Help!! Noob with 5v box mod with TI chip!!!

[asdaq]

Well that glue is pretty helpful right about now, lol. That 14500 will work with the 4050, but imr's are significantly better. There's only 1 cap and that can make a difference with whether or not a 14500 will work or not. I use both caps but oh well.

One thing I suspect is that the v-in is coming in off the master switch to pin 2, but the gnd to pin 1 looks empty. Anyone else verify this? That would place the gnd somewhere at the top where i can't make out detail, so perhaps the chip is miswired and acting as a 2nd resistor (?) which when combined with a LR atty just barely manages to do something (??)

 

[Gummy Bear]

There seems to be enough room down here for a trimmer pot.
But I can’t exactly tell what the part is at the end of the arrow. That may already be one. (or not)
I would guess it is a cap but, Anyway you will need to lift the chip up and solder a pot to the 2 pins just under where the arrow is and mount the pot in the space just below the chip. It is easy.

 

[asdaq]

The 1st pic through the green case it looks like a wire splice for v-in. Unfortunately all the wiring is on that side.

 

[Gummy Bear]

I see that now, and I don't see a gnd wire either. Need a better pic of the bottom of the chip. I wonder if it is glued in ???

 

[asdaq]

The other side view with the flash show that that mystery meat is probably a solder blob and some weird optic of the circle in the box itself catching the flash. There are 2 black wires and they both run to just below the fire switch and maybe both to pin3 ADJ-- which would do nothing much at all. Especially the way they look twisted together near the board. I think whoever built it got the board flipped over and got the pins backward. With the single cap to save room it would make sense to smooth out the v-in and conserve the board too rather than smooth out the v-out.

I think this depends on just how hard it is to get the parts out of that glue so that it could be re-wired....

 

[Curvychic]

It is glued in rather well (or epoxied) I will say that upon closer inspection, there's a wire coming up from underneath the chip with solder, but no connection to anything. There's also a red wire barely peeking out from under the chip as well and not connected to anything. My hubby pressed these together in case they came loose during shipped, but still nothing. I'm going to try to get some better pics of the insides. BRB

 

[Gummy Bear]

Wires that go no where is not good. This may be the root of your problem.
Not to worry tho, we will get to the bottom of it. This forum is full of some very clever people.

Oh yea,,, Un-press them till we figure this out.

 

[Curvychic]

Okay, so by the time I got back from my chiropractor visit, the overcast skies had gone and the sun is shining, so I just snapped some WAAAAAAAAAAAAAAY better pics outside. Hopefully, this will make things a little clearer???

Edited to add: I'm uploading these to photobucket so they will appear larger than they do here.

 

[Curvychic]

I just did for the picture and I will leave them that way until told otherwise. LOL

Wires that go no where is not good. This may be the root of your problem.
Not to worry tho, we will get to the bottom of it. This forum is full of some very clever people.

Oh yea,,, Un-press them till we figure this out.

 

[Curvychic]

Okay, here's a link to my Photobucket album with all of the pics that I've taken of the mod.
5V Box mod with TI

 

[asdaq]

OK, now I see it differently. I believe this pic shows things as they match the schematic and it isn't wired backwards.

Which wire is not attached then?

 

[Gummy Bear]

@asdaq
I got the high rez pics. it is wired good,,, the wires that she said didn't go to anything is where the output cap WAS.
I will zoom in and post it here so everyone can see (and hopefully agree) Give me a few mins.

 

[Gummy Bear]

See if you agree. The epoxy is even rounded where it use to be.

 

[Gummy Bear]

I somehow wonder if the failure to fire was these wires touching each other. (they are very close). I don't know if that would fry the chip either??????
But if you guys agree that this is where the output cap was then we need to get that back in and then test again before working on the VV pot.

 

[asdaq]

Yeah Gummy you got it, can totally see the cap was there now. And that is the V-out so those are supposed to be connected, that red wire and that lead, so that they are touching but not a solid connection gets the added resistance in the circuit. If they weren't touching at all then it wouldn't do a thing. Soldering those two together wouldn't be much trouble, and it should work again, but getting the cap back in and especially the negative leg attached would be a pain with the epoxy. hmm.

I'm pretty sure the chip itself is just fine, these can take a beating.

 

[AttyPops]

<munches bag of popcorn> <watches events unfold>

Why not send it in to this cool place I've heard of:

"Gummy Bear's PV Repair Shop".... reasonable rates for most devices....

I think there's a cigar-store Indian out front and a short little proprietor inside. Not sure if it's still open tho. Of course, you could try and do it by posting back and forth for a couple of months.........


EDIT: I'm probably going to get in trouble for this, since he hasn't offered, but ...... it's getting to the point of posting futility. Ripped out caps and iffy connections. Gummy... you could spend 5 times longer posting about it than it would take to fix it. IDK if that's a precedent you'd want to set tho.

 

[Gummy Bear]

I hear ya Atty. BTW what happened to you Atty pops song? That damn song would get stuck in my head every time I read you.

I think it would be easy to solder a new cap back in with a bit of heat shrink and it should be fixed. Then just solder in a pot from the top but finding a place for it with the replacement cap back in could be a challenge. But setting it to a fixed output lower than 5 volts would be easy. 5 volts is a bit to strong for me.

 

[AttyPops]

People started calling me "Pops".... So I changed it to something about "You can call me Hey, or you can call me Atty, or .... but ya doesn't hasta call me POPS!". It's been rotating since. Now I'm working on ticking-off all the "posted from my _____ via _____" people. lol. Got bored I guess.

CC will have to decide what she wants. Maybe you could summarize options for her?

 

[Gummy Bear]

Yeah Gummy you got it, can totally see the cap was there now. And that is the V-out so those are supposed to be connected, that red wire and that lead, so that they are touching but not a solid connection gets the added resistance in the circuit. If they weren't touching at all then it wouldn't do a thing. Soldering those two together wouldn't be much trouble, and it should work again, but getting the cap back in and especially the negative leg attached would be a pain with the epoxy. hmm.
I'm pretty sure the chip itself is just fine, these can take a beating.

It looks to me that connecting them is not the thing to do. This would tie Vout and Vin directly. There needs to be a cap in there. otherwise there will be a really funky voltage loop between vout and the battery circuit protection.

 

[Gummy Bear]

To sun it up when repaired it will look something like this


The cap (capacitor) is the blue things. You need to get one just like the one on the left side and solder it in between the two wires on the right.
Then re-test.
Is this something you are up for? it is easy,,, but only if you have a soldering iron.