RAS 115 power loss.

[jimmyboygr]

The motor can be stuck from friction of stuck bearing or a lot of melted plastic,but you would hear a grunt noise trying to rotate(like in many ets cases).ras is indeed a powerful machine,but after the gearing that reduce the speed and increase the torque.At the armature
head,torque isnt enough to rotate it as hard if there is something really stuck
But in your case it starts rotating and then stops,right?In this case I would firstly look at the ptc thermal resistor(2 red cables from fields to electronics)that is the easier to do,and then at electronics,also check the solenoid magnetic ring on top of the armature if it rotates with the armature.It is what the electronics "see" to determine the true speed of the rotor and decide the voltage to set.
I am feeling sceptical on suggesting to a non professional to bypass the control electronics and give power direclty to brushes,but
since I am new here,I am not aware of the forums rules regarding safety.Or maybe it is common sense that everything done is on your own risk,so maybe I am exaggerating  [unsure] [big grin]

 

[AlexThePalex]

I am feeling sceptical on suggesting to a non professional to bypass the control electronics and give power direclty to brushes,but
since I am new here,I am not aware of the forums rules regarding safety.Or maybe it is common sense that everything done is on your own risk,so maybe I am exaggerating

[member=69210]jimmyboygr[/member] Since you're a Festool employee, you should be more sure about what is or isn't allowed here than any of us.

Frankly, I am surprised by the openness of the technical advice you give here, seems to me like a corporate no-no. As far as I know, the official Festool stance regarding repairs has always been, send it in to our service department, do not try to do this yourself. But members have never been discouraged or prevented from speaking about it amongst themselves.

Common sense? In Europe, or Australia, or other parts of the world, that might be true. But this is an American run forum and in America it is about what a lawyer can convince a judge of what can be said or not. Nevertheless, Festool USA has never stopped anybody here from talking about repairs of their tools, only subjects like modifications or hacks and plain stupidity have been deleted.

Regarding the by-pass of the electronics module, I don't see how that is anymore dangerous than what you suggest. Repair of tools mainly consists of screwing and unscrewing of parts and replacing them as a whole. Some people find that easy to do, others are not so comfortable doing that and prefer to have it taken care of by a professional. But as long as you open the tool's housing, you expose electric parts that can carry a current, doesn't matter which part you're exactly looking at.

I do like your technical input, I see that as an opportunity to learn. Are you part of Festool's repair department?

This ptc thermal resistor, which part is that exactly, and how do you find out if it works or not?

[attachimg=1]
 

 

[jimmyboygr]

Sorry if I did not make my self clear,maybe because I did not translate something correct in my head,I tried to write the steps of thinking/repair I would do as part of the repair department.Although it is not the same as starting the machine,hearing it or feeling it yourself.
I tried to explain that this is not something that is reccomended to do by someone inexperienced and non professional,but I dont want to come to a forum and be "that" guy that.Since I am not here to write on every post that everything should pass a Secutest
before and after a repair,and send it to official repair etc.I am here to help people that have already made uptheir minds telling what
I would do or think.Sorry If i did not make myself clear and some misunderstanding occured.The last thing I want is getting in trouble
for trying to help.

 

[AlexThePalex]

Hm, there is no trouble here from anybody for you, why would you interpret it like that?

Only person that might give you trouble is your employer if you say things not in line with corporate policy.

 

[jimmyboygr]

The 2 cables that go from fields to the electronics are the ones that can also make the machine change speed.They mostly have 60ω
resistance,they are with the fields as number 2.I usually use there spare ones from the shop to quickly check,others could use a resistance or their sccrewdriver to short the pins on the electronics.although you know...its wronggg  [tongue]

 

[oldie]

Back in the day, out in the field, would (crudely) test:
Positive thermistors by 'hovering' the tip of a soldering iron very close to the component. As the thermistor warmed up, the effect on the device (tool in this case) could observed.
Similarly, a negative thermistor could be checked with a very quick blast with freezer spray.

If have access to spec' information, or, a known good thermistor of same type to compare with - can measure the DC resistance with a multi-meter at ambient temperature - after disconnecting one leg of the thermistor of course.

I would never short a component out - unless I knew for sure, what the effect upon the circuit would be.

