Questions about moving some high temp junctions.

[Spork Schivago]

Hello,

I have a need to move some of these "junctions". I'm not sure what they're really called. They appear to be ceramic and from what I can tell, they just allow me to hook one wire to one or more wires. I'm uploading a picture and I put a red box around the items I'm talking about. I've moved one of them closer, but I need to move the others. There could be a good deal of temperature by them.

Is there anything I should know about before doing the rest? From what I can see, all I gotta do is drill a hole for the other ones, tap that hole and then physically move the junctions closer to the base of the heating elements. We're going to go look for some high temperature bolts to put in the old holes, so we don't get a lot of heat going under the heat shield through the old bolt holes.

[Spork Schivago]

Re: Questions about moving some high temp junctions.

The bottom left is the one I already did. I should probably physically straighten it up a bit.

[rhomanski]

Re: Questions about moving some high temp junctions.

I don't know what temps your talking about. It looks like you could do as planned. Check it often when you first start using it. Keep the wires off the heat shield. Don't use tie wraps, use tie chord. It's made of nomex. If you need something to keep the wires up. http://www.dupont.com/products-and-s...ent/nomex.html .

It's still dangerous to do because your not an engineer and neither am I. Check it after each use when you first start using it and keep an ABC fire extinguisher nearby. I keep an extinguisher in each car and the kitchen and garage.

[stj]

Re: Questions about moving some high temp junctions.

is it a dichloric halogen light fitting?

[Spork Schivago]

Re: Questions about moving some high temp junctions.

is it a dichloric halogen light fitting?

It might be, I don't know. It kinda feels like ceramic, like it's made out of the same material that the old IR heating elements are made out of. Kinda like those old wire insulators for that knob and tube wiring or whatever it was called.

The originally designers seemed to think it was fine, I can't really see there being a lot more heat closer to the base of the heating elements that are already there. The wire for the new heating elements have these little ceramic type rings around them (I think to protect against heat) and then the wire that actually goes from junction to junction, I believe that's high temp insulation around that, kinda like the stuff you find on K-Type thermocouples.

I think the wiring is wrong. On the side of the unit, there's two switches. One says RIGHT HEATER, the other says LEFT HEATER. By looking at where the wire goes, one of them seems to connect to have the heating elements, like you'd suggest. However, when I follow the other side switch, it seems to connect to EVERY heater.

There are warnings and safety switches that kill the power. The warnings say if you smell something burning or burnt plastic, turn it off immediately! I don't think the people who built this were qualified engineers. I think they just threw a bunch of parts together and probably had no idea how this unit actually runs. I've tried contacting them via e-mail but never got a response. I actually tried a few times.

[Spork Schivago]

Re: Questions about moving some high temp junctions.

I don't know what temps your talking about. It looks like you could do as planned. Check it often when you first start using it. Keep the wires off the heat shield. Don't use tie wraps, use tie chord. It's made of nomex. If you need something to keep the wires up. http://www.dupont.com/products-and-s...ent/nomex.html .

It's still dangerous to do because your not an engineer and neither am I. Check it after each use when you first start using it and keep an ABC fire extinguisher nearby. I keep an extinguisher in each car and the kitchen and garage.

Just the basic temps you'd reach for stuff like BGA rework. I wouldn't think anything too crazy. I'm not actually adding anything, just switching out heating elements with nicer ones. When the unit arrived, a few were broken and needed to be replaced. I never got a response from the original makers of the unit and instead of going for the cheap 15$ Chinese heating elements, I went for the nicer Elstein's.

I don't think I need to use any ties, my plan is just to move those junctions that are already there a little closer because the Elstein's don't have long enough cords. All the cords for the ceramic heaters and the wire that goes from junction to junction, they all seem to be protected from heat.

I guess the main concern is the base of those ceramic heaters, the only part of the ceramic heaters on the underside of the heatsink. The ones with the clips going through them...do they actually produce heat? I was under the impression that good ceramic IR heating elements produce pretty even heat throughout the whole element. Just not certain if the base that gets the clip gets heated as well or not. I appreciate the advice! I'll be sure to keep our fire extinguisher around when I fire it up.

Thanks!

[Spork Schivago]

Re: Questions about moving some high temp junctions.

Here's a drawing of how I think the electricity flows through the circuit. I just traced the line. It seems like the switch for the LEFT HEATER connects to the exact same heating elements as the one that is listed as the switch for the RIGHT heater. I'd of thought some of these heaters wouldn't be hooked to other ones. Like one switch would heat up half the ceramic heating elements, the other switch would heat up the other half, both switches on would heat up all the preheaters. Am I missing something here?

[diif]

Re: Questions about moving some high temp junctions.

I don't think putting bolts in the holes is the right idea. If the bolts do warm up then the hear will transfer down them and radiate out under the shield. Better to blank with a small plate held in place with a small dab of high temperature 350c silicone.
Both heaters come on at the same time. The BGA is in the middle and the whole of the board needs to be heated.

