Coffee Roasting: HotTop Programmable Upgrade

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From TMC Wiki

1 Coffee Roasting: HotTop Programmable Upgrade
2 Should I attempt the upgrade ?
3 Performing the Upgrade

[edit] Coffee Roasting: HotTop Programmable Upgrade

This TMC Wiki page describes the procedure for upgrading an original or digital HotTop to the full programmable "P" model, using the upgrade kit

It should be used as an additional resource to the official upgrade instructions, which can be found here

If you read the official instructions, then look at this wiki, you will find extra notes and links which may be of additional help to you in dealing with the particular steps in the upgrade process.

[edit] Should I attempt the upgrade ?

I'm not going to attempt to discuss whether you need more control over your roasts, I'm only going to try and answer whether you should attempt to perform the upgrade having decided that you want it.

There are effectively two main aspects to the upgrade procedure for the HotTop programmable:

Electrical

This is actually a lot easier than you might think, because you are mainly moving wires which connect to numbered points on the old circuit board, to similarly numbered points on the new circuit board. The main difficulty with this is that you have to disconnect them all before you reconnect them, they can't be done one at a time ! But, you can number them with a permanent pen, take photos, etc. basically whatever you like to identify them clearly before you remove them. Do you feel confident wiring a 3 pin mains plug ? Could you competently replace a light switch or mains wall socket in your house ? Then I think you'd stand a very good chance of being able to deal with this. There is also an additional complication of an earth wire to unscrew and later refit, and a couple of plastic cable ties to cut and replace, but this is not especially difficult either.

Mechanical

If you've ever had the (dis)pleasure of taking apart any commercially made electrical item, and later successfully put it back together, then you will probably have an idea what to expect here. Self-tapping screws into plastic and metal mounts, obscure plastic lugs, and the sometimes slightly unpleasant realisation that something has definitely been built to a price. The HotTop is no different in this respect, I'm afraid. But it is pretty logical in the disassembly and reassembly process. You just need plenty of space, plenty of patience, and plenty of care not to mark the shiny metal and soft plastics. If you are already comfortable in regularly removing the drum for cleaning, without damage, then you ought to be able to deal with the level of disassembly required. Only splitting the top from the base is particularly challenging the first time.

Having said that, it's only fair to be clear, that this upgrade is entirely at your own risk. You have an upgrade kit worth pretty much the same as the roaster itself, which you could break, not to mention incur some damage to the roaster. So think about it, and consider whether you know a responsible (or even skilled) adult who could at least help ! There is also the remote possibility to consider that it might not work once you get it all back together, and if that is the case, could you, or do you know someone else who could, help diagnose the problem ?

[edit] Performing the Upgrade

[edit] Preparation

[edit] What's in the box ?

LCD control panel
Main circuit board
LCD Panel to Main circuit board interconnect (8 wire cable)
Optional longer Chaff Tray safety switch cable (2 wire cable)
Spare cable ties
Selection of spare screws

Most notably, there are no instructions for fitting the upgrade, nor is a user manual included, so you might want to print off some from:

Note: These documents, particularly the fitting instructions, are updated from the copies available from HasBean, which are what I actually used. In particular, issues regarding separating the base and top of the HotTop seem to be covered in more detail now.

[edit] Picking the Right Tools

Essentials
- Small Crosspoint (Phillips) screwdriver (for the earth wire screw)
- Medium Crosspoint (Phillips) screwdriver (for pretty much everything else)
- Small to medium pair of needle-nosed pliers (for assisting in the disconnection of spade connectors, etc)
- Small pair of cutters (for cutting cable-ties)
- Permanent Marker pen / liquid paper pen (for marking spade connectors before removing)
- Flat blade screwdriver with the end taped with electrician's tape or similar, for use as a wedge to remove the control panel

Optional
- Torch
- Anti-static strap (optional, for those who are paranoid about zapping expensive control boards)
- Digital camera (to take clear photos of how things fit together, in case you forget)
- A large towel or soft cloth / mat to protect the HotTop as you dismantle it

[edit] Remove the Drum

Official HotTop instructions for drum removal

This step should be familiar to any existing HotTop user who cleans their drum and removes it for cleaning chaff out of the inside of the drum enclosure.

[edit] Remove the Rear Air Filter

Just lift it out via the handle, per the normal procesure for replacing it.

[edit] Disassembly

[edit] Removal of Control Panel

Official HotTop instructions for removal of the Control Panel

I'm not convinced a large flat blade screwdriver with the end taped with electrician's tape is the best bet here. Although the tape will help prevent scratching the plastic, you still have a hardened steel screwdriver being used to prise apart soft (especially the control panel itself) plastic parts.

There is a real risk of denting / nicking the bezel edge of the plastic control panel itself as you try and "free" at least the first plastic clip, and it's a shame therefore, that the one to start with is the top middle of the panel.

However, it is best to start with that top middle one, and it's hard to think of a better way to get them apart. Possibly a wooden lolly stick, although I didn't try that myself. My original panel was not a great fit to start with, and came out easily.

Lesson: Work slowly, patiently and methodically with this, try not to apply any more force than is strictly necessary, and don't get cross with it.

After the entire upgrade, and with the new panel in place, which seems much more rigid, I couldn't get that to budge and there's some sensitive electronic connections sitting just behind those plastic lugs in case you're careless and slip. And I only wanted to take it off again for some photos !

Lesson: Don't clip in the new control panel until you are sure everything else is in place.

[edit] Cut the Cable Ties

[edit] Label and Disconnect Wires from the Main Circuit Board

[edit] Unscrew the Earth Wire

[edit] Locate and Unscrew the Side Panel Screws

[edit] Separate the Base from the Main Body

[edit] Remove the Old Main Circuit Board

[edit] Reassembly

[edit] Install the New Main Circuit Board

[edit] Re-attach Base Wires to the New Main Circuit Board

[edit] Replace the Base

[edit] Replace the Side Panel Screws

[edit] Re-attach the Earth Wire

[edit] Replace the Remaining Wires on the Main Circuit Board

[edit] Use New Cable Ties to Tidy the Wires

[edit] Replace the Rear Cover

[edit] Replace the Rear Fan Assembly

[edit] Install the New Control Panel

[edit] Finishing Off

[edit] Replace the Filter

[edit] Replace the Drum

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