Warning; do not use x68000 or FM Towns VGA adapters +LCD TVs

[uroko-sakanabito]

I unfortunately have to say that this could kill your RGB out;

My old 26" LCD TV has killed my x68000 RGB out a few months ago.
Today, my 32" LCD TV has killed my FM Towns RGB out.

I have no idea why this happens but people using VGA monitors seem not to have this problem.
Fortunately i have a video card installed in my Fm Towns and can use this RGB out now.

[TrevHead (TVR)]

hmmm i didnt know something like this could even happen, intresting

[uroko-sakanabito]

Believe me, it happend and costs me around 200$ ^__^

[Ganelon]

This is good stuff to be aware of. I've considered plugging my X68000 to my LCD more than once...

[uroko-sakanabito]

I really have no idea why this happens but i had never any problems with three different adapters on many other monitors.
Other people use this setup for years now without any issues. So using a normal VGA monitor seems to be fine but no LCD TVs !

[Kron]

Are you sure its not just failed due to the age of the system? Isn't it a one way video stream thats not getting any information back?

[uroko-sakanabito]

100% sure, yes

[Fudoh]

Isn't it a one way video stream thats not getting any information back?

depends on the cable layout. You can build RGB Scart cables which are 100% one-way. As long as such a cable is used, it's 100% impossible that a display kills the system's video output.

@uroko-sakanabito: i would really blame the cable(s) you've been using and give it a closer look to tell exactly what has caused the feedback.

[uroko-sakanabito]

One cable was the official PC98 to VGA converter, the other is a cable build from a friend who has used it with FMT and X68k without any problems.
If i connect both defective outputs to my x68k monitor i still get a picture but it is running through the screen.

[ShmupSamurai]

Yikes, thanks for the heads up!

[Ghegs]

Moved to Hardware.

[uroko-sakanabito]

Sry, was not sure about the Topic, thx for moving !

[Ed Oscuro]

Why would you tempt fate twice?

Just to clear up some apparent confusion, are you talking about "normal" RGB (the round port) or DB-15 computer output (looks like a VGA connector but with only two rows)? On the X68000 Compact that is labeled "Analog RGB" but shouldn't be treated as such. It's a machine-specific pinout.

I have the feeling I'm missing something important (why this is supposedly working on CRTs but not LCDs for instance), but to follow through on the last bit:

Looking here: http://www.gamesx.com/wiki/doku.php?id= ... ese_rgb-15
Pin 7 of the X68000's DB-15 output is computer data and is +5V. On the FM Towns it's Composite Sync.
I didn't know of a PC98 to VGA adapter, but that's an entirely different system!

Somewhere on that site, Lawrence has warned against trying to put X68000 output on a FM Towns, or vice versa, because of the voltage pin differences!

So it's no surprise that it blew up. Don't feel too bad, though; I'm sure this is just the last gasps of the battle between Sharp and Fujitsu fucking over their customers back in the day by providing plugs that seem to be the same but aren't. Probably lots of other monitors and video bits were killed off back in the day for exactly this reason.

You should head over to NFG Games and post a thread there about it.

If this really is 'regular' RGB then none of this applies, of course.

[papa_november]

It should not be possible to do this. The power supplied at the video port should not be enough to cause any real damage; at least in the X68000, the RGB lines are adequately protected. Your adapters are wired wrong; why did you use composite sync at all when VGA uses component sync?

I've plugged my X68000 into two LCD TVs so far. They didn't work (stupid non-standard sync), but caused no permanent damage.

If you have an X68000 that isn't a Compact or Pro, you can try to scavenge a replacement video DAC board from a dead machine on YAJ.

[uroko-sakanabito]

Sorry i have made a misstake, it is a PC9801 to VGA Converter, you can use it with a FM Towns without any problems, some yahoo sellers include this adapters with their high priced refurbished FM Towns Systems.

