Lardo Boffin wrote: ↑Sun Dec 15, 2019 12:43 pm
Presumably the major issue with bent pins on an IC is that it makes maintenance more difficult in the future?
Would it be possible to fit a low profile socket, then fit another socket (pins bent out) and put the IC in that? Only the sandwich socket is modified and the RAM chips are easily swappable?
Or would the additional socket start to cause issues with good connectivity from IC to PCB?
It’s for each person to decide which method they prefer. My primary reason is so that I can swap ICs easily (during fault finding or when experimenting or modifying). And I have no issues with modification of PCBs. When I make PCBs, if I make a mistake, or change my mind later (original part no longer available for a reasonable price say, or in order to amend the functionality), I have no scruples about cutting tracks. The same as original equivalent manufacturers would have done, and indeed did do in the past. Both Acorn and Sinclair amongst others recommended modifications (by service agents) to existing PCBs and until a new board issue could be produced, included modifications to the current production run. Sometimes this involved bent pins, but other times it included cutting tracks. Sometimes both. Often the actual method used depended more on practically and ease rather than anything else.
If ZX81s were ultra rare, then yes, then you would maybe keep it completely original. But that means keeping it as a 1K byte machine. All of the ZX81s that I have modified arrived in a poor state, either incomplete, non-working, faulty or damaged in some way. So if not repaired/fixed, they could have just been binned. The working ZX81s that I have in good condition have not had any modifications carried out. Although I dare say I am behind compared to some members here with the number of ZX81s that I have bought
. In fact, I have only modified four ZX81s so far out of the twelve that I have (some are in storage in the awaiting attention “pile”), and one of these had already been changed from a stock model (a TS1000 issue 3 board where someone had cut R30 out). How many people have ripped the guts out of the modulator so that a composite video circuit board can be fitted inside?
If there is space (in a ZX81 there is space for at least a single extra socket, that is PCB socket, ‘sandwich’ socket and IC) and if the existing socket contacts are still tightly fitting, yes you can use a couple of stamped pin sockets to act as adaptors. Or use a single socket if all the bent pins are going to be picking up signals via wiring that does not need to access the existing PCB socket contacts (unless the existing socket is a turned pin socket). Or use a single socket mounted on stripboard with suitable pins to fit in the existing PCB socket. However this later approach may expand the contacts in the existing PCB mounted socket, such that if a chip is reinserted, not all pins may make good contact
.
Most sockets these days are described as low profile. If you want really really low profile, that means that the socket pins must be designed such that the part that acts as the socket for the IC pin also goes through the PCB. Hence the PCB holes have to be a bigger diameter. These won’t fit in an existing socket.
Anyway, I’ve waffled on for far too long. Do only what you feel happy about
.
Mark