Topic: Speccy problems  (Read 2730 times)

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Offline DBloke

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Speccy problems
« on: June 18, 2011, 11:14:23 PM »
I was doing a audit/testing of all the systems at The Lass and found that the ZX Spectrum's that we have have "Problems" they show garbled garbage on the screen.
I say "They" as there are two of them. Any one know any fix for them? We kinda need them working for In Da 80s
There is also a Speccy +2  128k (tape) that wont read tapes. It trys to load them, but don't go anywhere.
Again is it a easy fix?

Or know anywhere that I can get them fixed *Hint hint*
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Offline questor

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Re: Speccy problems
« Reply #1 on: June 19, 2011, 09:21:29 AM »
I can't help you with the garbled screens - that could be a number of things - none of which are simple to detect or fix and if its the ULA thats gone then good luck.

The +2 could simply be drive belts - the tape drives on the original +2 (the light grey one) were belt driven and need to be replaced - is the tape actually moving and does it look like a smooth motion and at the right sort of speed?

I'm sure other friendly people on here will offer further suggestions.

I'm sure the team at Replay Events Ltd who are supporting this event will be able to source some replacement machines and parts.

RCM has plenty of spectrums in stock but as far as I know has not been asked to be involved in supporting this event.


Offline Womble

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Re: Speccy problems
« Reply #2 on: June 19, 2011, 11:46:16 AM »
I was doing a audit/testing of all the systems at The Lass and found that the ZX Spectrum's that we have have "Problems" they show garbled garbage on the screen.
I say "They" as there are two of them. Any one know any fix for them? We kinda need them working for In Da 80s
There is also a Speccy +2  128k (tape) that wont read tapes. It trys to load them, but don't go anywhere.
Again is it a easy fix?

Or know anywhere that I can get them fixed *Hint hint*

Could be a range of things, including the dreaded bad ULA, but bad RAM in the lower 16K is the most likely which comprised of eight 4116 chips. This can be caused by a few things but as the chips require 3 separate power supplies, 5V, -5V and 12V and these have to come on all at the same time and go off in the right order or simultaneously of the chips are killed. The most common cause is either a failure in the power regulators which cause one of the power rails to drop off which kills the RAM. This is why unplugging or plugging in things on the back edge connector often killed a speccy, it shorted out or pulled one of the power lines low momentarily which caused the 4116 RAMs to die.

Might be all the 4116s, might just be one but as they each contribute 1 bit to the byte the loss of a single one will take the system down.

Not a particularly easy fix I am afraid.
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Offline DBloke

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Re: Speccy problems
« Reply #3 on: June 19, 2011, 12:30:57 PM »
Pictures of the problems
http://img17.imageshack.us/img17/5651/photo0620t.jpg
http://img39.imageshack.us/img39/4772/photo0622u.jpg

I can see if I can get one of them down to you. (and sort you out for any repairs done)

If bugger all can be done.....
They will become part of the decore.
(To bad I cant wire them up as a PC keyboard)

The +2 could simply be drive belts - the tape drives on the original +2 (the light grey one) were belt driven and need to be replaced - is the tape actually moving and does it look like a smooth motion and at the right sort of speed?
Yes it looks like they are moving at the right speed
Quote
I'm sure the team at Replay Events Ltd who are supporting this event will be able to source some replacement machines and parts.
Quote
RCM has plenty of spectrums in stock but as far as I know has not been asked to be involved in supporting this event.
You guys are welcome to come along to this or Computer Club (next one is on the 28th)
Been speaking with Andy over on the email thing. No response
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Offline AndyRCM

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Re: Speccy problems
« Reply #4 on: June 19, 2011, 12:45:41 PM »
Erm, sorry to butt in here a bit I did respond very early on . . . but got no response back from anybody - so I assumed that our stuff was not needed . . . I can't make it now for personal reasons (I am away that weekend).
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Offline DBloke

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Re: Speccy problems
« Reply #5 on: June 19, 2011, 03:47:01 PM »
Ill see whos bringing what.

I think we might be sorted for them (But its nice to have the systems at the pub all the time)

Looked into the possible PC keyboarding of them and came across a turn into a PC mod (running Speecy emu to complete the set), but I shouldn't get my hopes up on trying this as
A - there not mine and B - I am not that technical
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Offline Spirantho

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Re: Speccy problems
« Reply #6 on: June 24, 2011, 10:26:21 PM »
I realise it's probably a bit late now but I do Spectrum repairs as part of my business. :) (www.mutant-caterpillar.co.uk/shop/ and eBay mutant-caterpillar).

