Another broken computer: Epson HX-20

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jonb
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Another broken computer: Epson HX-20

Post by jonb » Tue Nov 26, 2019 12:14 pm

Hi

Just got one of those HX-20s from a well known auction site, "untested". I've opened it up and I can see why, now. The NiCD battery has leaked and the display and cassette ribbon cables are eaten away. Question is, how viable is it to repair? Ideally I'd be looking for spares, but I could just wire them point to point using ordinary ribbon cable. There aren't that many wires.

They are flexi cables:


IMG_6317.jpg


One has 14 wires, the other 12 so should be doable.. but I'd rather replace the ribbons and keep the main board connectors. There is some corrosion evident on the display board but I think it's recoverable.

Any ideas?

Other thing is that no PSU came with it so I will have to make one up. Yes, I know it must run with the battery in place (I've got that far thanks to CMcDougall).

Thanks
JonB

RobC
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Re: Another broken computer: Epson HX-20

Post by RobC » Tue Nov 26, 2019 12:30 pm

If you can work out the pitch and orientation of the original cables, you may be able to source replacements.

I replaced the keyboard connectors in my A4 - they can be expensive but I searched for FFC on said well know auction site and eventually found some that did the job at a reasonable price.

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jonb
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Re: Another broken computer: Epson HX-20

Post by jonb » Tue Nov 26, 2019 2:00 pm

Standard pitch as it turns out.


IMG_6320.jpg


It's still dead. I need some technical docs for it. Maybe the battery is so depleted it is unable to hold any charge at all.

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jonb
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Re: Another broken computer: Epson HX-20

Post by jonb » Tue Nov 26, 2019 2:09 pm

Ohh hang on. I turned it on and got two beeps. Wiggling the display cable made the screen flicker. Nothing sensible displayed, just lines.

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Re: Another broken computer: Epson HX-20

Post by CMcDougall » Tue Nov 26, 2019 7:52 pm

as per PM, one of mine only had 3 wires rusted for LCD, so I just soldered them across with that thin white wire.

I don't have the batterys in either of mine, I threw them straight out the nearest window! :D

where the flying lead goes from battery to MB, I just went direct to the MB
with 1Amp 5V USB adaptors from mobby phones :D

see thread here : viewtopic.php?f=45&t=13893
ImageImageImage

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jonb
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Re: Another broken computer: Epson HX-20

Post by jonb » Fri Nov 29, 2019 1:49 pm

Well I've been sort of lucky. A guy in the Netherlands sent me a replacement display module and I am seeing stuff on the screen.


IMG_6325.jpg
Garbled menu

That is part of the menu. There are six options that come up, with every other line garbled. Each option when selected drops into the monitor, apart from the CRTL-@ initialisation option, which gives a prompt for the time and date. This can't be entered because some keys are not working, notably 0 and 1 (menu does ignore 1, actually , and here's why).

I've checked the keys in the monitor and it looks like some groups are not working, commensurate with rows / columns on a typical grid type keyboard array. So I am looking for loose connections on the keyboard now. Of course, fixing that won't sort the display out.

By the way, I tried connecting a 2A 5v PSU to the battery connector but it didn't work.

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Re: Another broken computer: Epson HX-20

Post by marcusjambler » Sat Nov 30, 2019 11:11 pm

I tried connecting a 2A 5v PSU to the battery connector but it didn't work.
Curious.. I normally power my HX20s with a beeb psu (5vdc) straight to the mobo battery connector no worries.
Are you connecting to the external connector or the motherboard?
Same as Col I think...

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jonb
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Re: Another broken computer: Epson HX-20

Post by jonb » Sat Dec 07, 2019 1:54 pm

Well, I think I will have to do something about the keyboard first, as it cannot get into BASIC without a working "2" key..

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Re: Another broken computer: Epson HX-20

Post by GeoffB17 » Sat Dec 07, 2019 7:48 pm

Jon,

I'm a bit mystified about some of what you say about the screen.

You say, or suggest, that you've been doing something in the Monitor. If this is working, i.e. giving you a useable screen, then the screen is OK?

The Menu is constructed within virtual screen and then displayed, like everything else (I understand). If the other menu options (2 onwards) are not set to anything, then they would show nothing. It's odd that your screen shows something, even if garbage. I doubt this would be progs in BASIC RAM (after this time), but maybe there is software in ROM? Does your device have special ROMs installed?

Geoff

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jonb
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Re: Another broken computer: Epson HX-20

Post by jonb » Sun Dec 08, 2019 9:59 am

I said all options drop into the monitor. Screen is still bad but there is enough shown to see it’s in the monitor. It doesn’t look like there’s any special ROMs, so the other options showing are hard to explain.

The screen hardware is faulty. This module was sent to me by someone and he said it has this problem, but it is better than the original module which doesn’t work at all, thanks to the battery leaking all over it and rotting the thing.

The module comprises of a number of LCD controllers which handle various parts of the screen. It should be possible to identify which controllers have failed and swap them out. This’ll be a bit risky as they’re surface mounted but it can be done with patience and a steady hand. Maybe.

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Re: Another broken computer: Epson HX-20

Post by tricky » Sun Dec 08, 2019 10:42 pm

Incase you don't know it, the Floppy Days podcast has been covering the HX-20 in the last few episodes and should be starting the beeb next.

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Re: Another broken computer: Epson HX-20

Post by jonb » Sat Dec 21, 2019 11:51 am

Now for an update.

I reassembled the thing having had no success with the replacement display - in fact, it is worse than when I pictured it. I am waiting for a spare keyboard from the same very generous fellow; then I might be able to initialise it.

I did try doing the CTRL-@ initialisation again after I'd got it back together and I think it is now going into BASIC. I saw the ghost of an EPSON message, then a Copyright on the screen (these are parts of the HX-20 BASIC sign on message) so I am pretty sure it is in BASIC. This is an achievement of sorts, but I am still in need of a display module as both of mine are not working properly (the original module is totally dead, the replacement one shows stuff but it is really garbled now, much worse than my posted picture earlier on in the thread). But I have a working MOSU (the main board) and I have no doubt the printer and tape unit are OK. If I can get the keyboard working (there are quite a few bad keys) I might be able to connect it to an external screen (via serial and a program running on the PC) - it requires a specific command to enable that I cannot enter with a dodgy keyboard.

Meanwhile I'm still seeking a working screen module...

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