Service manual

Wells-Garnder Color Vector Monitor Guide
Page 47 of 73
How To Make A 'Tempest' Monitor Trouble-Free
Here is an article from the April 15, 1983 issue of Play Meter magazine (page 191). The article is
from a regular feature in the magazine called "FRANK'S CRANKS" by Frank "The Crank"
Seninsky. This hack is essentially no different from the Atari Zener diode input protection
modifications, except the Zener diodes in this hack are properly biased using resistors to the
rails, and 1n914's are dropped into the circuit to clamp the input to the within the +/-8.2V from
the 1n4737 Zeners. (thanks to Mark Spaeth for the description)
HOW TO MAKE A 'TEMPEST' MONITOR TROUBLE-FREE
Atari's Tempest, when it is working, is not a bad game. It's just a shame that the monitors only
last a few weeks (sometimes only days) between service calls. Most of the time, the monitor sits
neglected on a techroom shelf.
Atari has developed a monitor protection board [included earlier in this text] to protect the
monitor's components (2N3716 and 2N3792 "X" OUTput transistors, two each located on
chassis frame) if and when there is a RAM lock-up on the Tempest CPU board. I want to clarify
that the Wells-Gardner monitor is not at fault. Also note that on the later Atari games, the
protection circuit has been incorporated into the board circuitry. [These statements seem to imply
that this "fix" is compatible with the Atari upgraded P314s as well as P327s and P339s and will
provide additional protection; in fact, I have seen it on a P327 before. It is sufficiently ambiguous
that the exact opposite can be inferred. Judging from the areas of the board it alters, I would say
it is incompatible (duplicates) the other fixes in this section.]
It's common knowledge that you can purchase a broken Tempest game cheap. With about 20
minutes of your time and a couple of dollars in parts, it is possible to add just six common
components to the monitor deflection board and have a Tempest that will stay on location and
work.
The parts required are:
• two-1N914 diodes
• two-1N4737 diodes
• two-1K OHM 1/4 W resistors