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Phil Allison <pallison49@gmail.com>: Dec 09 05:54PM -0800 Hi all,   recently I replaced a toroidal mains transformer in a 5 or 6 year old Crown XLS602 power amplifier. This was a 240V, 800VA size tranny with the secondary winding giving of 75-18-0-18-75 volts.   http://cdn.avsforum.com/3/38/38365662_vbattach143596.jpeg   The toroidal was made by a Chinese company - NRE Electrical Manufacturing Co Ltd.   www.fsnre.com   The primary had shorted turns and luckily I had another very similar toroidal on hand that did the job - after adding a small 18-0-18 tranny as well. No other faults were found with the amp.   Failures of such large transformers is quite rare, so I began to unwind the thing to have a look and also get some heavy gauge winding wire too. It was a real bugger of a job cos both the secondary and primary had been "bi-filar" wound. The shorted turns were found near the core, right where the twin primary winding is split and series wired. No big surprise there.   But then there WAS a big surprise underneath - the toroidal core itself. Normally there are precision made, tape wound cores with molded plastic caps covering the sharp edges. Not this one.   The corner edges had simply been ground off by hand and covered in cloth tape. The core itself looked rough and uneven - then I realised it was made from dozens of separate strips of steel, spot welded to each other, end to end and of varying thicknesses and widths. The tranny was made from scraps !!   Some dirt poor Chinese had hand assembled the core using rusty off cuts and sweepings from the floor from some transformer factory. The centre hole was perfectly round but the outside diameter varied by 3mm due to all the joins.   One would reasonably suspect such a "Frankenstein" core of having poor magnetic performance - but all my testing showed it was perfectly OK.   The Chinese are getting desperate.       ... Phil

"William Sommerwerck" <grizzledgeezer@comcast.net>: Dec 10 04:58AM -0800 "Phil Allison" wrote in message news:74b01fcb-f8a3-4ed4-8c71-211590078138@googlegroups.com...   > The Chinese are getting desperate.   Which is basically good for the West.   After WWII, the Japanese realized they had to export high-quality products to compete. Not all Chinese manufacturers have caught this, and some compete solely on the basis of price. Until they do, they will never be the real threat they have the potential to be.   I'm reminded of the joke about Japanese products in "BttF 3".

Mike <news@mjcoon.plus.com>: Dec 10 09:55AM -0600 On Tue, 09 Dec 2014 17:54:49 -0800, Phil Allison wrote:     > One would reasonably suspect such a "Frankenstein" core of having poor > magnetic performance - but all my testing showed it was perfectly OK.   > The Chinese are getting desperate.   But perhaps there are also rich Chinese who will pay good money for a genuine hand-made artisanal artefact!   Mike.

"Gareth Magennis" <sound.service@btconnect.com>: Dec 10 09:53AM Peavey Classic Chorus 212 uses those IC's.   http://elektrotanya.com/peavey_classic_chorus_212_sch.pdf/download.html     Gareth.       <jurb6006@gmail.com> wrote in message news:77732216-2a0a-4424-84f8-8240c030ff84@googlegroups.com...

"hrhofmann@sbcglobal.net" <hrhofmann@sbcglobal.net>: Dec 09 02:10PM -0800 I have a couple of "sealed" devices that apparently have negative temp coefficient devices inside of them that are placed between a power outlet and the lights. The lights start out at 1/3 normal brightness and come up to full level in 5-10 seconds. Soft turn-on means less light failures. I would like to have/make several of these, but I don't know what is inside the boxes and don't really feel like tearing them apart if I don't have to.   Suggestions!

John Robertson <spam@flippers.com>: Dec 09 02:22PM -0800 > I have a couple of "sealed" devices that apparently have negative temp coefficient devices inside of them that are placed between a power outlet and the lights. The lights start out at 1/3 normal brightness and come up to full level in 5-10 seconds. Soft turn-on means less light failures. I would like to have/make several of these, but I don't know what is inside the boxes and don't really feel like tearing them apart if I don't have to.   > Suggestions!   Research Thermistors.   John :-#)#   -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

"hrhofmann@sbcglobal.net" <hrhofmann@sbcglobal.net>: Dec 09 02:28PM -0800 I was being lazy, had hoped for some part numbers <g>.

