Genuine Gonbes CGA/EGA/YUV/RGB To VGA converters

[eidis]

 Hi Guys !

I went on eBay recently, and found this:

Gonbes GBS-8200
http://www.ebay.com/itm/Arcade-Game-CGA-YUV-EGA-RGB-Signal-to-VGA-GBS8200-Video-Converter-Board-EP-/171607311018?pt=AU_ArcadeMachineAccessories&hash=item27f497c2aa

Gonbes GBS-8220
http://www.ebay.com/itm/CGA-EGA-YUV-RGB-to-VGA-Arcade-Game-Video-Converter-2VGA-Dual-VGA-GBS-8220-v-h9-/361130891284?pt=AU_Components&hash=item5415141814

The manufacturers claim that they both are able convert 15/24/31khz signals to VGA. If so, then this would be the ideal adapter for connecting the X68000 to a standard PC monitor. The cost is somewhere from $20 - $25. Has anyone tried them and if so, are they worth to consider ?

Keep the scene alive !
Eidis

[H68k]

Considering the price of the thing and if it's not gonna f..k your X68k's video output IC's in any bad way.. then it maybe a very nice cheap alternate to a Micomsoft XPC-whatever indeed.

Does anyone know what the latency is on it's signal conversion? anything more than a few milliseconds is going to make games that require twitch reflexes and precision timing a bit of a swine to play.

[costa]

I´ve got one of these for a long time, and used more successfully on CPC 464/6128.
Tried also with CGA and did not work on Sinclair PC200 but worked on Olivetti Prodest PC1, and after that I just forgot about it... did not even bother to check with X68000, and also heard from a friend or two that it is not worth it.

[eidis]

 Hi Costa !

Could you please confirm if it is compatible with X68000 ?

Keep the scene alive !
Eidis

[costa]

All right, I can do it.
I was avoiding playing with this converter and the X68000 because I have monitors that work fine for the X68000, but since you and more people may be interested in a know how this converter deals with the X68000 RGB signals, I will run some tests.

The board has three different inputs that might concern to us:
5 pins EGA/CGA (can ve used with RGB inputs)
8 pins RGBHS
DB9 RGBHV

and two VGA outputs.

I will try these three inputs and let you all know.
Cheers.

Hi Costa !

Could you please confirm if it is compatible with X68000 ?

Keep the scene alive !
Eidis

[Opethian]

I used one for a short amount of time and they work fine until you change resolution. I think had to reset the GBS it to get the picture to stabilize after a resolution change.

[gabby32]

Tell me please, this converter can work with computers fm-towns. I am having problems with my FM-TOWNS Ⅱ CX20.
I can not get the normal picture on the XRGB-3 mode 24khz.

[ericb59]

I have one for the X68000 but this doesn't work good for me.

X68000 -31Khz -> VGA Input   -> Image on monitor, but not very good.
X68000 -15Khz -> VGA Input   -> No image


But I can have a 15Khz picture on my PC Screen if, I melt the Vsync and Hsynch  signal from the X68000 !!
Sometimes the image is stable, but most of the time, it is very jerky.

X68000 -15Khz ->  VGA Input (With Hsync and Vsynch connected together -> Good Image on monitor, but jerky.

[costa]

Thanks mate, you saved me some time.

This confirms what I suspected and have heard: the GBS-8220 does not perform satisfactory for the X68000. That is why I did not even bother to test before.

It works quite well for Amiga and Amstrad for example, but some computers simply don't like it. It is'a very cheap converter, we can't expect too much of it anyway.

Eidis, if you want further tests, I can still do it.

I have one for the X68000 but this doesn't work good for me.

X68000 -31Khz -> VGA Input   -> Image on monitor, but not very good.
X68000 -15Khz -> VGA Input   -> No image


But I can have a 15Khz picture on my PC Screen if, I melt the Vsync and Hsynch  signal from the X68000 !!
Sometimes the image is stable, but most of the time, it is very jerky.

X68000 -15Khz ->  VGA Input (With Hsync and Vsynch connected together -> Good Image on monitor, but jerky.

[Neshek]

I have one for the X68000 but this doesn't work good for me.

X68000 -31Khz -> VGA Input   -> Image on monitor, but not very good.
X68000 -15Khz -> VGA Input   -> No image


But I can have a 15Khz picture on my PC Screen if, I melt the Vsync and Hsynch  signal from the X68000 !!
Sometimes the image is stable, but most of the time, it is very jerky.

