- Reviewing a cheap CRT degaussing wand - 16 Updates
| Rayner Lucas <usenet202101@magic-cookie.co.ukNOSPAMPLEASE>: Jan 12 08:48PM Hi all. This post is a review of the cheap "green stick" CRT degaussing wands, as I haven't found much discussion of them and some other repairers of vintage monitors may find it useful. CRT degaussing tools seem to be hard to find these days. Occasional used ones come up for sale, and there are still some to be found in the US. However, in the UK they're near-unobtainable. The main source seems to be eBay sellers in China, all of whom are selling the same type: a wand- style degausser in a green plastic shell. So, having a couple of CRTs with purity problems, I bought one to see if it would do any good. The wand cost about 15 GBP and arrived within a couple of weeks. There was no documentation included, leaving me with just the specs given in the eBay listing, which read: -Relative magnetic field: 70MT -Load current: 1A -Working hours: 20 seconds -Power: 220V -Specifications: About 31*31*200(mm) The outer shell is some soft semi-translucent plastic (polythene?), and feels extremely cheap. A momentary switch pokes out of the top of the casing (a momentary switch is good, as it stops me accidentally leaving the coil energised). The wand came with a moulded two-prong plug, which I had to cut off to fit a UK plug. And... I have never seen mains cable that thin before. It is, at least, double insulated, but the conductors are at most 28AWG and possibly even thinner (it's hard to measure stranded cable, but the diameter is somewhere around 0.25mm to 0.35mm). The strain relief clamp in the UK plug wouldn't even hold the cable until I wrapped some extra plastic around it. Oof. Looking at the ampacity ratings on the Wikipedia article for American Wire Gauge, that cable must be very close to, if not exceeding, its recommended current rating. It feels worryingly plausible that someone, somewhere made the calculation "it's fine, if they push the button for too long the coil will burn out before the cable insulation melts". However, the tool does what it's supposed to and noticeably reduced the blotches visible on the CRT display. I used the standard technique of powering the coil from a couple of metres away, bringing it up to the CRT face, circling it around a couple of times, then smoothly backing away two or three metres before switching off again. I definitely recommend sticking to the stated maximum of 20 seconds continuous operation and letting the wand cool fully before using it again. The heat seems to take a few seconds to conduct to the outside of the casing, so it's not until after you've switched it off that you feel how warm it's really getting. I popped the end cap off the casing to take a look inside, but haven't disassembled it further. Strain relief is just a knot in the mains cable. I don't see any current limiting apart from the coil itself. The coil is wrapped around a core of steel plates, and seems to have some more plastic insulation around it. The non-business end of the coil seems to have some copper mesh shielding. Hooking the whole thing up to a component tester, coil resistance measures around 140 ohms, with an inductance of 320mH. In summary, Pros: - Cheap. - Does what it's supposed to. Cons: - Not particularly sturdy. - Probably not the safest thing ever, use with caution. If there were better-quality tools available, I would definitely buy those instead. But there weren't, and this one did at least provide the functionality I needed. HTH, Rayner -- Big-8 Management Board: https://www.big-8.org Homepage: http://magic-cookie.co.uk |
| John Robertson <spam@flippers.com>: Jan 12 02:00PM -0800 On 2021/01/12 12:48 p.m., Rayner Lucas wrote: > wands, as I haven't found much discussion of them and some other > repairers of vintage monitors may find it useful. > CRT degaussing tools seem to be hard to find these days. Occasional used ... > functionality I needed. > HTH, > Rayner I use a large Weller Soldering Gun when I can't find one of the degaussing coils in the shop... John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| Ralph Mowery <rmowery28146@earthlink.net>: Jan 12 05:27PM -0500 In article <fpmdnckH4tWUgWPCnZ2dnUU7-K2dnZ2d@giganews.com>, spam@flippers.com says... > I use a large Weller Soldering Gun when I can't find one of the > degaussing coils in the shop... I also used the Weller or what ever Gun I had handy on the old CRTs. Just about any coil of wire will work that does not draw too much current. |
| Rayner Lucas <usenet202101@magic-cookie.co.ukNOSPAMPLEASE>: Jan 13 12:56AM In article <MPG.3a67ec6b38b8737098a116@news.east.earthlink.net>, rmowery28146@earthlink.net says... > I also used the Weller or what ever Gun I had handy on the old CRTs. > Just about any coil of wire will work that does not draw too much > current. Oh, that's a neat idea, I never thought to try a heating coil. I did consider making my own, but with no idea what spec to aim for, buying one seemed like it had a better chance of success :-) Rayner -- Big-8 Management Board: https://www.big-8.org Homepage: http://magic-cookie.co.uk |
