Salvaging Transformers

[Jye]

Hello all

In my part of town we are about to have a "Curb side pickup" day, where everyone puts all there large junk out on the street to be picked up and taken away. There are always a lot of old TVs and stereos thrown out and I would like to know what should I look out for if I want to salvage some transformers for use in chip amps?

Cheers
Jye

[ofb]

forget the televisions. do not open televisions. that's high voltage territory.

look for 70s stereo components from the better brand names like yamaha and technics and even kenwood. these are the ones that weigh a fair bit and usually have a little wood trim.

look on the back and you may see a rating like 260va right there where the power cable goes in.

i'd grab these. however, the transformers tend to be center tapped and in the 30-0-30 range. that's getting a little high for a lm3875 gc, and you can't do the dual bridge. you're not likely to get a 20v dual secondary.

you might in newer gear -- i don't know. i've only salvaged the older gear. the only newer amps i've opened tended to have small transformers and a heck of a lot of secondaries (possibly for the digital display and whatnot).

you might also look at salvage for useful chassis.

you might also look in the vents of equipment you're not sure about. if it's really heavy and has a big pair of caps staring at you, then that might be good to grab. you can always chuck it out next "curb day".

and keep an eye for really good brand names. sometimes it's just amazing what people toss out. it can be very good gear that just needs the pot cleaned.

once you have something, you can often find out a fair bit about it with google.

i wish they still had "curb day" here.

[ofb]

jackinnj, no offense at all, but if you're going to suggest that then you should also talk about discharging it. there's serious danger for the novice here. it's not just an implosion hazard.

i really think discharging should only be learned hand-ons from someone experienced, rather than on-line. the cost of a mistake is too high. tv stripping is not something for someone just starting on gc's. experienced tube folk are much better placed to make that step.

i do appreciate the tip on trans source, though. good iron is pricey.

general note for others: the leaded glass shards may be classed as dangerous waste in your area. check with your local facility. this may make the free transformer less worthwhile.

[thomas997]

What do you mean by discharging it?


When I took apart a broken TV, it held a HUGE amount of charge.. I ground the cable that enters the glass many times, getting a spark each time.

Is that what your talking about?


It is dangerous.... be sure to take all the proper precautions.



If the transformer voltage is too high, see if it has seperate primary hookups for 220V. Or maybe you can regulate it too.

[Larin]

i've come across what must be an old power amp.
it could be worth all the hassle of dragging it home. it's got an ulveco trans that saysrim1/2- 117v 50hz, sek1/2 36,5v 7a, sek3/4 21,5v 7a,sek5/6 24,7v 1a. it also has 4elna caps 50v 10000µ and 6 63v 6800µ caps that look good. i took it thinking i could use the trans, heatsinks, speakerterms and some other parts.
anything worth taking care of?

[Larin]

that smily should have been a p

[psychosteve]

its probly 120v primary with a stepped secondry tap. probly single supply, ie, +v and 0v and you can probly onlt use one set of secondrys. those caps are the big thing. they cost a lot to get these days, if they have the screw terminals on them. good trans for single supply GC, if slightly low on volts, but good amp rating. better off using it for an N channel amp, look in solid state for some good, simple and powerful amps. c u later bud, steve.. ..

[psychosteve]

are you sure sek with 24.7 v is 1a (one amp) if it is it may be that you can use all the secondrys together? dont know with out seeing it. c u later, steve.. ..

[dnsey]

A word of warning!
Most UK TVs old enough to use large TXRs have a live or 'half live' chassis. In this case, the transformer DOES NOT provide mains isolation (it's an autotransformer), and is definitely unsuitable for providing LT for amps, etc.
They do have their uses, but if you know how to use one safely, you'll also know where it could be handy.
Even in the case of second-hand isolating transformers, be VERY careful when experimenting - the old gear might have failed because of a pri - sec short, and you might find HT on the LT side!

[Variac]

Jack,

While there is no doubt that there are useful things in old TV's , and that people who are knowlegeble could possibly deal with these dangers. It is absolutely prohibited on these forums to suggest that people open old television sets, because of the high voltage dangers therein, that remain even if the mains cord isn't connected. This isn't my rule, it is universally applied here.
ofb dnsey thomas997 should be listened to.
Sorry