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Looking for info on a Hobart HL-6

FrankIII's picture

Looking for info on a Hobart HL-6

Hello, I'm working on a Hobart HL-6 mixer. I know that I'm pretty much on my own with this one, but I hope others on this forum can chime in help with some answers I need. The problem with the mixer is that the motor does not turn. So I took off the top cover. Pretty easy 2 screws at the back of the unit facing upward near where the power cord enters. Take the plug and screw for the attachment nose off the front of the machine then gently move the cover forward past the nose and the cover comes off. The speed control stays with the cover and there is plenty of spare lead to just keep it aside. 

I was pleasantly surprised to find an Ankarsrum Motor inside! So maybe I can find someone with Ankarsrum who may be able to help me.

I've already checked the fuse and that is ok. When you turn the mixer on, the cooling fan in the stand starts running. At the center of the black housing on the motor, I was able to spin the motor armature and it spins ok. 

I took the 5 torx screws off of the transmission housing, and low and behold there is no grease. An oil of some type is in there instead. What type of oil and how much, maybe an Ankarsrum specialist may know.

Unfortunately the battery on my phone died, so I did not get any pictures of the inside of the transmission. It is very different from other mixers that I have seen. The end of the motor shaft has a worm gear on it much like other mixers but that similarity stops there. The worm gear then drives an EXTERNALLY toothed ring gear. The external toothed gear somehow drives the carrier and planet gears. It appears the sun gear actually drives an angle cut gear for the attachment hub, while the other end of this piece ends with a square shaft that drives the planetary gear set that drives the beater we all know. I was amazed at the design!

I did not find any broken parts or missing teeth in the transmission, so the problem may be due to the motor or controller board. I have already found the Hobart circuit board 917468 online and have that here. 

Inside the top cover, I found the schematic glued in. Looking it over, I saw that inside the motor is a component labeled "TCO" in series with the motor. I speculate this could be some sort of temperature control override or safety. Also in the block diagram for the motor is a hall-effect sensor for sending speed info feedback to the circuit board. Another this I spotted was a jewel I will probably never see, and that appears to be a 4 leaded assembly labeled as "Optional Timer". The jack that this timer plugs into on the main circuit board is empty and unused on my unit.

I know there is a lot here, but if anyone has experience with Ankarsrum transmissions with respect to quantity and type of oil and how to test the Ankarsrum drive motor and if there is a thermal safety that has tripped, this would be a good place to start.



BrianK's picture

Hello.  Amy, from the "Amy Learns to Cook" channel on Youtube, has one (possibly two) Hobart HL6s.  I remember in one of her review videos that she mentioned being in contact with someone who used to work at Hobart, and that someone else had several of these machines.  Perhaps if you contact her on her YT page, she could put you in touch with someone who knows about these machines.

FrankIII's picture

Thanks Brian, I check this out and see if I can get anywhere. If I had a working machine, I could compare one to the other, but if I can come across someone who used to work for Hobart, that would be even better.

FrankIII's picture

NOTE All this below was done AFTER verifying all the AC plugs were unplugged

The Hobart HL6 LIVES! I had a couple hours to spare this afternoon so I thought I would take another stab at the DL6 mixer. First I reasoned that if the small blower under the motor is running, then al least part of the main board is doing something. I went downstairs and found the old 5qt kitchenaid mixer that my wife got decades ago. I know they are not the same, but, I took the top off of the kitchenaid, then followed the leads on the motor and disconnected them. With an ohmmeter, I measured the resistance of the motor as it appeared at the leads ends. It measured 3.7 ohms on the kichenaid. I could hardly wait, but I needed to get the Kitchenaid back together first, dare I end up with a pile of parts and screws that could go to either machine. After I got the kitchenaid back together and working again, I put it back on the shelf. I then took the top off of the Hobart HL6. I disconnected one of the motor leads at P4 on the circuit board and with my ohmmeter, I measured 43 ohms. Much higher than in the kitchenaid.

Looking at the unit, I found 4 larger torx screws, 2 on the motor and 2 on each side of the transmission, plus 1 more smaller screw at the nose of the mixer directly under the accessory hub. With all of them out, I carefully juggled the assembly up and out of the stand while disconnecting any wires that getting tight or stretched.

Neat thing that at the end of the motor furthest from the accessory hub, is located the hall-effect sensor for motor speed feedback to the circuit board. It simply unplugs from the motor with a simple phone-jack type connector.

After getting the assembly free, I simply flipped it over thus exposing an opening where the small cooling blower under the motor directs air to cool the motor. Again with a meter, I measured from the white wire end that connects at the circuit board to the other end of the white wire where it is soldered to a motor winding inside the motor. I got 0.3 ohms. I repeated the same process for the black wire and got 0.2 ohms. At this point, I figured if the connections are good to this point, maybe it is the brushes. I took a small piece of sandpaper and took the guff off the commutating bars, 2 or 3 bars at a time. I rotated the armature a little, 2 or 3 more bars at a time and repeated the process until I'd gone all the way around.

Now, measuring the resistance of the motor at the meter leads, I got 2.9 ohms, much better than the 43 I had before. I put the motor back in place and tightened all the screws.

Trying to be thorough, I checked all the connectors and them plugged the HL6 back in. No smoke, and that was a good start. I turned the speed control and now I had nothing! No mixer motor and now, no small cooling fan motor. What a let-down! I unplugged the power cord and went to double-check things again. This time I found that the connector for the speed control unplugged itself. No wonder the control did nothing!!  I plugged it in, then applied AC power. The mixer came to life!!

Now, I just need to tidy things up AND determine what kind and how much oil to put into the transmission!


Precaud's picture

It is very gratifying to bring something old and useful back to life.

Moe C's picture
Moe C

You are a very methodical worker.

FrankIII's picture

Thanks,, Still cleaning this unit up, just a few small details to look after. The transmission oil type still escapes me. While the unit has a little in it, what is in there is about what you would get if you dipped each part in oil and then assembled it. While it may run for a while, I don't want to mess things up and burn up any transmission bearings.