Toshiba HX-10: no SCC, keyboard refurbishing

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By Wild_Penguin

Hero (641)

Wild_Penguin's picture

01-10-2015, 19:51

Hi dear fellow MSXers,

I've aquired a Toshiba HX-10 some time ago. It has a few problems:

1) There's no SCC in SCC games, at all (I tried several and I have other MSX's to try on so I know my SCC carts do work). Is my HX-10 broken, or does the HX-10 has the dreadful PSG+SCC (or any other in-cart sound source) mixing issue? Is this a common issue?

2) Some keys work very badly. (namely, spacebar, up cursor key, insert). But typing (letter keys) works well. Probably some oxidization and / or worn membranes. Has anyone furbished the keyboard of an HX-10? Any recommendations?

Also, the cart slot is very loose (I believe it has had some heavy usage previously), in that you just can't touch a cart, otherwise the MSX will reset. Sometimes it won't recognize a cart (it doesn't boot). The carts feel very loose, when you take them away, more loose than in any MSX I've ever tried. So I believe the slot is mechanically worn, and there's nothing else to be done besides replacing the connector, which will require some soldering.... this could also explain the missing SCC, in case the Sound IN pin has failed altogether in the connector.

Cheers!

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By ericb59

Paragon (1046)

ericb59's picture

02-10-2015, 07:04

i think your cartridge slot may have big problems !

By Wild_Penguin

Hero (641)

Wild_Penguin's picture

02-10-2015, 10:39

Ericb: I believe you are correct. I opened up the HX-10 and looket at the solderings, since the symptoms (wiggling the cart, or probably just sneezing at it causing reset) might be caused by cold or otherwise bad soldering. To my naked eye, it seems they are OK (but I need to find a magnifying glass to be sure).

Aso, I checked from the specs and SNDIN is in pin49, which is at the end of the connector. So, I believe if a pin in the connector will fail mechanically, the ones at the edge are the first ones to go (since they have less support)? So the missing SCC (I also tried FM-PAC) could be just caused by the connector. I will probably not be replacing this, because considering the gain (I have an MSX2 and several working MSX1s) it is too much work, also I'm not 100% about my soldering skills and I'm not sure I won't damage the MB in the process.

But if I were to replace it, does anyone know a good source of 50pin edge connectors? Locally I can only find ones that are missing the screw support holes at the ends (which might make the force of repeatedly inserting and removing carts break the solderings). I've found pictures of connectors with the screw support holes, so I know they exist....

As for the keyboard, I've found another thread about the HX-10 keyboard, and it seems it has mechanical switches that can be dismantled and cleaned... I'll take better look when I have the time (starting with the keys that have totally failed).

By Pac

Guardian (6406)

Pac's picture

02-10-2015, 18:07

I had the chance to repair a keyboard of this model. Some keys failed and the solder pads were broken, after resolder them everything ok.

By gdx

Enlighted (4695)

gdx's picture

03-10-2015, 01:59

1/ Check the contacts and soldering of cartridge connector, and also capacitors (follow the track from pin 49).

2/ It's easy to repair the keyboard keys of the HX-10 (for someone who knows how to solder).

http://www.msxvillage.fr/forum/topic.php?id=2418&pt=1#m56239

By Vampier

Prophet (2385)

Vampier's picture

03-10-2015, 08:23

I believe only the goldstar MSX-es suffered from a disabled SCC

By Wild_Penguin

Hero (641)

Wild_Penguin's picture

28-10-2015, 22:24

I got the non-working keys to work after dismantling them and cleaning - now at least the keyboard works. I actually needed to desolder one key just to learn how to open the mechanism, but after doing that I could dismantle the rest in-place (I might put up pictures later in case someone is in the same situation, to facilitate opening up the keys).

The issues with the cart slot still remain (I tried contact spray + toothbrush = no effect). But, I also suspect some of the electrolyte condensators capasitors may have dried out. I will see to it when I have the time / interest, and update here Smile

Sadly, I also noticed that the "UP" doesn't work on joyport1 (didn't try port 2 jet). Hopefully that doesn't mean a faulty PSG...

By l_oliveira

Hero (531)

l_oliveira's picture

29-10-2015, 14:53

If your MSX is the model with discrete chips, the PSG is not connected directly to the joysticks. The hardware uses one of the PSG ports as misc I/O so only one port is used for both joystick inputs. It has a pair of 74LS157 multiplexer chips to allow for two ports become one. If only one of the joy ports are affected, it will be one of these multiplexers.

By dhamiltongrey

Supporter (1)

dhamiltongrey's picture

06-04-2016, 13:15

Wild_Penguin wrote:

I got the non-working keys to work after dismantling them and cleaning - now at least the keyboard works. I actually needed to desolder one key just to learn how to open the mechanism, but after doing that I could dismantle the rest in-place (I might put up pictures later in case someone is in the same situation, to facilitate opening up the keys).

The issues with the cart slot still remain (I tried contact spray + toothbrush = no effect). But, I also suspect some of the electrolyte condensators capasitors may have dried out. I will see to it when I have the time / interest, and update here Smile

Sadly, I also noticed that the "UP" doesn't work on joyport1 (didn't try port 2 jet). Hopefully that doesn't mean a faulty PSG...

Hi,

I have 2 toshiba hx-10 keyboards and im desperate to fix the non working keys.. you mentioned you could provide pictures to show how to open the keys without removing them, could you please do this for me, id greatly appreciate it. if you could provide a description of the process and any tools needed that would be awesome.

kind regards
Davey

By Wild_Penguin

Hero (641)

Wild_Penguin's picture

06-04-2016, 17:42

I seem to have forgotten to share my HX-10 keyboard pictures here!

The album linked above wrote:

Some pictures to help dismantling the keyboard of this MSX model
These are from a HX-10SF, and probably apply to most european versions. Japanese versions may have a somewhat different mechanism!

A needle or similar is needed for the following procedure (just force it under the "flap"):

2nd picture in the album wrote:

The large "flaps" on the part on the right need to be bended just slightly away from the center to release and lift the part off.

Also, as a sidenote: the second joyport works. So, I at least know to look for a LS157 when I have the time / interest to look into this further... so thanks, l_oliveira!

By Wild_Penguin

Hero (641)

Wild_Penguin's picture

10-07-2016, 17:14

A small update about joyport: if you are in the same boat, check the pins! Pin1 was broken / missing from the connector Smile

I've done a bit more testing with MegaFlashRomSCC+ and a MFRSCC+SD. Although most game carts work, the MegaFlashRomSCC+ does not. Also, MegaFlashRomSCC+SD is not detected at all (I went into the trouble of loading msxmem.bas via the cassette interface -> the slot should get expanded but does not on this particular HX-10)

What I've done so far: I resoldered all pins on the slot connector (alhough they looked fine) -> that had (unsurprisingly) no effect. Also, I swapped all electrolytic capacitors (condensators), since that was recommended somewhere because of sound problems -> no effect on the missing SCC(or FM) sound.

I'll be swapping the whole connector (And the DB9 for joyport 1), but since I get no sound from the SND_IN even if I wiggle the cart while it is plugged in (if that does not cause the MSX to reset), I suspect something else is also broken (since I should get intermittent contact from pin49, if only the slot contacts was the cause, and that should cause at least crackling, which is not the case). But if swapping the slot connector does not help, I believe my electronic skills are at their limit...

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