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  1. Standard member SwissGambit
    Caninus Interruptus
    01 Jul '12 13:45
    In 15 years in the field of electronics, I have never seen the reference designator "GA" until I opened up my TV. I have a failed switching power supply. One of the AC input fuses keeps blowing. This GA component has a clear body. Inside is a tightly wrapped coil (?) of wire with two bands of (apparently) solder around the ends. My guess is that it is some fuse-like component that may have been blown along with the fuse.

    Anyone know what this is?
  2. 01 Jul '12 14:15 / 1 edit
    Originally posted by SwissGambit
    Anyone know what this is?
    Can you post a photo?
  3. Standard member sonhouse
    Fast and Curious
    01 Jul '12 16:21 / 3 edits
    Originally posted by SwissGambit
    In 15 years in the field of electronics, I have never seen the reference designator "GA" until I opened up my TV. I have a failed switching power supply. One of the AC input fuses keeps blowing. This GA component has a clear body. Inside is a tightly wrapped coil (?) of wire with two bands of (apparently) solder around the ends. My guess is that it is so ...[text shortened]... fuse-like component that may have been blown along with the fuse.

    Anyone know what this is?
    Sounds like a slow blow fuse. A photo would confirm it. If a slow blow fuse went it means there is a problem with some other part of the circuit, something else shorted out taking out a fuse that is supposed to delay the process of blowing out so transients generated by just turning on the power supply won't keep blowing a fast blow fuse.

    It's like an incandescent light bulb, there is an inrush current because the tungsten filament inside has a lower resistance cold than hot, so there is an inrush of several times the operating current but for only a short period of time, say a half second or so.

    Using a fast blow fuse in that situation would just mean the fuse would blow every time the bulb is turned on.

    Here is a wiki about fuses, see if the first photo is what you are talking about. Your description sounds like this is it.

    http://en.wikipedia.org/wiki/Fuse_(electrical)

    I don't find the GA designation for fuses but I found GMA which is a normal fast blow fuse.

    The only GA I know is 'gallium arsenide' which is a high power high temperature and fast transistor series or computer chips made with gallium arsenide. That doesn't sound like a semiconductor of any kind to me from your description. It might be a thermal protection fuse.

    Is that the one that is blowing? Usually thermal protectors are attached to the object they are protecting against high temperature, if the temp goes past the set point the device opens up stopping the current causing the over temp, sometimes they recover on their own, sometimes a one shot deal.

    Sorry if I am covering stuff you already knew. I guess you are an electronics tech? You work on computers?

    I found this little glossary of electronic designators:

    http://www.diybanter.com/electronic-schematics/307388-component-reference-designator-id-seb-ansi-reference-designators-pdf.html

    In the G section there was no GA, only G.

    Which doesn't mean it doesn't exist, only that it might be a company name instead of an electronic designator.
  4. Standard member SwissGambit
    Caninus Interruptus
    01 Jul '12 20:12
    Originally posted by sonhouse
    Sounds like a slow blow fuse. A photo would confirm it. If a slow blow fuse went it means there is a problem with some other part of the circuit, something else shorted out taking out a fuse that is supposed to delay the process of blowing out so transients generated by just turning on the power supply won't keep blowing a fast blow fuse.

    It's like an i ...[text shortened]... doesn't exist, only that it might be a company name instead of an electronic designator.
    Here it is - sorry for the photo quality:

    http://i48.tinypic.com/34gloop.jpg

    There are two ceramic slow-blow fuses in series with the AC input. When I first opened up the TV, both of them were blown. When I installed new fuses, one of them blew right away.

    This device, GA7001, is connected from one side of the AC input (after the ceramic fuse) to ground. I get no resistance from it, so if it is some sort of fusable resistor, etc., it's blown.

    It's OK if you cover some things I already know - yes I am an electronics tech - but I would rather have too much info than not enough. I work in the aerospace industry.
  5. Standard member sonhouse
    Fast and Curious
    02 Jul '12 00:12
    Originally posted by SwissGambit
    Here it is - sorry for the photo quality:

    http://i48.tinypic.com/34gloop.jpg

    There are two ceramic slow-blow fuses in series with the AC input. When I first opened up the TV, both of them were blown. When I installed new fuses, one of them blew right away.

