Author Topic: *Really* reliable beefy 5V PSU  (Read 1130 times)

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LambdaMikel

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*Really* reliable beefy 5V PSU
« on: 10:33, 24 February 18 »
Hi, it seems that with more and more extension cards and memory cards - ZMem, and 4 MB from Piotr - it is extremely difficult to get reliable behavior from CPC. I tried with 3 different PSUs on my 464 and Batman Demo, and got different results.
I have used 2 variable voltage, 2.5 and 3 A switching PSUs, and also the GT64 for PSU, and got different behavior of memory expansions. The behavior ranged from complete malfunction to "functions a little bit" (until Batman demo crashes).

So now I am thinking of getting a better PSU - what do people think of these two, which one would be best option for CPC 464?

https://www.adafruit.com/product/658


https://www.amazon.com/ALITOVE-Transformer-Adapter-Converter-Charger/dp/B06XK2DDW4/ref=sr_1_2_sspa?ie=UTF8&qid=1519460758&sr=8-2-spons&keywords=5v+power+supply&psc=1

https://www.cdiweb.com/ProductDetail/RS155-MEAN-WELL/312804/pid=568?gclid=CjwKCAiAt8TUBRAKEiwAOI9pABewoGNmc_EjzVI9XhRuu1w4raopHlFs_PlZm6yn4u6i-Isws7-K-xoC72wQAvD_BwE

This is my favorite so far:


https://www.amazon.com/Universal-Regulated-Transformer-Switching-Converter/dp/B076D9WMRX/ref=sr_1_4?s=electronics&ie=UTF8&qid=1519461778&sr=1-4&keywords=5v+5a+power#customerReviews

And, would it solve my memory expansion relability problems? Btw, the only mem expansion that really works reliably is XMem so far, never any problem with Batman demo (one disk version). The other expansions don't work for me, and it makes a difference "how it malfunctions" depending on the PSU I am using. Whereas for XMem, PSU does not matter and always works reliably.

What are people using to power their CPCs?

Cheers,
Michael
« Last Edit: 10:43, 24 February 18 by LambdaMikel »

Offline tjohnson

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« Last Edit: 12:19, 24 February 18 by tjohnson »

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Re: *Really* reliable beefy 5V PSU
« Reply #2 on: 13:10, 24 February 18 »
Because I am an old timer and I also use a CRT monitor I have a linear PSU. One of those used for audio. It easily gives you 8A and covers all the Amstrad needs while keeping the philosophy of the original PSU in the screen. Besides, it is very simple and easy to repair  :) . If you are interested on something like this I can send you some links. Problem is that they are very expensive  :-X


If you want a switching one, maybe you are in luck too. I have one stored upstairs that, as far as I remember, was beefy enough. Problem is that it was causing interference with the CRT screen, something that is more prominent in the plus range. If I find it, you can have it for free  :)

Offline gerald

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Re: *Really* reliable beefy 5V PSU
« Reply #3 on: 13:33, 24 February 18 »
Hi, it seems that with more and more extension cards and memory cards - ZMem, and 4 MB from Piotr - it is extremely difficult to get reliable behavior from CPC. I tried with 3 different PSUs on my 464 and Batman Demo, and got different results.
I have used 2 variable voltage, 2.5 and 3 A switching PSUs, and also the GT64 for PSU, and got different behavior of memory expansions. The behavior ranged from complete malfunction to "functions a little bit" (until Batman demo crashes).
Are all your extension powered by the CPC ?
If so, it may be the power switch that need a bit of cleaing.

Offline DaDMaN

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Re: *Really* reliable beefy 5V PSU
« Reply #4 on: 14:02, 24 February 18 »
« Last Edit: 14:04, 24 February 18 by DaDMaN »

LambdaMikel

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Re: *Really* reliable beefy 5V PSU
« Reply #5 on: 07:09, 25 February 18 »
Thanks all.
Stopped by at my local electronics store today (Frys), and found this one - 40 Watts (5 V, 8 A).
Unfortunately, it has not resolved my memory expansions issues (4 MB, 1 MB)  >:(

LambdaMikel

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Re: *Really* reliable beefy 5V PSU
« Reply #6 on: 09:14, 25 February 18 »
Are all your extension powered by the CPC ?
If so, it may be the power switch that need a bit of cleaing.

Thanks for suggesting this. However, all these CPC's work fine with XMem and the Batman demo, so I doubt it is the switch.

Offline Bryce

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Re: *Really* reliable beefy 5V PSU
« Reply #7 on: 10:31, 26 February 18 »
Two things:

- Remember that all those Amps have to flow through a tiny track on the CPC PCB. This will be getting hot and dropping voltage if too many things are being powered through the CPC... Until you reach the limit and the track on the PCB will burn through.

- 8A can cause serious damage if anything shorts out. So an accidental brushing of the monitor connector against an expansion PCB or similar mistake could destroy everything. You don't need 8A, add a 3A fuse at least to minimize the potential damage if something clumsy does happen.

Bryce.

LambdaMikel

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Re: *Really* reliable beefy 5V PSU
« Reply #8 on: 16:52, 26 February 18 »
Thanks for the advice, Bryce!
The

https://www.vellemanusa.com/products/view/?id=526643&country=us&lang=enu

lists some
  • overload protection: 105-150 % fold back current limiting with auto-recovery
Would that help prevent such desasters?

LambdaMikel

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Re: *Really* reliable beefy 5V PSU
« Reply #9 on: 16:57, 26 February 18 »
... well I sorted out by now that the ext. mem problems are not caused by underpowered PSUs.
One contributing factor is voltage calibration though. With 5.6 Volts, Piotr 4 MB Phortem demo
shows pixel errors. I have callibrated it manually to 5.00 V exactly now, and Phortem works, but
others still don't. I have also ordered an other PSU with "only" 3 A,


https://www.amazon.com/gp/product/B01D8ER6DS/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

which can also be calibrated / adjusted. I must say that is the main reason for getting this over a
standards plug-into-the-wall PSU in a plastic case. I will be using this one instead of the 8 A one
when it arrives.

Offline Bryce

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Re: *Really* reliable beefy 5V PSU
« Reply #10 on: 17:01, 26 February 18 »
Thanks for the advice, Bryce!
The

https://www.vellemanusa.com/products/view/?id=526643&country=us&lang=enu

lists some
  • overload protection: 105-150 % fold back current limiting with auto-recovery
Would that help prevent such desasters?

No, that protects the PSU when something tries to pull more than 8A, but 8A is enough to peel the traces off the CPC PCB, so the CPC would still be destroyed.

Regarding CPC voltages. The PSU output voltage should be set to 5.1V. This allows for some voltage drop across cables/traces etc and all ICs should get enough juice (most TTL chips stop working below 4.75V), but doesn't go above their limit (most TTL chips will start to fail above 5.25V).

Bryce.

LambdaMikel

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Re: *Really* reliable beefy 5V PSU
« Reply #11 on: 17:25, 26 February 18 »
Regarding CPC voltages. The PSU output voltage should be set to 5.1V. This allows for some voltage drop across cables/traces etc and all ICs should get enough juice (most TTL chips stop working below 4.75V), but doesn't go above their limit (most TTL chips will start to fail above 5.25V).

Cool, will do that, thanks!