Richard (UK)

 

[jimmyboygr]

You are absolutely right.the electronics/tool,already performs strangely,if someone doesnt have the spare part,or doesnt know the resistance in ambient as you said,they usually/unfortunatelly short it out or put a random resistor on the pins.this is done by some users or some generic repairshops offering cheap solutions.in most cases it is like this,when someone tries something cheap/unofficial,they pay it eventually more in the end.but many of these cases eventually end up to the official repair shop and the official part in installed.which in this case
it is the stator with the sensor.(used to sold seperatly many years ago.)

 

[oldie]

Jimmyboygr: thanks for response – appreciate your input to the forum.  My interest is that I have an old well used RAS115, so this thread might be useful to me one day.

Just double-checking, the thermistor is buried / embedded in the stator, and, therefore not easily replaced – if at all?  How would you suggest the OP checks his thermistor?

Wrt to the OP – as Alex suggested, it seems ‘convenient’ to check the mains directly to the brushes - it would quickly determine if motor wants to spin properly.  BUT, only if he is competent to do that, or, knows someone who is. 

Richard (UK)

 

[R0bbie]

To be sure, just connect the mains wire directly to the terminals of the brushes, by-passing the electronics module. If your RAS runs at full speed again you know there is no problem with the motor, or the brushes.

[eek] [eek] [scared] [scared]
Sorry I couldn't resist to chime in,
this is a universal motor, in theory two stator windings in series with the armature (rotor) windings.
Connecting mains directly to the brush terminals would prevent the stator to create a magnetic field, so the motor will not turn, also the current through the armature would be doubled.
This is a great advice if you like fireworks, chances are great that also the electronics would not survive.

[member=74022]Ilovemyras115[/member],
If you love your RAS115, have your machine checked by someone who knows what he is doing.

Regards,
Rob

 

[Ilovemyras115]

To be sure, just connect the mains wire directly to the terminals of the brushes, by-passing the electronics module. If your RAS runs at full speed again you know there is no problem with the motor, or the brushes.

[eek] [eek] [scared] [scared]
Sorry I couldn't resist to chime in,
this is a universal motor, in theory two stator windings in series with the armature (rotor) windings.
Connecting mains directly to the brush terminals would prevent the stator to create a magnetic field, so the motor will not turn, also the current through the armature would be doubled.
This is a great advice if you like fireworks, chances are great that also the electronics would not survive.

[member=74022]Ilovemyras115[/member],
If you love your RAS115, have your machine checked by someone who knows what he is doing.

Regards,
Rob

so I've been busy sticking and stacking oak for two days.

I was confident to just touch a live cable to the two terminals safely without frying myself (checking it was fused correctly) and see if it would turned the motor at full speed and post results here. I was hoping to get this done before the discussion has got to indepth.

are we now saying i should just send it off asap as even if it is the speed module i wont be able to change that myself?

I don't want to cause further damage?

I'm amazed no one has picked up on the fact that it broke when i loaned it to someone!

thanks for the help everyone.

Rich

 

[AlexThePalex]

Sorry I couldn't resist to chime in,
this is a universal motor, in theory two stator windings in series with the armature (rotor) windings.
Connecting mains directly to the brush terminals would prevent the stator to create a magnetic field, so the motor will not turn, also the current through the armature would be doubled.
This is a great advice if you like fireworks, chances are great that also the electronics would not survive.

Robbie, I have done this with many tools. I is perfectly possible and no problem at all.

In fact, with the older tools where there is no electronics module, the mains wire goes first to the switch, and then directly to the brushes. With the newer models, they just put an electronics module in between the existing circuit.

The electronics module does not do anything else but lower the current that goes to the motor, it is not a necessary element in the chain.

I wonder, have you actually repaired any Festools yourself before accusing me of incompetence? I have repaired dosens and dosens, all kinds, sanders, routers, drills, saws, vacs, you name it. Connecting the wires like this is just a way to find out were the problem is. It is not like we're going to hook 'em up like that, close the shell and start using the tool, this is for troubleshooting purposes only, with short runs. Just a process of elimination the find the faulty part.

[member=74022]Ilovemyras115[/member] , if you don't feel confident doing this yourself, send the sander to Festool to have it fixed. I think you should, because you don't sound confident at all.

 

[AlexThePalex]

Connecting mains directly to the brush terminals would prevent the stator to create a magnetic field, so the motor will not turn, also the current through the armature would be doubled.

With every brushed motor I encountered in Festools, there were two wires that go the the brushes, one on each side. If those are not the wires that carry mains current (L & N), which wires are those then?  [scratch chin]
 

This is a great advice if you like fireworks, chances are great that also the electronics would not survive.