And yes, you can use a X68k or FM towns with a LCD, i had this too working for a few weeks and then, BAM without any reasons. There is no way to blame the adapters, the where build from people how know what they where doing. I cannot say why this happens, they only thin i can say is that 2 different LCDs blow up 2 differend systems without any reason.

AND they where working on these LCDs a day before without any problems !
@ ED we talk about the normal x68k & FMT RGB out (same connector db-15) ^_^
I cannot register @nfg, my email is not accepted

So it's no surprise that it blew up. Don't feel too bad, though; I'm sure this is just the last gasps of the battle between Sharp and Fujitsu fucking over their customers back in the day by providing plugs that seem to be the same but aren't. Probably lots of other monitors and video bits were killed off back in the day for exactly this reason

^_^
from my personal experience;
i had the x68k via adapter on my fmtux for around 3 months
i had the fmt ux on the x68k monitor for around 1 month
and i currently have the fmt2 pc on the x68k monitor
- never got any problem, the x68k monitor finds every frequenz (15/24/31) and makes a perfect picture with the fmt

I only had problems with ****ing lcd tvs

[Fudoh]

And yes, you can use a X68k or FM towns with a LCD, i had this too working for a few weeks and then, BAM without any reasons.

ever thought of the possibility that you have voltage fluctuations in your home ? Do you use a power conditioner ? Do you use 115 to 100V adapters behind your voltage converters ?

Germany's power system is running at more than 230V average. The converters you use are just 2:1 converters, which means your output is more than 115V all the time - which is already very high for 100V rated computers. Now, if you might have had voltage peaks over the past weeks, you're easily getting into voltage levels which you might fry 100V machines.

For my high end gear (e.g. my HLD-X9 LD Player) I use a "100V converter" like you (which actually outputs 115V) and a 115 to 100V converter behind them, to make sure they're not overpowered.

[ZOM]

Wise fwom youw gwave!!

Just got an Expert HD system in, that apparently suffered the same fate: was killed by hooking it to a "modern" LCD monitor via a 15pin 2 rows d-sub to vga adaptor...
Anyone have a hint on where I should start replacing stuff? I'm too lazy to change every single component on the video board.

[Ed Oscuro]

Blllarrrgh, more buying rare stuff just to destroy it. Again somebody ought to post about this (again, if it was before) over at NFG games...this is twice now...

[ZOM]

^^I registered and posted about this there right after writing my post in this thread. No response yet.

To the Expert's previous owner's defense: he got an adaptor cable with the PC9801/X68000/FM-Towns description and was convinced it would work. Can't be true - looking at the pinouts of the different Japanese PCs the X68000 one is different enough... The strange thing is that apparently those cables work on CRT's and some modern LCD TV's but get fried if you hook it on a LCD computer monitor.

I don't have a clue what gets fried and what causes it. That is, I'm actually pointing my finger on the two Sync lines sonce the picture runs diagonally through the screen but otherwise seems to be okay... An other strange thing is that 15kHz games (tested with Nightmare of Druaga) sync properly horizontally but not vertically.

All resistors on the separate video-board seem ok, now to replace the caps(oh man...)
I hope all other components on it are ok, since 1)I don't have a clue what some of them are, 2)I'm a noob at this.

What I'm pissed about the most is that this would be otherwise a *perfectly* working machine; I peeked around a bit and everything is new - new caps on the boards, new resistors(well, they look like new). I'm convinced this one was well refurbished in a nicely working condition.

A junk Expert or Ace with a working video-board would save my day - but the shipping costs...yeah.

[Daigohji]

Now is the 68000 port on fire!

[Ed Oscuro]

To the Expert's previous owner's defense: he got an adaptor cable with the PC9801/X68000/FM-Towns description and was convinced it would work. Can't be true - looking at the pinouts of the different Japanese PCs the X68000 one is different enough... The strange thing is that apparently those cables work on CRT's and some modern LCD TV's but get fried if you hook it on a LCD computer monitor.

I think the real problem is that NEC, Sharp, and Fujitsu all used the same type of connector, that's the main problem I see. So buyers can't be blamed for assuming compatibility, especially when they're people mostly familiar with JAMMA (interchangeable for the most part) and consoles (completely interchangeable).

