Roland CR-78: Repair broken traces and pads

[tonewill]

Hello,
Can anyone please advice me on how to repair broken traces and IC pads? The board is double-sided and the traces are quite thin and close together. I want to make as good a job as I can. Is there a recommended kit or something I can buy? I'm okay with a soldering iron and have patients.
Thanks for any help.

[wackelpeter]

perhaps post some pics of the PCB and the broken traces... maybe someone has a clever idea... for example when it's broken between 2 components with legs were you can solder like diodes, resistors or some caps you can easily use a wire soldering between both Points...

I'm still having mine open since months, as i need to replace some IC's there and then will perhaps go to socket most of the IC's... and eventually re-cap the whole Thing...

[tonewill]

I've attached a photo. A bodge attempt was made with wires but I want to make it better than that.
Many thanks.

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[ringroad]

You could try a silver conductive pen to redraw the tracks - never having used one myself I don't know how how accurate you can get with them, and looking at that you'll need to be good at it. It might just be better to attach wires.

[tonewill]

Conductive pen isn't going to be fine enough. I've watched demos of these on youtube, much too crude.

If anyone can advice on repairing the tracks and pads or where to buy such things please let me know.

Thanks a lot.

[DES]

Wow. Thats going to require some work, patience, and a steady hand. I would look for an IC socket with extended length pins...something like the old wire-wrap style sockets. The big issue hear is it seems to be a double-sided board with connections to the IC on both sides. If you find a suitable socket, insert it into the holes but make sure it is ~1/16 to 1/8" above the top of the pcb to allow you to thread/loop fine wire under the socket and around the pin (put a hook on the end of the wire feed it under the socket around a pin then squeeze/pinch it together then a dab of solder. Use fine bare wire...24-28 gauge, whatever you can get hold of. I prefer silver when possible. If you have stranded hookup wire try using the steands. Once connected to the pins, route them along the original circuit path til you get to the broken trace and attach. hold the wire in place with crazy glue or similar (note crazy glue gives off terrible fumes when heated!)

Another possibility...Get a thin flexible circuit made that has the ic pin hole layout on it. Make it just big enough to fit over the pins. If you can, design the flex circuit so there is a little extra pad at each pin so you can attach leads to it.

Good luck...thats going to be 'fun' repair!

[tonewill]

Thanks very much for all the info Dave.

Regarding the solder pads for the IC pins, can 'replacements' be had in some kind of repair kit? I just wan't to get it as good as possible. I searched for repair kits online but came up with over-the-top kits for people who do this kind of thing all the time.

Thanks again.

[wackelpeter]

Reading DES's Reply following came to my mind:

Mounted on a piece of stripboard, are hte IC's Pins long enough to fit in the socket?

If yes, i would mount the IC on the copper side of the stripboard, of Course cut or drill the traces before, and make the stripboard a bit wider than the IC is, so you have 1 or 2 solder joints on each pin left... the you can solder the Pins of the IC to the stripboard from the side and replace those traces missing with small wires from there...

But would be very cautious because perhaps you could mess up the IC.

don't know if this would work, but perhaps worth keeping a short look at it.


Edit... just looked at it closely with an normal IC... doesn't work properly because the Pins are too short... could perhaps work instead with a additional socket with longer Pins... do they exist?

found something, but don't know if the pin amount Matches...

https://www.reichelt.de/IC-Sockel/DIL-24-NG/3/index.html?ACTION=3&LA=2&ARTICLE=113266&GROUPID=7429&artnr=DIL+24+NG&trstct=pol_2

or if These are also available with longer Pins they could work too perhaps

https://www.reichelt.de/IC-Sockel/SPL-20/3/index.html?ACTION=3&LA=2&ARTICLE=19398&GROUPID=7429&artnr=SPL+20&trstct=pol_7

[tonewill]

Thanks for the extra info, very helpful. This may be the answer if repair pads aren't available in small quantities. Dave mentioned the longer pin sockets also and those are available on ebay. I was hoping to make it look as near original as possible but it's looking less likely.

Thanks again.

[DES]

There was a company that used to make a trace repair kit..can't remember the name...and while you could replace individual pads on ICs, it was a pain to keep the pads in place while soldering especially if there were traces running between pads. Also you might be able to find the flexible IC circuits as very thin pcb material instead of the kapton/brownish flexible circuit material. Maybe in proto-typing supplies?

Saw a couple suppliers of wire wrap ic sockets on Amazon...Jameco has them too. CircuitMedic has kits though pricey from them...looks like JanelOnline sells some of the CircuitMedic stuff cheaper. You could look at adhesive copper tape and a sharp xacto knife...just watch your solder temp.

[tonewill]

Thanks for the extra info. I overlooked it on an earlier post but I'm not sure what the 'flexible IC circuits' are, are they circuits you get made to spec like normal circuits boards or are we talking about something else?