| Posted By
MCes
on 2019-06-17
01:20:27
 |  how lowering temperature for TED CPU chips
Recently I measured the current absorbed (5V line) by my plus4, it was near 1A
It means around 5W of dissipation, so my PLUS4 has to rise its inner temperature to reach the thermal balance for dissipate 5W.
This over-temperature is the ambient where TED and CPU are immersed, making their surface temperature more high.
how it's possible to lower the TED and CPU temperature? simply: putting them in a fresher ambient!
It can be done replacing old chips with chips that use more recent technology: they use a lot less power, and heat the ambient a lot less....
The first "oven" is the original PLA, but also the ROMset don't are joking....
Replacing PLA and 4 ROMset the current of my PLUS4 fall down of 30%!!!!!
There is a "direct relationship" between W used and over-heating inside the PLUS4, so now my PLUS4 have 30% less over-heating inside: my TED and CPU are immersed in fresher place, so they will be fresher (their temperature will be lowered by the same degrees as the internal temperature will be lowered)
I was thinking only to replace chips that are cheap to be bought, but if you replace the CPU with a "C-MOS substitute " the thermal gain increase: 80mA of less current!
Originally 1A now 0,6A: overheat is limited at 60% of nominal,
with benefit for all old chips, for the TED, and to Power Supply Unit too!
NOTE: all without modify the motherboard (and preserving in a drawer the expensive and rare original chips...).
The same idea can be applied to C16....
pics:
http://www.amibay.com/showthread.php?106641-PLUS4-(C16)-how-lowering-temperature-for-TED-CPU-chips
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Posted By
candle
on 2019-06-17
03:48:21
| Re: how lowering temperature for TED CPU chips
you said you're technical person, yet claims that all the current from power supply goes into heat producing 5W of power loss due to heating
is this a resistor? efficiency is zero? doesn't it run?
nmos based LSI use clocked logic, meaning clock have to be present all the time to preserve data inside, so, compared to CMOS chips are always active in most of their internal structure, plus it uses depletion mode n-mos transistors for semi pullups to make logical "1" - this two factors are why they heat up
is this bad? not really, it's not helping either
my plus4 consumes something around 690-710mA, BASIC chip is original, KERNAL was replaced with JiffyDOS i bought from retro innovations (image costs 8usd - not much compared to speed gain with sd2iec) and FUNCTION LOW and FUNCTION HIGH chips are removed
CPU is NMOS, although it is just 6502A and heats up nicely, DRAM chips are removed, BASIC chip too (for a test) and still i'm getting 0.695mA so i don't belive your data
you won't gain 0.4A by replacing just ROM's
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Posted By
MCes
on 2019-06-17
09:45:01
| Re: how lowering temperature for TED CPU chips
It's clear that english is not my language (I'm Italian) and I suppose that it's not your language too, so misunderstanding could occur, but...
I want divide in 2 points your sentences:
1) "efficiency is zero?"
2) "i don't belive your data"
1) YES, a machine that burn energy and produce information has a POWER efficiency of ZERO: all the energy (99,9%?) is transformed in unwanted heat, I not found other kind of energy in outgoing the body of my PLUS4 (into the pics you can also see that only the PSU is connected, no other cables) so my words are based on "law of conservation of energy"
https://en.wikipedia.org/wiki/Energy_conversion_efficiency
https://en.wikipedia.org/wiki/Conservation_of_energy
2) I declared the procedure of my experiment and linked the relative pics, so the sentence "i don't believe your data" imply that I am a trickster.
Different could be if you was putting my attention on a critical passage of the experiment where an error could accour, but you don't did it.
If you want you can take a PLUS4 (with original chipset) and made you my experiment: replacing ROMset with C-mos ROM and PLA with a GAL the current has to lower (less or more) of 30%, and swapping old CPU with a C-Mos one the current will lower of 80mA.
Reproduce exactly the experiment (at least the first step) and post the pics of the current in this different conditions: if I was a liar it will be clear, because an experiment has to be reproducible.
This will be in line with the "Scientific method"
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Posted By
MMS
on 2019-06-17
13:45:36
 | Re: how lowering temperature for TED CPU chips
Actually in C16 there is an additional heat source: the PSU gives an unregulated 9V, and it set to the proper voltage within the machine. (regulator)
This emits a lot of heat, and there was a similar experiment on ZX Spectrum 48K and 128K, how much heat they produce becasue of this. C16 works exactly in the same way, in fact can use ZX Spectrum PSUs.
In Spectrum +3 they changed the PSU to something similar to Plus/4 and C64 have, so that additional heat source (still exists in C16) disappeared.
Plus/4 is much smaller inside than the C16, so aregulator togeher with the extra ROMs and ICs this heat would boil the machine, but with the C64 type PSU it was still manageable.
C116: I have no clue how they manage temperature, but it should be high 
Actually one thing was not tried out yet (or at least not with measurements): the active cooling. AFAIK someone in the US has such acooling, but dunno how efficient it is.
I made a joke about it few years ago, but in fact I found it to be an interesting idea.
If you compare your "Hot points" map VS the potential airflow of a User port fan, it more or less fits to each other
Certainly the TED metal heatsing of the blocks the airflow, pls do not count with that, it was just a quick draw.
I mean more air goes towards the PLA and old ROM chips
But the 7501/8501 would get the cooling it deserves (certanly some heatsink does not hurt).
Unfortunately there are some issues:
-User port's 5V cannot provide enough current for a PC Fan. Some external fans for PC uses 5V DC from USB, but unfortunately still requires higher current.
It means you need an external USB power source
-The dimensions of the existing ones does not fit to the User port.
