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Cydrome Leader <presence@MUNGEpanix.com>: Feb 29 05:51PM > The total absence of any supplier stating they had new belts made me > move over to cutting my own belts , flat and square , from silicone > rubber kitchen products, no returns yet from broken examples.   I've always wondered about the freshness factor of their stuff these days. They must be selling dozens of belts a month these days.

N_Cook <diverse@tcp.co.uk>: Feb 29 06:38PM > My local plumbing supply house has not let me down yet as far as that is concerned. Not also that O-rings often do a fine job even where flat belts may be OEM. If there is any sort of lip on the wheels, there is rarely a problem. Note that diameter does not matter where belts are concerned as long as the tension is sufficient for traction. The pulley sizes are all that matters. And new materials often have a much higher tension strength than OEM belts typically of neoprene or even basic buna rubber. So, thinner O-rings may be used ILO flat belts if clearances are critical. And, as we all know, buna-rubber is not good around electrical stuff...   > Peter Wieck > Melrose Park, PA   The problem is balustre/bulbous pulleys which must have flat belts. If its possible to cant over the motor and pulley, it is possible to cut belts from smooth flat rubber sheet and offset the set by the degree of cant to the pulley axis. I often use Orings for pulley tyres, often using 3,2 to take up the width and one centred on those 2 to make the depth to bridge the gap to capstan drum or whatever.

N_Cook <diverse@tcp.co.uk>: Feb 29 06:41PM On 29/02/2016 17:51, Cydrome Leader wrote:   > I've always wondered about the freshness factor of their stuff these days. > They must be selling dozens of belts a month these days.   If I ran a company supplying rubber drive belts, I'd make great play in my blurb, that they are new cut/moulded stock. As none of the companies I've found selling belts for legacy equipment say this, I assume they only have old stock , next to useless stock.

Cydrome Leader <presence@MUNGEpanix.com>: Mar 01 12:03AM > my blurb, that they are new cut/moulded stock. > As none of the companies I've found selling belts for legacy equipment > say this, I assume they only have old stock , next to useless stock.   Nothing quite like an old plastic bag with the stained imprint of the rubber part.   Any idea how they correctly make say a VCR idler tire? Molded one at a time? cut from a tube? I've always wondered.

pedro <me@privacy.net>: Mar 01 11:23AM +0800 >for refurbishing a tape deck, I need some belts. I googled a few places but >nothing very inspiring (not a great selection).   >Anybody have a source they like and use?   Not much help to you, but here in downunder-land we have a parts supplier who has pretty decent range   https://www.wes.com.au/mediapub/ebook/wescat2014np/#1220

F Murtz <haggisz@hotmail.com>: Mar 01 10:55PM +1100 DaveC wrote:   > (If you're just going to Google, don't bother, I've already done > that…)   > Thanks!   In Australia, http://prime-electronics.com.au/

"pfjw@aol.com" <pfjw@aol.com>: Mar 01 05:37AM -0800 On Monday, February 29, 2016 at 1:38:30 PM UTC-5, N_Cook wrote:   > I often use Orings for pulley tyres, often using 3,2 to take up the > width and one centred on those 2 to make the depth to bridge the gap to > capstan drum or whatever.   http://www.allsealsinc.com/contoured-backup-rings.jpg   https://www.parker.com/literature/ORD%205700%20Parker_O-Ring_Handbook.pdf   Look up "back-up" rings - they will be flat on the OD, and concave on the ID (and may also be turned inside-out). And pretty much ideal for shaped pulleys, whether concave or convex. Some care will need to be exercised on choosing the material, however, as these beasts range from spongy-soft to PTFE (quite hard). Nitrile is probably the best option for small electronics applications. Again, the range of sizes available is quite astounding.   Peter Wieck Melrose Park, PA

N_Cook <diverse@tcp.co.uk>: Mar 01 02:43PM > Look up "back-up" rings - they will be flat on the OD, and concave on the ID (and may also be turned inside-out). And pretty much ideal for shaped pulleys, whether concave or convex. Some care will need to be exercised on choosing the material, however, as these beasts range from spongy-soft to PTFE (quite hard). Nitrile is probably the best option for small electronics applications. Again, the range of sizes available is quite astounding.   > Peter Wieck > Melrose Park, PA   There will always be sources of O-rings because they are used in all sorts of areas. Anyone know of other uses for the very thin flat drive bands <>0.5mm thick, other than old tape recorders and projectors? Vacuum cleaner bands are for power transfer and always too thick ,even sliced in half , retaining one fair face to go against the drive pulley. Some old style photocopiers used to use thin <>0.5mm and <>20mm wide rubber bands for paper conveyance, easily sliced down in width, but I only ever saw one size of perimeter

