BattleZone probs....

Been having another crack at fixing my BattleZone tonight and I'm somewhat
confused....

The last time I looked at it (a few months back) the self-test routine told me
that one of the ROMs was bad, now it's telling me that (another) one of the RAM
chips has failed.

I can't understand why this would be. I've tested all of the TTL on the board
with a logic comparator and none of the chips appear bad (I had to replace
three before) so it shouldn't be a memory decoding problem.

Now, before I got the machine my friend who owned it then had to repair the
Audio/Reg II board since the 2N3055 on it packed up. He replaced it with a
fixed voltage regulator (modifying the circuit appropriately) and I've noticed
that the voltage reaching the analogue vector generator board is a little on
the low side at 4.73V, just outside normal TTL power specs.

I'm assuming that this is causing my problems?

My friend couldn't get a 2N3055 which is why he used a voltage regulator
instead. Are 2N3055s still available, if not can anyone suggest a suitable
alternative as I intend to reverse his mods and put things back the way they
should be?

Back to tonight's "Voyager" (we're only about 18 months behind you guys on this
side of the pond).

  TTFN - Pete.

--
 Peter Pachla: Computer Hardware & Software Engineer,
               Sound Engineer,
               Arcade Machines Collector,
               Obsolete Computer\Games Console Collector,
               Barman,
               & General Fun Guy....
 E-Mail:       peter.pachla@virgin.net (primary account)
               peter.pachla@vectrex.freeserve.co.uk
               peter.pachla@wintermute.free-online.co.uk
--