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General Category => Technical Support => Hardware related => Topic started by: Sleazy on 21:23, 16 April 15

Title: please help, I've made a terrible mistake!
Post by: Sleazy on 21:23, 16 April 15
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?
Title: Re: please help, I've made a terrible mistake!
Post by: TotO on 22:29, 16 April 15
Probably the +5V PSU that you have used had the polarity inverted. Please, add a picture of it.
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 22:31, 16 April 15
Was the polarity wrong or something else? If not, then the CPC probably just has dirt on the power switch.

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 22:45, 16 April 15
(http://i23.photobucket.com/albums/b357/sleazycome/Mobile%20Uploads/DSC_0701.jpg)
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 22:48, 16 April 15
And was the polarity also correct?

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: XyphoesRe on 22:54, 16 April 15
Show us the other end of the cable with its connector you plugged into the cpc to check if polarity was wrong or right
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 23:06, 16 April 15
(http://i23.photobucket.com/albums/b357/sleazycome/DSC_0702.jpg)
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 23:09, 16 April 15
Hmmmm.... Polarity wrong. You've fried the CPC. It could be one or more ICs that have failed.

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: TFM on 23:12, 16 April 15
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!  :)
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 23:14, 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
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 23:14, 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.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 23:29, 16 April 15
Looks like I'm back on the lookout for a 464.

Many thanks for your help
Title: Re: please help, I've made a terrible mistake!
Post by: TFM on 23:31, 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?



Title: Re: please help, I've made a terrible mistake!
Post by: qbert on 23:40, 16 April 15
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


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.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 23:46, 16 April 15
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?
Title: Re: please help, I've made a terrible mistake!
Post by: qbert on 23:46, 16 April 15
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).



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

Many thanks for your help
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 23:54, 16 April 15
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
Title: Re: please help, I've made a terrible mistake!
Post by: kevin.c on 08:56, 17 April 15
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.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 09:53, 17 April 15
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
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 10:42, 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.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 11:00, 17 April 15
thats a great offer Bryce - thank you very much.


Where are you though? Are you actually in Sao Tome?
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 11:06, 17 April 15
: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.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 11:09, 17 April 15
ah cool (I'm actually surrounded by Germans as I type this).


yes please drop me a line
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 11:37, 17 April 15
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.
Title: Re: please help, I've made a terrible mistake!
Post by: qbert on 12:44, 17 April 15
Bryce, you're definitely a champ' !  :D

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.
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 13:48, 17 April 15
I don't like to see retro computers abandoned just because they are broken.

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: VincentGR on 17:27, 17 April 15
I am interested for the case/keyboard&tape deck if you are selling them  ;D
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 17:42, 17 April 15
Once my replacement has arrived I'll be offering it up on here - wanna wait to see condition of replacement first.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 13:10, 24 April 15
So replacement turned up.....


and it doesnt work! just a blank screen (power light comes on and monitor recognises input but nothing displayed).


I'm not having much luck.


(https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpa1/v/t34.0-12/11178555_10153019860637182_943578125_n.jpg?oh=49bfb0d62189f7618756987b09bc5f26&oe=553CB00E&__gda__=1430034975_ef795ff7cd0e653941dc800faa745dfc)
Title: Re: please help, I've made a terrible mistake!
Post by: Carnivius on 15:16, 24 April 15
Aw no.  :(


Also, strange place to keep your razor blades.  Don't do anything silly.
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 16:03, 24 April 15
Time to send BOTH PCBs over to me I suspect :(

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 16:23, 24 April 15
Aw no.  :(


Also, strange place to keep your razor blades.  Don't do anything silly.




Lol, I had been sorting through the cupboards in my spare room when the parcel was delivered - there was rubbish everywhere - I dont even know where the blades came from - I use an electric shaver.
Title: Re: please help, I've made a terrible mistake!
Post by: TFM on 19:26, 24 April 15
Nothing beats real blades  8)  ... therefore I gave up shaving...  :laugh:
Title: Re: please help, I've made a terrible mistake!
Post by: Gryzor on 20:05, 25 April 15
Best thing I've ever tried - double-edged Mercury safety razor. The old, traditional ones with the single, replaceable blade. Also: Super Iridium blade. Made in St Petersburg, blow everything else out of the water.

Off topic is off topic.
Title: Re: please help, I've made a terrible mistake!
Post by: TFM on 21:23, 25 April 15
Sorry for offtopic too, but isn't is called 'terrible mistake'. While shaving this 'terrible mistakes can happen of course. So, I never heart about Iridium blades, but that sounds really awesome!  :)  Thanks for the hint!  :)
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 13:56, 26 April 15
Best thing I've ever tried - double-edged Mercury safety razor. The old, traditional ones with the single, replaceable blade. Also: Super Iridium blade. Made in St Petersburg, blow everything else out of the water.

Off topic is off topic.

So why don't you use them? You were half / not shaved any time I met you :D

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: Gryzor on 14:00, 26 April 15
I was turning on the charm :D
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 14:01, 26 April 15
I was turning on the charm :D

It worked ;)

Bryce.
Title: Re: please help, I've made a terrible mistake!
Post by: Gryzor on 14:02, 26 April 15
Awwww, you.... =)
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 22:24, 01 May 15
So third cpc arrived today.. This time with a colour monitor.

It's missing the left shift key and the numeric  0. No problem I thought,  I have 2 donors here.

The first cpc is the smaller mobo later revision and the second is the earlier big mobo. Both have sprung keys.

This new cpc is actually different to both! It's keys are not sprung and the keyboard is hardwired rather than the thin ribbon of the other two. The mobo says 1983 rather than 1984.

At first the broken shift was constantly on so I had to remove the presser bit.  The Cpc is totally usable but isn't as pretty as I'd like.

How difficult is it to get keys that match? 

On the plus side I can now play Rainbow Islands rather than Greenhow Islands!
Title: Re: please help, I've made a terrible mistake!
Post by: Bryce on 22:28, 01 May 15
So the broken keyboard has "High" keys and a real connector to the PCB instead of flat cable? It must be a very early CPC. Getting those keys will be difficult, but you might be able to use the top half (keys and plastic frame) of one of the working/complete keyboards with the PCB of the old keyboard?

Bryce.

Edit: Ask Gryzor if you can have some of his fridge magnets. (He'll know what that means :D )
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 18:19, 19 May 15
Finally managed to get the last missing pieces and my 464 is now perfect.

Got them off a fella on Facebook who seems to fix cpcs as well as other systems.  Wonder if he is a member here?

(http://i23.photobucket.com/albums/b357/sleazycome/Mobile%20Uploads/DSC_0751.jpg)
Title: Re: please help, I've made a terrible mistake!
Post by: EgoTrip on 18:58, 19 May 15
What's that monstrosity doing next to the CPC monitor? I suppose it could be worse, its only a monitor. Could be connected to an actual C64.
Title: Re: please help, I've made a terrible mistake!
Post by: VincentGR on 19:00, 19 May 15
What's that monstrosity doing next to the CPC monitor? I suppose it could be worse, its only a monitor. Could be connected to an actual C64.

hahahahaha
actually this is one of the best monitors  ;D
Title: Re: please help, I've made a terrible mistake!
Post by: Sleazy on 23:04, 19 May 15
It's usually connected to an A600 or Cd32.  It is a nice monitor.  I got it for nowt last year off a mate who found it in his garage.