Wall Wart Woes!

[WoolyBully]

If there's a connector accessible, that often connects to ground.
Then you can measure from that connector to the power socket to determine
the ground connection. The other one is often positive.

There are exactly ZERO two wire corded wall warts which have the
negative of the output connected to ANY AC side conductor, you
dumbfucktard! They are 100% isolated from the AC side!

 

[Jasen Betts]

Hi Peter,



So, we're supposed to disassemble each such device (think: flimsy
snap-together construction... if not *gasp* solvent welded!) and
go on a reverse-engineering mission?

You can sort out polarity. And, you can put an upper limit on the
*voltage* (not to exceed the lowest WVDC of the caps on that line).
But, no idea as to current requirements.

All this work just so a vendor can AVOID marking his product clearly?
Hint to manufacturers: make your corporate logo smaller if you don't
have room for this information (<gasp>)

I had this happen with a network to printer interface, where the
wall wart just "walked", and they needed the printer to do the wages.
I spent half an hour trying to reach the agent on the phone and then
the the case came apart in my hands.

2 sided PCB, power socket , bridge rectifier, capacitor , 7805
I decided 12V, polarity unimportant, and 300ma sould be plenty
, (judging from the size of the printed heatsink)

A couple of months later the replacement wall wart walked,

 

[Don Y]

Hi Jasen,

I had this happen with a network to printer interface, where the
wall wart just "walked", and they needed the printer to do the wages.
I spent half an hour trying to reach the agent on the phone and then

Yup. I "rescue" quite a bit of surplus medical equipment (which is
ultimately shipped to "less fortunate" parts of the world). Losing
a wall wart/brick/power supply can easily turn an otherwise useful
bit of kit into a pile of scrap.

But, often these devices are made by small outfits (yeah, there are
the Siemens/Philips/etc. out there but there are also a lot of
MedicalDevices`R'Us folks, too!). They tend to go belly up. Or,
get bought up (by whom?). So, chasing down the vendor is often
a lot of work (especially if the device has some "age" to it -- you
might find the current owner of the design only to discover its
no longer supported: "The *guy* who designed that is no longer
with the company...")

To make matters worse, they often pick weird voltages that make
*their* life easier knowing that they are going to pay to have
a custom "power pack" built, regardless. (I think the appeal of
external power is the UL issue).

There's a fair bit of value to "guessing correctly" as medical
kit isn't the sort of thing you can walk into the local 99 cent
store to purchase: "I'd like two packs of chewing gum, a hair
brush and a fetal heart monitor, please..."

the the case came apart in my hands.

I've been looking for a good dremel/mototool for the express purpose
of slicing open solvent welded cases -- without making *too* much
of a mess of them that they couldn't, later, be reglued.

2 sided PCB, power socket , bridge rectifier, capacitor , 7805
I decided 12V, polarity unimportant, and 300ma sould be plenty
, (judging from the size of the printed heatsink)

A couple of months later the replacement wall wart walked,

Wouldn't it be *so* much nicer if the things had 4 parameters
printed/encoded on them: voltage, amperage, polarity, connector
type? Especially for the commonly used combinations!

But, even *this* wouldn't work! How long does the *barrel* need
to be? (a common problem with replacement bricks for laptops -- which
seem to have "thick cases" forcing the mating connector to be located
too far recessed inside the case for a "normal" barrel connector to
completely engage)

And, of course, the fact that these connectors don't stand up well
to the sorts of abuse they encounter!

 

[[email protected]]

Not where AlwayWrong is concerned.

Especially in this fucked up group.

We were hoping you'd leave.

 

[Don Y]

Hi Michael,

Have you considered one of the 4" table saws, with a very thin blade
to cut a grove around the case?

<http://www.harborfreight.com/4-inch-mighty-mite-table-saw-93211.html>

Hmmm... never thought of the "tablesaw" approach. That would really be
a win when it comes to making sure you just "kiss" the sides of the
case (usually, the innards are very close to the case wall, itself, so
"too deep" means *toast*).

