Is This a Power Supply or a Joke?

Sometimes the way designers decided to implement whatever they were building would make you wonder if they were serious or joking.

This failed GSC four amp regulated power supply has a number of ridiculous problems with its design--no fusing, closely spaced output terminals, and no other circuit protection to speak of. By comparison, Tripp-Lite's design looks like a work of art!

The large Motorola transistor tests bad. All other parts, including the transformer, minor components and the rectifier module seem to be good.

Category:

Science & Technology

Tags:

• uxwbill
• regulated
• power
• supply
• GSC
• four
• amp
• broken
• failure
• bad
• design

[g0fvt]

I wonder if they hoped there was not enough base drive to draw crazy current, 2N3055 is a great workhorse transistor but with poor gain, presumably there is a driver transistor?

[uxwbill]

@g0fvt Worse than that, seemingly. I totally overlooked the fact that a 2N6576 can't really be replaced by a 2N3055 because the 2N6576 has an added driver built in. I was in a hurry, didn't pay attention to the datasheet's information like I should have. When I replaced the transistor, things worked fine for a while and went haywire after several seconds.

So now I'm feeling kind of dumb. :-(

[0Fluxor0]

If you think about it.. They socketed that transistor with the idea that it would be the weakest link. And thus if you had to replace it, you could do so with some amount of ease. I do agree that the design does seem simple/cheap and almost crude. But I'm sure that it does perform the function for which it is made. Cool Video as always.

[uxwbill]

@0Fluxor0 I would totally agree with that observation. I got a replacement 2N3055 transistor (compatible to the Motorola part used, or so its datasheet indicates!) and a fuse holder. I'll put a fuse on the secondary side and that should certainly help.

[Jerkwad152]

@ATCRyderX

Those are sacred, ancient devices known as floppy disks.

[BlueFoxTV]

Wow how did that pass certification to be built. I hope you add a fuse before you use it.

[Yaga19]

lol, floppy disks

[SajjadBro]

I like your LCD, it lays eggs.

[TheChipmunk2008]

I saw this then realized those enamelled copper wires were carrying LINE voltage! Even at only 120... Dayum. Maybe that's how they figured they didn't need a fuse... use the primary winding leadouts as a fuse!!

[LHFmodfest]

I'd add a 1 amp fuse in line with the primary, and a Polyfuse to the output of the rectifier so both the rectifier and regulator transistor are protected. I'd also add some binding posts, insulation to those transformer leads and a 3 wire cord to provide a chassis ground.

This appears to be using the old zener diode + power transistor regulation trick and assuming the output isn't overloaded, the circuit is nearly indestructible assuming an adequate heatsink as this circuit runs hot by design.

[gliderp]

The transformer _might_ have a thermal fuse built into it. But considering what a cheap POS that supply is I wouldn't count on it. Fix it, and give it to someone you don't like. LOL.

[uxwbill]

@Fuzy2K Believe it or not, these weren't intentionally placed. :-) I had to put them somewhere while I was working my way through the candy inside each one.

[Fuzy2K]

@uxwbill Heh... I read your comment on the clock radio video about the "easter eggs" you put in some of your videos, and kind of chuckled at this quite literal example. :P

Intentional or not, I thought it was pretty funny. :)

[g0fvt]

@uxwbill A kind of nasty fix would be to use a few 3 legged regulators in parallel, at least that way you would get current limiting and thermal shutdown. You can parallel them by using a low value resistor in the output pin of each one, in practice a foot of thin wire from each to the common point will behave like an "emitter resistor" . You would need to hack the chassis a bit to get them to the heatsink but would work fine.. use 15v regulators with 2 diodes in series with load for 13.8v