Let the fun begin !!! ???

**JAZZCNC** · 21-02-2015

Originally Posted by Neale

I must stick a meter across my power supply some time and see what happens - I don't have any bleed resistor in place.

Probably not a lot.! Depends how you wired the control box.?
If the Drives are kept in the circuit and not removed say thru a relay then they will drain the Caps resonably quickly to within 5V last time I checked.

Not a fan of leaving resistor in all the time as it's creating heat and we want to remove it not make it.!

**EddyCurrent** · 21-02-2015

Originally Posted by JAZZCNC

Not a fan of leaving resistor in all the time as it's creating heat and we want to remove it not make it.!

I agree with this, I tried it and it's amazing how much heat 3 watts can produce, especially in a control panel size box.

**Neale** · 21-02-2015

Personally, I wouldn't bother with the resistor at all. Seems like unnecessary complication, given three or four drivers draining the caps on power-off. Main use would be draining the caps during testing with nothing else connected, but that's a bit artificial anyway. Heating was why I suggested the value I did, which would only be dissipating a watt or so, but why bother?

**JAZZCNC** · 22-02-2015

Originally Posted by Neale

Heating was why I suggested the value I did, which would only be dissipating a watt or so, but why bother?

Depends on how the control is wired.!
One reason to bother is that when a drive faults or E-stop occurs the motors will continue to rotate for fraction of second until power is drained. No big deal you'd think.!! . . BUT. . it is a big deal with Slaved motors if one drive faults and other doesn't because the one that doesn't fault remains under power until power is drained. The faulted drive removes power and stops rotating so the gantry gets racked every time.

**EddyCurrent** · 22-02-2015

Originally Posted by JAZZCNC

Depends on how the control is wired.!
One reason to bother is that when a drive faults or E-stop occurs the motors will continue to rotate for fraction of second until power is drained. No big deal you'd think.!! . . BUT. . it is a big deal with Slaved motors if one drive faults and other doesn't because the one that doesn't fault remains under power until power is drained. The faulted drive removes power and stops rotating so the gantry gets racked every time.

Unless you have the driver fault relays and enable signals integrated into the design, then they all stop together or as close together as possible.

**PAULRO** · 22-02-2015

Initially i was not going to use a resistor because of the drivers draining as pointed out. i've read a lot of posts that discuss this and i know a lot of the experienced`builders don't bother because of the reasons stated. but i will be using a relay in the e/stop circuit anyway and it will have an empty N/C contact available so it's an extra terminal for the resistor and an extra piece of cable to hook it in. i think that's all that's required anyway? if i don't use it i will definitely integrate the fault relays and enable signals as Eddy suggested. on another note my toroidal coil arrived friday. i should have the cap and bridge this week, hopefully. the coil has 3 windings http://www.airlinktransformers.com/c...nge/CM0625225/ the colours are as follows: coil 1 BROWN / BLUE 1.6 ohms
coil 2 BLACK / RED 0.5 ohms
coil 3 YELLOW / ORANGE 0.5 ohms
so i assume from this that the following
Coil 1 = mains supply 230 vac
coil 2 = 25vac
coil 3 = 25vac
and if i join BLACK and YELLOW together power up and meter across RED and ORANGE i should get 50 vac OR 0 vac . a change of the secondary coil arrangement if i read 0 volts. i will try it tomorrow to see.

**IanS1** · 22-02-2015

Recently bought one of the Airlink trafo's. Join black/yellow together and red/orange will give you 50v AC or there about.

**JAZZCNC** · 22-02-2015

Originally Posted by EddyCurrent

Unless you have the driver fault relays and enable signals integrated into the design, then they all stop together or as close together as possible.

Yes and exactly why I said depends on how control is wired.!! . . . Several why's to do same thing. Fact still remains that it's NOT ok if control NOT wired in correct Manner.!

**PAULRO** · 23-02-2015

i'll have to give that a go. above all the system has to be safe and i would like to use the functionality of what the boards have to offer . the notion of draining the caps as quickly as possible is still worth a shot too because if i have to go into a cabinet with caps holding a charge then i rather go in when they're safe. i'll probably put a cover over the psu to be on the safe side. either way at least the conversations on the blogs really bring it home about the safety and choices available.