It would also help (using a fence) to keep the cut straight.

I'd be concerned about the size of the blade (sloppy bearings causing
wobble plus it's thickness). The dremel approach seemed safer in that
regard -- small diameter/thickness. *But*, dremel means you've got to
have a lot steadier hand/eye!

 

[HectorZeroni]

Hi Michael,



Hmmm... never thought of the "tablesaw" approach.

Dremel makes thin, toothed cut off blades as well. Using the abrasive
one or the 'concrete saw' type only MELTS its way though the case. That
is no 'cutting' at all. The toothed cut-off saw works great though.

That would really be
a win when it comes to making sure you just "kiss" the sides of the
case (usually, the innards are very close to the case wall, itself, so
"too deep" means *toast*).

It would also help (using a fence) to keep the cut straight.

Yeah, but since when does one actually need to make a perfectly straight
cut in a lame little plastic case?

I'd be concerned about the size of the blade (sloppy bearings causing
wobble plus it's thickness). The dremel approach seemed safer in that
regard -- small diameter/thickness. *But*, dremel means you've got to
have a lot steadier hand/eye!

You mount the dremel, and you HOLD the work in your hand. You could
actually make a mini 'table saw' with the dremel itself.

 

[WoolyBully]

I think that's a UL requirement, but maybe not for really low power devices.

Power is not the reason. The fact that they are fully isolated and in
a non-conductive sealed case is the reason it may not be an actual
requisite.

 

[josephkk]

Have you considered one of the 4" table saws, with a very thin blade
to cut a grove around the case?

<http://www.harborfreight.com/4-inch-mighty-mite-table-saw-93211.html>

Damn, that is enough to make me rethink my dremel/rototool DIY solution.

?-)

 

[Don Y]

Hi Michael,

Those lttle saws are made for trim work, and making picture frames,
so the have to be stable. I've looked at them in person, and plan on
buying one later this year.

The reviews seem to complain that it has no balls. Not even
*prepubescent* balls! :-/ Id wonder if it really could handle
hard plastics when you see comments like:
"I purchased the tool because I thought it would make cutting
balsa and basswood easier. Sadly, it does not."

"I thought the underpowered reviews might be overstated, and
it would be fine if you just pushed your item slowly. WRONG.
I couldn't even cut through 1/8" thick hobby plywood"

"The engine is super quiet, yet it doesnt cut through anything
harder than cardboard. Bought it to cut PVC pipe, however the
motor wouldnt last an inch through the thin plastic. Motor needs
alot more power"

"In the store it looks great for the work that i do . Small
woodwork for fairs and etc . But the motor is not even strong
enough to cut through quarter inch birch plywood never mind
picture frame material"

You could use a piece of sheet metal and make a very thin blade with
just a few teeth (to mantain balance) to cut without melting the case.
I doubt the dremel can be held steady enough, and cut instead of
melting.

I am, now, thinking that I should look to see if they've made a
"jig" for the dremel that would effectively turn it into a
table saw or chop saw. That should afford the stability and
"small blade" features.

 

[Jasen Betts]

I've been looking for a good dremel/mototool for the express purpose
of slicing open solvent welded cases -- without making *too* much
of a mess of them that they couldn't, later, be reglued.

I usually open welded cases by whacking them with a light hammer.
eg: a 10mm diameter diameter mushroom-head bolt. The weld is a
weak spot and once you get the impact level right and which side of
the seam to hit sorted they'll usually part along the seam.

It works great on wall warts amd power bricks.

 

[Spehro Pefhany]

Dremel makes thin, toothed cut off blades as well. Using the abrasive
one or the 'concrete saw' type only MELTS its way though the case. That
is no 'cutting' at all. The toothed cut-off saw works great though.


Yeah, but since when does one actually need to make a perfectly straight
cut in a lame little plastic case?


