Hi all,
I've been poking around in the loft trying to find donor parts to get my sloppy tape drive back in actio when I found this bad boy,
(http://i66.tinypic.com/2j26ipu.jpg)
I can't remember messing around with it but I plugged it in anyway (Stupid, I know). The LED came on but no picture. On opening, it looked a bit grotty and the solder joints were suspect so I had a deeper look,
(http://i66.tinypic.com/deqw5h.jpg)
The underside was a bit more worrying though,
(http://i63.tinypic.com/m80jlz.jpg)
(http://i65.tinypic.com/25rgvbr.jpg)
The fat red wire from the 5v socket and the tiny bridging wires on the RAM look really gash and the flux/corrosion on the RAM sockets don't bode well.
Here are my questions:
1. Should I be worried?
2. Are the extra wires a bodged repair/mod?
3. Is it salvageable?
You can take a look at our motherboard scans here: http://www.cpcwiki.eu/index.php/Mainboard_Versions
It seems that version 3 mainboards had many patches.
I hope you have luck and cleaning and resoldering the sockets will bring your cpc back to life.
Sent from my iPhone using Tapatalk
Aaahhhh, I see that it's not just my board that has shitty flux all over it.
I assume then, from the scans, that the extra wires on my board are a workaround for duff traces found during testing?
Should be worth a clean up/re-solder............
That's a seriously bodged repair job. It's probably salvageable, but it would be a massive amount of work. It looks like the repairer destroyed the traces on both sides of the PCB while removing the old RAM, so the data lines had to be bridged, if he tore the vias out then it probably doesn't work yet. He did the same on the 74LS153 ICs and also filed the expansion pads away, so you would need to install centronics ports instead. I doubt it's worth repairing (and I don't often say that), keep it for spare parts.
Unfortunately I see boards in this state more often than I'd like, which is why I always say - If you're not 100% sure you can do the repair properly, give it to someone who can.
Bryce.
Wow... that is a seriously damaged one. I have never seen something similar in before :-X
I was given a 6128 PCB last year where the owner had done something similar to the two ROMs. But tearing the traces wasn't enough, they then drilled the pin holes with a 1mm drill, removing the vias completely. I got it working again, but it looked shit, so I've been using it for spares since then.
Bryce.
Thanks for your advice gents.
I think I'll keep it for a rainy day project.............
Sod it. I'm going to attempt a refurb on it. :o
One question, the KM4164B's. Do they have to be -15 or can I get away with -10 or -12?
Quote from: Homr836 on 18:59, 06 April 17
Sod it. I'm going to attempt a refurb on it. :o
One question, the KM4164B's. Do they have to be -15 or can I get away with -10 or -12?
Good luck :) - Less
ns is fine.
-10 and -12 are faster than -15, so yes.
Bryce.
My one has been printed wires only one side, and have 5cm between each components on other side... what are theses 464 boards ?
Quote from: freemac on 20:01, 06 April 17
My one has been printed wires only one side, and have 5cm between each components on other side... what are theses 464 boards ?
Eh... No you don't. Even the original 464 prototype was a two layer PCB. However, yours probably does have 5cm between the components as Versions 1 and 2 of the 464 had a long PCB, on version 3 they shrunk the PCB.
Bryce.
Chips were vertical on it.
Last time I opened it shall does suffer a lot. It's board is like dust.
Picture or it doesn't exist. I have no idea what you are describing.
Bryce.
Quote from: Duke on 19:32, 06 April 17Good luck :) - Less ns is fine.
Ahh ns. That makes sense. Maybe I should read data sheets instead of thinking it was a variation on the part No :picard:
ns with the least significant digit missing. ie: -15 = 150ns etc.
Bryce.
UPDATE!
I've removed the 5v socket, the cap, the RAM and the mux chips. Scrubbed the flux residue off and it looks like a very very bad desoldering job, so I took a couple of pics:
(http://i64.tinypic.com/23h8xgo.jpg)
The traces and vias for pin 2 on the multiplexers and pin 10 on IC113 have gone which would explain the tiny bridging wires that were in place before I started this.
(http://i65.tinypic.com/2nbvcqq.jpg)
The +5v pad for the power socket has been obliterated as have the traces which have been "repaired" using solder to cover what was left.
I can't see much more damage but need to have a poke around with the multimeter to make sure all the other traces are intact.
Can the damaged traces be reinstated with something like this? http://www.maplin.co.uk/p/circuitworks-conductive-pen-standard-tip-n73aa
I tink that it does not look so terrible now that it is clean. It is still bad but recoverable. If I was repairing it myself I would definitely solder wires to replace those broken tracks rather than painting them with silver. It is probably the most robust approach. Regarding the RAM I would be soldering sockets in there and then bridging the required places with wire soldered to their pins, underneath the board. For the expansion ports I would install centronics and get rid of the edge connections and for the PSU I would just solder a relatively thick cable :)
Quotefor the PSU I would just solder a relatively thick cable
[/size]
That would explain the big fat red wire that was hideously bodged in.
[/font]
Quote[/size]Regarding the RAM I would be soldering sockets in there and then bridging the required places with wire soldered to their pins[/font]
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They were already in place before I started, so hopefully it should come back to life once I've properly re-soldered them back on........
Quote from: Homr836 on 19:46, 18 April 17
Can the damaged traces be reinstated with something like this? http://www.maplin.co.uk/p/circuitworks-conductive-pen-standard-tip-n73aa (http://www.maplin.co.uk/p/circuitworks-conductive-pen-standard-tip-n73aa)
No, those pens make extremely unreliable connections and will only cause you issues. Solder the new sockets in place and then use jumper wires to replace the broken traces.
Bryce.
(https://68.media.tumblr.com/4b37dedcd561a03e8ddab543e8bb432b/tumblr_nawib209ad1sjb9uao1_400.gif)
IT LIVES!!!
Sort of..........I've just fired her up to check the functions and the screen is full of dots
(http://i68.tinypic.com/9kmsti.jpg)
The keyboard functions normally but I can't test any tapes as the play/FF spool has snapped and I can't connect my HxC,
(http://i65.tinypic.com/t83l1d.jpg)
None of the ICs are warm/hot. Is there a bad connection somewhere?
To do:
1. Wait for the Centronix connectors and fit them.
2. Source a replacement play/FF spool. (Industrial strength evostick doesn't cut it)
3. Find some case screws from somewhere as I have mislaid the originals.
4. Install RAM upgrade.
Can anyone help with points 2 or 3 please?
My bet is a dodgy address line from the CRTC or a corrupted ROM.
Bryce.