Trying to fix my ZxSpectrum+

For experts to discuss very technical stuff and newbies to ask why the Spectrum they bought off ebay doesn't work.
Hyuma
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Re: Trying to fix my ZxSpectrum+

Post by Hyuma » Tue Aug 06, 2019 12:11 pm

Ram arrived! Check pictures. There is still issue. :?

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I uploaded also a video, I pressed reset button after a bit.



As a test, i checked all voltage on upper Ram module on pin 8 and i have all 4.98V.
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Hyuma
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Re: Trying to fix my ZxSpectrum+

Post by Hyuma » Wed Aug 07, 2019 6:26 pm

I double checked the wires I soldered for Lower ram traces and I discovered a wire not connected!
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I download OTLA software and try to load some .tap:

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Last edited by Hyuma on Wed Aug 07, 2019 6:35 pm, edited 1 time in total.
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DouglasReynholm
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Re: Trying to fix my ZxSpectrum+

Post by DouglasReynholm » Wed Aug 07, 2019 6:35 pm

Hyuma wrote:
Wed Aug 07, 2019 6:26 pm
I double checked the wires I soldered for Lower ram traces and I discovered a wire not connected!
Image
Hurrah! Really happy to see this mate, I applaud your perseverance.

Also big thanks to everyone who helped Hyuma, I knew I could rely on you when they first enquired about their problems on another (inferior) website, and I suggested a better place to ask!

*sheds small tear and salutes
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Hyuma
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Re: Trying to fix my ZxSpectrum+

Post by Hyuma » Wed Aug 07, 2019 6:39 pm

I've noticed that with OTLA loading games some are working, some others not, dunno why... and not all keys are responding when i press... maybe the keyboard need some clearing or some other to check?
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Hyuma
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Re: Trying to fix my ZxSpectrum+

Post by Hyuma » Wed Aug 07, 2019 6:48 pm

DouglasReynholm wrote:
Wed Aug 07, 2019 6:35 pm
Hyuma wrote:
Wed Aug 07, 2019 6:26 pm
I double checked the wires I soldered for Lower ram traces and I discovered a wire not connected!
Image
Hurrah! Really happy to see this mate, I applaud your perseverance.

Also big thanks to everyone who helped Hyuma, I knew I could rely on you when they first enquired about their problems on another (inferior) website, and I suggested a better place to ask!

*sheds small tear and salutes
Thank you so much, friend! :oops: :oops: :oops:
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Ast A. Moore
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Re: Trying to fix my ZxSpectrum+

Post by Ast A. Moore » Wed Aug 07, 2019 6:49 pm

Hyuma wrote:
Wed Aug 07, 2019 6:39 pm
I've noticed that with OTLA loading games some are working, some others not, dunno why
OTLA can only modify the standard loader. It can’t magically scan and figure out every non-standard loading scheme. Also, keep in mind, that due to the way the OTLA loader reads from the port, you can’t press any keys while a game is loading; it’ll introduce errors.
Hyuma wrote:
Wed Aug 07, 2019 6:39 pm
and not all keys are responding when i press... maybe the keyboard need some clearing or some other to check?
You can manually short each of the pins of KB2 sequentially with each of the pins of KB1. If some are not responding, than the problem is either with the ULA, diodes D1–D8, or the PCB traces. If they check out, then the problem is with the keyboard membrane, which, in all likelihood, will have to be replaced.
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

Hyuma
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Re: Trying to fix my ZxSpectrum+

Post by Hyuma » Wed Aug 07, 2019 7:45 pm

I'm now cleaning the keyboard sheet, I found these black dirty lines on the tracks, with IPA very easy!

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patters
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Re: Trying to fix my ZxSpectrum+

Post by patters » Thu Aug 08, 2019 6:21 am

Usually the ribbon part develops microscopic fractures on the bend as the plastic degrades which eventually breaks continuity in those metallic paint tracks. Since you've got it open you should replace the membrane. The new ones are made of a better material.

I also applaud your persistence, it's been an interesting thread to check back on. It must be satisfying to have resurrected this machine.
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Morkin
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Re: Trying to fix my ZxSpectrum+

Post by Morkin » Thu Aug 08, 2019 8:05 am

I know nothing about electronics but like others enjoy following the progress of threads like these..

If it's at the point where it just needs a new membrane it's a great success story (even I can change one of those!).

It shows all your work and persistence have finally paid off. :D
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Muttley Black
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Re: Trying to fix my ZxSpectrum+

Post by Muttley Black » Thu Aug 08, 2019 8:29 am

Congratulations! Don’t bother keep or fix that membrane.
Change it with a new quality one. You can buy it from Retroleum.

Or if you can fix it, do that and keep it for testing ;)
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