figuring out what transformers these are - Page 1
Forum section: electronics / beginners

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: May 24, 2013, 01:43:58 pm
content: hello, i have been sorting my box of components that i was given a while back and i have come across two transformers which i do not fully know what they do...i believe the one on the left is just an isolation transformer which does 230V-230V as its come off of a board for UK mains voltage, i have no clue for the amperes thoughthe one on the right I also belive is 230V input as it is from a UK mains voltage product but i am unsure what voltage/voltages to as there are many pins on the underside. i have searched for the codes which are on top of the transformer (FL-2815 and KS 0206) but i am unable to find any datasheets.could someone help me either find a datasheet or tell me what they do?

author: Psi
author_rank: Super Contributor
timestamp: May 24, 2013, 01:52:16 pm
content: If i had to guess i would say they are both out of a computer powersupply.The one on the right looks like your typical pc psu transformer, the many taps will be for +3.3 +5 +12 etc.It will only work at a high switching frequency, probably around 50-100kHz (not 50/60hz mains)The one on the left is probably a common mode choke rather than a transformer.

author: Deagle
author_rank: Newbie
timestamp: May 24, 2013, 01:53:57 pm
content: Are those transformers from a tv?I stripped a panasonic? tv a few months ago, and I think I have one of the exact same transformers..I searched the code on the top of mine, but I didn't get anywhere. I think manufactures just get transformers made to suit their needs, so there is no need to release data on them. (don't quote me on that though)I havent tested mine yet, but here is the plan I had-1) use ohmmeter to determine which pins connect to what coils.2) pass low ac voltage into one winding, until approximate ratios are worked out, and finding center taps etc..

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: May 24, 2013, 02:14:56 pm
content: i found the board that the right transformer came off of and it does come from UK 230 50Hz mains, it has a few 0.1uF caps with it and the bridge rectifier alone with smoothing caps and other componants.comming off the board are connectors with labels :P-con, GND, aL5V, -8V, GND, 8V, GND, AL5V, GND, 3.7VD5V GND, A5V GND, 8V, GNDGND, -28V, AL5V, VF+, VF--8V, GND, 8V, D5Vi think this board came off of a DVD player with a VHD displayon the right transformer there is 1 pin with a space then 4 pins in a row and on the other side there is 1 pin then a space then 7 pins in a row if thats any help

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: May 24, 2013, 02:24:57 pm
content: this is a picture of the underside and which pins are connected to each other:same color pin = connected together

author: G7PSK
author_rank: Super Contributor
timestamp: May 24, 2013, 03:04:38 pm
content: The pins that are connected together are most likely to be thermal fuse links.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: May 24, 2013, 10:20:44 pm
content: So which pins should i put a low ac voltage into to check the ratios?

author: Psi
author_rank: Super Contributor
timestamp: May 25, 2013, 01:08:35 am
content: Quote from: carbon dude oxide on May 24, 2013, 10:20:44 pmIt looks like a ferrite core to me. You'll have to use high frequency AC to test it.(Unless im wrong and its an iron core.)When testing transformers it's a very good idea to have a lightbulb in series. (rated to whatever voltage your using to test)With all the secondary windings open circuit the primary will draw minimal current and the lightbulb will remain off. (or maybe glow slightly)If you pick the wrong windings or the transformer core is the wrong type or it's stuffed the lightbulb will safely light up.You can even go around shorting out the secondary windings to find which are paired with each other. If the lightbulb lights you've found a secondary winding pair.If you connect the wrong windings and don't have a lightbulb you may smoke the transformer or blow the breaker.

author: nukie
author_rank: Frequent Contributor
timestamp: May 29, 2013, 02:49:56 pm
content: Very useful tips thanks psi!