128K Toastrack spacer on top of RX box

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tridy
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Joined: Wed Oct 06, 2021 6:51 pm
Location: Stockholm, Sweden

128K Toastrack spacer on top of RX box

Post by tridy »

Hello.

What is the purpose of this spacer on the Toastrack?


Does it have to withstand higher temperatures?

toastrack_layer.png
Thanks!
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Tiger
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Re: 128K Toastrack spacer on top of RX box

Post by Tiger »

It is to protect the lead of the keyboard connection ...
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tridy
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Location: Stockholm, Sweden

Re: 128K Toastrack spacer on top of RX box

Post by tridy »

Got it. So, no high temps and I can use pretty much any soft foam material to replace it with.
Thanks!
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1024MAK
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Re: 128K Toastrack spacer on top of RX box

Post by 1024MAK »

If the membrane tails are close to or touch either the modulator or the heatsink for the 7805 voltage regulator, this can cause various weird faults.

The case of the modulator and the heatsink are electrically connected to the 0V/GND of the system. This affects the signals in the keyboard membrane circuitry.

If you don’t have a ‘rubber’ foot, or ‘foam pad’, use four layers of insulation tape.

Mark
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Tiger
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Re: 128K Toastrack spacer on top of RX box

Post by Tiger »

On a 128K Toastrack the heatsink is on the right side outside the case mounted. So there will be no connection with the membrane tails, isn't it?
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1024MAK
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Re: 128K Toastrack spacer on top of RX box

Post by 1024MAK »

Tiger wrote: Mon Oct 11, 2021 2:03 pm On a 128K Toastrack the heatsink is on the right side outside the case mounted. So there will be no connection with the membrane tails, isn't it?
Yes, on this model, the heatsink is not a problem.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
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