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Repair 82002A charger?
04-08-2014, 02:25 AM (This post was last modified: 04-08-2014 02:26 AM by Paul Berger (Canada).)
Post: #4
RE: Repair 82002A charger?
Well aside from broken wires my number one suspect would have to be the 400uF electrolytic cap if it went short it would pull down everything. Looking at the circuit diagram again the only thing that really makes sense is that 400uF cap, so I would suggest that the first thing you do is remove it and see if you get any output don't worry about plugging it in without that cap it won't hurt anything but the dc voltage might measure a bit lower. I guess it is possible that the transformer has failed too or a couple of the rectifiers have gone open. Does you meter have a diode check function?

CAUTION be careful poking around in there with the adapter plugged in oriented as described above, at the bottom of the board the line input prongs come through the board and the rivets there are live as well.

The transformer used in these probably cannot produce a lot of current. Does it get warm when it is plugged in? I did take a few measurements, with the top off, board facing you, and output cable at the top. The 400uF caps is to the left of the cable and beyond that there is a tab transistor that you cannot conveniently get to the pins, on the right is another transistor flat on the board under an aluminum rod. The diodes that make up the bridge rectifier are on either side of the transformer to measure the AC output of the transformer connect to the bottom end of the diodes against the transformer on either side it should be about 14VAC

You can connect to ground at the top of the diode on the right side adjacent to the transformer, or since tour cable is good it may be just as easy to pick up DC ground at the end of the cable. To the right of the transformer on the outside there is a 470R resistor and a diode that join at the top the voltage here should be about 5.2Vjust above them is the transistor that lies flat the center pin should be about 16V and either outside pin about 5.2V. The tab on the transistor next to the 400uF cap should be about 16V as well. That is about all that is really convenient to check.

At there is a schematic for an 82010A which would seem to be the same except it seems to have a fuse in one leg of the output side of the transformer.

With the adapter oriented as above, the tab transistor on the left would be Q2, the small transistor next to it Q3, and the components below them from the inside out would be D3, R3, R2, D1. The 400uF cap is C1. The transistor on the right is Q1 and below it again from inside out D4, D2, D5, ad R1.
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Messages In This Thread
Repair 82002A charger? - Marcel Samek - 04-07-2014, 01:09 AM
RE: Repair 82002A charger? - Marcel Samek - 04-07-2014, 03:24 AM
RE: Repair 82002A charger? - Paul Berger (Canada) - 04-08-2014 02:25 AM

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