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Mike Tomlinson <mike@jasper.org.uk>: Feb 26 03:07PM Fixing a ceramic heater for a family member. Started blowing cold air. It's very similar to this one:   https://en.wikipedia.org/wiki/File:Goldair_GCH200_ceramic_heater.jpg   It has a NC safety temperature switch fitted, this has failed open. One of the spade lugs has clearly overheated. The switch is shown at the bottom of this pic:   http://www.zuglet.com/ev/saturn/images/ceramicElement.jpg   It's marked KSD301 250V 10A. But there is no temperature marking :(   There is also a thermal fuse, this is OK.   This ebay auction:   http://www.ebay.co.uk/itm/262117559259   shows replacements with temperature values ranging from 40C to 160C. Can anyone suggest what value I should choose?   The heater works OK with the wires to the switch shorted, but I would like to replace it.   Thanks.   -- (\_/) (='.'=) Bunny says: Windows 10? Nein danke! (")_(")

Mike Tomlinson <mike@jasper.org.uk>: Feb 27 03:08AM >says the "overheat shutoff temperature" varies from 149 to 265 F, or >about 65 to 130 C. Note that this covers both ceramic and non-ceramic >heaters.   A useful data point, thanks.   >Taking mine apart,   You didn't have to go to that much trouble, but thank you.   > the ceramic core is about 3.25 x 3.5 x 0.5 inches, >or about 83 x 89 x 13 mm. If yours is very different than this, then it >may need a different temperature rating!   3.5" x 3.25", so very similar. There's 4 ceramic cores with two heat levels selected by a switch (heat level 1 = 2 cores operating, heat level 2 = 4 cores operating)   Ceramic elements are PTC so self-regulating to an extent.   >Google leads me to http://www.auone.com/showproduct13.asp?ProID=1849 . >The part I have looks like their "AUT-P" series (with the white plastic >tab)   That sounds like a resettable one.   >, which lets me *guess* that the "95" in the part number means >95 C (or 203 F). Again, this is _just a guess_.   It's also right in the middle of the "65 to 130C" shutoff temperature you quote above.   Many thanks.   >Please proceed with caution. The house you don't burn down may be >your own.   Obviously, I need to choose a sensible temperature for the cutoff - too low, and it'll trip on and off all the time. There is also a thermal fuse as a belt-and-braces measure at the top of the ceramic frame. I haven't looked to see what temperature rating it is. Obviously, if that fails, it will fail open permanently.   The ceramic element is held in place in a hard plastic frame, so isn't going to be allowed to get very hot.   I'll try a 95C switch with a temporary neon indicator on the feed to the element to see if it's cycling excessively, and go from there.   It's a nice little heater, very quiet and efficient, so worth a bit of time.   Thanks again.   -- (\_/) (='.'=) Bunny says: Windows 10? Nein danke! (")_(")

N_Cook <diverse@tcp.co.uk>: Feb 26 04:08PM On 26/02/2016 15:07, Mike Tomlinson wrote:   > The heater works OK with the wires to the switch shorted, but I would like > to replace it.   > Thanks.   I've never known the bimetal dome to fail on these, always the contacts or the little ceramic trigger out of position. First with a soldering iron barrel , confirm by listening for a click over, then repeat with a thermometer, glass or pyro.

Mike Tomlinson <mike@jasper.org.uk>: Feb 26 04:16PM En el artículo <napt3g$1id$1@dont-email.me>, N_Cook <diverse@tcp.co.uk> escribió:   >or the little ceramic trigger out of position. >First with a soldering iron barrel , confirm by listening for a click >over, then repeat with a thermometer, glass or pyro.   It's open circuit, with a burnt spade terminal. Trust me, it's u/s.   -- (\_/) (='.'=) Bunny says: Windows 10? Nein danke! (")_(")

N_Cook <diverse@tcp.co.uk>: Feb 26 04:46PM On 26/02/2016 16:16, Mike Tomlinson wrote: >> First with a soldering iron barrel , confirm by listening for a click >> over, then repeat with a thermometer, glass or pyro.   > It's open circuit, with a burnt spade terminal. Trust me, it's u/s.   But not the dome, hack into it and extract the dome. Now not constrained, you need to make sure it does not fly off , when it flips to the opposite state.

