TS1500 50Hz which resistor

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Paul
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TS1500 50Hz which resistor

Post by Paul » Sun Mar 31, 2019 9:57 pm

Hello, after years of owning a TS1500 and not daring to open it because it's in perfect condition I was able to buy a broken TS1500 in near mint condition. This had to be opened in order to be repaired.
I was lucky, it was just a broken Z80 that was socketed and a brittle membrane.
I made a composite mod and want to change it from 60Hz to 50Hz.
Does anybody know which resistor number it is in a TS1500?
Kind regards Paul
In theory, there is no difference between theory and practice. But, in practice, there is.
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Andy Rea
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Re: TS1500 50Hz which resistor

Post by Andy Rea » Sun Mar 31, 2019 10:04 pm

Not certain it can be done that way, least i never was able on my ts1500, however you can use and external rom and hardcode it for 50hz

regards Andy
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum
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Paul
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Re: TS1500 50Hz which resistor

Post by Paul » Mon Apr 01, 2019 6:23 am

Hi Andy, I guess it would be possible internally as well?
Which bytes have to be changed?
Do you know how the channel 2/3 selection works? Maybe this could be (ab)used for ROM switching?
Kind regards Paul
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1024MAK
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Re: TS1500 50Hz which resistor

Post by 1024MAK » Mon Apr 01, 2019 12:03 pm

Somewhere I’ve come across some comments from someone who wanted to do the same thing with his TS1500. If I remember correctly, although the ‘ULA’/gate array has a pin that is supposed to be the 50/60Hz input selection, changing the logic level made no difference.

I can’t for the life of me remember where I read about this.

Mark
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Andy Rea
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Re: TS1500 50Hz which resistor

Post by Andy Rea » Mon Apr 01, 2019 7:07 pm

Paul wrote: ↑
Mon Apr 01, 2019 6:23 am
 Hi Andy, I guess it would be possible internally as well?
Which bytes have to be changed?
Do you know how the channel 2/3 selection works? Maybe this could be (ab)used for ROM switching?
Kind regards Paul
Nice idea, worth looking into for sure.
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum
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Paul
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Re: TS1500 50Hz which resistor

Post by Paul » Mon Apr 01, 2019 7:20 pm

Inside the "Modulator" case there is a diode in the left front corner. The left pin of which is either 5V or 0V depending on channel selection.
I guess I don't need 60hz. Maybe I make an internal ROM with bigbang and sponzy. Black and white spectrum in a TS1500 case - crazy enough to get it done. :mrgreen:
In theory, there is no difference between theory and practice. But, in practice, there is.
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1024MAK
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Re: TS1500 50Hz which resistor

Post by 1024MAK » Tue Apr 02, 2019 6:32 pm

1024MAK wrote: ↑
Mon Apr 01, 2019 12:03 pm
 Somewhere I’ve come across some comments from someone who wanted to do the same thing with his TS1500. If I remember correctly, although the ‘ULA’/gate array has a pin that is supposed to be the 50/60Hz input selection, changing the logic level made no difference.

I can’t for the life of me remember where I read about this.
Found it, read through this thread ;)

Mark
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