I planned to rebuild a Commodore modem, but it would be a brutal action to cannibalize a working C= modem, when it could also work with a Plus/4. It is also rather hard to find one here, whil in US they are more frequently available, but prices going up + shipping cost.
-the airflow is typically from inside out, while I think in our case I thing the direct cooling with "from outside to inside" (as above) airflow could be better.
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Posted By
MCes
on 2019-06-17
13:54:49
| Re: how lowering temperature for TED CPU chips
A friend of mine is appassionated of photograph, I asked to him which is the best way to clean a lens, and he told me "avoid getting it dirty..."
Yes, I prefer make conditions that avoid the problems that otherwise will be resolved generating other kind of problems....
But if I have to put a fan I will connect it on "big capacitor" (9..11V: the rectified 9Vac)
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Posted By
MCes
on 2019-06-17
14:25:02
| Re: how lowering temperature for TED CPU chips
NOTE: in electronics equipments that has only 1 fan, normally the fan will be an "ejector" of hot air, so the fan has to aspire hot air from PLUS4 inner to eject it out of the computer case.
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Posted By
MMS
on 2019-06-17
14:44:56
| Re: how lowering temperature for TED CPU chips
Correct, it is the usual way
On the other hand I learn on my own hard way, that eg. DELL XPS210 fan with the eject method was much less efficient than the push method. As a result, my C2D E8500 always hanged due to overheat, tilll I reversed the airflow. It reduced the CPU temp by 6-8°C, though theoretically the same amount of air went through the heatsink.
The CPU was the hottest point in the PC
When the warmer air (already heated up by the northbridge and VGA card, not to mention the PSU) passed the heatsink it was certainly less efficient, than if the cool air pass though the same (despite as cubic m3/min was the same amount (no fan change is possible, special Dell connector). )
In this case the hot guy is the 8501, and will get a direct and cool airblow, and according to my experience, it should be just fine (or even more efficient) as will push out the hot air from the complete housing.
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Posted By
MCes
on 2019-06-17
15:04:10
| Re: how lowering temperature for TED CPU chips
@MMS
"more efficiently" indicate a problem: if the fresh air will going on hottest point then the overheated air will pushed inside the PLUS4 and the air will leaving calories inside the PLUS4 before it's outgoing.... not a good overall calories dissipation....
Ejecting hot air imply that the hot air will be out of PLUS4 as soon as possible (without overheating other parts) and fresh air will be aspirated by natural holes of the PLUS 4 case making cool the entire computer....
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Posted By
MMS
on 2019-06-17
15:11:45
| Re: how lowering temperature for TED CPU chips
I see your point, and tend to agree with that.
Only a real measurement could show, what will happen when you pull the heat from the ROMs+PLA towards user port, just passing the 8501.
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Posted By
Mozartkügel
on 2019-06-17
16:26:35
| Re: how lowering temperature for TED CPU chips
If you're not going to use the built in software, can you just remove the Plus/4 roms completely to reduce heat or are those needed for the computer to function at all? Or would it function like a 64k C16 with the roms removed?
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Posted By
Lavina
on 2019-06-17
17:53:26
 | Re: how lowering temperature for TED CPU chips
They can be removed (2 chips) and then you'll not have the "3 plus 1 on key F1" message when powering on. That's all.
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Posted By
Mozartkügel
on 2019-06-17
18:03:20
| Re: how lowering temperature for TED CPU chips
Nice! Thanks Lavina!
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Posted By
MCes
on 2019-06-18
03:15:56
| Re: how lowering temperature for TED CPU chips
Yes, but remember that are the old N-MOS ROMs that heat a lot, if you use modern C-MOS one you can have all: the roms in the sockets and a low power consump (lower heating)
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Posted By
MCes
on 2019-06-18
04:19:15
| Re: how lowering temperature for TED CPU chips
@MMS
if you push fresh air to CPU and the heated air will go on motherboard to gain the output: the shield of the TED will overheated by this hot air flux, so you could gain a little bit more on CPU dissipation but at which price?
all board will be overheated, ROMs, PLA and TED will be NOT (or not enough) cooled.....
I prefer lowering heat (exchanging ROMs and PLA with modern chips to lower 300mA gaining 1,5W of less heat), but If I had to put a fan I'll putting an ejector.
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Posted By
MikeZ
on 2019-06-18
06:39:00
 | Re: how lowering temperature for TED CPU chips
Why don't you explore Peltier cooling? I've used it successfully to cool a lithium battery charger in hot weather.
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Posted By
MCes
on 2019-06-18
07:07:30
| Re: how lowering temperature for TED CPU chips
@MikeZ
the hot side of peltier cell has to be placed out of the PLUS4 case, otherwise in thermal balance you has to sum the power used by cell at 5w absorbed by PLUS4 making dangerous this solution....
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Posted By
MMS
on 2019-06-18
12:15:27
| Re: how lowering temperature for TED CPU chips
Thank for the hints.
Peltier is a good solution to reduce temp below room temp. Maybe one of the few ones. It has requirements.
The problem is, that Peltier's efficiency is very low. So you need a rather big cooling (and PSU) capacity to cool down the "hot side" of the Peltier to get cooling effect on the other side. If your cooling is not efficient on the hot side, then the cool side become even hotter (than without peltier).
We use 20 pcs on our 10 prodution lines with 120mm fans each to keep a soldering tube cool. Every 2-3 weeks one gives up, due to inefficient cooling (dust and high temp next to prod.lines). We need active overcurrent protection otherwise it would melt all parts around. We currently runa project to add a higher capacity and more efficient water cooling on the hot side to extend the lifetime of the peltiers (and to reduce downtime on production lines)
https://forum.openag.media.mit.edu/t/water-nutrient-cooling-with-peltier-elements-fail/855
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