Timex Sinclair 1000 power supply polarity?

I picked up an old Timex Sinclair 1000 computer from a thrift store recently. It came with a 16K RAM pack, but no power supply. The power jack looks like a 1/8" earphone jack and is marked "9V" -- but no polarity is indicated. I don't want to fry this thing, anyone know what the polarity is supposed to be on this thing? (I've done some web searches and not found the answer yet...)

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  Roger Blake
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Roger Blake
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I suggest you track down someone else with a Timex Sinclair 1000 who will hopefully read the polarity diagram from its power supply, or has a multimeter handy in order to check. Contacting the guy behind this page for instance may give some positive results:

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eBay may be another place to look. Find someone selling one, and kindly ask if he/she can check the polarity. Other than that, spend some time searching the web for "Timex Sinclair

1000", even if it doesn't have the word "polarity" in it. Good luck!
Reply to
NoSp

Thanks for the lead, I'll fire him off a note...

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  Roger Blake
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Roger Blake

spam.)

I would take it apart and trace the wiring to any diodes or regulators. If I remember back that far, Sinclair had a habit of using 9V ac.

9V or so DC will usually work , either way round in this situation, but you need to get an idea of the current as well. 9V ac supply onto a requiremnent for 9V dc will not work

Was Timex the brand name given for Sinclair stuff sold in the States ?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

(I've done some

Must attend google school? Site found looking for "ZX81 schematic"

Check here, trace the connections to C3 and the regulator.

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Adrian C
Reply to
Adrian C

I read

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that there were some slight differences between the TS1000 and the ZX-81 which also included the circuit board. I'd physically inspect the traces from the power connector or wait for information from someone else who has a TS1000 instead of risking damage.

Reply to
NoSp

I had someone respond via email who said that the plug tip is positive.

Not sure how tough these are to open but if possible I'll verify by looking at the connections inside.

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  Roger Blake
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Reply to
Roger Blake

The schematic I pointed out has the US/UK differences marked. Video stuff. The site it's on is dedicated to the TS1000.

Yup, the UK drives on the wrong side of the road, so it's possible that the connector polarity had originally been wired the wrong way up as well :-|

Nope, just kidding - The French would do that. For the OP, the web site has a ZX81 assembly manual. Section 9 gives details of the power supply and polarity required.

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Adrian C
Reply to
Adrian C

I have had a number of TS1000 and ZX-81s; the polarity is tip positive.

Michael

Reply to
msg

You won't fry it. Most of those things were protected from the wrong polarity with a diode. The instructions say you can even put the jack into other openings on the TS1000 and it won't hurt it. I think the tip is negative and the supply needs to deliver 1400 ma. I found this in about

60 seconds.

ftp://ftp.worldofspectrum.org/pub/sinclair/technical-docs/ZX81_ServiceManualAndAssemblyInstructions.pdf

Watch the word wrap.

Reply to
Meat Plow

You may have read some web apocrypha but I have the actual machine and actual power supply right in front of me: the tip is positive (+9V) for the TS1000.

Michael

Reply to
msg

You are correct as it stated this in the link I provided that you conveniently omitted in your reply.

ftp://ftp.worldofspectrum.org/pub/sinclair/technical-docs/ZX81_ServiceManualAndAssemblyInstructions.pdf

  1. POWER SUPPLY If you wish to use your own power supply with the ZX81, it should conform to these specifications - D.C. only -positive to the tip of the 3.5mm jack plug. Need not be regulated, but should be well smoothed. Voltage - between 12 volts maximum and about 8 volts minimum (depending on smoothing) when on load. Current - not less than 600mA, or 1 2A of the printer is to work from the same supply.
Reply to
Meat Plow

The TS1000/Sinclair ZX81 are not protected with a diode. The 9VDC goes directly to the 7805 voltage regulator.

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Reply to
Aurel Boisvert

That's even better. I don't think a 7805 will do anything with a reversed voltage supplied to the input. I'll have to get one out of the parts bin and give it a try to be sure though.

Reply to
Meat Plow

these specifications -

but should be well

Thanks -- though the result is kind of anticlimactic since after hooking up a decent power supply as specified, this particular TS1000 appears to be dead as a doornail. I'll open it up and check it out when I have time...

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  Roger Blake
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Reply to
Roger Blake

rm to these specifications -

lated, but should be well

me...

am.)

I've used this approach on occaision and its worked. Connect the UUT to a variable power supply. Slowly advance the voltage while keeping a sharp eye on the current. If the current seems to begin to rise disproportionately, then you probably have the supply reversed. Lenny.

Reply to
captainvideo462002

these specifications -

regulated, but should be well

fwiw, You can use an ohm-meter to determine which of the power pins is connected do some other system ground/connector shield etc. The other pin is often, but not always the + pin. It's a good guess if no other info is available. mike

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Reply to
mike

Thanks for the tip. Though it seems I'm having nothing but bad luck with old computers at the moment. I also have an "Interact" 8080-based "home computer" that I purchased around 1980 or so. Decided to fire it up to check out some of the old games, and the thing appears to have cratered. For those not familiar with this somewhat obscure system, some info can be found here:

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Bummer, it's been about a year since firing this thing up and it worked perfectly last time!

The Interact is powered by a wall wart that puts out multiple AC voltages with the rest of the power supply located inside the main unit. These computers were pretty notorious for blowing out voltage regulators, will have to check and see if that's the case here...

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  Roger Blake
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Roger Blake

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