DK'Tronics keyboard not functioning

[kevman3d]

...and my 3+ hours of cleaning fun. In case anybody is interested, here's a 101 review of the process to fix this problematic device...

http://kevman3d.blogspot.co.nz/2014/01/ ... or-my.html

Now I have what looks like RAM issues causing a little crashing, but lucky I seem to have spares (a set of new ones I bought initially, and the "spare parts" old Speccy that I couldn't get working (but stoles its ULA to repair this one)). I also need to see if I can repair the speaker issues... But all fun.

I also managed to get files loaded from my MP3 player finally. I added 1 second of silence to the end of the audio files - the MP3 player seemed to end the audio before the data had completed loading (ie. preparing to play the next track). Which was fun for those games that loaded and didn't crash the speccy...

[acsi]

Excellent thanks for this as I have both the ZX81 and ZX Spectrum versions of this case/keyboard. I'm pretty sure the H key doesn't work on the Spectrum one.

Now I can hopefully fix it.

Thanks

[kevman3d]

Cool. Glad that was actually useful for someone...

I had started a PDF "Speccy tips for noobs" that contained the large collection of links, notes, photo's of everything I've done to fix the speccy here. I'm tempted to just blog it instead... I think it'll be easier then laying out a document to do it in snippets online... (the document is still a WIP)

[kevman3d]

I wondered why the numeric keypad was operating badly - I thought I was smart enough to remember the correct position of the buttons. I ordered them from top 1,2,3... as you'd think. The original has them starting at the bottom (with the top row being 7,8,9).

Thankfully google has plenty of pictures to make it clear that I just didn't think straight!

[acsi]

One speccy key back in action. Thanks for the instructions.

Had to have a game of JetPac after getting the speccy running.

[tezza]

Great blog post Kev!

[kevman3d]

One speccy key back in action. Thanks for the instructions.

Awesome! Good to hear - I guess there's really nothing much that can be broken when its basically a bunch of buttons on a simple PCB - other then the contacts wearing or becoming a little dirty.

Had to have a game of JetPac after getting the speccy running.

lol! Great minds think alike - I just played a little Jetpac, as well as the less-then-exciting Galactic Abductors - but since it was the first game I got (bought it along with Frenzy when we bought the spectrum) - well, a flash back to the day I got home with Speccy in box... That, and Frenzy (Bezerk clone by Quiksilva - played that yesterday, but it locked up).

I tried to load Manic Miner, but seems to be a problem with the upper ram as it just loaded and then didn't do diddly-squat. I also tried ZUB (a pretty cool game) and it loaded (48k game as well). But then crashed when I pressed the "start game" key. I've tested 3 sets of RAM and get pretty much different results - and have started to get just 16k show and not the rest after swapping around a little. I suspect it may not be the RAM itself, but one of the control IC's. I'm leaving that to another day (back to work tomorrow... Sigh! )

Great blog post Kev!

Thanks... I'll try and post up the rest of the stuff I've done last year over the next month or two... I've learnt a lot, and knowledge is wasted if its not shared. And once I suss the RAM issue, I'll plonk up more... I also have to swap out the speaker - that said, not having to listen to the screeching tape is not always a bad thing - specially since there's no way to switch the speaker off anyway (maybe that's something I think about when I wire in a new one - hmmmm)

[tezza]

... I've learnt a lot, and knowledge is wasted if its not shared. And once I suss the RAM issue, I'll plonk up more...

Yes, that's been my philosophy too. It's good to share these experiences.

Just on the RAM. I know nothing about Spectrum RAM but could it be a RAM speed issue? I know DRAMS can be of different speeds and if RAM replacement is with older chips that are too slow, problems can occur.

[kevman3d]

I know nothing about Spectrum RAM but could it be a RAM speed issue? I know DRAMS can be of different speeds and if RAM replacement is with older chips that are too slow, problems can occur.

lol! Luckily its just one type of ram, and one speed (and all from the same model machines)... I suspect its a control chip - or a broken track - or perhaps this machine's destined to be a 16k model. Oh, so many possibilities...
Alastair (Zigg.net) has been kind enough to supply technical suggestions for checking. If I can't work my way around this, I'll shoot him an email and ask if he has any thoughts on this.

Besides - if I'm desperate - I do know one of the speccies I got from Don is working just fine. But I'd just like to see this one machine running nicely - specially since I've invested so much stress into it already. Bwahahaha.

[kevman3d]

FYI : A set of clear keyboard labels for the Dktronics Speccy keyboard can be downloaded here.

http://kevman3d.blogspot.co.nz/2014/01/tech-re-labeling-worn-out-dktronics.html

I had quite a few worn-off labels. I couldn't find a "replacement label" product so I just made them myself. It took a while (so many damned keywords to type in a check). I was surprised how good they looked - I have a few piccies and the downloadable PDF for them on that blog post above. Hopefully they will come in handy.

[RonTurner]

Thanks for sharing this, that's exactly what I needed to fix my full travel spectrum keyboard

[kevman3d]

Thanks for sharing this, that's exactly what I needed to fix my full travel spectrum keyboard

No probs, and glad its coming in useful! If you printed it on glossy white, it could be used on anything really... I'll go and colorize the labels later and upload it as well so that people can get something with the green and red (and a light grey) as well. I noted the first release of the dk'tronic came with colour stickers anyway...

I'll also add the "colour" labels to the doco (for the front of the number keys) - I need to create those last few details to complete it properly... They stick on the front of the keys, which is lucky cause there's no way I could jam those into that key space.

[kevman3d]

I've updated the labels - I added the "colour" labels for front of the number keys. However, I've also created a coloured version, as well as a coloured version with grey background. If anybodies keen...

http://kevman3d.blogspot.co.nz/2014/01/tech-dktronics-keyboard-labels-part-2.html

[kevman3d]

lol! Well, while digging through old boxes to find materials to scan/rip for the NZFA archive, I found the small set-up manual for the keyboard stuck between a pile of old bank statements (why I have been hoarding 15+ year old back statements, I really don't know). Here's a piccy for anybody bored enough to be interested:

https://drive.google.com/file/d/0B-yNJZpBnrutQXpqaW5udkJiNmM/edit?usp=sharing

Funny how many other "lost" relics I find - a pile of old hardware, and more magazines, books and cassettes - and an invoice for my first Pentium (PII-300, 96Mb Ram, 4Gb HDD, FireGL 8Mb AGP, 15" display - TL systems - $4350 (inc. Hire Purchase fees and interest)). Forgot just how pricey things were back then...

Nice thing is that every time I go and dig around, I end up being able to repack things and get rid of at least another 1-2 boxes that were laying about.