Idiot building a MK14 thread
 

Evening all. I'm gathering the parts now for the build - still a few more to come in but thanks to all that have provided things so far.

Question:

I am assuming all chips should use sockets - what sockets should I use? For my PET work, I used turned pin, but I'm thinking it's better here to use DIL sockets. Is there a 'right way'?

Ta.

Colin.

Re: Idiot building a MK14 thread
 

You can buy turned pin gold plated 60 way single strip sockets for a few bob. I dont do much chip work anymore, but I always fit DECENT sockets when I do.
A few pics ( sorry, they are a bit blurred ) to show what I mean.
They are very easily cut to any length. They have very nice gold plated four finger actual connectors inside the strip. 100 cost me $25 so about 12 quid for you.

Joe

Re: Idiot building a MK14 thread
 

I always use these from RS, either Winslow or RS Pro, both equally good:
https://uk.rs-online.com/web/p/products/0813193/
https://uk.rs-online.com/web/p/products/0813187/
https://uk.rs-online.com/web/p/products/1831562/

Re: Idiot building a MK14 thread
 

The only argument against turned-pin sockets is that they are difficult to remove from a double sided PCB if you only have basic desoldering tools. This is a new-build board and should work first time and you shouldn't need to fit (or remove) chips more than once, so here I would say use turned-pin types.

The only thing you could potentially get wrong is to put a socket in 180 degrees out. While that wouldn't make any electrical difference (you could still plug the IC in the right way around) a socket fitted the wrong way around will, sooner or later, fool someone into fitting the IC the way the socket indicates it should be fitted - so try to fit them all the right way around.

On this particular PCB the 'key' to show you which way around the ICs / sockets should go is not as obvious as usual, but if you have the front / keypad area edge closest to you and the rear edge connector furthest away then ALL of the DIP ICs / sockets should be fitted with their pin 1 / notch / dimple end pointing towards the left hand edge.

Re: Idiot building a MK14 thread
 

They are the same as the strips I showed Phil. BUT, with single way you have one item on the inventory not as many as there are chips on the PCB. At average a quid each you can buy 12 sockets.

Joe

Re: Idiot building a MK14 thread
 

Although using 2off SIL strips means there won't be any indication which way round the IC needs to go (Although maybe the replica-PCB has it silk-screened).

And soldering SIL-strips, so that they are straight is a bit more tricky, as they can be a bit wobbly with only a single row. So might need to tack at the end first and re-heat / re-align. Otherwise inserting the DIL IC's can be a bit tricky (Can be anyway with turned-pin sockets, that don't have the raised sides many standard ones have, to aid pins going in straight)

Re: Idiot building a MK14 thread
 

I cannot believe the negativity!!!.
Ortek, have you ever tried soldereing the strip in with one pin first, so its perfectly aligned?. then soldering the remaining pins ?.

SiriusHardware, ever tried painting a little dot where pin one is?, or putting the same dot between the top pins ?, like pin 1 and 14
1 and 16
1 and 18
1 and 24 etc etc .

You can use a fine whiteout corrector,
or a paint marker,
which added to the origional single purchase of SIL strips, is still cheaper than buying one or two or three DIPS that fit??

Joe

p.s. IF you need remove a single strip, simply cut it into bits with sharp sidecutters and remove it pin by pin.
Then remove the solder with Soderwick or a vacuum pump.

The reason I suggested single strips is its one purchase, not 20 or 30 to suit the chips involved

Re: Idiot building a MK14 thread
 

I’ve changed to using standard sockets for most of my builds using older components. The problem I have with turned pin sockets is that they grip the pins of the IC tighter than the standard sockets, so the first few removals of the old component from a new socket can stress the pin of a difficult to replace component. After about five or six removals the turned pin socket doesn’t grip the component any tighter than a standard socket and I think when you get to ten removals they are weaker grip than the standard sockets.

By standard sockets I don’t mean the old texas instruments type that contact the edges of the pins, but the now common type that contact the inside and outside face of the pin.

If I’m experimenting with old components I might use the same part in three or more different boards, so it has to suffer three or more new sockets. I’d rather scrap and replace a socket, at the risk of damaging the board, rather than damage a dificult to replace component.

Its a different consideration for an old original board, but then the turned pin socket becomes a risk if it needs to be replaced.

As its just hobby stuff it doesn’t really matter about long term reliability or its ability to survive difficult environments, shock and vibration.

The turned pin sockets only improve reliability if you fit a component once and don’t remove it. One of my first jobs was commissioning and testing custom printers, the only way we achieved any kind of reliability was to tiewrap the Eproms to the socket and direct solder as much as possible.