A junk Expert or Ace with a working video-board would save my day - but the shipping costs...yeah.

Actually, I have a torn-apart Ace HD sitting here in various boxes. I, very stupidly, tore it apart to clean it out, and couldn't figure out / be arsed to put the proprietary PSU together again. You need it? It's not "junk" but the case has seen better days. I believe all the internal boards are fine though so if you can deal with the PSU it might be a complete replacement for your system! I don't need it because I have a new Expert sitting in a box and a Pro sitting in Japan waiting for me to get it shipped since '03.

[Endymion]

What kind of "VGA adapter" is this exactly? When I got my X68000 years ago it came with the weird cable, I just removed one end and made a VGA end of it and was done with it. I kept the end that I removed, so I could make a second cable with it using a VGA cable. But I never got around to it, it's kicking around here somewhere. Anyway, I've used the cable I made with several monitors, CRT, LCD, several HDTVs, CRT, LCD, and plasmas and never had an issue. Is this an adapter someone made or that was sold specifically for the X68000, or what?

[uroko-sakanabito]

Hey Zom have you replaced the video board allready?
You have to configure the switch.x settings before it will work right !
(not a big problem)

PS; Join the Facebook groups x68000 user club & fm towns user club if you want quick help or informations
- very active communitys rightnow

[ZOM]

Hey there, not yet - didn't have much time on my hands the past few months, so that machine is still sitting in a safe place waiting to be fixed.
(And I should really lift my buttocks and finally do something about it)
Also, holy moly totally forgot about this thread and totally missed Ed Oscuro's tempting offer, hopefully the ACE is still around...?

Anyways, thanks for the reminder - I'll keep you posted once I get back to it.

[Evilmaxwar]

Sorry to necro the thread but looks like someone might have found a way to repair this type of RGB output damage on the X68000.
The procedure he used is well explained on nfggames.com.
You guys might know about this already but i thought it would be a good thing to have the link in this thread.

http://nfggames.com/forum2/index.php?topic=4901.0

[Ed Oscuro]

Cool, glad to see something fixable in these. Hope it's not a common point of failure, though.

Also, holy moly totally forgot about this thread and totally missed Ed Oscuro's tempting offer, hopefully the ACE is still around...?

Yep, still 'round.

[channelmaniac]

The 74xx05 can only deal with so much current before it fries. The datasheets for the chips will show you what it can take.

Check the pins the signals are going to for grounding or for voltage feeding back into it.

Also, if you're on standard 110v in the USA check the outlets for proper wiring. If you have wiring that is reversed then you could be putting some NASTY voltages across a ground connection.

Home Depot sells a simple 3 prong outlet tester. Buy one and use it religiously.

[Evilmaxwar]

The 74xx05 can only deal with so much current before it fries. The datasheets for the chips will show you what it can take.

Check the pins the signals are going to for grounding or for voltage feeding back into it.

Also, if you're on standard 110v in the USA check the outlets for proper wiring. If you have wiring that is reversed then you could be putting some NASTY voltages across a ground connection.

Home Depot sells a simple 3 prong outlet tester. Buy one and use it religiously.

Even with the outlets and wiring done properly, I have also been wondering if this issue might not be related to the fact that X68k and FM-towns only have 2 prong plugs.
Maybe a ground voltage discrepancy between the two devices could result into said currents flowing through the wrong place.
Mind that im not an electrical expert in anyway but i sort of think there might be something there.

I just checked my "cheap" X68000-VGA adapter and the "shields" of the connectors are not even connected. This means that if there is a voltage difference between the chassis of the LCD and the Computer, there could be rogue current going through the chip.

There is actually a "ground" screw on both my FM towns and my X68k and im thinking that Simply connecting this to the Ground pin of your outlet or to the chassis of the LCD could be the proper safety measure against the kind of Failure described in this thread. I could also be totally off the track.
*Expert opinion would be appreciated here*