Adapter Konami PCB to Monitor for Bench

[NivagSwerdna]

I have a number of arcade PCBs from the 1980s Konami era which I bought not working and would now like to have a look at (the intention was to build custom IC replacements using FPGA/CPLD but I have never had the time)... anyway...

I don't have space for an arcade monitor at my bench (it's only a small room with little desk space) but I do have a computer monitor that could be switched.

How would I get Konami video from the PCB to a relatively modern computer monitor?

e.g. for example Scramble is 768 x 224

[font="Tahoma, Geneva, sans-serif"]Some PCBs have separate sync, some composite and I guess some probably have polarity the 'wrong' way around.[/font]

I did a bit of googling and found "Gonbes CGA / EGA / YUV / RGB To VGA Video Converter"




GBS-8200?

What do you think? Is that a reasonable converter?

Thanks in advance

 

[simonden]

The GBS-8200 can be found under multiple brand names and can normally be picked up for under £15 delivered from the likes of ebay.

I have a couple of them. It works for looking at a board for 5 minutes to see if it boots/graphic issues, but I wouldn't trust it for too long.

I had one of these plugged into monitor on an old sit down driver The monitor in the driving cab only had seperate H/V syncs (no Csync) and was trying to use one of these to send a CSYNC signal. The picture on the monitor screen was purple and after 15 minutes, the chassis caught fire. That could have been the monitor or it could have been the sync signal, since then I have used an Extron RGB for splitting/combining sync which is a fantastic device and can also be picked up for around £15 on ebay. (but doesn't convert from 15khz to 31khz).

There are alternatives, some flatscreen PC monitor accept a 15khz signal. Just need to check the specs, I have a Panasonic 42 inch plasma that accepts 15khz signals and had a Dell 19 inch PC moniitor that takes 15khz as well.

If you stick with a 31khz monitor, and it accepts csync (most standard monitors do) then the GBS-8200 should be fine on it's own for just testing a few minutes at a time, if not I would get an Extron RGB as well (or preferably an Extron scaler with sync splitter/combiner built in, such as the DVS-304 dvs304">dvs304 which are professional devices and can be got really cheap on ebay these days, one currently at £45 BIN).

simonden2021-03-18 10:48:56

 

[Lurch666]

I use an old portable CRT monitor for my testing.

The RGB from the jamma adaptor is fed into the scart and works for most boards.

It's only very early boardsets (midway 8080 and earlier) that have composite out.

If the boardset is not jamma then I build an adapter to convert it to jamma.

 

[NivagSwerdna]

Thanks both. I hadn't considered FIRE!

So a DVS-304 would scale it up to fit the screen but I still need a monitor scanning down to 15kHz?




So sounds like I probably need a DVS-304 anyway?


NivagSwerdna2021-03-18 11:09:44

 

[simonden]

So a DVS-304 would scale it up to fit the screen but I still need a monitor scanning down to 15kHz?

No it is an either or. If you have a 15khz monitor (best option) you don't need the DVS-304. The DVS-304 will scale up to a 31khz monitor but you will need to buy/make some custom cables.

 

[NivagSwerdna]

Any opinion on:
Extron DVS 304 versus Extron DVS 304 DVI ?



So the DVS-304 will cope with 15kHz 240p on one side and something more modern on the other side?




Looks like effectively it has a "VGA" connector on the out so I could plug it into a monitor (now a bit old fashioned)

with a similar connector?




My current computer monitor is a iiyama ProLite B2409HDS which seems to only have HDMI, DVI-D inputs so looks like I will need to buy a small monitor for the PCBs anyway.




(Sorry for the newbie nature of these questions... it's not something I have done before)

 

[simonden]

The DVS 304 DVI just replaces the VGA outport port with a DVI-I output port.

If your current monitor only accepts HDMI and DVI-D it only has digital inputs, not analogue. Not something I have come across before (no analogue inputs, not even VGA) but I haven't bought a new monitor for a long time, so maybe that is the way they are going.

The DVS 304 (and DVI model) and the GBS-8200 all output analogue signals so won't work with your current monitor natively.

There may well be an Extron item that also has A/D convertor as well as converting 15k to 31k, but your best bet will be to find a standard PC monitor that accepts 15-31khz (or have a separate monitor for Arcade).

 

[NivagSwerdna]

Hm... I must have been reading the specs I found via Google wrong...

The monitor is nothing special it is a iiyama ProLite B2409HDS

I downloaded the manual and got a rather different answer...

It has HDMI, DVI-D and 15 pin DSUB inputs... looking closely at the specs it supports..

Analog 24-80kHz Horiz, 55-75Hz vertical.

So just to be clear... the DVS 304 will take the 15kHz on the input side, sample it and put out something with a higher horizontal frequency on the output side?