Jumpers that "skip" and making resistors/diodes non-solder changeable - Page 1
Forum section: electronics / repair

author: analogix
author_rank: Frequent Contributor
timestamp: October 29, 2017, 12:50:58 pm
content: I've got some circuit boards (voice cards for an old digital drum machine) which can be configured differently according to which sound (contained in an EPROM) is used. Bent wires are soldered in place of jumpers and different resistors, diodes and I believe capacitors as well are used for thevarious sound configurations as described here.Since these boards are quite expensive I'm wondering how I can easily allow for jumpers and components to be exchanged without soldering/desoldering. I haven't checked the pin spacing of the jumpers yet, but assume they're standard 0.1" (obviously I need to check this).The challenge is that some of the jumper settings skip a pin or two and don't just join together two beside each other.Also, how can I allow a resistor, capacitor or diode to be easily removed and exchanged with another one without soldering?

author: Nusa
author_rank: Super Contributor
timestamp: October 29, 2017, 01:35:47 pm
content: The obvious solution is to put in pin headers in all the configurable locations. Then make up various jumpers with the components you wish to use. For the oddball ones, it'll have to be a flexible jumper of the right length. For the more standard ones, you may be able to use connector bodies (e.g. a 5 pin connector if the pins are 0.5" apart) to make a simple plug-in component.If you really want to get fancy, you can run wires to a configuration board with dip switches or row jumpers to switch various components in and out of each circuit. Or alternately a component breadboard instead of switches.Other variations on the theme, of course, but often the simplest is the easiest.

author: David Hess
author_rank: Super Contributor
timestamp: October 29, 2017, 01:44:18 pm
content: Install collet socket pins; they will hold the leads of small signal parts just fine.

author: analogix
author_rank: Frequent Contributor
timestamp: October 29, 2017, 03:03:32 pm
content: Thanks for both suggestions!I'm not sure I understand though.David Hess: I looked up collett sockets and came across these -is that what you're referring to?So a resistor for example can have its leads/wire pins pushed into those pins and stay there? But I imagine it would be easy to bend/break the resistor leads as well.On second thought: can pin headers be pushed firmly into those? In that case I could solder the resistor across the appropriate pin spacing and simply plug it in when needed.Nusa: I'm not sure if I've understood you correctly, but perhaps (after soldering the pin header rows in place provided the spacing allows for that) I could use Dupont connector for both the components (soldered at the appropriate distance, using a suitable number of pins for that spacing) and the "skip some pins" jumpers. And that way I could build up a complete "configuration sets" for a particular voice card setup, marking each connector with where they are to be used (i.e. "J7" or "R15" etc.) of course with a small dot of paint on the first pin on the PCB jumper and the connector to get the key pin right.Or for the "flexible jumper" (i.e. skipping a pin in some configurations) I could use two 1-pin Dupont connectors with a short wire soldered between the two. But I'm leaning towards bulding dedicated "configuration sets" with connectors that just plug into wherever they're needed, each set neatly organized in their own resealable plastic bag.The external PCB with the components and switches needed sounds elegant, but I'd have to find a place to mount it (so it won't just hang loosely around) and perhaps the long wires would cause noise problems etc.It's funny how the creative juices appear when you start discussing things

author: Nusa
author_rank: Super Contributor
timestamp: October 29, 2017, 03:37:02 pm
content: Yes, you understood me correctly. I was even thinking of dupont-style connectors, although the idea isn't restricted to them.If you reconfigure often, you may want to keep your ROM's in spare sockets to protect their pins, especially if you aren't set up to recreate those ROM's. Better to break a layered socket pin during insertion/removal than a ROM pin.

author: analogix
author_rank: Frequent Contributor
timestamp: October 29, 2017, 08:58:15 pm
content: Good suggestion. Luckily all that data is available from the website I linked to. I also back up my existing EPROMs just in case the ones I already have differ.Finally I'm considering getting ZIF sockets, but understandably not the rather pricey 3M Textool sockets. I'm hoping to find something usable (at least for my hobbyist use) on eBay. I should probably try a couple first, before re-socketing all my 9 or so voice boards (some of them have sockets for two EPROMs).I'm keeping my fingers for the pin spacing of the wired jumpers and the components to be compatible with the 0.1" standard...

author: David Hess
author_rank: Super Contributor
timestamp: October 29, 2017, 09:22:02 pm
content: Quote from: analogix on October 29, 2017, 03:03:32 pmExactly and it works very well. If the printed circuit board hole diameter is correct, then the collet socket pins can be sunk into the board as shown below.QuoteThis can be done but standard square pin headers are too thick. They make special ones to do this including DIP partslike this. I have seen these used to replace DIP packaged logic gates used as drivers which were burning out with a discrete transistor driver.

author: analogix
author_rank: Frequent Contributor
timestamp: October 29, 2017, 09:42:40 pm
content: Very cool! Thanks for the photos which cleared things up.I like the low-profile solution as I'm not sure how much available space there is until components butt into the next voice card. I bet using standard pin headers and Dupont sockets would raise the height quite a bit in comparison (there might still be enough room though -I'll have to do a little experimenting).Plugging the components in like that looks like a quick, tidy and clever solution, but I worry that their legs will break off after repeated removal/re-insertion. So if I need to go for the low-profile solution, it would be nice if I could use Dupont connectors as discussed earlier, pre-mounted with a resistor, diode, jumper connection or whatever and plug it in. Are there pins that match those sockets pictured available to for Dupont connectors (or some other similar type connectors for that matter)?And would this solution be strong enough or would they easily snap off with a little physical force? Pin headers should be fairly robust I think.