"pfjw@aol.com" <pfjw@aol.com>: Mar 01 07:41AM -0800 On Tuesday, March 1, 2016 at 9:43:00 AM UTC-5, N_Cook wrote:   > Some old style photocopiers used to use thin <>0.5mm and <>20mm wide > rubber bands for paper conveyance, easily sliced down in width, but I > only ever saw one size of perimeter   There are dozens of sources for miniature drive belts, ribbed, notched and flat. There are many hobby applications (I use them for drive belts on a miniature R/C submarine I am building (a 5-year project)). But consider robotics and any of several other applications, hobby and commercial.   http://sdp-si.com/products/miniature-belts-and-pulleys-inch.htm   http://www.bostongear.com/pdf/upload/lit/P-1482-BG_pg117-131.pdf   http://www.globalspec.com/industrial-directory/miniature_drive_belt   Are only a very few.   I find it interesting that those who are "in the trade" tend to think within the trade and not outside it. A lesson I learned from a former colleague that struck home came to me as follows:   Butch (his nickname, Bruce his given name) drove a Harley, kept a full-blood wolf as a pet (he was a registered, trained, wild-animal rescue professional) and drove our company truck for a living, and was a NASCAR fan - but, possibly the most gentle person I have ever met despite all visible indicators to the contrary. He would order his drive belts from Grainger at 1/4 the cost of the same Gates belt from HD, and this before the "net". He taught me that single-source parts really were not - that nobody made every part and piece of everything they sold, and that well over 50% of the time, the OEM source is out there, and ready, willing, and able to sell the *exact* part at a much more reasonable price.   Stuff is out there. It may not say Revox, Panasonic, Sony, TEAC or whatever on it, but it is certainly out there. Take 10 minutes to look and be pleasantly surprised.   Peter Wieck Melrose Park, PA

N_Cook <diverse@tcp.co.uk>: Mar 01 03:56PM > Look up "back-up" rings - they will be flat on the OD, and concave on the ID (and may also be turned inside-out). And pretty much ideal for shaped pulleys, whether concave or convex. Some care will need to be exercised on choosing the material, however, as these beasts range from spongy-soft to PTFE (quite hard). Nitrile is probably the best option for small electronics applications. Again, the range of sizes available is quite astounding.   > Peter Wieck > Melrose Park, PA   I read some interesting bits in that Parker pdf.   I wonder how you lathe-cut rubber drive belts? Mention of fungus, is that the reason that old belts "melt" into that intractable black gooey mess? and once one belt in some kit goes that way all the other rubber bits in the way of belts & tyres go the same way in rapid succession. I thought there might be mention of Richard Feynman and his unsurpassable NASA press-conference cutting-thru-the-crap demo with a hardware-shop O-ring and a glass of iced water as they brought up rocket propellants and O-rings, but no.

Look165 <look165@numericable.fr>: Mar 01 12:53PM +0100 Hello,   I need a part from Philips (shaver HQ6890).   It is the power control board.   It is no more available.   If someone has this part, please help me.   I have a recurring problem of recharging the batteries.   They are brand new.   The charging process seems OK but no heat and batteries KO after 2 seconds.   The board is P/N 4822 214 13061.   The shaver doesn't operate with the mains power supply which is OK, so it is a problem with the charging circuitry which is common to the motor when operated with the mains.   I checked with the schematic, but everything interferes with everything... it's quite a gas plant.

N_Cook <diverse@tcp.co.uk>: Mar 01 03:24PM On 01/03/2016 11:53, Look165 wrote: > when operated with the mains.   > I checked with the schematic, but everything interferes with > everything... it's quite a gas plant.   That bit of ebay for a guaranteed non-worker, for a parts-mule? is there a generic name for that bit of flea-bay ?

Dimitrij Klingbeil <nospam@no-address.com>: Feb 29 09:47PM +0100 On 28.02.2016 22:59, Dimitrij Klingbeil wrote: > from any earthed metal, thereby being a "light" load).   > The probe tip is not the issue, but the scope itself, hanging from > the probe ground, that is.   P.S.   There is a simple though unwritten rule about power supply testing:   "Never connect the ground (common, chassis etc.) of any test equipment to the switching node (power transistor collector, drain or power IC output pin and its associated signals) of a switching power supply!"   It is valid for all types, no matter if flyback, forward or resonant.   The reason for this rule is that a "switching node" usually drives a square wave with high voltages (some 500 to 600 V in a flyback, may happen to be as much as 800 or 1000 V in a resonant one), and that a significant amperage is readily "available" at that node too, due to the output transistor's low impedance. Neither is the supply designed to safely drive that into "RF ground" nor is the test equipment made for being "muscled around" at that sort of voltages and dV/dt rise times.   Grounding the test equipment would mean that the whole power supply (plus any safety isolation transformer) is being swung around and letting the test equipment "float" would mean to also swing around the test equipment. Apart from the obvious safety hazard, this can also damage the test equipment and even compromise the test equipment's electrical safety by frying the "Y" capacitors between mains and secondary or stressing the isolation barrier in the test equipment's power supply and / or mains transformer, possibly beyond the level of stress that it was rated for.   So, whenever you troubleshoot some switcher, take heed of this rule.   It's simple to remember, and it can save lives, test equipment, and some power supplies under test too :)   Regards Dimitrij

