Dewalt DW625E Router electrical fault

[flounder]

I was hoping I could get some advice from you fine folk regarding a fault I have with my router. I have a DW625E mounted in a table and it now has no speed control whatsoever, it just runs flat out regardless go which speed is dialled in. I have taken the speed control switch off and put an ohm meter across the terminals (there are three terminals two of which are also bridged by a capacitor). No matter which pair of terminals I measure across the resistance reading is constant and reads either 6 Mohms or 24Mohms regardless of the dial position. Now to me that would suggest that the switch is faulty and if it was just a basic potentiometer i would be confident about my diagnosis, but the switch clearly has more electrickery going on than just a variable resistor so wasn't sure if i am making an assumption with the lack of variable resistance reading?
Now my second dilemma is whether or not it is actually worth repairing! I can get a new switch for around £60. I bought the router second hand and although it has only had light DIY use over the last 2 years I don't know what has gone on before my ownership of for how long. I can buy a new DW625E for around £220 or a HitachiM12 for around £165. As it is going in a table permanently and I have a router lift i don't need a lot of bells and whistles and the Hitachi seems to have good reviews. So....is it with spending £60 to repair this router not knowing what other issues might be developing or should I bite the bullet and buy a new router with warranty etc. Are the Dewalt routers generally reliable over the long term?

Sorry for the ramble and thanks for any advice anyone can offer.

 

[flh801978]

Common problem with these routers is the magnet on the end of the shaft coming loose if it does that it will run a top speed regardless
easy to check or it has pulled off the shaft a little will also do the same thing

Ian

 

[Eric The Viking]

I have a similar router: Trend (T11).

You already have the top off: Gently lift the speed control circuit board out of the way, and check the pulse generating magnet is secure on the shaft. It's a plasticky, brown-black ring, about 5/8" across and 1/4" thick, and IIRC, it's a push fit onto splines, almost on the end of the shaft. You can see it in the middle of the speed controller board, but you really need the board out of the way to get fingers round it.

The one on mine came loose, but sort-of stayed on, because the cover stopped it dropping off the shaft entirely. The speed feedback pulses were erratic (presumably), and the speed control stopped working.

I secured it with Loctite. There's a thread about it with pictures if you use 'search'.

I hope that's the problem as it was a cheap fix.

E.

Edit: (apologies FLH - my post crossed with yours): my earlier thread with pictures is here

 

[flounder]

Just checked and the magnet is still firmly in place. I resigned myself to either buying a new switch or a new router so decided to button it back up to keep all the bits together. Plugged it back in to check that it was no different and now it is working perfectly!! There was a bit of dust build up around the switch/magnet so this could have been have been the issue I guess, alternatively there is an intermittent fault presumably in the switch and the clock is just ticking until it goes again!

 

[Eric The Viking]

Given the symptoms, it's almost certainly something to do with the tacho's pulse counting circuit.
At a guess the motor control board was slightly out of place (although mine was still running, just, with the magnet scraping on the bottom cover!).

If it does it again, look for dry joints around the Hall effect sensor (obvious block close to the magnet on the shaft), and I'd Loctite the magnet in place too, just in case. It is a common fault on these models.

Glad it's OK though.

E.

 

[flounder]

Thanks to both of you for the advice and the link to the previous thread. Hopefully it was just a temporary glitch and I will now enjoy countless years of impeccable service from it. On the other hand....

Kind regards

Lee