Strange issue trying to start my Amstrad CPC 464

[Nepsekie]

Hi    Completely new user here with zero experience working on old computers. I don't know if my question is stupid or unanswerable, so I'm just giving it a shot!
I just got my parents old CPC 464 out of their basement to try and relive some of those good old memories.
However, when I tried starting up the old fellow, I immediately hit a wall 

I plugged the keyboard into the monitor, turned on the screen and then flicked the keyboard on - for a brief second the "on" display lights up red, but then goes out and remains off even if I flick the keyboard switch again. Strangely enough, if I turn off the monitor and repeat the process; turning on the keyboard after the monitor has been rebooted, the "on" display flashes again, but nothing else happens and the machine remains dead. The monitor itself seems to work (gives of a sound and flashes when I turn the brightness wheel).

I've cleaned up most of the dust from inside the keyboard (motherboard and what ever else I could get at without making too much trouble), but I haven't dared tampering with the insides of the monitor.
I'm guessing somethings wrong with the power supply, but I wonder why it seems that turning the monitor off and on again is able to give the keyboard just the tiniest kick of life, before disappearing again.

If anyone can help or knows what might be going on, I would be much obliged 

[Dagger]

Could just be the on of switch on the computer. Just a poor contact. Take the computer apart and short the 2 contacts on the on/off switch with a pair of pliers etc and then turn the monitor on. If the Computer stays on while the switch is shorted then you have found the problem

[arnoldemu]

Welcome!

I had a similar problem on a cpc6128 and it turned out to be a voltage regulator inside the monitor itself.

But, I would try @Dagger's suggestion first because I also had a computer that wouldn't turn on reliably and it was a bad contact in the switch.

If it is inside the monitor then there are a few people on ebay who sell scart leads with power supplies and you can then connect it up to a television.

[Bryce]

Hi and welcome,
      it sounds like a regulator problem as arnoldemu said. Either the regulator circuitry is damaged, or something is shorted in the CPC that is causing the regulator to trip. Here's a test to do without opening anything:

Connect a generic 5V power supply (5V, negative on outer ring) to the CPC (monitor completely disconnected) and see if the power light then stays on. If the LED stays on, the regulator circuit in the monitor is damaged. If the LED goes out then the CPC has a short circuit inside. If the LED stayed on, connect the monitor (5 pin) connector and see if a CPC screen appears.

Bryce.

[Nepsekie]

Hi and welcome,
      it sounds like a regulator problem as arnoldemu said. Either the regulator circuitry is damaged, or something is shorted in the CPC that is causing the regulator to trip. Here's a test to do without opening anything:

Connect a generic 5V power supply (5V, negative on outer ring) to the CPC (monitor completely disconnected) and see if the power light then stays on. If the LED stays on, the regulator circuit in the monitor is damaged. If the LED goes out then the CPC has a short circuit inside. If the LED stayed on, connect the monitor (5 pin) connector and see if a CPC screen appears.

Bryce.

That did it    Thank you very much! That goes as well for the other replies!

[Bryce]

So it was a damaged regulator in the monitor?

Bryce.

[Nepsekie]

Well, I suppose, but then again, I haven't checked inside the monitor. Replacing the 5v cable with a new one connected directly to the socket made it possible to bypass the problem. I don't really know how to go about checking the actual issue inside the monitor, but it's not as pressing matter at the moment - still just trying to familiarize myself with OS :-)