Winner Announcement: Ben Heck's Portable ZX Spectrum!

Just watched the winner announcement video (finally) - as expected Ben mis-pronounced my surname [don't worry, it happens all the time - you wouldn't believe the spellings I get on my mail...]

https://www.youtube.com/watch?v=C4KD6zGztAE

(It's pronounced "somme-ee-aah-diss" - hence Paul Psomiadis]

Anyways...back to the porta-speccy and other things...

Porta-Speccy

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@Workshopshed - if you do add a resistor, be sure it's to the speaker itself, as adding it to the audio circuit will likely cause loading failures (the input needs to be at MAX for loading to work correctly).

Original Speccy

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Alas, my Interface 1 was on it's way out and has now been replaced - might muck around with the old unit and try to do a full rebuild instead of tossing it in the bin...might be able to resurrect it.

Harlequin 48k clone

================

Managed to finish the build, but I'm having A.V. Out issues...more on this later once I can take some pictures...

So, I finally got to see a game load on the Zx Portable this evening

Like paulpsomiadis I had issue with the audio cable, so I eventually got around to buying one with a low profile jack.

I used a bit of software called "Tapir 1.0" to play back a TZX file of ManicMiner (the Hello World of Spectrum Testing) at full volume through the headphone socket.

It loaded successfully and I made a guess what the keys were. The audio is very loud so I might add some tape and/or see if I can add a resistor to the audio circuit.

The gamed played as well as I can remember. I am absolutely terrible at this game so I only managed to get as far as the middle of the first screen before the boot came down. Unfortunately my battery was also exhausted by this point too so it shut down immediately afterwards. I'll give it another charge tomorrow to demonstrate to the family.

Hi Folks and sorry for the LOOOOOONG wait for these pictures...things have been VERY busy in ZX Spectrum land of late (more on this soon).

First off I'd like to say a HUGE thankyou to Ben, Karen, Felix and all the crew for picking me as a winner and presenting me with the gift of the porta-Speccy.

It's a huge honour and the first thing I've won since I was 4 years old.

(the last thing I won was a zoid toy called "zoidzilla" - any of you folks remember those?)

Anyhow, on to the pictures...

UNBOXING

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The box that it came in...

Opened...hmm strange black fabric???

AHA! Its a Benheck Show T-Shirt :-)

A porta-Speccy boxed...

...and unboxed

IMPROVEMENTS

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So after the initial testing I came across a problem...my audio cable was not plugging in properly...

As you folks can see here, there was a rim around the stereo jack

(or double mono jack to be precise)

After some quick dremelling, I made it so that it was flush with the case - so I can use any audio lead and they all fit now.

I also added a screened composite cable

(cheers for adding that convenient ground pad Ben)

BUSY IN SPECCY LAND

====================

So me and my Uncle decided to take out the old Speccy and give it a test along with the Interface 1 and Microdrive unit & micro casettes.

(I know Sinclair called them cartriges, but that suggests ROM to me, as in Genesis/Megadrive)

Alas, although it worked fine for a while, all of a sudden nothing...zip...bupkis.

Things were not happy in Speccy land.

IN A FIX

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So turns out that the Interface 1 was in pretty bad shape and entirely LESS resilient than the speccy itself...thus the ULA on the IF1 had shorted out and damaged the speccy as well.

Time for TLC and repairs...

Fixing the Speccy was relatively easy.

Here's a pic of the same board we own for reference

(not mine, just similar)

And Here you can see my speccy with the repairs

A close up reveals the replaced D9 (from my local Maplin store)

And as the equivalent for TR4 I used a E3055T with wires to swap the legs

{also if you look closely, it looks like TR4 was replaced before, as there are remnants of legs next to the pads I used}

After which I composite modded and re-capped the unit

I've also heatsinked the ULA, here's a closeup before it was covered

SIDE TRACKED

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On a pleasant side note I'm doing some other stuff

Like building a Harlequin 48k

(ZX Spectrum clone that re-creates the ULA with standard parts)

And a new addition to my collection - a ZX Spectrum ROM game

(yeah, these are RARE - I just happened to be on eBay at the right time)

THE NIGHTMARE OF THE INTERFACE 1

=================================

CRACKING UP

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The case was REALLY trashed - we got this unit on the cheap back in the day, and it shows...the original owner hasn't taken care of it at all.

Much superglue and epoxy was used to repair the case.

I also had to glue the edge connector as it was cracked as well...

(you can also see the original mod transistor and the old [busted] ULA here)

Then I had to order a new ULA (fortunately being sold on eBay) and wait...

...it arrived the next day! WHOA!