Re: Idiot building a MK14 thread
 

Many years ago Joe we used to buy just the actual metal sockets on a break-away strip,
no plastic surround, all metal - remember those? awful things, but cheap & cheerful :)
I may still have some, my synth was built using them IIRC
I have used Joes turned-pin strips, I plug a scrap IC in to orient them whilst soldering, doesnt even have to be the right length IC :)
Some of the turned pin sockets are decades old and have had (still do have) chips in & out gazillions of times like my eprom & pic programmers :)
Like everything, its just personal preference, you go with what you trust :)

Re: Idiot building a MK14 thread
 

I did use those once, but never again. At least they are easy to remove.

Timbucus was looking for some recently to build a replica champ, not sure if he found any though.

Re: Idiot building a MK14 thread
 

Yes, I also bought some of those metal strip socket pins (I do recall they had a particular name but can't recall it at the moment) back in the 80's, in order to mount a (non-standard width) LCD, above a 7106 DVM IC. But display pins were fiddly to align into these.
Although SIL strips are still very-useful for this etc. (I often use the fully plastic enclosed 32way cut-to-length 0.64mm sq pin type ones, for making particular lengths).

Re: Idiot building a MK14 thread
 

I apologise gentlemen, if I have spoken out of turn.
A MK14 ( which I know nothing about ) is eons old :shrug:.
I was answereing and adding my two bobs worth in terms of reliability versus cost to begin with.

I spent MANY years as a production engineer. I tried reduce costs and inventory as much as possible, while still producing MANY high quality products. I spent 12 months reducing the 3mm screw inventory from 40 to 3.

NOTHING fell apart!!.

With regards to removing and replacing chips in sockets, there is a way that DOES NOT weaken the socket grip. I have always used a screwdriver, of the correct length and width to gently remove each end of the chip by a half millimetre at a time. This will take about TWO seconds. IF you want the chip to fly out on a witches broom ?? well I cannot answer that.

I have NEVER had the problem of weakening turned socket grip. I did spend MANY months training up a production staff that KNEW what they were doing, if not understanding the electronics themselves.

To end this conversation, if Colin in Scotland wants a few lengths of turned, goldplated 60 pin single lengths, my email is in my details.

FREE!!!.

Joe in 'orsetraylia.

Re: Idiot building a MK14 thread
 

Joe, your input is always welcome and worth reading. I think Colin actually already has a fair stock of turned-pin sockets left over from his epic PET repair, so his question (I think) was simply whether he should use turned-pin sockets or 'conventional' ones.

Re: Idiot building a MK14 thread
 

Hi Joe, maybe the problem I’ve had with turned pin sockets is down to the quality of sockets available, they don’t seem to be as good as they used to be. Same as us I guess.

The socket strips are worth having in the spares box for odd sized chips. 32 DIL in 0.3 inch width isn’t easy to find, but two 16 pin dil seems to work ok. We used to use them for 4x16 segment displays as it was easier to line up adjacent displays.

I find the screwdriver only works on a full socket, the socket strip means levering against the pcb and I worry about damaging traces. I have one of the old chip pullers that grip the IC from both ends, but have managed to destroy a couple of chips if one end slips.

Owen I think the old socket strips were called soldercon, but memory might have faded and corrupted that.

Re: Idiot building a MK14 thread
 

I should probably expand on why I made so much of the orientation of the sockets. The project Colin is about to build is an MK14 replica on a modern home designed PCB. It so happens that on this PCB the screen printed indicators which show which way around the ICs should go are much less obvious than usual.

When the board is built it will be the orientation of the sockets which will be the most obvious indicator of which way to put the ICs in - hence my noting that it is more important than usual to put them in the right way around - especially if they are turned pin sockets, because safe removal of a turned pin socket from a double sided PCB usually involves chopping the plastic carrier to pieces so the pins can be removed individually.

The idea of a paint dot to serve as an indicator / reminder is perfectly sound but shouldn't be necessary once the sockets are fitted with their notched ends all pointing in the right direction.

Re: Idiot building a MK14 thread
 

Thanks all - this generated more discussion than I thought it might. I'll go see how many sockets of which type I have left over from before and take it from there.

Joe - thanks very much for the offer; I'll decline this time but I may be back in future.

Pin 1 is marked with a square pad on this board so even I should be OK getting the sockets in right. Famous last words.

Colin.

Re: Idiot building a MK14 thread
 

Yes! that was it :)

Re: Idiot building a MK14 thread
 

Anyway Colin, let us know if you are unexpectedly short of any other bits...

Re: Idiot building a MK14 thread
 

Watch out for the orientation of the reset button, its not obvious but if its rotated 90 degrees then reset will be permanently shorted to ground.

Re: Idiot building a MK14 thread
 

Yes, I recalled they were called ...Con, but I wasn't sure of the first bit.
So thanks for reminding us what these were actually called.

And now found these featured in a vintage Molex catalogue (Coincidentally on the Deramp SWTPC etc info website, I'd recently been looking at for info on that and the Smoke Signal Broadcasting SS-50 Bus compatible cards).
See page 14 of this catalogue (page 16 of the PDF):
https://deramp.com/downloads/swtpc/h...talog_1973.pdf