The electronics would not survive? You mean, they break from lying unused on the bench?

 

[R0bbie]

Connecting mains directly to the brush terminals would prevent the stator to create a magnetic field, so the motor will not turn, also the current through the armature would be doubled.

With every brushed motor I encountered in Festools, there were two wires that go the the brushes, one on each side. If those are not the wires that carry mains current (L & N), which wires are those then?  [scratch chin]

I think you must contact Festool advising them to delete the stator windings, that should save them a lot of money.
 

This is a great advice if you like fireworks, chances are great that also the electronics would not survive.

The electronics would not survive? You mean, they break from lying unused on the bench?

Where did you instruct (probably a noob) to disconnect the electronics?

 

[R0bbie]

[member=74022]Ilovemyras115[/member] , if you don't feel confident doing this yourself, send the sander to Festool to have it fixed. I think you should, because you don't sound confident at all.
[/quote]

Now thats good advice [thanks]

 

[Ilovemyras115]

so to end this thread and settle (maybe)  the dispute.

The noob has removed the power lead from the tool.

disconnected the two black leads from the speed controller that run off into the body as that seemed like a good idea to isolate the speed controller.

made up a short lead with spade connectors touching the brush terminals and clamped the tool to the bench with connectors securely touching the brush terminals, then using connector blocks attached the mains lead to the short lead. switched it on and it went pop [blink]. no motor spinning.

So i rebuilt the machine not wanting to repeat the action that went pop and switched it on. for about 10 seconds the tool worked perfectly with speed controller working then the tool stopped again, motor buzzing but not rotating.

So tell me what happened please? defo time to send it off but if anyone has any guesses at what going on then great. may as well bundle all the stuff due for service in with it too...

critics critique please

 

[AlexThePalex]

I think you must contact Festool advising them to delete the stator windings, that should save them a lot of money.

I think not. By the way, that's not an answer. Since you're the expert, what do those 2 wires do that connect to the brushes?

Where did you instruct (probably a noob) to disconnect the electronics?

Maybe read the thread instead of just throwing words around.

But: a noob? That's not how we talk to eachother around here. Maybe drop the attitude, this is not 4chan.

 

[AlexThePalex]

so to end this thread and settle (maybe)  the dispute.

The noob has removed the power lead from the tool.

disconnected the two black leads from the speed controller that run off into the body as that seemed like a good idea to isolate the speed controller.

made up a short lead with spade connectors touching the brush terminals and clamped the tool to the bench with connectors securely touching the brush terminals, then using connector blocks attached the mains lead to the short lead. switched it on and it went pop [blink]. no motor spinning.

So i rebuilt the machine not wanting to repeat the action that went pop and switched it on. for about 10 seconds the tool worked perfectly with speed controller working then the tool stopped again, motor buzzing but not rotating.

So tell me what happened please? defo time to send it off but if anyone has any guesses at what going on then great. may as well bundle all the stuff due for service in with it too...

critics critique please

I am disappointed there were no fireworks. But pop? You mean the breaker popped?

If the breaker popped, you made a short circuit somewhere, or there is a short circuit inside the motor because it burned out.

I have no further suggestions for you through the net like this.

 

[R0bbie]

I think you must contact Festool advising them to delete the stator windings, that should save them a lot of money.

I think not. By the way, that's not an answer. Since you're the expert, what do those 2 wires do that connect to the brushes?
Conduct current

Where did you instruct (probably a noob) to disconnect the electronics?

Maybe read the thread instead of just throwing words around.

But: a noob? That's not how we talk to eachother around here. Maybe drop the attitude, this is not 4chan.

Again, where did you instruct the OP to disconnect the electronics?

 

[Ilovemyras115]

Yes the breaker went, nothing was touching that shouldn't have been.  no fireworks unfortunatley

The motor worked perfectly after this exercise for a burst so hopefully its the speed controller.

either way it earns me money, ive got alot of carving and scribing to to and i need it so ill send it off. I'm in cornwall so i wouldnt trust anyone around here to fix it quickly.

thanks for input. ill post the result from festool.

 

[R0bbie]

Yes the breaker went, nothing was touching that shouldn't have been.  no fireworks unfortunatley

The motor worked perfectly after this exercise for a burst so hopefully its the speed controller.

either way it earns me money, ive got alot of carving and scribing to to and i need it so ill send it off. I'm in cornwall so i wouldnt trust anyone around here to fix it quickly.

thanks for input. ill post the result from festool.

To bad man, keep us updated [cool]