sci.electronics.repair@googlegroups.com

Google Groups

~BD~ <Bo@ter.Dave.invalid>: Nov 11 07:43AM Hi   Since my son recently picked up and 'fiddled' with my remote Honeywell sensor for my central heating system, I been experiencing erratic behaviour of my heating system.   The receiver unit in my airing cupboard had a red light instead of green. I've changed the batteries in the sender unit and have myself 'fiddled' with the controls until everything appears to work properly.   This morning, though, there was once again a red light on the receiver unit and the bathroom radiator was cold. Although the pipes around the tank were hot, there was was once again a red light on the receiver unit. I've pressed the reset button and the central heating pump is running again and the bathroom radiator is getting hot.   Has anyone any suggestion about possible cause and how to rectify?   -- David B. Devon, UK

Fletcher <fletcherfletch@example.com>: Nov 10 09:45PM -0500 Sometime around Thu, 07 Nov 2019 16:20:46 -0500, micky <NONONOaddressee@rushpost.com> wrote.....   > sharpen pencils.   > Ours didn't even suck in the pencil. You had to push it in. Worked just > fine.   Thanks to all for the advice for fixing broken plastic gears. Broke with cyanacrylate & decided to give up on the epoxy. Paid $30 at Staples to replace the crappy Boston with Bostich. http://img4.imagetitan.com/img.php?image=20_image5626.jpg Any ideas for inventive re-use of the old Boston worm gear & transformer?

Fred McKenzie <fmmck@aol.com>: Nov 10 10:42PM -0500 In article <qqai0s$171r$1@neodome.net>,   > Thanks to all for the advice for fixing broken plastic gears. > Broke with cyanacrylate & decided to give up on the epoxy.   Do you know what model your Boston sharpener is? You might try E-Bay. I see various replacement gear prices ranging from $7 to $21.   I also see someone selling a "parts only" model 17 that needs a new gear!   Fred

Cursitor Doom <curd@notformail.com>: Nov 10 04:54PM On Sun, 10 Nov 2019 08:14:36 -0800, Michael Terrell wrote:   > What's life, without a challenge? :)   A challenge has to be, by definition, ultimately achievable. Removing this cap is *not* achievable. I would have to destroy the entire VNA to get it out. What a rotten design.       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 09:56AM -0800 On Sunday, November 10, 2019 at 11:24:08 AM UTC-5, Ralph Mowery wrote:   > Those little component testers for around $ 20 really get to me. They > seem to work really well in most cases as to identifying components and > their values.   I bought a Nano VNA for $42.87 with some Ebay bucks that were about to expire, but I haven't tried it yet. I am currently trying to get another door and a handicap ramp installed at my home. The current exits all have too many steps to go up and down. I haven't been in my shop building for several years, because it is too much pain to get out to it, and stand at the workbench. Once the modifications are done, I will have room for a small bench in that room.   I am retired, so I no longer have access to the multiple workbenches of test equipment that I used on my last job.   I agree about those component testers being useful. I have a couple. Another one that is handy is a $10 VGA monitor test generator.

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 09:58AM -0800 On Sunday, November 10, 2019 at 11:19:15 AM UTC-5, Cursitor Doom wrote: > connect a capacitor across the mains supply it needs to be X rated, but > *leaving out* such a capacitor, x rated or not, is not going to kill or > injure anyone.   X capacitors are to filter RF from the power lines. Y capacitors are for safety.

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 10:00AM -0800 On Sunday, November 10, 2019 at 11:54:24 AM UTC-5, Cursitor Doom wrote:   > A challenge has to be, by definition, ultimately achievable. Removing > this cap is *not* achievable. I would have to destroy the entire VNA to > get it out. What a rotten design.   Those plastic capacitors were supposed to be high rel, but they didn't expect the cases to craze, and fail. What model is your VNA?

Cursitor Doom <curd@notformail.com>: Nov 10 07:21PM On Sun, 10 Nov 2019 10:00:10 -0800, Michael Terrell wrote:   > Those plastic capacitors were supposed to be high rel, but they didn't > expect the cases to craze, and fail. What model is your VNA?   It's the 8754A. It tops out at 1.3Ghz which was, a long time ago when I purchased it, was a respectably high frequency! In fact it's still the highest practicable frequency band allocated for radio hams, which was another good reason for me to choose it.       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Cursitor Doom <curd@notformail.com>: Nov 10 07:35PM On Sun, 10 Nov 2019 09:58:21 -0800, Michael Terrell wrote:   > X capacitors are to filter RF from the power lines. Y capacitors are for > safety.   I suspect you're going to have a few contradictory views about that sweeping statement from some of our not-so-polite regulars here! ;-)   I can *just* access enough to snip the blown cap out and discard it. I think I'll fit a new one to the end of the power lead instead; it's my only option realistically.       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

John-Del <ohger1s@gmail.com>: Nov 10 02:30PM -0800 On Sunday, November 10, 2019 at 10:20:06 AM UTC-5, Cursitor Doom wrote:   > Thanks for that, Michael. I think I've found the cap you refer to, > straddled across the mains incoming supply, looking rather jaded, bulgy > and cracked.     But did it cause a bang loud enough to be heard in a shower?   I had a TV do that back in the 80s, and what it did was launch an electrolytic clean off the board. I found some paper packing and eventually the cap itself. The TV still worked and the only evidence left on the board was two very clean leads where the cap used to sit.   Even though you found a pretty good suspect, I'd look the rest of it over very carefully for a couple of leads and no part between them.