| Trevor Wilson <trevor@rageaudio.com.au>: Jan 13 12:48PM +1100 On 13/01/2021 7:48 am, Rayner Lucas wrote: > functionality I needed. > HTH, > Rayner **I have always been an audio tech. I have always avoided TV work where possible. However, back in the day, I would frequently perform a CRT degauss, using my Han-D-Mag head demagnetiser. I found that it could deal with any degaussing requirement. https://www.ebay.com.au/itm/Tape-head-demagnetiser-demagnetizer-Han-D-Mag-220-240V-/271234117484 Geez, they're expensive nowadays. I still have mine. -- Trevor Wilson www.rageaudio.com.au -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Phil Allison <pallison49@gmail.com>: Jan 12 06:08PM -0800 Trevor Wilson wrote: ================ > deal with any degaussing requirement. > https://www.ebay.com.au/itm/Tape-head-demagnetiser-demagnetizer-Han-D-Mag-220-240V-/271234117484 > Geez, they're expensive nowadays. I still have mine. ** I once acquired a demagnetiser that, far as I could tell, was incapable of demagnetising anything. Had no effect on tape heads or the tiniest screwdrivers. It was the Teac E1 as listed in your link. So acting on a hunch, I made a coil of enamel wire ( about 15 turns) just big enough to slip over the head concerned and energised it from a small 6.3V tranny. The coil would get quite hot in about 30 seconds. While energised, I popped it over the head and slowly removed it far away. Totally worked on even the most magnetised heads. Necessity is ....... ..... Phil |
| danny burstein <dannyb@panix.com>: Jan 13 04:47AM [snip] Back, umm... 1977ish.. (*whew*) I took a slotted steel wallmount bookcase rail (about 1/4 by 1/2 inch by 4 feet), wrapped some, umm, probably #18 lampcord around it, and wired it to a 12VAC transformer. I added in something like a 50 watt 120vac lamp (lighbulb) in series as a current limiter. Yeah, I had no idea what I was doing. Anyway, I then plugged this into a 120VAC power strip, put on some safety gloves and goggles, held it near the tv, and had my friend turn on the power strip. It worked! 1990ish I used a handheld Radio Shack brand tape degausser for the same purpose. And yes, it worked, too. So these things are doable... -- _____________________________________________________ Knowledge may be power, but communications is the key dannyb@panix.com [to foil spammers, my address has been double rot-13 encoded] |
| John Robertson <spam@flippers.com>: Jan 12 10:47PM -0800 On 2021/01/12 4:56 p.m., Rayner Lucas wrote: > consider making my own, but with no idea what spec to aim for, buying > one seemed like it had a better chance of success :-) > Rayner You need something that puts out a large AC field - like the unshielded transformer used in soldering guns. An electric heating coil has a very small magnetic field, I'd say it was most unlikely to be useful for degaussing... John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| John Robertson <spam@flippers.com>: Jan 12 10:50PM -0800 On 2021/01/12 5:48 p.m., Trevor Wilson wrote: >> wands, as I haven't found much discussion of them and some other >> repairers of vintage monitors may find it useful. >> CRT degaussing tools seem to be hard to find these days. Occasional used ... > deal with any degaussing requirement. > https://www.ebay.com.au/itm/Tape-head-demagnetiser-demagnetizer-Han-D-Mag-220-240V-/271234117484 > Geez, they're expensive nowadays. I still have mine. A bit cheaper on this side of the pond: https://www.atrtape.com/products/han-d-mag John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| Rayner Lucas <usenet202101@magic-cookie.co.ukNOSPAMPLEASE>: Jan 13 08:05AM In article <E6qdnUhTbNb5CmPCnZ2dnUU7-LPNnZ2d@giganews.com>, spam@flippers.com says... > transformer used in soldering guns. > An electric heating coil has a very small magnetic field, I'd say it was > most unlikely to be useful for degaussing... Ah, thanks, I get it now! I don't have a soldering gun, but it would certainly have been a lot easier to find one for sale than a degaussing coil. Or I guess I could've looked around for something else with a transformer I could salvage. Rayner -- Big-8 Management Board: https://www.big-8.org Homepage: http://magic-cookie.co.uk |
