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Power supply problem?

Started by angelcaio, 14:50, 09 August 25

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angelcaio

Hi
This past week I've been experiencing a lot of stability issues with my Amstrad CPC 464.

I've been experiencing frequent crashes, screen distortion, booting with a black screen, booting with a highlighted border and a gray screen, and it keeps crashing.

I recently replaced the DDI1 clone disk controller with a DDI4 clone without memory expansion.

It's been working for a week.
Before experiencing all these problems, I ran some power consumption tests by connecting the GTS 65 monitor to a smart plug and measured and recorded the consumption data in different scenarios:

There shouldn't be any memory conflicts because Piort sent me the ddi-4 memory expansion disabled after explaining that I had an MX4 with an X-Mem connected and didn't want conflicts between them.

I've tried two different CPC464s and the same GT 65 monitor with the same result.

The controller connected alone does work correctly.

My question is if the consumption can be supported  by the GT 65 power supply or should I buy an alternative power supply to connect the CPC464.

The MX-4 expansion board doesn't have a power connection because I bought it without diodes due to previous problems I had with it.
I mentioned this years ago on this forum, 8and TotO replaced my old MX4 with one without diodes and without a power supply   (https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/issue-with-a-mx4-board/msg168022/#msg168022).
so that it could be powered directly from the CPC expansion port.  This has been going on for years and I haven't had any problems until today.

Any idea?
Do you recommend a PSU?
Or could it be another problem?
Thanks in advance

angelcaio

Update.
Today I connected everything except the AMX Mouse, and everything works fine.
The moment I connected the mouse to the system, it crashed in less than a minute.
The mouse is powered by the GT65, and a cable connects to the 5V input of the CPC.
This worked until I replaced the DDI1 Clone with a DDI4 Clone without memory expansion.
I tried powering the mouse with a 5V adapter, but it doesn't work if it doesn't detect any power on the output cable (the one that would connect to the CPC).
Simply measuring the output with a multimeter (it reads 5V or so) makes the AMX mouse work again, until the multimeter cables are removed. I've thought about connecting something that has a 5V power consumption (the red and black cables from a USB mouse to a female barrel connector). Is that a good idea?
Does anyone have another solution? Thanks

GUNHED

GT64/65 are 40 years old now, they deliver too few power. Try to use more PSUs for expansions. Never get power directly from the 5 V line of the monitor if you can use an extra PSU.

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pelrun

The only difference between a monitor "delivering too few power" and one that works fine is a minor adjustment of the VR501 trimpot. It doesn't matter if your new PSU can supply 4A at 5v when the oxidised connectors and connections in the CPC immediately drop half a volt before getting to any ICs. A CPC will be far happier when fed with 5.3V, even if it's only 1A.

Brocky

#4
Quote from: pelrun on Yesterday at 15:29The only difference between a monitor "delivering too few power" and one that works fine is a minor adjustment of the VR501 trimpot. It doesn't matter if your new PSU can supply 4A at 5v when the oxidised connectors and connections in the CPC immediately drop half a volt before getting to any ICs. A CPC will be far happier when fed with 5.3V, even if it's only 1A.
i noticed this too... even with a brand new (recreated) 464 board and brand new power connectors, voltage getting to the chips was always dropping half a volt or more as soon as it hit the board (using external 5v/2A wall wart..a good one!..and no access to an original monitor)... i used a bench power supply set at 1.5A (highest ive seen it pull with 3 expansions on a MX4 expansion board was only 1.2A), and then adjusted the voltage until the z80 read close to 5v on a multimeter... the voltage on the PSU and power jack was up around the 5.6v range...

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