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 02:41PM -0800 On Sunday, November 10, 2019 at 2:22:02 PM UTC-5, Cursitor Doom wrote: > purchased it, was a respectably high frequency! In fact it's still the > highest practicable frequency band allocated for radio hams, which was > another good reason for me to choose it.   The only manual that I have only covers operation, but it is dated 1978. The design life was typically 15 to 20 years at that time, so it lasted twice that time. It does show the IEC power connector and voltage selector on the rear panel. That is where the line filter should be. It looks like it might be a Corcom 6J4 Power Entry Module. That 6J series is available with and without a filter.

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 02:51PM -0800 On Sunday, November 10, 2019 at 5:30:42 PM UTC-5, John-Del wrote:   > But did it cause a bang loud enough to be heard in a shower?   > I had a TV do that back in the 80s, and what it did was launch an electrolytic clean off the board. I found some paper packing and eventually the cap itself. The TV still worked and the only evidence left on the board was two very clean leads where the cap used to sit.   > Even though you found a pretty good suspect, I'd look the rest of it over very carefully for a couple of leads and no part between them.   I had a HP desktop computer lose an electrolytic capacitor in the power supply. The can blew out through the fan, along with flames.   I've had the large (160uF, 250V input capacitor in a v0ltage doubler explode in a TV while it was on the workbench. Confetti for about 20' radius. :)   I had just installed a new amplifier in a car dealership. They called the next day that t had a loud hum. Lightning had hit the early Japanese business telephone system's optional paging adapter. It blew the cover off the metal box, and it was another mess of confetti all over the old telephone equipment room. They replaced it, and that one exploded a week later. Neither design had any surge protection. Both times, their neighborhood was hit with 100W of 60Hz hum and other noise from the PA horns in their used car lot.. ;-)

Cursitor Doom <curd@notformail.com>: Nov 10 11:14PM On Sun, 10 Nov 2019 14:30:39 -0800, John-Del wrote:   Me:   >> straddled across the mains incoming supply, looking rather jaded, bulgy >> and cracked.   > But did it cause a bang loud enough to be heard in a shower?   We're assuming it was this X cap as it's clearly damaged, but I admit I would expect from the bang (which I did hear *whilst* in the shower 30' feet away) I'd have expected to see more extreme damage to that cap than I did.   > left on the board was two very clean leads where the cap used to sit.   > Even though you found a pretty good suspect, I'd look the rest of it > over very carefully for a couple of leads and no part between them.   You're right. I need to eliminate the possibility that the x-cap damage had maybe been there since years ago and I still haven't found the true culprit. If that may be the case, then what other part from where could account for it? I've already eliminated the big electrolytics from suspicion.       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Fox's Mercantile <jdangus@att.net>: Nov 10 05:32PM -0600 On 11/10/19 5:14 PM, Cursitor Doom wrote: > I need to eliminate the possibility that the x-cap damage > had maybe been there since years ago and I still haven't > found the true culprit.   Capacitors across the power line, when they fail, they fail spectacularly. And usually fast enough that they don't always take out the line fuse.   This is why they make X caps. When they fail they, in addition to failing short, they don't explode with a vengeance or set fire to themselves or the surrounding bits.   Y caps, on the other hand, go from the line, or neutral to ground. They are designed to fail open.   <https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/>       -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

Cursitor Doom <curd@notformail.com>: Nov 10 11:43PM On Sun, 10 Nov 2019 14:41:48 -0800, Michael Terrell wrote:   > selector on the rear panel. That is where the line filter should be. It > looks like it might be a Corcom 6J4 Power Entry Module. That 6J series > is available with and without a filter.   This one has no mains filter AFAICS; just that busted cap. I do have the *full* service and operating manual so I'll take a look and see what that says tomorrow as it takes a month of sundays to find anything I need in it. But like I say, if there *is* a filter, it's going to be nano-sized and next to useless.       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Cursitor Doom <curd@notformail.com>: Nov 11 12:50AM On Sun, 10 Nov 2019 17:32:51 -0600, Fox's Mercantile wrote:     > This is why they make X caps. When they fail they, in addition to > failing short, they don't explode with a vengeance or set fire to > themselves or the surrounding bits.   You seem to be contradicting yourself in the second paragraph. You initially say "they fail spectacularly" then you say, "they don't explode with a vengeance". It can't be both, so which is it?           -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Fox's Mercantile <jdangus@att.net>: Nov 10 07:33PM -0600 On 11/10/19 6:50 PM, Cursitor Doom wrote:   > You seem to be contradicting yourself in the second paragraph. You > initially say "they fail spectacularly" then you say, "they don't explode > with a vengeance". It can't be both, so which is it?   Capacitors, NOT X rated.   Vs X rated.     -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

