Don't know if this is the right place, but got to start somewhere..

Look at the picture.
What component is the PH46-one?
It looks like it's been overheated.
I think it is a FET-transistor in a SOT-223 capsule.

Anyone know where to get a new one, or a replacement of different kind?

I'm not 100% sure if it is malfunctioning, because the unit works, except it has difficulties charging the inboard battery. Maybe it is a connection there..?!

The unit is a Satlook micro+/G2 satellite finder.

what is that blob on top of it?

Well, probe it with whatever ya got. If you don't have a scope, at least put a DMM on it. If you can determine it's a transistor, a diode test between each pin can tell you what general kind of transistor it is - BJT vs MOSFET. P vs. N.

Possibly the chip that drives it.
http://www.national.com/ds/LM/LM2578A.pdf

looks fried to me!

The blob is something that has grown up from the capsule I think. I guess I can tear it off by using a nail, since it is softer and more powder-like. But I don't, since this instrument works pretty well after all. I bought it used, and knew it had trouble with charging.
I was hopeing that someone here would recognize the shape of the component and tell this is a .....!
Maybe it isn't that easy.
I found a possible match googling for PH46 SOT223.
PH46 - SOT 223
But it doesn't tell me much. Maybe something from Fairchild-semi..?! No match at their web site.

I have a Fluke 189dmm, but my knowledge about transistors and such is poor. I know PNP and NPN, I know diode, but coverting it to practise..
This unit has a sandwich layout with2 pcb, and this component is hard to reach do to covering parts..

Looking at ELFA webpages, - transistor , gives me a match for the shape as SOT223, but no more...

Cool that someone has replied after all

-

Searching for SOT223 6n0, gave me some more hits.
Like this one.
Don't understand the language, but it may seems like a Aopen motherboard has a similar component.

I'll keep looking..



This post has been edited by Dunno on March 21, 2009 10:17 am

probably a FET.......maybe one of the far eastern ones......

some of them dont have english datasheets

try loooking there

there are websites that contain fr eastern electronics componants

yep , that part blew it's guts out .
i did some looking around ... no dice .

i'd check with the manufacturer ...
or a forum dedicated to the product .

who made that board with no Ref-Des's?

Is there a Q, U, or VR around it anywhere?

A burn mark. Too bad it obliberated some of the part number. The device is a 6N0xx, whatever that is.

It's probably a FET. Some things to test for:

Pin 1 is commonly the base/gate on this type of package. The heatsink and pin 2 are usually in continuity and are the collector/drain. Pin 3 is usually the emitter/source.

The small 10R resistor on pin 1 strongly suggests MOSFET over BJT.

Working on these presumptions:

N-FET: diode test will show a +0.5ish V drop between pin 3 and pin 2, only. (Red probe on pin 3, black probe on pin 2). However, if fried, there may be no positive diode test between any pins. Pin 3 is likely to be in continuity with ground rail or a negative rail. (Test for continuity between pin 3 and the negative lead of nearby electrolytic capacitors.)

P_FET: diode test will show a drop from pin 2 to pin 3, only. However, if fried, there may be no positive diode test between any pins. Pin 3 is likely to be in continuity with one of the positive rails. (Test for continuity between pin 3 and the positive lead of nearby electrolytic capacitors.)

It should go without saying that it's a good idea to repeat these tests once the parts is removed.

As for part replacement: First you should figure out what's driving the gate, because it is quite likely fried, as well. When you're ready to proceed, you should measure the voltage of the device or check nearby electrolytics to determine the max voltage rating you will need. I don't know what package that is, offhand, but you should be able to find the package type by browsing catalogs. Knowing the response frequency would be advisable, but you might as well guess if you don't have the measurement tools to check... Just go for the highest frequency response (lowest on/off times) and lowest on resistance you can find for a reasonable cost. You might even come across some similar ID numbers while looking.

But be aware that a host of other components, such as high speed diodes, can come in 3-pin packages similar to transistors. It's probably a FET, but you should verify it as best you can.

From another forum, someone suggested the component may be from Prewell.
I can see they have something called a medium power amplifier named PH465 , and it is a SOT89. Could be a match?!

One more thing is that this unit should have a backlight for the LCD. The menu option is there, and I got confirmed today, it used to be backlight.

Could this part be a driver for backlight?
The backlight I think must be of some EL-Film or foil type, because the LCD is very thin, and It has 2 lead connection the foil.

You can see here:


This kind of light uses an inverter and higher voltage (ac) I think?

Anyone see a connection here, between an amplifier component and the backlight?


There are two "problems" with this unit.
The first is the charging: The included "transformer-less" charger does make the unit charge, I can tell from the display, but the batteries don't last nothing. (rated 13,8v dc)

I took a chance and used a transformer-kind of powersupply, with 12 v DC rating, actually close to 14 with a multimeter. This one makes the unit last 30min, and that is ok. (as promised by seller)
I don't know if this "charger" will harm the unit more or less than the other one...

The posible blown part does not get hot with neither the two chargers, or when I use the unit. (not very strange since it's probably blown).
The unit works as supposed, as long as there are power in the batteries.

I wonder if the blown part is about the backlight... and not the charging-circuit.
The battery-pack is close to new, and the manufacturer claims 2 hours og usage..

BTW. The colors on the picture with the blown-up part, may look worse on the picture than actual. The brown parts around is more yellow, and is from soldering and solderingpaste rather than over-heating..

Prewell PH465


[edit later]
I found a small chip called HV830, which I believe is a high voltage el foil driver. It get's very hot by the way. On a different place than the PH46 thogh.
Maybe the heat is because of something else malfunctioning in it's circuit.

This post has been edited by Dunno on March 23, 2009 07:24 pm