Hi all

I dug out my old MSX the other day after about 12 years and after hooking it up I found that I couldn't get it to work. When I switch it on all that comes up is a black screen (no msx logo or letters or anything). The caps lock light doesn't come on either if you press the button, not sure if that is significant. It is a Toshiba Home Computer HX-10 64k. Does anybody have any ideas about what might be wrong and how to fix it?

Thanks!

Sounds like you've got no power.

No, the power light comes on and it turns the tv screen black when I switch it on so it has power.

If the power-led burns then it is not the power supply

mostly in a Toshiba is a chip broken. The LVA-510, a Pal-encoder.

Oh dear, that doesn't sound good. Can anything be done with it?

After so long inactivity periods, drained or leaking capacitors are a common cause of malfunctions. I don't have the experience of Repair-Bas; but, just out of curiosity, can a chip be broken after 12 years of no use?, maybe constant and extreme temperature changes can do that?. The only obvious reason I can think of is corrosion in humid environments...
Anyway, you can try an easy maintenance procedure. Open it and try to resettle all the IC that are mounted on sockets (probably none in the Toshiba ), it's one of the effects of temperature changes. If there're no sockets, try to examine carefully the components looking for corroded pins in the ICs and "strange" capacitors (leaking, crystallizing, fat ones).

maybe you have the vdp broken? the vdp supply also the clock to cpu so the fact that the caps lock does not react to keypresses may mean that the z80 does not get it's clock from vdp.

just, opens the case, and press the z80 cpu in its socket or any chip in its socket....

after 12 years the contacts are oxidated just needs some clean, if it has a battey, maybe it drops its content.

It's good advice if there are any IC's in sockets (often none, sometimes VDP in MSX is socketed), to try pull them out, and re-place them in their sockets.

But before you do: can you verify that ALL power supply voltages are present (and within normal range)? Maybe power led runs off 12V, but 5V is missing - or vice versa. A voltmeter is enough to check this. Had a Sony F700 recently with similar problem: screen black, but diskdrive & leds behaviour seemed normal. +5, +12, -12V and clock signals were all present. But then I found there was another 9V regulator (7809 type) that fed only a few components on the video board. Replaced it, and everything was fine again.

Power led on, black screen & caps lock not responding? That usually means a Z80 not doing what it normally does. Could be dead Z80 (I've personally NEVER EVER seen that), bad/no clock signal, or ROM (rarely) / RAM (more often) problems.

If all supply voltages are okay, no fuses are blown and no funny looking / badly smelling capacitor in sight, you need someone who knows his way around the inside of such machines. If someone like that lives near you, you could give 'em a call. But at that point, I'd consider forgetting it, and look for replacement machine. Toshiba HX-10 is quite common, and dirt cheap if you can find one 2nd hand. For same money you can find other MSX1 machines easily, and perhaps MSX2 for a bit more money.

If this were a nice MSX2, or even 2+/TurboR, OK. But why invest a lot of time fixing your MSX1, when someone else a few blocks away dumps a working one in the trash, because it was offered for sale but no-one cared to get it? Pick your battles...

Quote:

just out of curiosity, can a chip be broken after 12 years of no use?, maybe constant and extreme temperature changes can do that?. The only obvious reason I can think of is corrosion in humid environments...

It's possible. All components age differently, but IC's are not usually components that die simply of 'old age'. Dead IC's are often the result 'catastrophic' events, where the user did something, and immediately knows something bad has happened: mechanical damage, coffee spill, static discharge, cartridge plugged in powered-on machine, things like that.

With aging, mostly you're looking at mechanical problems of *some* kind: corroded contacts in IC sockets, connectors that go bad, PCB traces that break because of repeated flexing of a circuit board (eg. when cartridges are inserted / unplugged). Capacitors that dry up / leak (=less capacity) or short circuit are common, and sometimes memory chips or CPUs go bad. But not because IC's die from old age, but because there are so *many* components that form a working machine. Only 1 of those has to die (from whatever reason), for the machine to stop working.

replace the LVA-510

Problem solved.
I hope, but mostly that is the problem.
I do not have the possiblities to look througt Internet in your computer

Does it give sound if you insert a game cart?

My MSX machine has a RAM disable switch on the back ( previous owner mod ) and I can tell you that a black screen could also mean it can't find enough RAM to boot.

Does anyone have datasheet for LVA510? I can not find it anywhere...