News:

Printed Amstrad Addict magazine announced, check it out here!

Main Menu
avatar_Sleazy

please help, I've made a terrible mistake!

Started by Sleazy, 19:23, 16 April 15

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Sleazy

I hope someone can help.

I got a Cpc464 a couple of weeks ago.  It was working great last night.  I just tried to power the keyboard with a 5v adapter and nothing happened,  no light no nothing.

Now when I plug into monitor I still get nothing.  There's power getting to monitor but keyboard is utterly dead.

Have I ruined it?

TotO

Probably the +5V PSU that you have used had the polarity inverted. Please, add a picture of it.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Bryce

Was the polarity wrong or something else? If not, then the CPC probably just has dirt on the power switch.

Bryce.

Sleazy


Bryce

And was the polarity also correct?

Bryce.

XyphoesRe

Show us the other end of the cable with its connector you plugged into the cpc to check if polarity was wrong or right

Sleazy


Bryce

Hmmmm.... Polarity wrong. You've fried the CPC. It could be one or more ICs that have failed.

Bryce.

TFM

600 mA is a bit weak. The native CTM delivers about 1400 mA. Can that be the cause?


The previous given advice of cleaning switches etc. is a good idea.


Good luck!  :)
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Sleazy

Quote from: Bryce on 21:09, 16 April 15
Hmmmm.... Polarity wrong. You've fried the CPC. It could be one or more ICs that have failed.

Bryce.

Sounds like it's not an easy repair then.?

Guess I have ruined it.

Gutted

Bryce

Even with 600mA, the polarity was wrong. Cleaning switches won't help. The RAM has most likely failed, maybe the Z80 too and who knows what else.

Bryce.

Edit: It can be fixed of course, but it can get expensive depending on what's actually damaged.

Sleazy

Looks like I'm back on the lookout for a 464.

Many thanks for your help

TFM

Quote from: Bryce on 21:14, 16 April 15
Even with 600mA, the polarity was wrong. ...


Upps, you posted to quick. Are you sure that wrong polarity will fry it? Does it make sense to check with a PSU or right polarity at all?



TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

qbert

#13
From my own experience, vintage RAM chips are still found easily. If the most fragile component of them all (as Bryce suggests), it can be easily replaced, provided you know how to solder and really want it (it may be easier to solder sockets instead and just plug the sensibles RAM chips on the sockets).

Whatever, you need a detailled diagnosis before doing something like this. RAM fail is usually detected as a frozen screen when booting : the system should power on before that.

Can you confirm the red power led stay dark ?
Bryce... is there a simple way to check the nearest discrete components near the power input ? I always thought that the failling of an only component will immediately open the circuit and protect the other ones.
A multimeter could be a good friend for this job, but we need someone familliarized with this hardware.  ;D


Quote from: Bryce on 21:14, 16 April 15
Even with 600mA, the polarity was wrong. Cleaning switches won't help. The RAM has most likely failed, maybe the Z80 too and who knows what else.

Bryce.

Edit: It can be fixed of course, but it can get expensive depending on what's actually damaged.

Sleazy

The power led stays totally dark. It didn't even light when I plugged it into the adapter,  usually I would expect it to light with the surge before failing?

qbert

From my point of view, that story is ridiculous. A least, never trash the whole unit. In case you are not able to repair, many components inside are possibly still functional and will make good spares for another failling unit. The "Gate Array" (chip labelled 40007 or 40010) being the most precious of all !

(And of course the whole plastic casing may be swapped with a less beautiful unit).



Quote from: Sleazy on 21:29, 16 April 15
Looks like I'm back on the lookout for a 464.

Many thanks for your help

Sleazy

Oh don't worry.  I'm not binning it. Hopefully I can pick up a tarry looking but working keyboard and use this as a donor.

It's really nice and clean

I feel so stupid

kevin.c

#17
You said  power led stays totally dark. This means short circuit, and this is the hope! First IC that faild with reversed Vcc and got voltage down could protect the rest, but for sure some more IC'c could be damaged.
Look  on Bryce's personal text please (under his photo). It's not a joke, it's  Good Electronic Engineers war cry.

Sleazy

Thanks,  I think a repair is way beyond me. I wouldn't know where to start.

I think tracking down another keyboard and if necessary using this on to spruce it up is the way forward

Bryce

If you send it to me (just the main PCB, not the whole computer), then I can test it and repair whatever is actually broken (if it financially makes sense).

Bryce.

Sleazy

thats a great offer Bryce - thank you very much.


Where are you though? Are you actually in Sao Tome?

Bryce

:D No! My confusing flag is sort of a running joke since I joined (I move islands regularly). I'm actually in Germany. I'll send you a PM with the details / address etc if you want.

Bryce.

Sleazy

ah cool (I'm actually surrounded by Germans as I type this).


yes please drop me a line

Sleazy

Many thanks to Bryce for his kind offer,  I have managed to acquire another working keyboard unit for £20 delivered.


Harsh lesson learned.


Many thanks to all of you for your comments, this really is a friendly and helpful community.

qbert

Bryce, you're definitely a champ' !  :D

Quote from: Bryce on 08:42, 17 April 15
If you send it to me (just the main PCB, not the whole computer), then I can test it and repair whatever is actually broken (if it financially makes sense).

Bryce.

Powered by SMFPacks Menu Editor Mod