First off, here's a reference pic of the internals...

And after I removed the damaged ULA, added a socket and moved the mod transistor.

Here's the socketed ULA in place.

And the innards of the microdrive

Then both units after re-capping

Of course, anyone who may have used microdrives knows that you have to remove the run-down foam pads on the micro casettes and replace them with felt pads.

So off I went to do this with all 12 micro casette cartriges.

End result was that we saved 9, but lost 3 in the process.

Of the 9 remaining 1 was pretty useless, as it rarely read properly. (should be O.K. if we format and re-use) 5 were faulty with either partial or full program loads and 3 of them STILL worked PERFECTLY (after 30 years!!!).

You can see how to re-pad the tapes HERE:

https://www.youtube.com/watch?v=6j3tsCT-Ivk

Here is a shot of the program we use to create a selection menu for our M.D. tapes

(basically a menu to load multiface 1 snaps)

This is where the real issues began - the IF1 would work fine for minutes or hours, then all of a sudden the screen would glitch and bug out with lines and blocks.

We would adjust the IF1 and microdrive cable and things would be fine for a while, thren glitchy again.

Worst of all is that this was RANDOM - sometimes it worked for minutes, other times for hours...

TAKE ME TO YOUR LEAD-ER

========================

To eliminate the issue I built my own microdrive connection cable using an old 5.25" floppy connector cut in half, some IDE cable and 2 bits of credit card.

Worked out quite well and also transferred data nicely.

But then the glitches returned - so it wasn't the lead.

Also clearly NOT the microdrive unit, as it read and wrote discs fine.

(even if the R/E/W head needs occasional cleaning)

THIS JOINT AINT BIG ENOUGH

==========================

So I figured old PCB...old solder..maybe dry joints?

I then proceeded to re-tin all the joints on the PCB...

Again we though we were good...nope glitched again a few minutes/hours into use.

WE HAVE THE TECHNOLOGY, WE CAN REBUILD IT!

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So I'm a bit at a loss...

The service manual may be helpful, but trying to test the unit when it sits under the speccy is a royal pain in the you-know-what.

https://wos.meulie.net/pub/sinclair/technical-docs/ZXMicrodriveInterface1AndInterface2_ServiceManual.pdf

FYI - I have already checked continuity on all the board traces and looked at the board on a light box for trace breaks...everything checks out OK.

I've also re-sprung the edge connector plug so it grips the expansion port on the speccy properly.

Also note that the speccy isn't the issue, as other expansion peripherals work just fine - which means maybe another component somewhere is dying after the original ULA got fried.

So I'm researching into doing a full rebuild of the IF1, starting by checking each of the components for faults by de-soldering them - then putting brand new bits in to replace them.

I already have the data sheets for all the original parts, just need to find equivalents or the identical modern parts...

If you guys have any ideas gimme a shout and I'll try those beforehand.

Will post here when I can :-)

THE FUTURE

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Future plans include

1) Re-capping the porta-Speccy (those black caps are cheapy Chinese ones - yuck!)

2) Finishing the Harlequin 48K

3) RGB video for the original speccy - YUV to RGB schematic HERE:

http://piters.tripod.com/zx.htm

4) [maybe] and SMD version for the porta speccy to get RGB!

(depends on the success of 2)

5) 128K or more RAM upgrade for the Harlequin and original Speccy

(obviously requires a ROM change too)

6) Internal AY sound chip and stereo speaker sound upgrade for the Harlequin and original speccy

<can't remember where I saw these right now...>

7) Sampling my tapes collection

Runs out of ideas - sad bunny face :-(

LOLZ ;-)

Guilty as charged!

and I thought I was so clever . . . . . 

Hands up if you went into WHSmiths and typed this, or a ruder equivalent

During my chilhood in malaysia, my passawayed father is a soldier and also thinker, but he not allowed everybody in my house to have stuff that includes games, toys if that thing not from him... and i kind of suck in academic esp math, i love sci-fi, computer, but cannot afford that kind of stuff with my parents premission..my first day with so called computer is when my age 20 and now i'm turn 37, i now collected stuff like floppy disk A, B, old computer, old laptop, i own raspberry pi 2 with ubuntu mate 16.04 on it, so if i can get stuff like atari exp, dead or alive, please give to me... my stuff i get it mostly from grabage, and i love it

I never had much chance to use a ZX Spectrum, but I'd really love to experience it at some point. The first machine I really remember gaming on was an Atari 800.

Looking forward to some pictures from you Workshopshed

Thanks to element14Dave the ZxSpectrum portable arrived safely today. Hopefully some details of it in action later this evening.

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