Got my order, check out these parts

[Dr Zeus]

Hey Perry,

I had some questions about this order I just received from a high quality american reseller. They had a good price going for me on IRF3205PBF, so I bought a sleeve. Do these look like real IRF3205 parts? The pair above the 4 are actually an order of IRF3205 (w/ lead) I got off ebay awhile back - while these came in a sleve signifying IR as the manufactorer, the newly aquired order is in a slightly different package. For comparison, the lower sleeve is IRFZ44N also just purchased from the same place.

Old stock (2) from eBay on top, new order (4) below




The blue package is IRFZ44. The unmarked package are the new IRF3205PBF


Here are the SKUs on the new sleeves of parts


I also picked up this, a 55w 2.7ohm resistor. Should this work well on its own as a current limiter when working on stuborn amps?

[Dr Zeus]

Here is the datasheet on the large resistor. I hooked it directly to my 10A supply, and it gets hot. VERY hot. Although the specs say it can withstand 350C. After about 3~4 minutes on my 10A supply it hit 310C before i cut the juice.

http://download.siliconexpert.com/pd...al/hlmnhlm.pdf

Update: OK I think this resistor will work OK, at least on good amps. On ones with shorts it'll run really hot as expected, but amps which are not blown should keep the resistor pretty cool. At least now I have something better than intuition as the current limiter. 3~4 minute intervals on a shorted amp is like a million times more service time than one which I couldnt get to power at all.

[Perry Babin]

I've never seen the label on the 3205s. The offset dimple is new also. The ragged edge (where the plastic meets the metal tab) on the one on the left is also strange.

Is the back of the transistors perfectly smooth if you run you fingernail across the areas that look rough?

You don't generally need to leave power applied with a direct short for more than a few seconds at a time.

Where did you buy them from?

[m4ick]

I got some 9640s like that, didn't work properly. I bet they weigh less than other 3205s on a scale. My 9640s felt like they weighed less than originals.

Or maybe they just felt more flimsy.

[Dr Zeus]

Where did you buy them from?

Perry, i bought the IRF3205PBF from Arrownac.com for $0.55 each. I swear I've never seen them priced that low anywhere before. They are still on Arrow's site too:

IRF3205PBF for International Rectifier | Arrow Electronics Components

Thanks guys. Should I smash up one of these and have a look at the insides?

[timwebb]

i just got some from there. they look the same but they work fine. just used some in a 2000 brutus.

[Dr Zeus]

Timwebb, thats good to know they worked in your brutis. Were you able to test the amp hard?

Perry, the backs of these are 100% perfectly smooth, even though the one on the left looks to have a spot, its just a smooth polished mark.

[Perry Babin]

If you compare them, you need to compare apples to apples. The 3205Z will have a different die than the non-z (or any other) version.

I think I'd trust arrow. I've never had a problem with anything that I've purchased from there.

[timwebb]

yea its ran at .5ohms and never gets hot.

[ian33]

open one up just to make sure.