Timex Sinclair 1000 repair

[JKnightandKARR]

I don't know - it seems that it would be better to just buy a replacement (https://www.vretrodesign.com/products/vla81-zx81-ula-replacement - and it has 13 5-star reviews) rather than trying to build your own.

Plus it always bothers me when someone produces a document that has a large percentage dedicated to "not my fault" disclaimer legalese.

Haven't found that site at all, I just get the one with no shipping to US available.... besides FleeBay. lol THANKS!

[granz]

Glad to help. I hope that it helps get your Sinclair working.

[JKnightandKARR]

I don't know - it seems that it would be better to just buy a replacement (https://www.vretrodesign.com/products/vla81-zx81-ula-replacement - and it has 13 5-star reviews) rather than trying to build your own.

Plus it always bothers me when someone produces a document that has a large percentage dedicated to "not my fault" disclaimer legalese.

Do me a favor? Can you put in your info in there, like you was buying one, minus payment info, and see if it accepts your address?  It says cannot ship to my address. Wonder if it's a terrif thing??

[granz]

Yep, I'm getting the same:

Shipping not available
Your order cannot be shipped to the selected address. Review your address to ensure it's correct and try again, or select a different address.

You are probably correct about it being a tariff issue. Maybe holding off for a while until other countries cut back on their tariffs on U.S. products, and then we can cut back on products from them.

[Chris Savage]

You are probably correct about it being a tariff issue. Maybe holding off for a while until other countries cut back on their tariffs on U.S. products, and then we can cut back on products from them.

There are Tindie stores I have previously purchased from that are not shipping to the U.S. currently (some are in the U.K.) because of the tariff issues.

[JKnightandKARR]

Yep, I'm getting the same:

Shipping not available
Your order cannot be shipped to the selected address. Review your address to ensure it's correct and try again, or select a different address.

You are probably correct about it being a tariff issue. Maybe holding off for a while until other countries cut back on their tariffs on U.S. products, and then we can cut back on products from them.

You are probably correct about it being a tariff issue. Maybe holding off for a while until other countries cut back on their tariffs on U.S. products, and then we can cut back on products from them.

There are Tindie stores I have previously purchased from that are not shipping to the U.S. currently (some are in the U.K.) because of the tariff issues.

Crap....... was hoping for $35 vs $50......

[JKnightandKARR]

Yep, I'm getting the same:

Shipping not available
Your order cannot be shipped to the selected address. Review your address to ensure it's correct and try again, or select a different address.

You are probably correct about it being a tariff issue. Maybe holding off for a while until other countries cut back on their tariffs on U.S. products, and then we can cut back on products from them.

You are probably correct about it being a tariff issue. Maybe holding off for a while until other countries cut back on their tariffs on U.S. products, and then we can cut back on products from them.

There are Tindie stores I have previously purchased from that are not shipping to the U.S. currently (some are in the U.K.) because of the tariff issues.

Well, I got these 2 items.... more then wanted to pay, but no other options....
https://www.ebay.com/itm/306717973814
https://www.ebay.com/itm/177966875115

Will find one of these to replace the 5v regulator.... the one in there gets REALLY hot, so better be safe than sorry, I'd get it on there but $6.99 + like $8.xx shipping is ridiculous....
https://www.ebay.com/itm/305400148473

[granz]

I seem to recall that the heat sink on my Sinclair ZX-81 was pretty big, and that it had a "spring" that transferred heat to the metal paint on the inside of the case. Maybe if you put that large of a heat sink on the voltage regulator (7805 IIRC) it will keep it cool enough.

[Chris Savage]

Will find one of these to replace the 5v regulator.... the one in there gets REALLY hot, so better be safe than sorry, I'd get it on there but $6.99 + like $8.xx shipping is ridiculous....https://www.ebay.com/itm/305400148473

It's so funny you mentioning the Traco TSR 1-2450. I get mine from Digikey. They're a great replacement for the LM7805, which does dissipate a LOT of heat, since it's a linear regulator. Just be aware that the minimum input voltage is 6.5V@1A.

[JKnightandKARR]

I seem to recall that the heat sink on my Sinclair ZX-81 was pretty big, and that it had a "spring" that transferred heat to the metal paint on the inside of the case. Maybe if you put that large of a heat sink on the voltage regulator (7805 IIRC) it will keep it cool enough.

Maybe, IDK.... might have large enough heatsinks, even something from an old motherboard.

Will find one of these to replace the 5v regulator.... the one in there gets REALLY hot, so better be safe than sorry, I'd get it on there but $6.99 + like $8.xx shipping is ridiculous....https://www.ebay.com/itm/305400148473

It's so funny you mentioning the Traco TSR 1-2450. I get mine from Digikey. They're a great replacement for the LM7805, which does dissipate a LOT of heat, since it's a linear regulator. Just be aware that the minimum input voltage is 6.5V@1A.

Wall adapter is 9v@1A, so shouldn't be a problem...  lol

[granz]

I seem to recall that the heat sink on my Sinclair ZX-81 was pretty big, and that it had a "spring" that transferred heat to the metal paint on the inside of the case. Maybe if you put that large of a heat sink on the voltage regulator (7805 IIRC) it will keep it cool enough.

Maybe, IDK.... might have large enough heatsinks, even something from an old motherboard.

Again, if I remember correctly, the heat sink on my ZX-81 was simply a flat square of aluminum - maybe 2" by 2". That should be simple enough to make, and being flat, it fit inside the case with no trouble.

[Chris Savage]

Wall adapter is 9v@1A, so shouldn't be a problem...  lol

The great thing about a switching regulator is that there's a LOT less waste in heat when your input voltage is higher. On the LM7805, as your input voltage goes up, the regulator has to dissipate more heat to regulate.

[granz]

Yes, and as the original regulator is linear, using a 7V wall wart, rather than the original 9V power supply will keep the 7805 temperature much lower. Using the switching regulator replacement will keep the temp lower also.

[JKnightandKARR]

Yes, and as the original regulator is linear, using a 7V wall wart, rather than the original 9V power supply will keep the 7805 temperature much lower. Using the switching regulator replacement will keep the temp lower also.

I bet my adj power supply would work.

[granz]

I bet my adj power supply would work.

Yep. Two things:
1) Make sure that you have the correct polarity. I'm not certain about the TS, but some power supply connectors from back then had the center negative, and the outer positive. Make sure that you get that right.
2) Check the datasheet for the actual 7805 regulator that is actually on the PCB. Find out what the minimum input voltage is, and make sure that you don't set the power supply below that.