    This device, GA7001, is connected from one side of the AC input (after the ceramic fuse) t ...[text shortened]... ech - but I would rather have too much info than not enough. I work in the aerospace industry.
    That designation is only a PC designator, the part next to it VA7001 seems to be a cap. that GA part has color codes on it also. Maybe an inductor, the color code would indicate the inductance rating. The GA7001 doesn't mean squat unless you had the photfact for that TV and the BOM.
  6. Standard member SwissGambit
    Caninus Interruptus
    02 Jul '12 00:19
    Originally posted by sonhouse
    That designation is only a PC designator, the part next to it VA7001 seems to be a cap. that GA part has color codes on it also. Maybe an inductor, the color code would indicate the inductance rating. The GA7001 doesn't mean squat unless you had the photfact for that TV and the BOM.
    VA7001 is apparently a varistor. I looked up the part number. All the capacitors on the board have the standard "C" ref des.
  7. 02 Jul '12 08:46
    Originally posted by SwissGambit
    VA7001 is apparently a varistor. I looked up the part number. All the capacitors on the board have the standard "C" ref des.
    Is there a number on the board (for the board as a whole)? You might just get lucky and find the circuit diagram online somewhere.
  8. Standard member sonhouse
    Fast and Curious
    02 Jul '12 12:07 / 1 edit
    Originally posted by SwissGambit
    VA7001 is apparently a varistor. I looked up the part number. All the capacitors on the board have the standard "C" ref des.
    I'm going with inductor for that GA part. I think the tell is the color code markings.
  9. Standard member SwissGambit
    Caninus Interruptus
    02 Jul '12 15:44
    Originally posted by twhitehead
    Is there a number on the board (for the board as a whole)? You might just get lucky and find the circuit diagram online somewhere.
    Yes, the board has a part number, and I googled for it. I found several of them for sale, but no schematics, unfortunately.

    At least I know where to buy one if I can't fix this.
  10. Standard member SwissGambit
    Caninus Interruptus
    02 Jul '12 15:45 / 2 edits
    Originally posted by sonhouse
    I'm going with inductor for that GA part. I think the tell is the color code markings.
    Only trouble is, why would they put an inductor from one side of the AC input to GND?

    Edit: And also - all the other inductors are designated LXXXX.
  11. Standard member sonhouse
    Fast and Curious
    02 Jul '12 21:04
    Originally posted by SwissGambit
    Only trouble is, why would they put an inductor from one side of the AC input to GND?

    Edit: And also - all the other inductors are designated LXXXX.
    Good point. L=inductor. Hmm, could it be an inrush current limiter? An inductor would still do that too. The color code means something. I was thinking maybe thermal overload protection but those devices are almost always near the part to be protected, glued in place sometimes. You might look on Sam's Photofacts, see if you can find the circuit board.

    http://www.servicesoftware.com/sams.asp
  12. 02 Jul '12 22:59 / 1 edit
    If it's part of a rectifying power supply it could be a switching diode.

    EDIT:
    Someone asking the same question here

    http://www.electronicspoint.com/component-t246630.html

    and here

    http://forum.allaboutcircuits.com/archive/index.php/t-68669.html
  13. Standard member sonhouse
    Fast and Curious
    03 Jul '12 00:29 / 2 edits
    Originally posted by googlefudge
    If it's part of a rectifying power supply it could be a switching diode.

    EDIT:
    Someone asking the same question here

    http://www.electronicspoint.com/component-t246630.html

    and here

    http://forum.allaboutcircuits.com/archive/index.php/t-68669.html
    Interesting that you found those links. It is probably some kind of suppression, but the color code has to say something. Maybe a voltage rating, it fires at XX volts?
  14. 14 Aug '12 02:11
    Originally posted by SwissGambit
    Only trouble is, why would they put an inductor from one side of the AC input to GND?

    Edit: And also - all the other inductors are designated LXXXX.
    some sort of filter?
  15. Standard member sonhouse
    Fast and Curious
    15 Aug '12 19:40
    Originally posted by joe beyser
    some sort of filter?
    It might be something like a thermal protection device, you would only need it on the hot side of the AC. An inductor might be in place to limit inrush current, but without a DVM or inductance meter, it is hard to tell. If you stick a DVM on it and it shows basically zero ohms, you know it has to be some kind of protective device. Have you DVM'd it yet?