JPAC: not sure of some things

[Ummon]

   I have an older model JPAC I'm using with my candy. The monitor is 15/24khz. Though I've read the information at Ultimarc (which is obviously amended for the new version), some of the behavior mine exhibits is contradictory to what seems should be normal function, hence I have the following questions:
 
 
- In the attached imagae, what are the jumpers left of the video jumpers for?
 
- The video jumpers are supposed to do what exactly?
 
- The JPAC is supposed to screen 31khz signals. Does this mean only 640x480, and nothing above?
 
- Whether using the JPAC or a hacked cable, the brightness seems the same. Does this mean the video amp isn't working?
 
- On the following page - http://www.gamesx.com/arcade/jamma.htm - it shows the last two connections from the bottom of the jamma connector (purple and blue near the end of left in the picture) to be player 4 and 5 buttons. Though there are leads connected on mine, I don't think they're to these buttons as I get no key presses in Mame or notepad. How common/recent is this in jamma?
 
- audio amp connection: also on the above linked page, it says the +12v on the jamma harness are for the audio amp. I assume this means whatever's connected to the edge connector at these points must be feeding the amp for it to work. If yes, does the JPAC support this?
 
- Lastly, the older JPAC models' keysets are programmable, right?

[AndyWarne]

Thats a very old board, there have been 3 versions since that one.

The jumpers on the left are for USB or PS/2 connection, and also for default MAME codeset or downloaded codeset. Yes the codes are programmable, using the older WinIPAC utility on www.ultimarc.com/download.html.

That version did not have a video amplifier.

With the jumper on 31, it will only allow 31Khz through and block all other higher or lower horizontal frequencies. On 15 it will only allow 15 etc. With both 15 and 31, it will divide a 31 Khz signal in half so there is a picure on an arcade monitor.

Button 4 is routed on the edge connector but 5 and 6 are not. Butons 4-8 are connected on the screw connectors.

The J-PAC has no connection on the edge connector to any of the JAMMA power supply voltage pins.

Hope this helps.
Andy