Panel Mounted Speed Regulator Module?

[ericmark]

OK that tells me a lot. If I explain how it works then maybe you can work out the fault. It is in essence a switch mode power supply and what it does is switch on and off very rapid and it varies the on to off ratio. The time on is called "Mark" and the time off is called "Space" hence why it refers to the Mark/Space ratio.

Likely there is something like a 555 timer which in turn switches a FET or other type of transistor.

The main advantage of this type of control is the heat generated is low. First developed for front loading VCR machines because of the cooling problems it has grown to everything from welding sets to mobile phone chargers.

However they are very hard to repair. Unlike the standard power supply you can't follow the progress with a meter and find the problem in real terms the way to repair is to swap bits until it works.

Much depends on cost of unit in first place. A 555 timer costs a few pence and what I did was to swap the chip for a IC holder then try a new chip. If it was not the chip I could remove the good chip as not soldered. With a card costing £100 swapping the 4 chips first was worth the risk but with a card costing £5 it would not be worth time and possible throwing good money after bad.

It will require using a solder sucker to de-solder all the pins which if you are into electronics may be worth while but unless you are reasonable with soldering iron likely not worth the effort.

From what that PDF says it does not measure the back EMF but likely it will want a reasonably smooth supply. With the small transformers you put into the wall often there is no smoothing. So step one try powering from a battery. One of those lantern batteries should do.

If it works from a battery try sticking a large electrolytic capacitor across the output of the power supply. It may work. Having a power supply switching on and off as it will do if either a switch mode or simple rectified is going to really mess up a device trying to work a timer.

It may not be a 555 could be a 74121 or even a simple 741 op-amp but likely the charge time of some capacitor is what sets the mark space ration so it really does need a constant supply.

If it works on a 996 battery then may be worth while using a small lead acid like those used in alarm panels.

Do let us know how you get on. I was it seems right when I said a multi-meter would not really help.

 

[phaeton]

Thanks Eric,

The motor I am using and the speed regulator I am having such difficulty with are both made by MFA and therefore should be compatible. I am going to phone them tomorrow and go over my setup, which is basically just a circuit to power a small 3 - 12v DC motor.

Will update.

Ric

 

[bernardgreen]

From memory the frequency is 1200 Hz. The supply must be a linear supply and not a switched mode supply. Reverse polarity protection is provided so reversing the input should not have caused any damage.

They do not have much filtering on the output so there is a lot of high frequency energy radiated from the leads both input and output. There is probably a limit on maximum length. It might be that bunching output and input leads together causes instability if the supply is not very low impedance,

 

[phaeton]

From memory the frequency is 1200 Hz. The supply must be a linear supply and not a switched mode supply. Reverse polarity protection is provided so reversing the input should not have caused any damage.

They do not have much filtering on the output so there is a lot of high frequency energy radiated from the leads both input and output. There is probably a limit on maximum length. It might be that bunching output and input leads together causes instability if the supply is not very low impedance,

Thanks but help, I am a tyro. UK tv is 60Hz, US tv is 50Hz (I think?) because I'm also having trouble with HDMI cables; how does 1200Hz relate to this if at all please? But indeed, the info sheet says "average 1200Hz". I need a crash course in electronics.

Yes, the unit is polarity protected but it will remain inert if the polarity is reversed, then it's a guessing game: is the unit inactive or has it stopped working properly? Nothing to tell you. I'm going to have another go at it tomorrow whatever happens. I have to use the voltage adaptor because I haven't got anything else to give me DC power, unless I used a standard 9v supermarket battery (size of a reduced matchbox) but how long would that last and is that DC?

 

[bernardgreen]

It will be inert if the input polarity is reversed.

You can use a 9 volt battery and instead of the motor use a small torch bulb as the load. Start with the control turned down to minimum before connecting the bulb. Then you can us a 3 volt bulb provided you do not turn the power up to full.

 

[ban-all-sheds]

I think before jumping in with both feet BAN should read the instructions that came with the controller.

I did read the instructions.

In doing so I noted the part which says "Connect the input leads to the power supply observing the correct polarity."

I would agree no circuit diagram and it requires some guess work but seems it uses a very high frequency so a multimeter would be of little use.

The multimeter is to use on the power supply output, so that the polarity of the unmarked leads can be determined and allow them to be corrected correctly to the controller.

But now we know that getting it wrong will just mean nothing happens, not that the controller will be damaged, which is good news.

 

[ban-all-sheds]

I went through 7.5, 6, 5, 4.5 & 3v to test for speed.

