Author Topic: 2021 Craftsman Bench Jointer CMEW020 - help me reverse engineer/hack this please  (Read 1918 times)

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Offline floobydust

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In a perfect world you have a beefy enough isolation transformer good enough for the motor under full load.

Check your life insurance policy, floating the scope is very dangerous. If your shit is not together, you will have a bad day. I'll do it with an analog scope (not DSO with SMPS and Y-capacitors) and never to anything lethal for floating potential. Floating it to Neutral would probably start a heated discussion so I will not recommend it, although it can be done.

What I would do:
Leave scope normally plugged in to mains (PE grounded). Probe only using the tip, no GND wire connected, so the scope's reference is PE through its line cord. Without grounding the scope probe, you are limited for looking at low frequency stuff but connecting it (GND) to Neutral is a bad idea because the motor's return current will rip through the scope to PE, and damage it internally.

Ch. 1 on point of interest (should range from mV (shunt) to mains V plus transients- using x100 probe)
Ch. 2 on Neutral (should be a few V under motor load)
Set scope to math, subtract Neutral from point of interest.
AC Line trigger the scope

The motor is a large source of EMI due to the brushes arcing. I don't get spectacular results with Rigols in high-EMI lab setups. Neutral will also be noisy and a few volts different than PE. If your Neutral is quiet enough, then you can just ignore it and free up the second channel.
The IC's circuit is awkward with referencing everything to -VDC as the common, so drink lots of coffee. I wonder if the IC really does decent load/speed compensation.

Your tests can be very interesting, but just be prepared to abandon ship if the test equipment isn't enough, rather than take on high risk. It's not worth it.
 

Offline jakeisprobably

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Well I have lots to share but I need to prepare and polish the visuals first. I'll try to avoid adding controversy about how I probed things. Unfortunately my (unhacked) DS1052E is not fast enough to see any transient voltage spike beyond the effects of the default snubber values. I didn't test it with the snubber disconnected entirely though. With it connected I didn't see anything major.
 Both the BTA26-600B and BTA26-600BW work, the 'BW that I tested showed a slightly higher Vpp for whatever reason. I didn't investigate further, but I have the waveforms saved.
  I have a spreadsheet with resistances measured to and from GND and -VS to all pins for all chips so far. I now have three tested and verified working chips from 2 sources and three defective chips (not including the Jointer's) with more still in transit. Indeed it seems there is an issue with IC quality if any conclusion can be made from such a small sample size. Three out of the five I received two days ago each had a different failure mode. One has shorted power, one has no feedback connections on pins 4..7,  and the last has low resistance values on the compensation amplifier/buffer IIRC.
  Interestingly, the set of 5 chips have sharp-ish top epoxy, the kind I usually associate with refurbished chips, but the casting stamp designator format and dimensions on the bottom of all five are matching just with different letter/number combinations. I belive they were all from the same manufacturer. They don't match the Jointer's chip cast markings, and nothing matches the third chip I have either. These faulty chips are exactly that. They all have pins with expected values on various pins with a failed block somewhere on the IC. Overall, I'm building up a map of what the "good" range of resistance values are and measuring everything as soon as I receive them. I hope I see some pattern in any future failures if I have any.
 I will have more visuals to come, but it looks like my conclusion will be to just add a socket and swap the chip.
 

Offline wizard69

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Honestly I'd chalk this up as a lesson learned.   These days everything with the Craftsman logo on it is junk and that is being kind.   That is really sad to say but I wouldn't trust anything marketed as Craftsman.

In any event you probably want to get you jointer to work, the first thing you need to determine is what sort of motor is in the machine.   Figure that out and then go out and buy a real motor controller form the likes of KB controls or similar.   Do that only if you think the motor will last which it likely won't.

Your best bet would be to simply buy a single phase motor and run it directly off the line.   Even here you may need to change the belt drive and the guarding around that.

Now given all of the suggestions above to get it running, ignore those and return the piece of junk and demand your money back.   There really is no excuse for such crap being shoved down our throats.   When it comes to tools sometimes you will not have a local option, you will likely have to order a decent machine via other avenues.
 

Offline jakeisprobably

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The machine is made by Shinmax Industries https://www.shinmaxindustry.com/
All are the same:
Delta 37-070
Porter Cable PC180JT
Craftsman CMEW020
The first part of the above part numbers is the sticker company, not to be confused with actual sticker manufacturing companies. These are sticker sticker companies. Note: sticker sticking is also subcontracted. As far as I know ""Craftsman"" has always been a sticker sticker subcontracting kind of brand. Like most of the 80's-00's stuff was made by Ryobi (aka all Craftsman part numbers that start with 315.xxxx. IIRC the 113.xxxx stuff is most of what was "Made in the USA" and was the part number prefix for Emerson.
  Venture capital is what it is. They are counting on consumer ignorance and resistance to change in order to market their overpriced junk. If that bugs you more than it does me, maybe you're motivated enough to beat them at their own game and seek out the best value products for you, forging your own path. For instance, when Sears sold Craftsman stuff made by Ryobi. Ryobi made better stuff at a better price under their own brand.
History repeats. Shinmax's house brand is Cutech: https://cutech.tools/
Their 8 inch wide bed, spiral cutter, and bed extensions model is listed at a really nice price, and is very tempting if shipping is reasonable IMO.

Attached is my spreadsheet with test results for 17 total U2010B chips tested in and out of circuit. Maybe someone that knows more about silicon can comment about the range of values and anomalies. Is the range of resistance values seen here normal?
   I am really surprised the chips labeled ALI-12 and ALI-14 worked. Chip 12 appears to have major issues with the sense pins and 14 has no connection on Csoft at all. Of the bad chips on sheet 2, my favorite is the one with no connection to the ground pin.
The spreadsheet was made with Libre Office, but also saved as an xlsx file for 'doz users, and/or there is a PDF.
« Last Edit: April 16, 2021, 03:03:39 am by jakeisprobably »
 

Offline Ground_Loop

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I understand you're trying to fix this for fun,  but please understand that there is absolutely no reason to have speed control on a jointer.   If you really want to use this tool then the motor needs to be directly connected to mains.

It's a criminal level shame what accountants did to the Craftsman brand.
« Last Edit: May 01, 2021, 03:44:37 pm by Ground_Loop »
There's no point getting old if you don't have stories.
 


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