Science
01 Jul 12
01 Jul 12
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?
01 Jul 12
3 edits
Originally posted by SwissGambitSounds 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.
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?
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.
01 Jul 12
Originally posted by sonhouseHere it is - sorry for the photo quality:
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.
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.
02 Jul 12
Originally posted by SwissGambitThat 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.
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.
02 Jul 12
Originally posted by sonhouseVA7001 is apparently a varistor. I looked up the part number. All the capacitors on the board have the standard "C" ref des.
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.
02 Jul 12
Originally posted by twhiteheadYes, the board has a part number, and I googled for it. I found several of them for sale, but no schematics, unfortunately.
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.
At least I know where to buy one if I can't fix this. 😛
02 Jul 12
Originally posted by SwissGambitGood 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.
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.
http://www.servicesoftware.com/sams.asp
03 Jul 12
2 edits
Originally posted by googlefudgeInteresting 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?
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
15 Aug 12
Originally posted by joe beyserIt 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?
some sort of filter?