X68000 -15Khz ->  VGA Input (With Hsync and Vsynch connected together -> Good Image on monitor, but jerky.

You probably did that, but tried to hold auto scan button for a few seconds?

Maybe a sync cleaner would do the trick?

[ericb59]

Yes, already tried...
Sometimes it works, sometimes not... 

[eidis]

 Hi Guys !

Could someone post pictures of the before mentioned device in action ?

Keep the scene alive !
Eidis

[Neshek]

Could it just be a sync issue?
If so, a sync stripper/cleaner anyone?
LM1881 chip thingie?

[ericb59]

After some more testing this day, it appear that the jerky at 15Khz is the fault of the  GBS8200 board's power supply.
It need a stable 5V, 5A power supply.

[Neshek]

After some more testing this day, it appear that the jerky at 15Khz is the fault of the  GBS8200 board's power supply.
It need a stable 5V, 5A power supply.

Good to know.
Efficient design... The thing is supposed to require 5v 2A... :/

[ericb59]

yes sory , it 2A

[BlueBMW]

I tried one of these cheap converters once before with the x68000. I  could never get consistent usable results with it so I gave up on it.  XPC-4 is expensive but it just works.

[costa]

I tried one of these cheap converters once before with the x68000. I  could never get consistent usable results with it so I gave up on it.  XPC-4 is expensive but it just works.

Yes, that is the key point: inconistency... and that is the reason I too did not even bother trying it with X68000.
I also don't  like the extra box hanging around, that is why I don't go with a XPC  and stick with my lcd monitors and the litle sony pvm for a superb crt image - although quite small, it does a great job at 15khz. The pvm is amazingly affordable these days, but the one I have can only do 15 khz, so no way to have it as primary monitor.

[X-Col]

I use my old Amiga Microvitec 1438 multi sync monitor with the X68000. Superb picture.
But one day it will die, then what?
We need an affordable solution for modern monitors, pity this one falls short... 

[BlueBMW]

I only use the xpc-4 if I want the x68000 on a big tv.  Normally I run it on an Nec XM29.  Doesnt help for 24k stuff but it works great for 15/31k.

[Neshek]

Multisync CRTs get rare, expensive and old...

Tried to do some homework... I was thinking of trying to do an internal solution for my x68000 to be able to plug directly modern monitor in it.. Probably many mistakes but better having dumb ideas than being braindead Could be braindead with dumb ideas? You be the judge ^^'

GBS-8200 has a lot of issues.. Thing is there is no decent 15/24/31khz "middleware".. Either 20$ GBS or couple hundred euros hardware... :/
Plus there are several versions.. V3, V4, HD9800 V5 (though it looks like v4, firmware difference?)... And licenced manufacturers.. Even seen a derivative with HDMI output. Any chance someone has v5?

As it seems the GBS-8200 board market is arcade screen replacement, correct me if i'm wrong but jamma boards use composite sync. GBS won't take separate sync for frequencies under 31khz. Old 15khz computers with separate horizontal & vertical sync or weak Csync signal had issues from no signal, blank screen, losing signal after some time to garbage. Some work though.. Amiga, Amstrad, MSX are mostly okay with it. Seems RGB voltage is different from Jamma. Is that a big issue? Maybe the case with X68000? The board uses TTL level RGB and positive sync of 0.76volts. Don't know for computers...

Would 74LS86 or another chip do the trick to get a good and compatible sync signal?
I have seen some diagrams.. on Atari users forum..
I have seen positive results using LM1881 for separating H and V sync so maybe with a 74LS86 to do the opposite.. Getting a clean composite sync..

This thread is interesting and this diagram looked nice. Others in the thread.
http://www.atari-forum.com/viewtopic.php?f=15&t=17153&start=100#p203262
Need to be registered to see something ^^'
Also this one:
http://www.atari-forum.com/viewtopic.php?f=15&t=22668

Then i leave the expertise of these solutions to others. I'm not into electronic stuff that much :/
So a question.. Is wiring together H and V Sync dangerous for the x68000, the GBS or both?

Anyway, if nobody's up to it, i'll try once i get some vacation and spare time ^^'
I guess i'd start with a 74LS86.

If i fry the x68000, i'll get an Atari ST running with it. Almost identical computers with same quality games anyway..
(Joke)
(I repeat, it was a joke)
(Don't hurt me)