Mike Tomlinson <mike@jasper.org.uk>: Feb 27 06:56PM >On mine, the frame also extends back towards the intake to >hold the fan motor and make a venturi/shroud for the fan blade.   Yes, same here. It's all one piece. The section holding the ceramic element is square, then there's a short cylinder to the fan housing which is square. The lot fixes to the back half of the enclosure with 4 screws.   I suspect this is pretty much a commodity part made in China and badged with OEM logos as required.   I've ordered the 95C switch, pretty sure that'll do the trick. Thanks again for your help, have a virtual pint on me :)   -- (\_/) (='.'=) Bunny says: Windows 10? Nein danke! (")_(")

Dimitrij Klingbeil <nospam@no-address.com>: Mar 02 10:28PM +0100 On 01.03.2016 22:29, Chris wrote: > the probe) at ALL times and bob's your uncle, you can't go wrong. > That way you are only placing about 15pf || 1M loading on the DUT. > HTH.   You must be meaning X10 setting. Common scope inputs as well as probes are not designed to handle the typical peaks from power supplies at X1.

Chris <cbx@noreply.com>: Mar 02 10:36PM On Wed, 02 Mar 2016 22:28:47 +0100, Dimitrij Klingbeil wrote:   > You must be meaning X10 setting. Common scope inputs as well as probes > are not designed to handle the typical peaks from power supplies at X1.   Fair point! But I use an externally selectable decade attenuator for anything over 400V so X1 is good for me. But yes, in the absence of that, X10 would be the way to go.

Cursitor Doom <curd@notformail.com>: Feb 25 02:46PM On Thu, 25 Feb 2016 09:00:07 -0500, legg wrote: > Sounds more like you're getting closer to root cause.   I'm afraid not. It didn't happen yesterday when I first hooked the psu back into the scope so this is a fresh fault - and probably my fault for not testing the psu's output voltages properly before plugging it back in. :(   > Troubleshoot the (unidentified?) signal board.   May have to wait til the latter part of next week; I have to leave later today for a 5-6 days due to family-in-law commitments.

Cursitor Doom <curd@notformail.com>: Feb 25 12:53PM On Wed, 24 Feb 2016 17:51:21 -0600, Jon Elson wrote:   > like to see parts running that hot. Especially in something that might > get buried in a shield housing deep in the bowels of some piece of gear > like a scope.   I couldn't agree more. Coming from the germanium semiconductor generation where even slightly too much heat was terminal, I still like to go by the rule of burnt thumb: if if it burns your thumb it's too hot. In which case derate, derate, derate.   > So, does the scope actually run correctly?   I didn't get the chance to find out! Began this morning trying to get some voltage readings off the psu outputs and there was nothing there to read. To cut a long story short, further investigation reveals something has gone short-circuit on one of the signal boards. When the psu is removed and run from my make-shift dummy load, it's still 'fine' with its new diode (not quite right, but functioning to high degree). So clearly I jumped the gun slotting it back in the scope when it still wasn't 100% and now it's damaged something - typical! I'm running out of time now as we have to leave later to spend a few days with 'er mother 300 miles away and whilst I shall still have internet access there, I'm not allowed to take any test gear with me. Ain't life great?

Cursitor Doom <curd@notformail.com>: Feb 25 03:45PM Final update for the time being as I have to leave soon now:   That short turned out to be intermittent. I hope it was just due to something shorting out on the bench that won't happen when the casing is back on because you all know what a bitch it can be to trace intermittent faults. Anyway, that fault has now disappeared, so I took some voltage measurements before the 20W resistor got to hot (from 19'C to 60'C takes about 1.50s now) and I have:   61.7 12.7 5.8 0 -5.8 -12.7 -62.4   This is with the psu board plugged into the scope and all power connections made except for the VHT stuff.   The correct figures according to the manual should be:   60 12.7 6 0 -6 -12.7 -60   So very close! Looks like the main transformer may be ok after all.

Cursitor Doom <curd@notformail.com>: Feb 25 03:51PM On Thu, 25 Feb 2016 00:36:16 +0100, Dimitrij Klingbeil wrote:   [...]   Dimitrij, I will have to run these latest checks you suggest next week now as I have to leave on family matters and have no choice other than divorce. The PSU is now putting out near-enough the correct voltages in the 6-60VDC range as required when connected up to the scope and the transformer is virtually silent. It's just the power resistor heating that's causing concern. If you think of anything else, please leave your thoughts here. If not, I'll proceed with your checks on my return. many thanks again.

