Heat sink on Spectrum ULA - is there any benefit?

Lardo Boffin
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Heat sink on Spectrum ULA - is there any benefit?

Post by Lardo Boffin » Thu Nov 16, 2017 5:34 pm

At the risk of being a fire starter ( :twisted: ) I have to ask the question - is there any benefit to fitting a heat sink to the rubber key Spectrum ULA?
It obviously has a bigger case than the ZX81 and therefore more air inside but given its lack of airflow will it have the same net effect of just heating the air around the ULA more effficienty without really cooling it any?

Thanks!

Lardo, duck and cover, Boffin
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

Lardo Boffin
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by Lardo Boffin » Thu Nov 16, 2017 5:35 pm

Obviously I will have already fitted a new regulator and be using a modern PSU.
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

Moggy
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by Moggy » Thu Nov 16, 2017 5:40 pm

No need for duck and cover Lardo it's a sensible question. :D

I think the speccy would benefit from a fan cooling solution but if memory serves the motherboard covers the whole case bottom give or take, so positioning would be more difficult than the zeddy, of which i intend to fully modify.

As for airflow in a standard speccy? Just as bad as the 81 I would think and therefore any heat-sinking would probably just as useless without forced air.

I know of one user on the WOS forum who has a spectrum 48k+ (the one with the vents back and front) and he has a floor mounted blower doing the business!!

Lardo Boffin
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by Lardo Boffin » Thu Nov 16, 2017 6:01 pm

Moggy wrote:
Thu Nov 16, 2017 5:40 pm
No need for duck and cover Lardo it's a sensible question. :D

I think the speccy would benefit from a fan cooling solution but if memory serves the motherboard covers the whole case bottom give or take, so positioning would be more difficult than the zeddy, of which i intend to fully modify.

As for airflow in a standard speccy? Just as bad as the 81 I would think and therefore any heat-sinking would probably just as useless without forced air.

I know of one user on the WOS forum who has a spectrum 48k+ (the one with the vents back and front) and he has a floor mounted blower doing the business!!
I did think about the fan solution! A 30mm square fan will just about fit in the raised part:-
6F7552B1-0DA3-407D-B9B9-EA737450CB1C.jpeg
(658.35 KiB) Downloaded 438 times
There is about 17 to 20mm of clearance above the ULA.

If you glued little feet to the top of the case and stick the fan to those you could mount it blowing down onto the ULA and cause some air flow. Whether it would just recirculate the hot air or get rid of any I don’t know. I suspect it would just recirculate as it is not pulling in cool air from outside.
I don’t really want to cut holes in the top of the case!
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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1024MAK
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by 1024MAK » Thu Nov 16, 2017 7:29 pm

It depends on a number of factors.

First, the different issue ULAs produce different amounts of heat. The early types ran hot. The later ULAs used a lower power design, so run cooler (well, warm instead of hot).

Second, yes the rubber key has poor ventilation. The plus keyboard is much better.

Back in 1984, my issue 3 rubber key got left on for days in a row. It never seemed to suffer.

Also, the later ULA design appears to be far more reliable than the earlier type.

So if you have removed the 7805 series voltage regulator and replaced it with a switching type (RECOM or TRACO), and your board is an issue 3 or later, I would not worry about it.

But, I have just noticed that you have an issue TWO! AND a ULA5C112E!

Hmm, not much space for a heatsink anyway, and not much space for a fan...

How long do you intend using it for, I mean, number of hours continuously powered on?

Mark

sirmorris
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by sirmorris » Thu Nov 16, 2017 9:06 pm

Ok, what about (I'm not kidding) building something like this??

Not one of those exactly, but something _like_ it? Like, for a speccy? Perhaps shaped like interface 2, you'd plug the speccy in so there's a blower into the expansion slot.

Benefits:
* Big slow fan is possible - lots of air, low noise.
* Works with all speccys without mods.
* Skookum as.

Lardo Boffin
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by Lardo Boffin » Thu Nov 16, 2017 10:03 pm

sirmorris wrote:
Thu Nov 16, 2017 9:06 pm
Ok, what about (I'm not kidding) building something like this??

