Dewalt DW788 Scroll Saw Problem

I've never done any scroll sawing and didn't want to invest in a new high quality scroll saw until I am comfortable with the skill. I bought a used DW788 for $100.00 knowing it needed some repairs. After spending another $100.00 for a new on/off switch and variable speed control with the circuit board, it works great. I do have one question however. When I increase the speed past about 600 rpm, it starts to skip and stall and actually slow down. It doesn't knock or make any other bad sounds. It just seems to start skipping strokes. Does anyone have any idea what may be causing the problem?
I have been doing some limited research on the DW788. Dewalt didn't put a lot of effort into posting much information about it on their web site. Can someone tell me the difference between the 788 and the 788L models?
Thanks
Ted
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I can't but I have the 788...I have never heard of the 788L model. As a matter of fact, I can't find anything on DW788L except from 2 sites who sell parts.
The 788 is an excellent machine. I would suggest opening the frame and check out the works. Possibly disconnect the motor from the cam. See if the motor still slows down. Then you have 2 questions. Is the problem with the motor or the new switch speed controller.
If it doesn't slow, you should start looking for gummed up works which may be overheating the motor. Don't overlook bent parts which may be doing the same.
Good luck.
tedln wrote:

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One more thing. Don't forget to check the brushes.
tedln wrote:

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On Sat, 22 Mar 2008 17:44:02 -0700, tedln wrote:

Users Manual: http://download.sears.com/own/00924470e.pdf
According to the Dewalt service site the difference between the DW788 and the DW788L is the DW788L includes the stand. http://www.dewaltservicenet.com/SearchResults.aspx?q=DW788
Parts Docs: (Follow the link from the above service link if you can't get these long links to work. The page looks funky, the doc links are the pdf icons on the left of the DW788 page, same links as below)
http://www.dewaltservicenet.com/Products/DocumentViewPDF.aspx ? productidV82&typeId475&documentId33
http://www.dewaltservicenet.com/Products/DocumentViewPDF.aspx ? productidV82&typeId475&documentId34
Probably not what you want to hear after you've already spent the money and time. Below is knowledge for other potential buyers out there.
You will have a decent machine if/when you get it all running. However, for your next purchase both plansnow.com and popular mechanics compared and reviewed scrollsaws and both gave good ratings for the Ryobi SC164VS entry level scrollsaw $99 new with 2yr warranty ($79 on sale), and other manufacturer/models for under $125 new with warranty. Definitely not as good as a new DW788, but it might have been a better unit to decide whether or not you like to use a scrollsaw, rather than getting something that needs service. Your time spent acquiring parts and repairing adds up and you may never know if it is working as well as it can unless you can find a new DW788 to compare. I prefer new with warranty for my own "test" purchases, if I can find a unit well reviewed for under $100. That way I'm working the day of purchase. Then I can decide what features in the more expensive units I really need and what's missing in the cheaper unit, stability, bed length, etc.. After 2yrs when the warranty runs out I can probably still recover 1/3 of the cost ($25-30) by selling it used or give it away as a gift. Or use it in assembly line production, leave one tool set up at 45deg angle and one flat 90deg to speed production without constantly resetting/re-checking the angles. I'm definitely not in favor of cheap tools, but if you only need a tool to finish a job or need it for test driving, sometimes a well reviewed cheaper unit will do to start. I wish I could afford your testing budget.
DW788's are $419 new with warranty so you still have a way to go. $100 + $100 parts + shopping time + repair time + still doesn't work right. Get the stall problem fixed and you should have a decent sturdy workhorse for less than new cost.
http://plansnow.com/reviewscroll.html http://www.popularmechanics.com/home_journal/workshop/1274521.html
As for the stall problem, don't have one, sorry can't help there.
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