BUNN LPG re-assembly issue - Page 2

Grinders are one of the keys to exceptional espresso. Discuss them here.
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JohnB.
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#11: Post by JohnB. »

As with the G series it looks like it would be impossible to put the burrs in wrong unless you attached one upsidedown. :lol:

Was the grinder working fine before you took it apart? Did you mess with any of the wiring?
LMWDP 267

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Robot (original poster)
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#12: Post by Robot (original poster) »

Well, as it turns out the motor WAS spinning the wrong way! Ben Z was correct in having me check the motor, which I immediately dismissed as an improbably cause of the failure. What was happening was that the polarity of the motor was REVERSED because I had installed the shaft housing upside down.

Why would I do such a stupid thing? Well, because for some reason the factory decided to put a sticker on the shaft housing and when I re-assembled everything I had the sticker right side up so that a normal person could read it. I figured they used the sticker as a way of telling which direction the shaft should be installed in. Turns out that they didn't follow that reasoning. The CORRECT way was to make sure the sticker on the shaft was UPSIDE DOWN, thus ensuring the blades are turning in the right direction. Counter-Intuitive, and something I wouldn't have considered if it wasn't for the help of you fine folks on this forum.

Thank you all for your help and support on this!

Now moving onto the Strega and why for the love of God I can't pull a decent shot after switching out the screen with the HQ from espressoparts! :lol:

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Robot (original poster)
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#13: Post by Robot (original poster) »

Well,

I do have another question, but this is more electrical and wiring related. I'm modding the case and would like to bypass the controller PCB and just bring is straight across the line. I'd like to use a momentary contact pushbutton as my 'on/off' switch. The only problem I am having is the wiring.

The Motor has two red wires, a white wire and a black wire. I'm having a hard time tracing the flow of electricity. Can any wiring experts chime in and help me wire this with a simple 'on off' switch?

I'd really appreciate the help. :D

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UltramaticOrange
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#14: Post by UltramaticOrange »

Far from being an expert, but I can tell you that typically the black wire will be your negative wire, white is ground and red is positive. As for the two red wires, I suspect one is for 110v and the other 220v. Can you find the part number on the motor (if you're very lucky, there'll be a diagram showing which wire is which)? Also, check the circuit board for any markings for where the red wires connect.

If we can't figure out which red wire is which by inspection, you'll need some kind of multimeter. Obviously this means poking around the grinder while plugged in, so be careful.

I do have a last-resort (read: you don't want to spend $40 on something you'll only use once and don't mind risking your fingers/pride) method, but requires lots of caution, so I'll save it for now.

Okay, I had instructions posted here, but frankly, there are too many variables involved for me to feel confident that my directions are right without seeing something of the circuit. Any clues on what the the PCB does? I'm concerned that they're converting AC to DC on it.
If your tiny coffee is so great, then why don't you drink more of it?

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Robot (original poster)
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#15: Post by Robot (original poster) »

Orange,

Here is a line diagram of the whole unit. I've tried almost every combination (safely) and it really just came down to having the black wire connect to the black on the motor and having the white wire connect to the white on the motor. BUT, it didn't actually work! The motor was making sounds like it was working, but it was actually just vibrating. Obviously I did something wrong, but can't figure what!

I'm going to try a few other things just in case, but any help you could give would be great!

Robot


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Robot (original poster)
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#16: Post by Robot (original poster) »

Yes, sum of all fears. It is an AC to DC conversion, and I think I blew the board when I made a wiring error when trying to substitute the standard switch with a momentary pushbutton. Well, I guess I will have to see if I can possibly get an adjustable frequency drive from my company and give it a shot.

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UltramaticOrange
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#17: Post by UltramaticOrange »

Based on the diagram it looks like there's more circuitry in the casing for the motor. The wire I've marked in yellow (red in reality) simply sends a signal to the motor that tells the motor to spin. The wire I've marked in red is the power wire.

If I'm correct, then you've got two wiring options here.
1: Replace the switch from the wire marked in yellow with your switch.
- or -
2: Remove the switch from the wire marked in yellow and then connect those to ends together. Clip the wire marked in red and install your own switch.

I think #2 will have a better chance of success, but #1 is the safer because you're retaining more of the original circuit design.

Of course, if you think you messed something up, try to reconnect the circuit it to the way it was originally and test if the unit works.

If your tiny coffee is so great, then why don't you drink more of it?

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UltramaticOrange
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#18: Post by UltramaticOrange »

Been meaning to ask. Does it live?
If your tiny coffee is so great, then why don't you drink more of it?

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