Toshiba HX-10 Recovery

By bagpuss22

Supporter (6)

bagpuss22's picture

05-04-2018, 03:35

Hi all,

I am trying to get a Toshiba HX-10 back from the dead.

The symptoms are the 'common' black screen but there is no response from the keyboard, CAP SHIFT etc.

I have found that the Z80, ROM and a single IC from the upper 32K had failed and these have been replaced.

I have tested the video board (LVA510), TMS9929, new ROM, new Z80 and all upper (32k) and lower (video 16k) memory and all are serviceable.

Voltages seem good, as seen on the lower 16k.

Yet I still have the same symptoms. Question

Any suggestions appreciated.

BP

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By PAC

Guardian (5236)

PAC's picture

06-04-2018, 18:32

By Wlcracks

Champion (321)

Wlcracks's picture

07-04-2018, 15:12

Is the cart slot shorted? Is the reset line high. Does the interrupt toggle? I thought the HX-10 had an custom vdp from Toshiba?

By bagpuss22

Supporter (6)

bagpuss22's picture

08-04-2018, 20:31

Hi there,

I have checked the forum message you sent but that is a bout a system that is showing some
signs of life.

I will check the cart slot and reset line and see what I can find. The HX-10 uses a TMS 9929 which
works OK in another HX-10.

By Colemu

Hero (531)

Colemu's picture

10-04-2018, 18:58

It's the heat that kills HX-10's, they're like ovens! Eek!

I don't use mine now for this reason.

It's a shame as they are solid machines, built like tanks!

My machine used to exhibited these symptoms and it was a dead Z80..

By jltursan

Prophet (2162)

jltursan's picture

10-04-2018, 19:53

They also suffer of cold solder joints, probably due the big temperature differences when overheating.

By valkyre

Champion (416)

valkyre's picture

10-04-2018, 20:59

My toshiba hx-10 is still going strong, 33 years on!

By bagpuss22

Supporter (6)

bagpuss22's picture

13-04-2018, 13:02

I have another which has video glitches but a new LVA510 sorted that out.

really would like to find a circuit diagram for the HX-10 so I can try and see why
the other one will not run correctly.

Smile

By rderooy

Hero (578)

rderooy's picture

13-04-2018, 13:25

Surprisingly for a computer that was relatively common, nobody ever even scanned the manuals. Some manuals of the era actually contained the circuit diagram, but probably not in this case.