If you're using a controller which is also reducing the average voltage to control the speed, try it with the adapter at 12V.

 

[ericmark]

Many of the adaptors rectify the output but do not smooth it. For a switch mode controller to work it will require a smooth output. The AC wave from show below has the bottom

True sine wave

• ericmark
• 8 Dec 2009
• 2

bit reversed when rectified which will mean there are a series of points where there is no voltage. There are a number of ways to fill in these valleys the most common is a simple electrolytic capacitor. A rechargeable battery would also do the same thing.

Even if your drill only runs for 1/2 a minuet before the battery becomes discharged using a battery instead of a power supply will confirm if it's the type of power supply or faulty controller.

If you use a regulated power supply in the main these have soothing built in and likely they will work but before suggesting replacing the power supply testing with a battery would seem to make sense.

I remember as an apprentice building a windscreen wiper pause controller and I built it using a 74121 chip connected it to a 12 volt battery and it worked A1. So installed in into my mini. Complete failure as the spikes from the ignition upset the timing chip. Reading the instructions it would seem this unit is also affected by outside spikes the report says how a PMR radio upset it and that was not even hard wired or close to it so any power supply which is not smooth is very likely to cause it to malfunction.

With my radios I use a battery to increase the smoothing and even then on the odd time I will find the AC ripple is sneaking through. Even something like arching brushes on the drill could upset the unit in your case so the battery test is well worth while.

 

[phaeton]

It will be inert if the input polarity is reversed.

You can use a 9 volt battery and instead of the motor use a small torch bulb as the load. Start with the control turned down to minimum before connecting the bulb. Then you can us a 3 volt bulb provided you do not turn the power up to full.

Thanks - that will be a useful diagnostic if I get into a pickle on the second attempt.

R

 

[phaeton]

I went through 7.5, 6, 5, 4.5 & 3v to test for speed.

If you're using a controller which is also reducing the average voltage to control the speed, try it with the adapter at 12V.

That is another excellent idea - I certainly didn't boost it up to 12v last time, more like 6v.

Thanks,

R

 

[phaeton]

... using a battery instead of a power supply will confirm if it's the type of power supply or faulty controller.

Well at the moment the adapter is running the motor faultlessly so it seems to be all right. The problem is inserting the speed regulator into the circuit. I will be using a fresh regulator later today. Fingers crossed for that.

Thanks.

 

[ban-all-sheds]

Try the existing regulator with a 12V bulb.

 

[phaeton]

I took no chances this time and used colour coded wiring to connect the regulator while marking the generic wiring '1' & '2' in case I needed to reverse polarity. Then I was delayed 2+ hours by the insulation tape of two days ago unsticking itself & unraveling, which let one of my connections slip out of position & broke the electrical circuit. I then had to resort to tying the wire into position. Sad. This achieved I got the motor to turn by way of the regulator, so I now have speed control.

When I hit the on, a high pitched whine issued from the regulator which scared the life out of me - remember I almost blew myself up a couple of days ago; but the whining is just a side effect from the regulator - they told me after I phoned the company, nothing to worry about.

Thanks for help.

Onward.

Ric

Ps. does anyone know of a brand of decent electrical insulation tape which sticks & doesn't shred on the spool please?

And where can I find 'wire crimps' which you can plier onto the end of raw wire please, they tidy wire ends up a treat, I noticed these on an old set of electrical wires I reused

Thanks again.

 

[ban-all-sheds]

Then I was delayed 2+ hours by the insulation tape of two days ago unsticking itself & unraveling, which let one of my connections slip out of position & broke the electrical circuit.

I then had to resort to tying the wire into position.

And the reason you won't solder the wires in place is....?

And where can I find 'wire crimps' which you can plier onto the end of raw wire please, they tidy wire ends up a treat, I noticed these on an old set of electrical wires I reused

They're called bootlace ferrules, and you need proper crimping tool, not a pair of pliers.

 

[ericmark]

Aldi and Lidi sell the crimp kits from time to time. There are two basic types of crimp pliers.

The cheap type have no way to show the user if under or over pressure is used but likely good enough for your job.

The expensive type have some method of setting the pressure some look like mole grips. For mains work these are a must but not really needed for your job.

Maplin likely sell both types and motorist shops tend to sell cheap ones.

Insulation tape degrades in time and more likely you had an old role than wrong make. 3M do all sorts of tape but really although you can get high quality more likely just an old role.

Glad to see all up and running.