I have to agree with Lewm on this one. I made my living for decades servicing all sorts of audio gear. I would regard it as highly unusual to see a chip failure!!
That is worth repeating: I would regard it as **highly unusual** to see a chip failure!!
Usually you see dirty switches and controls that result in poor speed regulation, electrolytic caps failing- that sort of thing.
So I would see an explanation like this as a bid for a lower price on a prospect.
Now, if you live in a tropical environment, the chips are in a little more danger, from corrosion. If you want some simple protection, you can 'pot' the chips with silicon sealer, the clear kind similar to aquarium sealer. I should point out though that in tropical environments the circuit boards in general are in great danger, so usually you have other concerns that far outweigh the chips... In non-tropical environments this is probably not an issue.
These days I do far less servicing than I used to, but I still maintain my own vintage analog synthesizers that I play in my band. They use a lot of unobtainium chips too! I would say the major force that causes the price of such ICs to rise on eBay is mis-diagnosis of other problems in the synth (usually bad connectors and electrolytics)! I see it all the time....
That is worth repeating: I would regard it as **highly unusual** to see a chip failure!!
Usually you see dirty switches and controls that result in poor speed regulation, electrolytic caps failing- that sort of thing.
So I would see an explanation like this as a bid for a lower price on a prospect.
Now, if you live in a tropical environment, the chips are in a little more danger, from corrosion. If you want some simple protection, you can 'pot' the chips with silicon sealer, the clear kind similar to aquarium sealer. I should point out though that in tropical environments the circuit boards in general are in great danger, so usually you have other concerns that far outweigh the chips... In non-tropical environments this is probably not an issue.
These days I do far less servicing than I used to, but I still maintain my own vintage analog synthesizers that I play in my band. They use a lot of unobtainium chips too! I would say the major force that causes the price of such ICs to rise on eBay is mis-diagnosis of other problems in the synth (usually bad connectors and electrolytics)! I see it all the time....