[stj]

Re: Questions about moving some high temp junctions.

i cant even make out the first foto - top-right block has a vanishing wire to it's left.

[Spork Schivago]

Re: Questions about moving some high temp junctions.

I don't think putting bolts in the holes is the right idea. If the bolts do warm up then the hear will transfer down them and radiate out under the shield. Better to blank with a small plate held in place with a small dab of high temperature 350c silicone.
Both heaters come on at the same time. The BGA is in the middle and the whole of the board needs to be heated.

So the switches are useless? Either the whole preheater is on or off? There's no middle right side / left side like they claim?

The way it comes from the factory, bolts are going through those holes. They're long bolts and I can see them on the side that has the IR heating elements. We used much smaller ones so the metal part of the bolt is sticking out like it was when it was brand new. I found those ceramic blocks:

http://www.aliexpress.com/store/prod...742215948.html

So, just so I'm clear, when someone buys this BGA unit brand new, there's four bolts that go through the pre-heater and are exposed on the side that gets all the heat...m4x20's I believe they are with a .70 pitch. We replaced with them m4 x 15's so that extra 5mm isn't exposed.

Since I cannot easily get rid of the four bolts that go through the heat shield that hold those little ceramic terminals on the underside of the heat shield, would you still do away with the four stainless ones we used as "fillers" so the heat doesn't get through so easily? I'd like to add, there's a few more sheets of metal that would act as a heat shield before we get to the inside of the unit where the PCBs are. Perhaps they did this because of the screws? What do you think?

[Spork Schivago]

Re: Questions about moving some high temp junctions.

i cant even make out the first foto - top-right block has a vanishing wire to it's left.

Unfortunately, the default wiring is a freaking mess! The second photo is the preheaters and the tray. There's two small wires that come off that tray, they go to the switches, LEFT HEATER, RIGHT HEATER. I outlined them in blue on the second photo there. Then, there's two big wires that plug in. They actually go inside the unit and that wiring is a freaking mess, even more so! It's a nightmare trying to see what goes where! I bet those people that wired circuits before PCBs came out would be able to figure it out.

The first photo was with the tray still attached to the BGA rework unit. I think if we wanted to, we could build a much nicer unit than this for less than a grand!!!

[Spork Schivago]

Re: Questions about moving some high temp junctions.

I don't think putting bolts in the holes is the right idea. If the bolts do warm up then the hear will transfer down them and radiate out under the shield. Better to blank with a small plate held in place with a small dab of high temperature 350c silicone.
Both heaters come on at the same time. The BGA is in the middle and the whole of the board needs to be heated.

I wanted to add those bolts I got are stainless steel. We went for stainless steel because stainless steel has a low thermal conductivity. Do you think heat would really travel a lot down those stainless steel bolts to the point where it'd matter? Thanks!

[diif]

Re: Questions about moving some high temp junctions.

I didn't see any bolts in the initial photo so made my comment.
It's done now and probably doesn't matter much anyway.

[Spork Schivago]

Re: Questions about moving some high temp junctions.

I didn't see any bolts in the initial photo so made my comment.
It's done now and probably doesn't matter much anyway.

I'm sorry, I should have been more clear. In those terminal blocks, there's a whole in the center. Inside that hole is a m4 x 20 (I believe) 0.70 pitch screw. I think they're stainless but not sure. They go through the heat plate and stick out on the side that gets all the heat. It came that way and we could see the screws sticking through before we did anything.

I unscrewed them to move the terminal blocks so I could plug the ceramic heating elements wires into the blocks because the new IR heating elements had shorter wires and wouldn't reach. That's what left that open screw spot. We followed what the original designers did and just drilled a hole and tapped it with an 4 x .70 tap. Instead of using the same screws though, we went down and bought shorter ones, so they don't stick out. This worked real good, but we had the old holes still open. We bought 4 of the shortest screws we could find, that where stainless to fill them.

I have to agree with you on this, I just don't think the original designers did a good job designing this BGA unit. It's a bit pricey but it's kinda cheap, you know? I think that's why there's so many safety features, like the double breakers on the side, the emergency big red emergency stop button, the two side switches, plus whatever's in the GUI. I think they were trying to cover their butts in case something started catching fire.

The wires inside, they're kinda small gauge. The amperage that this unit is supposed to be drawing I think should have 12 gauge wire. This is at best 14 gauge, maybe even 16! I know when you're going shorter distances, you can sometimes get away with that but still, for the money they're charging, you'd expect they would have spent some of that profit on making a better unit, you know?

[Spork Schivago]

Re: Questions about moving some high temp junctions.

What do you guys think about those switches though? Are they properly wired or should I rewire this somehow? If so, any suggestions on how it should be wired up? I can show more pics of the unit, with the tray removed and maybe even the inside where the PCBs are, if you guys want.

[keeney123]

Re: Questions about moving some high temp junctions.

Just looking at the picture it looks like something from a Brown Stove top range. They have a bi-metal temperature control. Anyway that is what that remind me of. stoves, ranges use to use asbestos wire. I don't if they still do?