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G0752 speed control problem

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John281

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#1
I have a Grizzly G0752 lathe which is the same as the G0602 but with variable speed that I bought new about three years ago. Last year, the speed control started acting up in that the speed would change erratically as the speed knob was turned. I replaced the potentiometer and it was OK for about a year but started doing it again recently.

Has anyone else had a similar issue. I'm not sure, but it looks like the manufacturer might have changed the part number of the potentiometer on the newer machines. I haven't called Grizzly yet but that's the next step.
 

roadie33

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#2
I'd call Grizzly and explain that you replaced it once already and now it's acting up again and you noticed they use a different PN now.
Might be able to get a free one out of them if they were defective to begin with.
 

mksj

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#3
I have had the same thing happen with the Chinese speed pots on other machines with factory VFDs, the tension on the wiper seems to go and possibly the film resistance wears out. If you need to buy a replacement, you are better off sourcing something better. I typically replace them with higher quality mill spec. 1 or 2W pots either conductive plastic or wire wound with a rating of 1M+ turns MTBF. I would check the resistance of the current pot, based on the Delta-E VFD specs used for this machine they indicate a speed pot of 5K ohm. I have been using the precision 3 turn ETI wire wound, or 1 turn film pots, they are military grade and should last a long time as they are rated for 10 million turns.
3 turn 5K wire wound
https://www.ebay.com/itm/2-ETI-MW22B-3-5K-5-1W-3-Turn-Wirewound-Potentiometers/201057249723
1 turn 5K conductive plastic
https://www.ebay.com/itm/ETI-System...SP22E-SB-5K-1W-SP22ESB5K-Nib-New/122837307285
 

markba633csi

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#4
You might try spraying some contact cleaner into the pot if you can find an opening in which to spray it- sometimes they get gunked up and cleaning
can work wonders. If you don't have contact cleaner you could try dunking it in alcohol and then drying it out thoroughly- I've revived a fair share of pots that way
Mark
 
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