author: eugenenine
author_rank: Frequent Contributor
timestamp: October 29, 2017, 09:46:37 pm
content: Maybe they are soldered because vibrations might cause socketed components to come loose.

author: David Hess
author_rank: Super Contributor
timestamp: October 29, 2017, 09:57:57 pm
content: Quote from: analogix on October 29, 2017, 09:42:40 pmI have never had the leads break off.After multiple insertion/removal cycles, the collet sockets get a little looser but I have never had them unintentionally release a lead.Quote from: eugenenine on October 29, 2017, 09:46:37 pmThe fingers inside the collet socket pin grip the leads very well and actually make better contact than a wiping connection. I have used them in high vibration applications like automotive engine compartments without problems even when upside down or sideways.

author: Ian.M
author_rank: Super Contributor
timestamp: October 29, 2017, 10:11:21 pm
content: You can use another strip of turned pin collet sockets as a plug, and solder the jumper wires into the top of the plug. The result will be similar in height to the socketed EPROMs. However as the site you linked to only lists a single connection for each jumper for each configuration, an insulated tinned solid copper wire, of the same diameter as the socket pin, with the ends stripped and formed to fit at the right spacing will do nicely. Cut the ends just long enough to get a screwdriver blade between the socket and the wire to aid removal. The wires will lie nearly flush to the jumper sockets and protrude less than the chips do. For jumpering adjacent pins, bare wire is permissible.

author: analogix
author_rank: Frequent Contributor
timestamp: October 31, 2017, 12:00:05 am
content: Are you saying those collett pins are supplied in break-off strips just like the pin headers? So I could solder one row into the PCB and stick another on top (with the component soldered in, or a wire across for a specific jumper)?That sounds like an ideal solution: low profile and as simple to plug in as a Dupont connector onto a row of pin headers, but without the fuss of assembling the connectors. My only concern is if these are possible to get as cheaply as pin headers/Dupont connectors on places such as eBay? I tried searching for "Collett pin" or "Collett socket" but I didn't find anything resembling what we're discussing here. Perhaps it goes by other names.Oh, another thing now that we're talking collett pins: they look very similar to "turned DIL IC sockets" (perhaps they're the same thing?) of which I have one soldered into a computer motherboard (so I could easily replace a 28 pin EPROM in that location).I'm now about to mount a add-on PCB on top of that socket (and the EPROM on top of that again). The add-on board has a "wire-wrap" type socket made out of two rows of pin headers, so as to have its legs go through its PCB and allow mounting on the motherboard's IC socket. The problem of course is (as you've already pointed out) that pin header's aren't compatible with those collett pins. The only solution I could find to the problem is to get hold of a normal DIL IC socket, plug the add-on board on top of that, then plug the IC socket into the turned socket on the motherboard. Is this the way to go or are there better solutions?

author: Ian.M
author_rank: Super Contributor
timestamp: October 31, 2017, 12:07:59 am
content: Keywords: turned pin SIL

author: David Hess
author_rank: Super Contributor
timestamp: October 31, 2017, 05:19:58 am
content: Quote from: analogix on October 31, 2017, 12:00:05 amThey are the same thing.

author: Ian.M
author_rank: Super Contributor
timestamp: October 31, 2017, 07:42:49 am
content: m-m (pin on both sides) turned pin header strips:http://hobbycomponents.com/connectors/439-01-254mm-40way-sil-turned-pin-m-m-headers-pack-of-5Fit them to any board that must connect to a turned pin socket. You'll generally find the result is far more secure than square pin headers in a leaf spring DIL socket.N.B. the two sides may not have equal pin diameters. check which side fits the socket better before soldering them!One trick when you need a socket on the top in the same location as the header pins without any offset and all pins connected 1:1 is to assemble a turned pin socket on the top side of the daughterboard, solder it, then put a dob of solder paste in each socket hole of another turned pin socket, fit it to the protruding pin ends on the bottom of the board of the first one and reflow it to make all the connections permanent.m-f turned pin socket strips:http://hobbycomponents.com/connectors/392-01-254mm-40way-sil-turned-pin-m-f-headers-pack-of-5Now you know they *CAN* be obtained, you'll probably do better finding an EBAY supplier.

author: analogix
author_rank: Frequent Contributor
timestamp: October 31, 2017, 10:13:35 pm
content: Nice!Those long (turned) pin header strips are probably the solution for that add-on board. I think the solution is to desolder the existing (square) pin headers and replace them with those turned types.Thanks for posting the photos. Yes indeed -I will look for similar pin/socket strips on eBay for way less than most other placesSo I got the time to check one of the PCBs which I want to modify and I'm glad to say the components (resistors, diodes etc) as well as jumper pins are all 0.1" (see attachement)The only exception as far as I can see is one 3 pin jumper-row where 4 pin headers partly match. Does this appear to be another standard (which turned pin headers/sockets are also available)? See attached photos.

author: Ian.M
author_rank: Super Contributor
timestamp: October 31, 2017, 10:34:15 pm
content: Oh lovely, you've got an 0.15" pitch header footprint. WTF were the designers thinking?For that, save the loose pins you invariably get when you snap the SIL socket strips to length and insert them individually, then use loose wire jumpers.N.B. When cutting wire jumpers for collet sockets, for easier insertion and longer socket life, you may need to dress the ends lightly with a fine stone to remove the corners of the burr left by the dykes.