Ribbon Cable for Internal ROM Socket

[t0nyt]

Well i tried the Viglen socket (with one of Chr$ ROM boards) on the working rebuilt QL mobo (no Microdrives attached) but it doesn’t quite work

It boots up and shows TK2 splash at top, then lets me select F1/F2 and then goes to the selected screen BUT then there’s no cursor and it doesn’t respond to any further key press (hung?)

I guess I need to check continuity of the ribbon cable but was wondering if anyone has any other thoughts on why it would get so far but then hang please? (I know nothing about electronics)

My only fallback currently is to take the cartridge assembly out of the equation and cut off the socket and solder the ribbon to a ZIF, but will be messy

Many thanks
Tony

[Derek_Stewart]

Hi,

There has been many attempts to produce a ROM, Expansion Port flexible cable.

Which failed, due the noise into the cable, the quality of the soldeed joints has a detriment effect on the data flow.

You might need an Oscilloscope to identiy the signals on the cable connections

[t0nyt]

Thanks Derek. Just been doing some testing (to prove continuity was ok from QL end to pin sockets in cartridge ROM port) and came to the conclusion the length of cable was probably the issue (nearly 60cm)

From what you say I think I can conclude there's no point continuing with this anyway

Many thanks
Tony

[Derek_Stewart]

Thanks Derek. Just been doing some testing (to prove continuity was ok from QL end to pin sockets in cartridge ROM port) and came to the conclusion the length of cable was probably the issue (nearly 60cm)

From what you say I think I can conclude there's no point continuing with this anyway

Many thanks
Tony

try reducing the length of the cable.

[t0nyt]

Thanks Derek. Just been doing some testing (to prove continuity was ok from QL end to pin sockets in cartridge ROM port) and came to the conclusion the length of cable was probably the issue (nearly 60cm)

From what you say I think I can conclude there's no point continuing with this anyway

Many thanks
Tony

try reducing the length of the cable.

Hi Derek,

I don’t have the parts to make it shorter other than cutting the ribbon and joining it together with IDC plugs. And I don’t really have the dexterity any more to solder a ZIF on as I was thinking.

Will come back to my QL when I’ve managed to source an alternative solution for switching ROMs (have setup alerts for eBay etc, so fingers crossed)

Thanks
Tony

[t0nyt]

Well I've made a bit of progress

Firstly I realised this particular Viglen cable assembly used the really old style floppy connector for the cartridge connector, so I was able to just cut off a length of ribbon cable and fit a new connector I had (so no joins needed)

However, I get the same result

So I re-fitted Chr$ ROM board directly in the QL and the same thing happens!

So am now wondering if when I tested the mobo, prior to starting all this, whether the same thing was happening and I just didn't notice. Otherwise it seems I've damaged something.

Could someone confirm the QL should work ok without any Microdrives fitted please? (tried to find one of my spares to fit, but don't know where I've put the damn things)

If it SHOULD work without a MDV fitted then I'll assume my original testing was flawed and try it in my spare QL I know is working fine

Many thanks

[Pr0f]

I've tested QL mainboards with no Microdrive's attached - and yes - they will boot. The ZX8302 and some form of IPC does need to be present and working

Dave.

[t0nyt]

I've tested QL mainboards with no Microdrive's attached - and yes - they will boot. The ZX8302 and some form of IPC does need to be present and working

Dave.

Thanks. I’ll put another set of ROMS in the mobo to see what happens before I risk the ROM harness in my spare QL then

If I have a faulty zx8302 or IPC could this be why it seems to start ok but then hangs please?

Thanks
Tony

[t0nyt]

Success!

I tried an original JM ROM set in the re-built mobo and again that hung. So I must of missed the fact it wasn't working properly when I put it back together in the first place

So I bit the bullet and fitted the cable assembly in my Spare QL (routed the cable thru the top of the ROM port slot for now, as running it out the expansion port trapped the wire between the keyboard plate and CPU as this one is fitted with one of Chr$ internal memory expansions, and I was worried about how hot the CPU could get) and it starts and works fine so far

I'll keep it in the spare I think and hope I can get a proper/better solution for the main QL

Many thanks

[t0nyt]

While testing to see if my mouse worked with QIMSI Gold on this QL I discovered that the ROM Port wasn't working (other than supplying power to QIMSI Gold). I thought maybe I'd damaged the ROM Port getting the ribbon cable header thru the gap

So I took the ribbon cable out of the equation and the ROM Port worked again!

I have 9 Viglen Cartridges, but 1 of them is quite different to the others (bottom one in image below) so I decided to use that with the QL as the pins all pinged thru ok from one end of the cable to the other

But it seems the differences in this cartridge knocks out the ROM port, but allows everything else to seemingly work normally because when I switched to using one of the other 8 cartridges the ROM Port is working ok!

The main difference that I can see is that along 3 sides there appear to some kind of resistor packs or something?

I was wondering if anyone has any theories as to what might be happening please? Am considering cutting off the "resistor packs" and seeing what happens as it's of no use to me otherwise. Any thoughts please?

Many thanks
Tony