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mike <ham789@netzero.net>: Jun 17 02:01AM -0700 On 6/15/2015 9:55 PM, David Farber wrote: > when the cable from the volume control gets plugged in. If you meant > anything else, I'm not sure what you meant. :-)   > Thanks for your reply.   My Bad. When you said thru-hole caps, I made the wrong assumption. There's no reason you can't solder to the feedthrus. Be aware that they're not very robust. If the hole is big enough, stick a tiny wire thru for the connection. I use solid wire-wrap wire for such things, but a strand from a stranded wire can work.   If there are only 2 layers, you could ream the hole if necessary If there are inner layers, you will break some other internal connection.   Another issue is that if the corrosive stuff from the caps ate the connection, there may be other issues to follow.   I fixed a TEK scope once where the cap goo ate feedthrus for some distance around the caps. Finding where to bridge the gaps was challenging without schematics.   The goo is difficult to clean off, but if you don't do it thoroughly, you'll be fixing it again later. It gets under the SMT chips. Alternating simple-green and alcohol and a toothbrush a few times should take care of it.   I'm far too lazy to decipher the manual. If the caps go other places, you can bridge to there instead of the connector.

John-Del <ohger1s@aol.com>: Jun 17 09:23AM -0700 On Wednesday, June 17, 2015 at 5:03:14 AM UTC-4, mike wrote:   > If the hole is big enough, stick a tiny wire thru for the > connection. I use solid wire-wrap wire for such things, but > a strand from a stranded wire can work.   I just repaired a Snap-On Modis OBDII scanner in this manner. This is a multi-layer board, but fortunately the liquid damage was limited to a top to bottom connection, not an internal one.   Years ago I was given a roll of transformer wire, which is very thin and lacquer coated. This will snake into very small plated through holes and it did perfectly in the scanner. If the scanner were a double layer board, it would have been simple enough to drill a small hole next to the dead feed through, but on a multi layer, that's out of the question. Transformer wire is ideal for pushing through a blackened feed through. Single strands from stranded wire is certainly thin enough, but it won't have the stiffness to push through most plated through holes.

Matthew Connor <connah@gmail.com>: Jun 17 05:09AM -0700 Good morning, all! While technically minded, I am brand new to repairing PCBs. I'd therefore greatly appreciate relatively simple explanations and your indulgence of my ignorance.   I recently obtained a Geiger counter which was in need of being rebuilt. Because it was manufactured in 1962, the components are large and provide me with plenty of working room. After desoldering all components, I took a locksmith's file (very small and fine) and took off just the immediate outer layer of the leads of the components. My intention was to remove existing solder and any other "gunk". As soon as I began to see the copper color of the lead showing through, I stopped and moved on to the next. After doing this for all components, I soldered them back in and everything is working perfectly...for now.   I ran across some information AFTER doing this that tells me that might have been a bad idea. Are component leads coated with something protective that I should have left on? Should I expect earlier-than-usual failure from any of my components since I filed off this outer layer? Any insight is much appreciated.   Thanks a ton!   Kindly,   Matthew Connor

"Ralph Mowery" <rmowery28146@earthlink.net>: Jun 17 10:20AM -0400 "Matthew Connor" <connah@gmail.com> wrote in message news:b6ab304d-6484-4e6a-8b07-078de3b352b1@googlegroups.com... >protective that I should have left on? Should I expect earlier->than-usual >failure from any of my components since I filed off this outer layer? Any >insight is much >appreciated.   Most component leads are tinned. That is the copper wire is coated with a thin layer of solder. This makes it easier for soldering. Copper will oxidise very fast, so don't scrape the tinned wires to bare copper. It will not hirt anything,but just make soldering more difficult. When repairing circuits use some 60/40 solder with rosin core flux. That is unless you run across some of the newer lead free stuff. You might alos want to get a bottle of the liquid flux to use. Just make sure the flux is for electronic work. There is some acid flux that is made mainly for plumming. It will tend to draw moisture out of the air and corrode the copper in electronics.   If you think there is a lot of crud on the wires, use one of the Scotch Bright typw pads to just shine them up, but not enought to remove the old solder. It is often recommended to tin the bare copper wires before soldering them.   I doubt you will get any failure because you scraped off the coating.

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jun 17 11:58AM -0400 On 06/17/2015 10:20 AM, Ralph Mowery wrote: > solder. > It is often recommended to tin the bare copper wires before soldering them.   > I doubt you will get any failure because you scraped off the coating.   You can get RA flux (rosin, activated) in solder or in a bottle. It cleans off oxidized leads very well. Kester 44 solder is RA, and you can get the same stuff as Kester 1544 (only in gallons or pails unfortunately). However, MG Chemicals 835 RA flux is available from Digikey or Amazon in much smaller quantities for about 10 bucks. I use a small bottle with a stainless steel needle.   When the needle clogs up (as it will), just touch it with the iron and it magically clears out.   Cheers   Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics   160 North State Road #203 Briarcliff Manor NY 10510   hobbs at electrooptical dot net http://electrooptical.net

John-Del <ohger1s@aol.com>: Jun 17 09:14AM -0700 On Wednesday, June 17, 2015 at 8:09:27 AM UTC-4, Matthew Connor wrote:   > Thanks a ton!   > Kindly,   > Matthew Connor     A lot of work for probably no real reason. If the solder wetted properly on the leads, then no further action is required. Occasionally you'll run into a component lead that defies soldering. Normally, cranking the heat on the soldering station and adding some flux will crack the oxidation and the solder will flow out.

Andre Majorel <cheney@halliburton.com>: Jun 17 01:18PM > consistent when measuring those eroded contacts with a multimeter. If > the element is stuck on it's possibly been busy preventing a fire.   > It's an entire thermostat, made by Ka Wo in Dongguan China.   Gordon Bennett ! I'd like to have your web search skills !   > this part. To determine if his is working, pass mains voltage through > it to a suitable load such as a small light bulb (or measure it > in-circuit at mains potential). Please do it safely.   Wouldn't a thermostat have more hysteresis than is good for the ferments ? Either they're counting on the thermal inertia of the water in the yoghurt to smooth the temperature variations or there is a sensor hidden somewhere in there that I can't see.   The person who's doing the repair is as puzzled as I am and has given up on it. The cost (time, money, effort) and the fire risk if he gets it wrong make buying a new yoghurt maker more attractive. So that's another one for the dump. :-/   Sorry for wasting your time. At least I've learned a few things. Thank you all.   -- André Majorel http://www.teaser.fr/~amajorel/ It is difficult to get a man to understand something, when his salary depends upon his not understanding it. -- Upton Sinclair

Matthew Connor <connah@gmail.com>: Jun 17 05:37AM -0700 Good morning, all. I'm brand new to hands-on electronic repair so please pardon any silly questions.   I recently acquired a Geiger counter manufactured in 1962 and I am rebuilding it. The PCB is 4" x 4" and 0.062" thick. The part of the chassis to which it mounts has four steel legs that protrude 1.45" perpendicular to the plane of the chassis. The four corners of the PCB screw onto these steel legs.   I would like to know some options for making the PCB more shock resistant should the unit ever get dropped. Is there any such thing as, say, shock-resistant washers that could go over the four screws and sit between the PCB and the steel legs to which it's mounted? Or is there a better way?   Any suggestions geared towards a newbie would be greatly appreciated. Thanks, all!   Kindly,   Matthew Connor

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