MJC <gravity@mjcoon.plus.com>: Feb 25 02:18PM In article <nalek2$k2e$1@dont-email.me>, nospam@no-address.com says... > the power factor gets lower, the total current draw increases (imagine a > constant current due to resistive load plus an additional current due to > the reactive part of the load, which increases).   Your wonderful description of resonant circuits reminds me of an experience I had as an apprentice. I was given the job of trying to lay down a silicone insulating film generated by polymerising a silicone vapour in a high voltage AC plasma. (I don't remember why it had to be AC.)   We didn't have any special HV AC supplies but stores did have a signal generator and powerful audio amplifier. I managed to scrounge a large open-centred coil (meant to generate a magnetic field around a bell-jar) and a collection of high voltage capacitors, waxed paper in steel cans with ceramic terminals on top.   With these I built a series LC circuit which generated a satisfactory plasma. I'm afraid I don't recollect any measurements. Health-and-safety consisted of large hand-written warning notices!   However despite being distracted by my plasma I also noticed that the poor capacitors, excellent with DC no doubt, didn't like the AC current they were subjected to, and bulged, leaked and fizzed. The experiment was terminated abruptly!   Mike.

Cursitor Doom <curd@notformail.com>: Feb 25 02:39PM On Thu, 25 Feb 2016 14:18:07 +0000, MJC wrote:   > open-centred coil (meant to generate a magnetic field around a bell-jar) > and a collection of high voltage capacitors, waxed paper in steel cans > with ceramic terminals on top.   I'm guessing you mean like this:   http://www.ebay.co.uk/itm/SIC-SAFCO-2-2uF-2-5KV-2500V-DC-HIGH-QUALITY- PAPER-IN-OIL-CAPACITOR-NOS-/151689743255? hash=item235169cb97:g:N3sAAOSwKrhVXwzP   I still have a couple of dozen of this type here.

Cursitor Doom <curd@notformail.com>: Feb 26 08:26AM On Thu, 25 Feb 2016 23:48:16 -0800, jurb6006 wrote:   > Are the chopper transistors getting hot ?   The main chopper is a TO-3 cased BJT with a closely-finned heatsink bolted to the top of it. By the time the resistor starts to emit a scorching smell, the chopper hasn't even had the chance to get barely warm.   > Did you actually check the resistance of that resistor that is getting > hot ?   Yes, it's exactly 20 ohms as specified. But please don't ask me to do any other checks for the next few days as I'm staying over 300 miles away at present.

Cursitor Doom <curd@notformail.com>: Feb 26 08:52AM On Fri, 26 Feb 2016 00:47:32 -0800, jurb6006 wrote:     > That is probably the only way to troubleshoot this. You ain't finding > anything with the ohmmeter, but it isn't shutting down. Something is not > showing up unless under voltage. Ohmmeters can't detect that.   Hhmmm. As I've said before, I'm reluctant to replace that power resistor with anything higher rated. At the moment it's acting as a robust detector that something isn't right. I don't want to replace it and then find the excess energy has burned out the transformer primary instead!   Dimitrij has already given me some steps to follow for resonance checks when I get back and I'm trying to keep the suggestions made here in an orderly queue, so thanks for your input which is appreciated, but no further test ideas from anyone for the time being, please!!!

"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Feb 26 05:36AM -0600 "legg" <legg@nospam.magma.ca> wrote in message news:k32ucb9jaaa5t2ndnkmoruegf3116ib12p@4ax.com...   > Sounds more like you're getting closer to root cause.   > Troubleshoot the (unidentified?) signal board.   > RL   Yes! Once you get it fired up again, start looking for parts getting HOT on those other boards!   mz

Cursitor Doom <curd@notformail.com>: Feb 27 12:42AM On Thu, 25 Feb 2016 00:36:16 +0100, Dimitrij Klingbeil wrote:   [...]   Dimitrij, I think you may have missed this I posted elsewhere so I'm re- posting it here now for you personally:   "Final update for the time being as I have to leave soon now:   That short turned out to be intermittent. I hope it was just due to something shorting out on the bench that won't happen when the casing is back on because you all know what a bitch it can be to trace intermittent faults. Anyway, that fault has now disappeared, so I took some voltage measurements before the 20W resistor got to hot (from 19'C to 60'C takes about 1.50s now) and I have:   61.7 12.7 5.8 0 -5.8 -12.7 -62.4   This is with the psu board plugged into the scope and all power connections made except for the VHT stuff.   The correct figures according to the manual should be:   60 12.7 6 0 -6 -12.7 -60   So very close! Looks like the main transformer may be ok after all."   Making progress! :)