You mount the dremel, and you HOLD the work in your hand. You could
actually make a mini 'table saw' with the dremel itself.

I carefully squeeze them in a big vise/vice to distort the case near
the seam and crack the ultrasonic or solvent weld (shift the case in
the jaws to propogate the crack around the outside). You can very
easily re-glue them afterward. I've probably done half a dozen and
have not killed a wall wart yet. Very clean and straightforward.



Best regards,
Spehro Pefhany

 

[Don Y]

Hi Michael,

I wonder if they know how to use a small saw? You can't push stuff

Dunno. It would be telling to know how many (remaining) digits they
have on each hand! :> There's also some question as to how accurately
(and truthfully) they write their reviews. (i.e., the "balsa wood"
review was misleading.

through as fast as you do on a 10" saw. PVC is brittle and hard on saw
blades, and it slows down the blade on my full sized table saw. I've
talked to a couple other customers in the store who had one and they
liked it, so wo knows?

I tend to be leary of HF. Looked at a drywall lift, there, and asked
myself: "Do I *really* want to be standing under a 100# sheet of
drywall supported by *this*?"

 

[[email protected]]

Power is not the reason. The fact that they are fully isolated and in
a non-conductive sealed case is the reason it may not be an actual
requisite.

AlwaysWrong still holds his perfect record.

 

[Don Y]

Hi Michael,

100 pounds? That must be over an inch thick. If one had failed,

4'x8'x12' @ 5/8" thick is ~85 pounds. And you have all that metal
hanging over your head, as well (maybe you'll be lucky and *only*
the drywall will bop you on the head -- not the metal cross members
holding it up! :> )

there would have been a lawsuit and it wouldn't be for sale. You do

We did a lot of research on lifts. Just reading the comments of other
buyers indicates that lifts fail with some regularity. The best
lifts seem to be made by PanelLift (sp?). They are signifanctly
heavier constuction: e.g., the upright is 3" instead of 1.5 - 2",
heavier gauge steel, better quality welds, larger casters, larger
cable, etc.

But, they are 3x-4x the price of the chinese imports! :<

Not to detract from the HF item (there are lots of other "chinese"
offerings in that market, as well. They all look oddly similar
with the exception of PAINT color! :> ) but we figured it wasn't
enough of a guaranteed improvement (i.e., labor+risk reduction)
to justify the expense.

 

[WoolyBully]

AlwaysWrong still holds his perfect record.

You are full of shit. Power level is NOT the reason, you fucking know
nothing asswipe!

 

[[email protected]]

You are full of shit.

Still perfect.

Power level is NOT the reason, you fucking know
nothing asswipe!

Still...

 

[Don Y]

Hi Michael,

Are they being used properly, or have they been overloaded?

IIRC, all "claimed" to handle at least 150 pounds. All claimed to
be able to handle a 12' sheet.

So, if you assume 1/2" wallboard, that's at least 80 pounds.
Step up to 5/8" for another ~25% and you're at 105 pounds.
Make the *leap* to "fireboard" would add *another* 25% (130#)

I can't imagine anyone hanging anything thicker/denser than
that and needing a lift! (Maybe backerboard but you wouldn't
even be able to get a lift *in* the sorts of places you'd use
that!) In fact, the sorts of "DIY'ers" who would opt for such
a product would probably be stuck at the 8-12' 1/2" end of the
range -- so, 50-80 pounds on the lift, max.

(*two* sheets, STACKED??? :-/ )

The problems I recall were related to welds breaking, the
brake not holding and flimsy construction, in general. A
common complaint was "the box arrived "all beat up" and
possibly "missing pieces" (which could have just fallen out).

Invariably, the customer KEPT the purchase as the cost of
return freight was exorbitant!