Not one of those exactly, but something _like_ it? Like, for a speccy? Perhaps shaped like interface 2, you'd plug the speccy in so there's a blower into the expansion slot.

Benefits:
* Big slow fan is possible - lots of air, low noise.
* Works with all speccys without mods.
* Skookum as.
Now that IS an interesting idea sir Morris!

You would have:-

*A large ish case with a fan in it
*Take the power from the edge connector
*Have a through connector on the back
*Blow the air into the spectrum through the edge connector port

So the case would have to have a rubber gasket around it to form a reasonable seal. Push it in and cool air is sucked into the spectrum. No mods required. Nice!

Anyone got a 3D printer? :?:

Edit - no real reason not to do similar for the zeddy.

Edit 2 - probably better to suck air through the computer towards the fan as this will help make the seal rather than pushing the air constantly trying to break it.
Last edited by Lardo Boffin on Thu Nov 16, 2017 11:31 pm, edited 2 times in total.
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

Lardo Boffin
Posts: 811
Joined: Sat Nov 26, 2016 2:42 am

Re: Heat sink on Spectrum ULA - is there any benefit?

Post by Lardo Boffin » Thu Nov 16, 2017 10:18 pm

1024MAK wrote:
Thu Nov 16, 2017 7:29 pm
It depends on a number of factors.

First, the different issue ULAs produce different amounts of heat. The early types ran hot. The later ULAs used a lower power design, so run cooler (well, warm instead of hot).

Second, yes the rubber key has poor ventilation. The plus keyboard is much better.

Back in 1984, my issue 3 rubber key got left on for days in a row. It never seemed to suffer.

Also, the later ULA design appears to be far more reliable than the earlier type.

So if you have removed the 7805 series voltage regulator and replaced it with a switching type (RECOM or TRACO), and your board is an issue 3 or later, I would not worry about it.

But, I have just noticed that you have an issue TWO! AND a ULA5C112E!

Hmm, not much space for a heatsink anyway, and not much space for a fan...

How long do you intend using it for, I mean, number of hours continuously powered on?

Mark
Ah yes that is my phantom key press Spectrum that was missing a resistor! My everyday Spectrum is an issue 3B but I was thinking about giving one of my now multiplying Spectrums to a mate for Xmas. He had one as a kid but no longer does - when I was talking about such things recently he looked a bit wistful about no longer owning one.
Chances are it would not get a huge amount of usage. Certainly never more than a couple of hours at a time anyway.
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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gammaray
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by gammaray » Thu Nov 16, 2017 11:16 pm

As before, I would put the heatsink on the ULA but drill a hole behind RF modulator where the US side for channel 2/3 normally protrudes and then mount micro fan there. It will be enough flow to remove heat. I would put Styrofoam around RCA, EAR and MIC jacks to prevent air flow from that close gap.

https://www.ebay.com/itm/SEPA-MF15B-05L ... Sw~fpZuY3Z
ts1500 RF PLUGS.jpg
ts1500 RF PLUGS.jpg (16.76 KiB) Viewed 1133 times
Being as I have TS1000/1500's, I could drill out the UK hole but it would not be as effective as US drill out for UK models which is in proximity to the ULA.

Instead I could take 1500 cases, replace the rubber keypad and motherboard to Spectrum and then drill out slots in top of cases and mount fan there.

edited for accuracy
Last edited by gammaray on Fri Nov 17, 2017 4:23 pm, edited 1 time in total.
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

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1024MAK
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Re: Heat sink on Spectrum ULA - is there any benefit?

Post by 1024MAK » Fri Nov 17, 2017 2:29 am

Lardo Boffin wrote:
Thu Nov 16, 2017 10:18 pm
Chances are it would not get a huge amount of usage. Certainly never more than a couple of hours at a time anyway.
Should not be a problem then ;)

Heat level inside will be a lot lower than if used as originally manufactured (due to the switching regulator replacing the 7805), so the ULA should be okay, even without a heatsink.

Mark

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