Improving Timex/Sinclair Tape Loading

Discussions about Sinclair ZX80 and ZX81 Hardware
Lardo Boffin
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Joined: Sat Nov 26, 2016 2:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Tue Jan 23, 2018 8:41 pm

TMAOne wrote:
Tue Jan 23, 2018 12:20 pm

How's the board coming Lardo? I'm on pins and needles here,...
Ian
Sorry for ‘going dark’ for a while - been rather busy trying to sell a house and pack and not get REALLY angry with the conveyancing solicitors who it turns out are completely inept.

Any way I just need to connect the switch and battery and I can test! Fingers crossed that will be this week. And that I have not bodged somewhere...
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

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1024MAK
Posts: 1914
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Improving Timex/Sinclair Tape Loading

Post by 1024MAK » Thu Jan 25, 2018 2:21 am

I've moved the posts discussing the direction of current flow to their own new thread: Direction of current flow.

Mark

Lardo Boffin
Posts: 714
Joined: Sat Nov 26, 2016 2:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Mon Jan 29, 2018 10:44 pm

Well I finished the assembly (finally) but sadly it does not work. I get nada.
I checked the resistance as per the pretest checks and got just over 1000 ohms.
The batteries are fine.
The LED is fine.
I get power to the board when switched on.
When I jumper pins 1 and 11 the LED does not glow.
When trying the tape recorder playback the LED does not glow even when playing a known good tape at a volume I know it loads at.
Argh. It must be a Monday. :cry:
Maybe someone else should have been entrusted with the only PCB?

Some photos in case anyone can spot any obvious gaffs?
A827BD2A-1B46-46BA-ADF7-028102FBA6CD.jpeg
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2F6F62A1-0635-4657-A220-FADAB565B97B.jpeg
(444.71 KiB) Downloaded 338 times
C090761A-826F-4FE6-B3AC-25DA32A94763.jpeg
(525.85 KiB) Downloaded 338 times
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

makeit2day
Posts: 28
Joined: Sat May 10, 2008 2:31 am

Re: Improving Timex/Sinclair Tape Loading

Post by makeit2day » Mon Jan 29, 2018 11:54 pm

You may have some connections that need to be checked for good soldering. Use a magnifier to see if they are soldered properly
(no cold soldered joins), check for shorts also with your wires connecting on the board.

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sirmorris
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Joined: Thu May 08, 2008 5:45 pm
Location: oxon, uk

Re: Improving Timex/Sinclair Tape Loading

Post by sirmorris » Tue Jan 30, 2018 5:59 pm

You should check continuity between solder points. I don't know if you remembered that there were a couple of broken tracks that were needing to be jumpered. I sent an image showing the places where I knew for sure that the tracks were cracked.
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Lardo Boffin
Posts: 714
Joined: Sat Nov 26, 2016 2:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Tue Jan 30, 2018 10:27 pm

sirmorris wrote:
Tue Jan 30, 2018 5:59 pm
You should check continuity between solder points. I don't know if you remembered that there were a couple of broken tracks that were needing to be jumpered. I sent an image showing the places where I knew for sure that the tracks were cracked.
You did indeed! I had looked at the board and it looked like they had been sorted and thought no more of it. However... Doubtless when my ham fisted soldering occured I undid some of your fixing. Having done some continuity testing I found this:-

05B0F0BF-FF58-49A2-BC76-C4D76C4E4B9D.jpeg
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Two dodgy areas.

The lower one is one of your fixes and should be easy to deal with.

The upper one is definitely mine. What is the best way to fix this? Jumper directly from the left hand pin (1) to the dodgy pin (2) or try and attach it closer to home? Note that pin 1 to 3 and 4 is fine.
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

User avatar
1024MAK
Posts: 1914
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Improving Timex/Sinclair Tape Loading

Post by 1024MAK » Wed Jan 31, 2018 1:38 am

For short sections of broken / cracked / missing tracks, unless the track is too thin, I normally solder on a cut to length off-cut resistor or diode lead. That is, across the break. Tin the tracks (carefully), tin the wire. Then hold the wire in place with a screwdriver, while heating with your iron.

If the track is too thin, or too fragile, then I use insulated wire to link the two nearest component pads/connections.

Mark

Lardo Boffin
Posts: 714
Joined: Sat Nov 26, 2016 2:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Wed Jan 31, 2018 11:07 pm

I have fixed the two issues. And although it doesn’t look pretty I now have continuity where I should. Ignore the fact that it looks like my fixes are short circuiting. - they are not as the jumpers are sat above the board.

C36673F3-ADF9-4720-A1FA-2F9588DB5ABA.jpeg
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I have tested every pin for continuity and every pin for shorts and all appears ok.

I am still not getting anything if I jumper pins 1 and 11. I am still getting about 1000 ohms for the resistance test.

What voltage should I get at the board when it is switched on? Assuming that tells us anything?
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

User avatar
sirmorris
Posts: 2821
Joined: Thu May 08, 2008 5:45 pm
Location: oxon, uk

Re: Improving Timex/Sinclair Tape Loading

Post by sirmorris » Wed Jan 31, 2018 11:56 pm

About +1.5V between gnd & + terminal, about -1.5 between gnd & negative terminal. About 3v between + and -. Elsewhere? Who knows :D

Have you had a close look and checked for shorts anywhere? I'm a little concerned by the left-most signal wire in the picture above. If signal touches the ground plane then you won't see any signal.
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Lardo Boffin
Posts: 714
Joined: Sat Nov 26, 2016 2:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Thu Feb 01, 2018 12:07 am

I have checked pretty much every pin for shorts but I will double check the leftmost signal connections thanks.
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

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