"Maynard A. Philbrook Jr." <jamie_ka1lpa@charter.net>: Dec 09 05:52PM -0500 In article <70c9883e-dadd-4321-b17e-658390393da0@googlegroups.com>, hrhofmann@sbcglobal.net says...   > I was being lazy, had hoped for some part numbers <g>.   They call them "NTC Thermistors".   Look at Mouser, you need to estatemate the wattage your light string uses so you can properly select the correct one that will create the voltage drop you need when cold and reduce down to it's minimum value when hot.

Phil Allison <pallison49@gmail.com>: Dec 09 02:54PM -0800 > I have a couple of "sealed" devices that apparently have negative temp coefficient devices inside of them that are placed between a power outlet and the lights. The lights start out at 1/3 normal brightness and come up to full level in 5-10 seconds. Soft turn-on means less light failures. I would like to have/make several of these, but I don't know what is inside the boxes and don't really feel like tearing them apart if I don't have to.     ** The devices are probably "NTC thermistors".   http://www.ampron.com/UploadFiles/Others/20130712150338_50489.jpg   They come in a range of sizes and resistance values.   You need to measure the cold resistance value to establish the latter.   Last time I needed some, I found them on Ebay from dealers in HK.   ... Phil

"hrhofmann@sbcglobal.net" <hrhofmann@sbcglobal.net>: Dec 09 09:11PM -0800 Thanks for the info, I'll measure the cold resistance tomorrow, right now the lights are all on.

gopherbar@gmail.com: Dec 09 08:20PM -0800 On Sunday, March 9, 1997 12:00:00 AM UTC-8, Nigel Cook wrote: > email diverse@tcp.co.uk > hints/tips on homepage http://www.tcp.co.uk/~diverse/ > regards, Nigel   www.radiomuseum.org/r/hameg_oscilloscope_hm103.html

"Arfa Daily" <arfa.daily@ntlworld.com>: Dec 10 02:22AM "John-Del" <ohger1s@aol.com> wrote in message news:c2ff664d-8ad1-4ebe-82ec-4dd48cbcdbad@googlegroups.com... >> do.   > Price I guess. I don't work on all that many music amplifiers, but I > don't recall ever seeing one with speaker protection relays installed.     Lots with semiconductor output stages have output relays, if for no other reason, to stop the switch-on thump as the rails stabilize, but mainly for speaker protection purposes. Some of the speaker protection circuits can be very complex. One that comes to mind is that Ecler, that spawned the original discussion about magnets on the relays.     In the case of home audio, they do provide protection because outboard speakers can be pricy (much more expensive than the amp), and folks wouldn't be thrilled to see their amp take out their speakers. In the case of a music amp, they're self contained so I guess manufacturers figure they can sell new drivers if they blow.     Only combos are self contained. There are just as many heads and slaves in use, and these drive external speakers. Contrary to what you believe, the prices of some of these drivers can be eye-watering ...   Arfa

KenO <kenitholson@yahoo.com>: Dec 09 11:49AM -0800 Ian,   "Most were revived by "tickling" the contacts with the leads from an old fashioned car battery charger."   Did you check what the Voltage was for "Revival"so you could use universal lithium charger?   Do you know the output specs for the "universal lithium charger from the Lidl discount store"?   Also what does "LiDl" mean? Googled and found http://en.wikipedia.org/wiki/Lidl but do not think this is it.   Thanks for the suggestions.   Ken

KenO <kenitholson@yahoo.com>: Dec 09 12:06PM -0800 Mike,   Since asking the "taking cellphone battery apart?" found some good views for the Nokia. Seems like mine is an early version that has small screws holding the end plate on.   If you (or anyone else) are interested would post photos but need to be told how.   Thanks again for the help.   Ken

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