Help with Mach2 heating element rewire please

[BLHealthy4life]

Hi.

First of all I want to thank "n00b 0f l337" for helping me bring back my Mach2 from the dead. He helped me through the process of removing the controller and rewiring everything so that the controller is no longer needed.

However, I need help with the heating element (evap head, backplate) wiring.

I can connect them directly to the mini PSU and feed the heating elements 12v, which I did temporarily to see how hot they get - They get pretty dang warm with 12v...I never remember them getting that warm before when run from the Mach2 controller.

SOO, how much voltage do I need to feed the heating elements to get them back to a resonable temp? And what size potentiometer do I need to install to achieve this voltage?

Thanks!

BL

[n00b 0f l337]

5-8v ;)
Not sure about the size pot though, never been good with that sorta E- stuff.

[tim-]

th heat elements is 5watt each? you could put them on 12v in serie (which means they get 6v each..

if they are 5watt each you will need ~12v 1A to feed them with.

[BLHealthy4life]

th heat elements is 5watt each? you could put them on 12v in serie (which means they get 6v each..

if they are 5watt each you will need ~12v 1A to feed them with.

How do I wire in series?

[n00b 0f l337]

Wire from psu --> wire to heat pad in clamshell --> wire out of heat pad then to wire to heat back plate --> then to wire back to psu.

[BLHealthy4life]

Wire from psu --> wire to heat pad in clamshell --> wire out of heat pad then to wire to heat back plate --> then to wire back to psu.

sounds easy enough, I'll try it...


Thanks!!

[tim-]

for example:
+ from powersupply to first wire on first heat pad (doesn't matter which wire as it's a resistor), then the other wire you put on first wire on second heat pad. then the last wire you put on - on powersupply.. really easy.. then you have them in serie :)

little bit dangerous to do such stuff if you don't know what you're doing.

[HoriWanderFuLL]

just wire em up on the 5v rail on a molex connector...from your psu ?

thats what i would do if 12v was to hot ..

[Thickbrit]

Both heating elements in my mach have 12v stamped on them,however i'm not sure if that is what the controller feeds it and whether it operates constantly.Check back later and i'll take a voltage reading from the controller for you.

[PhilippF]

I would not recommend wiring them in series as you dont know how the resistance changes with temperature. An extreme example is when you wire two lightbulbs in series, one will glow full and the other one will stay dark. This is because the resistance of the wire rises with higher temp and at the same current through both lightbulbs the one with the higher resistance gets more power (because of the higher voltage drop at the higher resistance) and gets even hotter until finally one glowas, one stays dark.

I dont think it will be this extreme with the heating pads, but to be on the safe side, connect them in parallel. You can get 7 Volts from a computer power supply by connecting the + wire of the pad to the yellow 12v line and the - wire of the pad to the red 5v line (12v-5v=7v).

If this is still too much, connect between red (5v) and black (ground), so you have 5v.

Regards,

Philipp

[Thickbrit]

The mach controller runs the elements at 10v.

[PhilippF]

You could use 3 diodes in series to burn 2.1V of voltage before the heatpads.

[BLHealthy4life]

Hi.

Thanks PhilippF and ThickBrit!!

Much appreciated info!

BL

[BLHealthy4life]

You could use 3 diodes in series to burn 2.1V of voltage before the heatpads.


What kind/size of diodes should I use?

[PhilippF]

As you live in the states, I looked some up at RadioShack:

http://www.radioshack.com/product/index.jsp?productId=2062575&cp=2032058.2032230.2032269&parentPage=family

1.79$ for a pack of three.

Make sure they can dissipate the heat! So dont cut the connecting wires too short.

Regards,

Philipp

[BLHealthy4life]

As you live in the states, I looked some up at RadioShack:

http://www.radioshack.com/product/index.jsp?productId=2062575&cp=2032058.2032230.2032269&parentPage=family

1.79$ for a pack of three.

Make sure they can dissipate the heat! So dont cut the connecting wires too short.

Regards,

Philipp

Hi.

I do not want to install something that is going to be creating a bunch of heat.

Anyone know what size POT to use to drop 12v to say 9v-10v?

Thanks
BL

[n00b 0f l337]

POT's will burn off the heat as well I beleive ;)

[PhilippF]

I dont know, what current flows through these heating elements. If you have a current meter, just wire all up without the diodes and measure current at 12V.

Then multiply the current in amperes with 2.1V and you get the power you can expect to dissipate in the diodes in Watts (in reality, you will get a little less, as current will drop at 10V).

Divide by three and you get the power you dissipate in each of the three diodes.

About 0.5 Watts per diode should be no problem at all, if you get more than that, you should consider mounting the diodes on a PCB to dissipate heat through the copper surface or get other diodes in a larger case (TO220).

If you use a poti, this would also have to dissipate the same power and you would not have a fixed voltage drop but a voltage drop correlating to the current.

I would prefer the diode solution.

Regards,

Philipp