Embedded Files
Wecome To The New Home Of TheEPROM9
Jumper Wire Fun
Jumper Wire Fun
The CASIO PB-700, it use to go every where with me. When I first got it off eBay it did not work although I knew this before hand. The only thing to do when you have a dead device is to fix it. It would get damaged by continued disassembly so I took a shot when I reparied it for the last time. It is sadly designed to be never opened after it was built. There are of photos of inside it on Google, my camera was not handy when I first did the repair.
The device had a broken battery connecter, so that was replaced with one from my junk box. A past leak of some old battery's had corroded through a trace on the PCB. So all that was needed was a jumper wire to replace the trace. As there are millions of wires in the device already, the new wire did not look out of place. The device is SMT and non SMT components soldered in SMT style, so soldering the new wires was tricky, but I succeeded and got my self a computer that I use to take almost every where with me. I think I have done this repair about five times now & I think I have finaly managed to sucessfuly nutralise the alkaline from the batterys.
This was a quite funny irony I had back in the day. The computer is designed for programming, so I ask the programmers in college to program the device. Every one of them failed at it. The only thing any one of them except me was able to do is make it beep. I was the only one able to program it to do maths and print interesting stuff on the screen as well as just make it beep.
When it comes to CASIO PB-700 repair from a leaked battery, always look at the traces on both sides of the PCB, it is a common issue with these machines. It is only a double sided PCB, not multi layered. Always test at the points where the trace goes through the PCB to the other side as this was where the corrosion had done the damage in mine.
Look for good solder pad, something on component or PCB pad further down the trace. Then solder a jumper wire to it. Also the computer is alsomost 40 years old so you should check to see if the electrolytic caps are still good and check the crystals frequency as I have herd of them losing their frequency over time, although I think that only applies to the ones in the cans. Correct me if I'm wrong about the crystals.
Some links with more info:
https://www.old-computers.com/museum/computer.asp?st=1&c=474
Page updated
Google Sites
Report abuse