Zx spectrum tape loading issue

A place to discuss the ZX80's and ZX81's younger brother - the Sinclair ZX Spectrum
repetto74
Posts: 43
Joined: Tue Dec 20, 2016 7:46 pm

Zx spectrum tape loading issue

Post by repetto74 » Tue Dec 20, 2016 7:54 pm

Hi guys

I have refreshed a ZX spectrum 48k with a new keyboard layer and front case. The machine will power up and seems to work good. Unfortunately I cannot load tapes. I tryed with an old working cassette deck but all I get is a black and white checkered border on screen and no loading sound. :?

Any ideas what this could be ? Hardware failure ? Cassette deck or tapes damaged ??
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gozzo
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Joined: Fri Jul 08, 2011 7:52 pm

Re: Zx spectrum tape loading issue

Post by gozzo » Wed Dec 21, 2016 2:57 am

hmm, that checkered border shouldnt happen? do border colours appear correctly if use the BORDER command? if not need to check the LM1889 and its 12v supply, and the 4.433 crystal...this shouldnt stop loading though, if colours otherwise ok, could be some weird fault within the ula..????

gozzo
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Joined: Fri Jul 08, 2011 7:52 pm

Re: Zx spectrum tape loading issue

Post by gozzo » Wed Dec 21, 2016 2:58 am

also colour problem could just be that the tv is not tuned in correctly, or set to wrong colour standard, but again this will not stop loading.

repetto74
Posts: 43
Joined: Tue Dec 20, 2016 7:46 pm

Re: Zx spectrum tape loading issue

Post by repetto74 » Wed Dec 21, 2016 12:13 pm

Hi gozzo

When powering up I get the normal prompt screen black text/grey background.
May you tell me a couple of border colour commands as I am not used to Spectrum but was more a Commodore 64 user. :-)

The tv is ok and working when hooking up other computers.

repetto74
Posts: 43
Joined: Tue Dec 20, 2016 7:46 pm

Re: Zx spectrum tape loading issue

Post by repetto74 » Wed Dec 21, 2016 12:19 pm

Also I do not know the real integrity of the cassette tapes I own. Most of them have C64/spectrum games on each side and I did have problems loading C64 programs with some of them (30 years of dust and humidity not so good)
Anyway I should normally have a colored screen and hear the loading sound at least.

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1024MAK
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Location: Looking forward to summer in Somerset, UK...

Re: Zx spectrum tape loading issue

Post by 1024MAK » Wed Dec 21, 2016 3:19 pm

To change the border colour, use the following command:

Code: Select all

BORDER n
where 'n' is a number between 0 (black) and 7 (white).

As you may know, the 48k ZX Spectrum uses a command entry system where pressing a key or key combination enters a command word all in one go. So don't try to type the command words out letter by letter. BORDER is on the 'B' key.
Image(Link)
You can also write a program to cycle through all eight colours:-

Code: Select all

10 FOR a=0 TO 7
20 BORDER a
30 PAUSE 100
40 NEXT a
The ZX Spectrum will display horizontal coloured stripes when it detects a loud enough cassette data signal. It requires a audio source that has a very strong output signal. Which in practice means a mains powered mono "shoe box" recorder with the volume turned up to at least 3/4.

The leads should have 3.5mm mono jack plugs. Stereo jack plugs will not work, as the electrical contacts do not line up correctly. If using a stereo audio source, use only the left or right channel. Don't connect the channels together. So this means you need a 3.5mm stereo jack plug to two 3.5mm mono jack plugs. Connect one to the ear socket on the ZXSpectrum and leave the other loose and unplugged.

You should also be able to hear the tones via the ZX Spectrums internal speaker. If you don't hear any tones, the ULA in the ZX Spectrum has no chance of detecting the loading signal.

Mark

repetto74
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Joined: Tue Dec 20, 2016 7:46 pm

Re: Zx spectrum tape loading issue

Post by repetto74 » Wed Dec 21, 2016 3:56 pm

Hi Mark

Manu Thanks for this clear explanation. I tested the BORDER command and unfortunately confirm that the border will still be displayed on a checkered black and white pattern despite the OK prompt of the spectrum.
Have maybe to precise that the spectrum has been moded to allow video composite connection but as far as I can see a picture I do not think that missing color is due to a bad mod.
I may have an hardware failure somewhere :roll:

As you say the recorder is a "shoe box" tape loader and recorder dated end of 80's.
How do you see the difference between a mono and a stereo 3.5 mm jack ?

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1024MAK
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Re: Zx spectrum tape loading issue

Post by 1024MAK » Wed Dec 21, 2016 4:19 pm

Wikipedia article here includes this useful picture:-Image
Left to right: Jack plugs 2.5 mm diameter mono, 3.5 mm diameter mono, 3.5 mm diameter stereo, 6.3 mm diameter stereo.

Mark

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1024MAK
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Re: Zx spectrum tape loading issue

Post by 1024MAK » Wed Dec 21, 2016 4:24 pm

In case it is a problem with all colour, try this:-

Code: Select all

10 FOR a=0 TO 7
20 PAPER a
30 PRINT "colour ";a
40 NEXT a
50 PAUSE 500
Mark

repetto74
Posts: 43
Joined: Tue Dec 20, 2016 7:46 pm

Re: Zx spectrum tape loading issue

Post by repetto74 » Wed Dec 21, 2016 5:38 pm

OK 1024MAK things are getting much more clear now for me. :geek:

I did some testing. I checked first the ram available with :
PRINT PEEK 23732 + PEEK 23733 * 256
and got 65535 in return so all 48k available.

I have checked the audio jack and confirm to you it is a stereo jack on both ends so you confirm this one is useless to properly load programs? The tape loader looks ok as you can see on the picture it should be one eligible to work with the Spectrum.
The speaker on the spectrum is also working when pressing a key so no loading+no audio coming out as you said the ULA is not getting data at all. The stereo jack may be the culprit then ;)

Regarding colors, well after keying in the little loop I cam out with this :roll:
My spectrum is definitely missing colors. I do not know now if this is due to the composite mod (it is rather simple to do I do not see where I may have done something wrong) or a component failure. The checkered black and white border let me think of an hardware problem though.
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