Cursitor Doom <curd@notformail.com>: Feb 29 11:18PM On Mon, 29 Feb 2016 21:47:38 +0100, Dimitrij Klingbeil wrote:     > So, whenever you troubleshoot some switcher, take heed of this rule.   > It's simple to remember, and it can save lives, test equipment, > and some power supplies under test too :)   I'm grateful for that expansion, to be honest. I was kind of struggling to get my head around what you were getting at in your earlier postings; didn't make much sense to me on the first read through and although after a second read I was beginning to sense your meaning, it still wasn't 100% clear. At least now I think I can finally see where you're coming from. Naturally I read up on safety precautions when dealing with switchers from books I have and all sorts of diverse sources on the net, but I can honestly say that what you have outlined above has NOT been covered by anything I've seen or read up until now. This would seem to be a glaring omission on the part of those who we rely on to prime us up on the hidden dangers and pitfalls of troubleshooting such equipment. Another good reason for me to avoid dealing with switchers in future if at all possible!!

Cursitor Doom <curd@notformail.com>: Feb 29 11:21PM On Mon, 29 Feb 2016 21:47:38 +0100, Dimitrij Klingbeil wrote:   > P.S.   > There is a simple though unwritten rule about power supply testing:   Oh, I just noticed you did in fact actually state it's an "unwritten rule" - well my personal experience of searching on the subject can certainly confirm that!

Dimitrij Klingbeil <nospam@no-address.com>: Mar 01 01:05AM +0100 On 01.03.2016 00:21, Cursitor Doom wrote:   > Oh, I just noticed you did in fact actually state it's an "unwritten > rule" - well my personal experience of searching on the subject can > certainly confirm that!   At least myself, I have not seen it being being explicitly explained or written anywhere yet, but it's sort of "common knowledge" in a way...   Among engineers who design power supplies, this seems to be taken for granted - too self-evident to warrant explanation apparently. Others, among them the many who design low voltage circuits and prefer to buy their power supplies off the shelf, rarely get to see switching nodes driven with significant fractions of a kV with fast rise times. That leaves their awareness of the "tricks of the trade" rather limited.   Power supply design is both a science and an art, and the power supply "artists"' rites of initiation can sometimes involve strange things :)   Anyway, never fear, but always exercise logical thinking, conservative judgement and be aware of side effects - that would be my advice here.   Dimitrij

jurb6006@gmail.com: Feb 29 04:29PM -0800 >"Never connect the ground (common, chassis etc.) of any test >equipment >to the switching node (power transistor collector, drain or power IC >output pin and its associated signals) of a switching power supply!" >"   Well now that you wrote it, it is no longer unwritten. :-)   But I know what you mean. It is pretty much RF and if the caps don't short it out it can burn you some. If the voltage is high enough you don't even have to touch it. I got burned by the cathode of a damper tube in a color TV set once. That is half of about a 70 KHz sine wave clocked at 15.734 KHz. Arced to my finger, burnt and cauterized all the way to the bone. On blood, but it sure did smart. And then it felt funny for like six months after.   Can you imagine that on the chassis and probes of your scope ?

Cursitor Doom <curd@notformail.com>: Mar 01 09:21AM On Mon, 29 Feb 2016 16:29:47 -0800, jurb6006 wrote:   > Can you imagine that on the chassis and probes of your scope ?   Not really. It's too weird. Maybe I could simulate it in spice to get a better idea of what's going on here. Anyone got a model suggestion for a 'hanging scope'?

"Ian Field" <gangprobing.alien@ntlworld.com>: Feb 29 08:20PM "Jeff Liebermann" <jeffl@cruzio.com> wrote in message news:ba97db1lj47i18hbd1kg8quimd9n0d15d3@4ax.com... > fuel gauge and controller chips.   > This might be of interest: > <https://media.blackhat.com/bh-us-11/Miller/BH_US_11_Miller_Battery_Firmware_Public_WP.pdf>   Looks interesting - thanks. >>charge control chips - those I can maybe find online.   > Just Microchip, not Az Microchip. > <http://www.microchip.com/design-centers/battery-management>   Last time I used the term; "microchip" - everyone assumed I meant just a chip.

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