Happy to give free advice, though, too, if it helps.
Ian Gledhill
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Mutant Caterpillar Games - vintage computers and games in our shop!
http://www.mutant-caterpillar.co.uk/shop/

Offline DBloke

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Re: Speccy problems
« Reply #7 on: July 03, 2011, 04:01:54 PM »
There not remade yet.

how much do you charge (as said screen is garbled)
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Offline Spirantho

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Re: Speccy problems
« Reply #8 on: July 03, 2011, 05:11:42 PM »
Hi,
I charge £30+parts for a Spectrum, but I'll do both for 45 including postage back to you.
I charge £10 per difficult part, and I think one of your Spectrums has a bad Z80, so it may go to 55 if so. Looks like both ULAs are good though- the other one probably just has a bad lower RAM chip or two.
I can sort your +2 for another 15 too.

If you like I can convert 48Ks to composite video too, gratis.

Let me know if I can help!
Ian Gledhill
ian@mutantcaterpillar.co.uk but with a hyphen between "mutant" and "caterpillar"
Mutant Caterpillar Games - vintage computers and games in our shop!
http://www.mutant-caterpillar.co.uk/shop/

Offline DBloke

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Re: Speccy problems
« Reply #9 on: July 05, 2011, 10:37:39 AM »
Do you do free quotes?
(Ok maybe not free as id pay postage unless your anywhere near Manchester)
Lets say if I send one to you you will figure out the problem tell me the price and if I want it done I say yes if not I just get it back and I get saving for that conversion (To a PC)
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Offline Spirantho

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Re: Speccy problems
« Reply #10 on: July 05, 2011, 07:07:23 PM »
It can get a bit complicated. :) Basically:

Simple answer:

I can't easily do free quotes, but that said if you account for a £30 charge you'll always get at least a diagnosed Spectrum with IC sockets ready for your own parts.

More detailed answer:

What I do is essentially this:
If I have to work on it, then it'll cost £30 (including postage and VAT). If I don't, then it costs postage back to you.

It can get a little complicated because the nature of Spectrums is that 99% of the time you don't know what's wrong till it's fixed - so I can't do a quote as such.
If I can't repair a Spectrum (never found one like that yet - touch wood! :) ) then I would just charge postage as well, but that very rarely happens as I have all the bits I need. :)

Essentially even if you don't get a repaired Spectrum because you don't want to pay for the parts, then for your money you'll still get a Spectrum that you can fix yourself. In other words, your Spectrum will return to you with sockets ready for you to put your own parts in. If it's just a dead ULA, then for the £30 I'd stick a new ULA in and not charge you, as ULAs are socketed already.

In other words:
£30 buys you a Spectrum that's either fully working or fully diagnosed with sockets ready for parts.
Each expensive part (Z80, ULA, ROM) will cost £10 with a maximum of £25.
Each cheap part is included in the price. I may charge a couple of quid if I have to use up many RAM chips.
New membranes would cost £15 extra (they're the posh ones Rwap makes, not the cheap ones) - that's how much they cost me more or less.

That's just for one Spectrum, though - if you send more than one then obviously you'll benefit from economies of scale, as postage costs go right down.

Also, because it can get expensive, I'm happy to mod Spectrum 48Ks to composite video for nothing, and if it's looking expensive I can re-cap your Spectrum too (i.e. replace all the old electrolytics with new ones - electrolytics are the main thing to fail after a few decades and it tends to improve the picture quality too). That way your Spectrum may cost more than a new one, but yours will be guaranteed (I always do 1 month guarantee) and with fresh components, ready for a good few years more.

For what it's worth, my motive behind repairs like this isn't all about money, it's also my hobby :) I just want to try and earn a living doing what I love, which is keeping old machines going, hence my company.
Ian Gledhill
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Mutant Caterpillar Games - vintage computers and games in our shop!
http://www.mutant-caterpillar.co.uk/shop/

Offline DBloke

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Re: Speccy problems
« Reply #11 on: July 05, 2011, 09:55:10 PM »
Nar its ok now. We have two more in the pub.
Looks like there going to become PCs when I get the cash together
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