Cursitor Doom <curd@notformail.com>: Nov 11 01:44AM On Sun, 10 Nov 2019 19:33:18 -0600, Fox's Mercantile wrote:   > Capacitors, NOT X rated.   > Vs X rated.   So you're saying the x-cap that looks like the culprit can't be, then? Maybe you're right; we'll see in due course....       -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 06:37PM -0800 On Sunday, November 10, 2019 at 7:50:14 PM UTC-5, Cursitor Doom wrote:   > You seem to be contradicting yourself in the second paragraph. You > initially say "they fail spectacularly" then you say, "they don't explode > with a vengeance". It can't be both, so which is it?     They are designed to burn away the short, so there is no contradiction. The foil is very thin, so it vaporizes away from the point of failure, leaving the remaining part of the capacitor, in circuit. If you measure the capacitance of a damaged X or Y capacitor, it will be lower than marked.

Fox's Mercantile <jdangus@att.net>: Nov 10 09:30PM -0600 On 11/10/19 7:44 PM, Cursitor Doom wrote:   >> Vs X rated.   > So you're saying the x-cap that looks like the culprit can't be, then? > Maybe you're right; we'll see in due course....   Oh for fuck's sake. X rated capacitors are a recent development. There weren't any when HP built the VNAs. They used standard capacitors at the time. Like everyone else. Which, is why, when it failed, it failed spectacularly.     -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

Alex Borroughs <alexb@att.net>: Nov 10 12:26PM -0500 On 11/10/19 5:24 AM, Clive Arthur wrote: > microscope.  If I have to do more than I can manage to hold my breath > for, I use a snorkel.  Works well.   > Cheers   I ended up going with Mr. Horton's solution as I also made the "5 layer" device and added an activated carbon layer as well using a spare, non-functional fan as containment. Device works pretty darn well. I haven't done any soldering yet, but it has done a remarkable job just cleaning the air in one of the bedrooms.   Sounds like someone does surface mount soldering. I attempted it once and the result was disaster and haven't done so since.

Ralph Mowery <rmowery28146@earthlink.net>: Nov 10 12:36PM -0500 In article <qq9h87$70m$1@dont-email.me>, alexb@att.net says...   > Sounds like someone does surface mount soldering. I attempted it once > and the result was disaster and haven't done so since.   Smd for the most part is very easy, However you have to have the proper equipment to do it.   I bet that Mantis is nice, but as a hobbiest I can not afford to put $ 1500 to much more than that in it. I did buy an Amscore scope 10x for about $ 200 that works well . A hot air wand and very small soldering pencil is needed. The one for around $ 75 is good enough for very casual work. Just don't drink coffee for about a week before trying it.. I don't drink coffee anyway.

jlarkin@highlandsniptechnology.com: Nov 10 10:29AM -0800 On Sun, 10 Nov 2019 12:26:29 -0500, Alex Borroughs <alexb@att.net> wrote:   >cleaning the air in one of the bedrooms.   >Sounds like someone does surface mount soldering. I attempted it once >and the result was disaster and haven't done so since.   That's about all that I do. I was intiially terrified of 1206 parts. Now I find 0402s to be mildly annoying.       --   John Larkin Highland Technology, Inc   lunatic fringe electronics

whit3rd <whit3rd@gmail.com>: Nov 10 02:05PM -0800 > I don't worry about solder smoke. I've been soldering since I was 3 > years old.   Though the solders of the 1960s didn't scar your lungs, the fluxes in use nowadays are sufficiently diverse that a precaution or two might be appropriate. Like air conditioning to prevent perspiration, a bit of airflow so the work isn't upwind of your face might be a good soldering-station idea. Consider the musical warning "Smoke gets in your eyes".

Michael Terrell <terrell.michael.a@gmail.com>: Nov 10 06:43PM -0800 On Sunday, November 10, 2019 at 1:30:16 PM UTC-5, John Larkin wrote: > >and the result was disaster and haven't done so since.   > That's about all that I do. I was initially terrified of 1206 parts. > Now I find 0402s to be mildly annoying.   Be glad that you don't do Microwave work that sometimes use 0201 or 01005 capacitors, at a fraction of a pF. They look like dust, in the container. :(

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.