Rheilly Phoull <rheilly@bigslong.com>: Feb 27 07:23AM +0800 On 27/02/2016 6:00 AM, Cursitor Doom wrote:   > They're a PITA - IME at any rate. This is one of the better explanations > on how to deal with them:   > https://www.youtube.com/watch?v=Z38WsZFmq8E   The power suction jobs take some beating :-)

Julian Barnes <jb9889@notformail.com>: Feb 26 07:08PM hey guys,   I need to remove a sub-miniature audio transformer from a PCB. It should be a piece of cake and always has been in the past, but something's different about this one. At those odd times previously when I've done this, I've just used a soldering iron and a vacuum pump to melt the joints and suck off the solder. The pins are then free and the part almost drops off by itself. This one is not so simple, though. It's a double-layer board and the transformer is mounted directly on top of the traces that feed it. On the reverse side, I can see the end of the transformer's leads poking through just proud of where a pad would normally be, but in this case, there are no pads 'cos there are no traces; just tiny, isolated circles of solder around each lead-end. I guess I need to get at the actual solder joints proper on the top side, but the transformer is sat right on top of them making it totally impossible to even see the joints I need to get at! Whut gives here? Are these things deliberately designed to be unserviceable nowadays? Is that the idea? Bastard manufacturers want us to buy new stuff instead of fixing old? Sigh. Does anyone know a ruse to defeat this darstardly scam?

N_Cook <diverse@tcp.co.uk>: Feb 26 07:28PM On 26/02/2016 19:08, Julian Barnes wrote: > nowadays? Is that the idea? Bastard manufacturers want us to buy new > stuff instead of fixing old? > Sigh. Does anyone know a ruse to defeat this darstardly scam?   Diamond encrusted cutting wire?

"tom" <tmiller11147@verizon.net>: Feb 26 02:29PM -0500 "Julian Barnes" <jb9889@notformail.com> wrote in message news:naq7rg$3c4$1@dont-email.me... > nowadays? Is that the idea? Bastard manufacturers want us to buy new > stuff instead of fixing old? > Sigh. Does anyone know a ruse to defeat this darstardly scam?   Hot air desoldering tool.   This one works nice:   http://www.ebay.com/itm/281501377815?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT   Consider adding ChipQuick to lower the melting point.   http://www.ebay.com/itm/CyberDoc-CHIP-Quik-Quick-DESOLDERING-REMOVAL-ALLOY-2ft-FOUR-4x-6-5-inch-STICKS-/141758972378?hash=item21017e41da:g:XGcAAOSwPgxVLEkM   And flux.

amdx <nojunk@knology.net>: Feb 26 06:46AM -0600 My cable company is switching over to all digital and forcing the use of a Digital Transport Adapter (DTA).   If I look at the channel on HDMI vs RF, the picture is smaller with a large boarder around the outside. I think the problem is in the DTA, it is a Cisco DTA 170HD. Anyone know how to get around this?   Mikek

amdx <nojunk@knology.net>: Feb 26 07:06PM -0600 On 2/26/2016 3:47 PM, amdx wrote: > letter box. > I'll poke around this evening to see if I can find something. > Mikek   I found it! There is a screen setting in the menu of the DTA. Set it and it's good.   Thanks, Mikek

Cydrome Leader <presence@MUNGEpanix.com>: Mar 02 11:26PM > Google results?   > I?ve seen several brands, but it?s hard to judge from a distance.   > One personal recommendation beats a hundred choices.   It depends on the rubber, but 303 aerospace protectant will soften and swell some rubbers. They don't say it will, and it's not supposed to, but it sure as heck does. The best part is my bottle of it has a cracked and crazed label. Maybe the bottle should have been treated at the factory, or it leaches though the bottle. Not really sure.   The beauty of it over solvents like turpentine is it has a very mild smell and wipes up easily and isn't a hydrocarbon solvent.

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