33).

U90, U91, U92, U93 have a high failure rate.

Video Circuit;
U15-CRT controller...pin 18 display enable (video blanking) generates the raster.
No video info U4
No sync U15.

White raster probably Video RAM (U4).

[SAT (aka GANDHI)]

Bally ProVideo tests...(S.A.)...