- Thread starter malcolm
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What time of the day does the settings drop? if its 9am 12pm or 5 pm which is when everyone is making breakfast lunch and dinner there will be a voltage drop, seems silly but I have had this problem many times, if this is the case, you can get a voltage limiter, fit this to your supply then plug in, if it is a new set and has a voltage limiter already fitted you can check this.
shenion
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Might be interesting. I would think replacing the transistor with a adjustable voltage regulator would not be difficult.
Would probably need a different potentiometer as it would need to go across the motor.
malcolm
& Clementine the Cat
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I've measured volts into the welder and it's quite constant at 240V while the welder is welding. Here's the post with the measurements if you have any ideas. I'm convinced there is an electronics fault in the PCB and Weldequip has very kindly sent another PCB for me to try, though he is thinking torch liner problems due to underuse. Hopefully can try it at the weekend.
Would be interesting to see how far the forum can develop the SIP welders. I'd like to do some sort of objective measurements like grey shirt guy to quantify the various improvements. Baseline ought to be with the original torch liner. Probably won't get around to doing anything until about March, but we could get a design before then. Could always send you the PCB from the SIP I have and pick up another SIP for the actual measurements.
rtbcomp
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Or replace the pot with a pulse width modulator to switch the tranny on and off, this would increase low speed torque and reduce heat dissipation in the transistor.
Maplin do this http://www.maplin.co.uk/module.aspx?ModuleNo=30310&doy=19m12
It will only work from 6 to 15v, but I see no reason why it shouldn't be used to drive the base of a power tranny instead of a motor.
Coupled with Bump's independant PSU it could be a neat solution.
That certainly looks interesting to integrate. I may have a prod about over the festive period to see how easy it would be to do.
malcolm
& Clementine the Cat
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There's a guy in the states selling very chunky motor speed controllor using PWM (see I'm learning things) on eBay - http://cgi.ebay.co.uk/DC-Motor-Spee...ryZ42899QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Takes 12V or 24V with jumpers so might be a little more flexible than the Maplin one (certainly looks the part with the big heatsinks). Though up to 30 amp so maybe not so happy running at the very low end? Same price as the Maplins one.
Takes 12V or 24V with jumpers so might be a little more flexible than the Maplin one (certainly looks the part with the big heatsinks). Though up to 30 amp so maybe not so happy running at the very low end? Same price as the Maplins one.
rtbcomp
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Should be OK, easier than messing about getting one to drive a transistor. The current rating is the maximum it can handle, they control the motor by switching it on and off quickly, not by controlloing the current through it, so the low end isn't effected.
mart
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My understanding regarding the portamig range (and certainly the 181 model that Malc has) was that the wire feed is adjusted indepentently of the amp settings not with the amps control knob(s). Weldequip??
mart
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What i am saying is that with the Portamig range the knobs for course AND fine settings are the power settings, and that there is a separate knob solely for the wire speed- (the wire speed being unaffected by either the course or fine control knobs)
Malc is saying that his Portamig is one of the type that adjusts wire speed WITH the power settings. I take that to mean it is the SAME control knob for both power/wire speed -surely not?
This is how my small SiP works.
rtbcomp
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Can't speak for the Portamig, but my SIP adjusts the speed with the power knob, the speed knob itself is used to fine tune the speed.
mart
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That is right. I am only referring to and interested in the portamig here. Still awaiting weldequip`s thoughts on this though. Being able to adjust wire speed independently of the power settings is one of the key features of the portamigs i would say.
malcolm
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The wire feed does alter to suit the power settings - quite handy as you don't have to alter the wire speed knob when changing power settings.
The wire speed knob is for fine tuning the wire speed though has a big range on each setting from crawling pace to far too fast. I think the fact it also alters to suit power setting means it can be made less sensitive so easier to fine tune. A lot of welders work like this, and it's a big help.
No luck on my PCB so far, but I do have a natty little motor control posted direct from Tailand with a little elephant on the stamp.