I hung a lot of 12 foot sheets on ceilings. Three step ladders,
three workers and three hammers with plenty of drywall nails. The
screws weren't availible back then. We did a bunch of 12' * 12' rooms in

I opted for the old "T" deadman and strategically placed (temporary)
supports fastened to the (unfinished) walls (Think: lip to hold one end
of wallboard in place). But, I only had ~500sq ft of ceiling to
deal with (I will rethink this if I opt to so the rest of the house).

under 10 minutes each. I've put up 4' * 12' sheets on walls, run

I hung the walls vertically. Most of ours are taller than 8'. So,
easier to just stand the sheets upright, side by side. This also
eliminates the need for any butt joints. Slightly more taping but it's
an *easier* taping job!

horizontal by myself. Back then, people used jomemade Tees to hold it

Yes, a "deadman". See above.

against a ceiling, if they couldn't find enough people to do it like we
did.

Unfortunately, most of my friends have (conveniently?) bad backs. I
should learn to develop a similar malady when *they* come looking for
help! ;-) (unfortunately, that's not in my nature :< )

 

[Don Y]

Hi Michael,

In that case they should have refused the shipment and let the
carrier fight it out with the shipper. What I was thinking was the way
some bozos treat their tools. Toss them into the back of a truck and
let it bounce around, bang them into walls and use them for seats or
worktables. That would weaken then to the point of failed welds.

I got the impression that these folks tended to be "weekend DIY'ers".
I.e., buying for *a* particular job -- and worrying about how they'd
get rid of the thing, later.

As I said, I visited HF, looked at stuff available on-line, and
checked out a couple of the traditional tool rental places. The
latter had, by far, more "substantial" devices. The (initial) appeal
of purchasing was anticipation of other parts of the house that I
wanted to tackle (higher ceilings, etc.).

But, ~$700 for the "nice" lift seemed ridiculous -- given that I
had no plans of going into that *business*! :>

(I will probably opt to rent the nicer lift when I tackle some
of the higher ceilings -- and just get myself very organized so
it's a 1-2 day event)

I now have a bad knee, wich means it's going to be a real pain to
drywall a couple bedrooms by myself. At leat all I have to do is the
walls, since I'm going to use 2' *4' celing tiles.

Bummer. Note that my "suspicious" comment above (re: friends' bad
backs) is intended tongue in cheek. I don't doubt that they *do*
have back problems (apparently pretty common). It's just, er,
"disappointing" not to be able to call on them for this kind of
assistance...

 

[Don Y]

Hi Michael,

That makes sense, if you don't have any help. The rent should be less
than a cheap model.

Rent *is* cheaper -- if you are quick about it (i.e., have a period
of uninterrupted time that you can devote to the job) *and* have a
small job! E.g., each room you tackle has to have its furniture
"rearranged" if not *removed*. Doing that for several rooms at
a time can be a real mess! :<

I have open wounds on my legs that I've had for over two years, with
makes most projects difficult but they haven't stopped me.

<grin> I am waiting for the "consequences" of earlier abuses
to catch up with me. E.g., I used to regularly move pinball machines
by crawling under them and lifting them onto my back. (Hint: they
are not lightweight!) Thankfully, I've learned to stop doing that
sort of thing... (but pinball lifts are not worth the space they
require)

 

[amdx]

Yes, a "deadman". See above.


Unfortunately, most of my friends have (conveniently?) bad backs. I
should learn to develop a similar malady when *they* come looking for
help! ;-) (unfortunately, that's not in my nature :< )

I have a new appreciation for bad backs, I herniated a disc 21 months,
28 days, 4 hours... If I could go back I would not do what I was doing.
Sciatica, nerve pain, phantom pains out of nowhere, tight calf and thigh
feeling, back pain.
It is just so much easier to not move from a comfortable position.
You can be fine and 5 minutes later in hurts and vise versa.
It's better now than 20 months ago, better than 10 months ago,
I think I may get over it someday. Surgery was recommended but
I didn't like the idea of have a hole drilled through a vertebrae
to get to the disc for trimming.
Rant complete.
Mikek