Re: Major Havoc

From: William Boucher <wboucher6_at_cogeco.ca>
Date: Mon Jul 02 2012 - 15:39:56 EDT

Four things to note...

1/ The T-to-MH conversion board provides pincushion correction that is needed to make MH look okay on a wg6100. Obviously the corrected output would look wonky on an Amp which requires no such correction.

2/ The mods suggested for the wg6100 are not required to test out the game. Nothing bad will happen if you run the game without those mods. Assuming that the mods we are talking about are the addition of zener diodes across the transistors on the bottom of the deflection board, those were only added as a cheap way to limit the output current in the event that something went wrong with the game. The intent was to prevent major meltdowns of the monitor while the machine was on route and sitting there for many hours or days with a major problem. I have seen several cases where adding the zeners actually caused problems for certain games.

3/ The MH board that you have may need a few small wire jumpers added to it in order to make it into a "conversion" version. Dedicated boards do not feed "pre-X" and "pre-Y" signals to the specific edge fingers as required by the conversion board.

4/ Another difference between dedicated boards and conversion boards is the crystal frequency. There was a slight difference in the frequency introduced to make the apparent speed of the spinner seem more like the original roller controller. The slower clock has other effects as well, such as the pitch of certain sounds. The change may also have been made to slow down the vector drawing rate so that the wg6100 could better keep up.

If you need, I can provide photos of my own conversion board output section so you can see which edge pads to first isolate and then wire to which pins
The crystal frequencies on my board are...
Y1 = 9.216 MHz
Y2 = 8.000 MHz

I'm pretty sure that the required changes are all documented in the original Atari conversion docs...
http://www.biltronix.com/Space_Duel_to_Major_Havoc_Conversion_Files.html
The above link provides the docs pertaining to the Space Duel conversion but I'm sure that I have the Tempest specific ones if you need them (let me know).

William Boucher
http://www.biltronix.com
  ----- Original Message -----
  From: Kevin Moore
  To: vectorlist@vectorlist.org
  Sent: Monday, July 02, 2012 2:39 PM
  Subject: VECTOR: Major Havoc

  Have a question concerning the tempest to mh conversion.
  Just repaired a mh board, everything looks great on my pat9000 bench. That is until I plug in the conversion board set. The the video goes all sorts of bad. I've checked over the components on the adaptor board and have found no fault.

  Reading over the conversion documents it looks like there is some mods needed to the wg6100 before I go and do those mods I'd like to understand better what they are for. Mind you I'm running an amplifone setup in the pat so I would actually have to convert my tempest to check this thing out.

  Kevin

---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com
Received on Mon Jul 2 15:40:08 2012

This archive was generated by hypermail 2.1.8 : Mon Jul 02 2012 - 15:50:00 EDT