| Trevor Wilson <trevor@rageaudio.com.au>: Jan 13 07:20PM +1100 On 13/01/2021 1:08 pm, Phil Allison wrote: > While energised, I popped it over the head and slowly removed it far away. > Totally worked on even the most magnetised heads. > Necessity is ....... **My Han-D-Mag demagnetises everything. Heads, TV screens, screwdrivers, etc. As for necessity, I had a Naka in the other day and my part time employee told me that the Han-D-Mag was too big to reach the heads. I dug out this crappy little demag I bought years ago. Didn't work. Stripped it down, re-wound the coil with thicker wire and ran it off 12VAC. Works a treat. BTW: I have this neat and VERY sensitive magnetometer used to test for residual magnetism. -- Trevor Wilson www.rageaudio.com.au -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Trevor Wilson <trevor@rageaudio.com.au>: Jan 13 07:21PM +1100 On 13/01/2021 5:50 pm, John Robertson wrote: > A bit cheaper on this side of the pond: > https://www.atrtape.com/products/han-d-mag > John :-#)# **That's more like it. -- Trevor Wilson www.rageaudio.com.au -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Phil Allison <pallison49@gmail.com>: Jan 13 01:24AM -0800 John Robertson wrote: ================== > >> current. > You need something that puts out a large AC field - like the unshielded > transformer used in soldering guns. ** Utter nonsense. Such trannies radiate SFA mag fileld. > An electric heating coil has a very small magnetic field, ** But that is *not* what a soldering gun loop is. Single turn sure - but a carrying about 250 amps !!. So, at close range the same as a 25 turn coil carrying 10 amps. Much like the example I posted earlier that WORKED like a treat. ...... Phil |
| "Peter W." <peterwieck33@gmail.com>: Jan 13 04:57AM -0800 https://www.zoro.com/gc-electronics-specialty-tool-degaussing-coil-9317/i/G2187702/ https://www.travers.com/portable-magnetizerdemagnetizer/p/57-081-121/?gclid=Cj0KCQiA0fr_BRDaARIsAABw4Etup-m1bJ4WR6u5u86ELikWOl0rDsERXNjJ6Tsio0439R18RN6wxGgaAqo7EALw_wcB https://www.ebay.com/i/123990657206?chn=ps&mkevt=1&mkcid=28 Guys and gals - these things are available OTC here in the US. Why not in the UK? Oh, but they are: https://www.bartington.com/degaussing-wand/ https://www.ebay.co.uk/itm/NEW-CRT-MONITOR-DEGAUSSING-COIL-Arcade-TV-Repair/123990657206?hash=item1cde6b48b6:g:CkcAAOxyKsZRwenD For a one-off use, I would likely stick to the soldering gun - does the trick, even if used "off-label". I bring my 100/300 watt Craftsman gun to Kutztown for the occasional chassis connection, and it is as often as not borrowed by the TV guys for cleaning up the old TV pictures, but seldom for soldering. But if I had to do this every day, or even every week, I would likely invest in a purpose-built device from a reliable maker and reliable source. As I am fond of writing: The Internet is your friend! Peter Wieck Melrose Park, PA |
| Ralph Mowery <rmowery28146@earthlink.net>: Jan 13 10:11AM -0500 In article <53f918e3-7caf-4aed-bbb1-dbbb5fe189aan@googlegroups.com>, peterwieck33@gmail.com says... > For a one-off use, I would likely stick to the soldering gun - does the trick, even if used "off-label". I bring my 100/300 watt Craftsman gun to Kutztown for the occasional chassis connection, and it is as often as not borrowed by the TV guys for cleaning up the old TV pictures, but seldom for soldering. > But if I had to do this every day, or even every week, I would likely invest in a purpose-built device from a reliable maker and reliable source. As I am fond of writing: The Internet is your friend! I thought most crt screens had a coil around then that helped degauss them every time they are turned on. Unless someone puts a magnet near the screen I doubt that many would need degausing. With almost everything switching to the flat screens there is probably very little need for a dedicated degausing coil unless your shop specilizes in restoring old electronics. Hard for me to see any shop or one doing much work would not have a soldering gun that could be used. Maybe many do not know the soldering gun could be used. |
| "Peter W." <peterwieck33@gmail.com>: Jan 13 07:57AM -0800 > I thought most crt screens had a coil around then that helped degauss > them every time they are turned on. Unless someone puts a magnet near > the screen I doubt that many would need degausing. They do. And, whereas I am not in the vintage CRT hobby, there are any number of applications and any number of reasons why the on-board degausser may not be there, adequate, or even functional. There was (RIP) an individual not far away whose hobby was restoring video arcade games - commercial grade - with the big Curtis-Mathis CRTs in them. And he had half-a-dozen (at least) degaussers of various types and natures that he used regularly. But, apparently, failure of the on-board degausser was common enough that he was prepared. I keep some small, but very powerful magnets with me most of the time - is that painted pipe steel, copper, or possibly something else? Or that light can? What grade stainless *might* that be? And they will stick to most flat-screens - but not cause any distortion. But get one within 10" or so of the big Sony 32" CRT TV (c. 2001) at home and watch the show. Of course, the on-board coil works on that one, still. Peter Wieck Melrose Park, PA |
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