Assessment and fault finding… will it work?
My recent purchase of a Sony Discman D-121 from EBay has arrived. Just as described it wasn’t really working so I decided to give it a once over to check condition.

Cosmetically it’s in very good condition, open the battery compartment and it’s a different story, definite signs of corrosion and at this point I’m thinking the worst. I put two batteries in to check, the display comes on and shows some strange indication of “HI VOLTS” even though all I have are the two AA batteries in. Strange.


I do manage to play one song but that’s it, any slight move and it skips and hops and shows a raft of other error messages that don’t Instil any confidence into me that this is going to have a good outcome. Then the CD drive motor breathes its last. That’s it….kaput.


So I open up the unit, and put the circuit board under the microscope. The area around the corroded battery terminal has progressed on to the board and a couple of the circuit board tracks have been totally destroyed. A few components look to have issues and have some spurious test results. A check for continuity with the multimeter confirms that one track is dead and another is intermittent at the very least.

I clean the offending section of the circuit board with IPA and this just confirms the issue, but at least it looks cleaner. If this had been the only issue I’d have happily soldered in a couple of thin wires to the undamaged track to ensure a reliable continuity.


A further look around the board, and there’s nothing blatantly obvious, but seeing this unit was produced in 1993 it’s now in its 31st year of use I also suspect the capacitors (of which there are many) may well be of that era of suspect capacitors I discussed on a previous post. Read here: Capacitor plague
The main drive motor is known to fail after time and a sure sign is if the CD jumps when moved off the horizontal, apparently this is due to bearings becoming misshapen due to use.
This unit therefore is beyond economical repair for me, and I’m not going to progress it any further. The good news is that I can use the unit for spares and as a number of these older units have interchangeable parts, I’m hopeful that as I have a few more units turning up later this week they may have a willing donor.
So the recycling goes on, and that’s always a good thing.
Happy day to you all.














































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