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My 2k+ may have a logic board problem!
drllama
I love my HotTop, and I'm the first to admit it's overdue for a full strip-down and cleaning.

Meanwhile, I've been having some odd behavior that led to yesterday's failed roast and I hope that it's nothing more serious than connections coming loose and fear it's time to replace one or both logic boards.

What started out was the display was acting oddly. I run the roasts using Artisan from my laptop and only really ever use the display to watch the temperature during cooling.

At one point recently I noticed that the display was very dim. A few roasts later it wasn't coming on at all. Telemetry coming through to Artisan was fine, so I wasn't overly concerned.

Until yesterday. Yesterday the display was flickering, and I was getting very odd readings from the temperature probes. First of all, they seemed to be reading very very high. ET was well over 450 by about 7 minutes, and when Artisan dumped at 395, first crack hadn't even finished.

But that's not the weird part. The weird part is that I only seemed to be getting telemetry from the roaster ever 45 seconds or so. Artisan was showing flat lines until the temp would shoot up a bunch, then flatten right out again, all the way through the roast.

Any thoughts? I plan to tear it down completely on Sunday, give everything a thorough cleaning and looking over, then if all looks good reassemble and try a test roast. If all goes well I'll just shrug it off as "Well, that's weird" and keep on, but with a wary eye out. Otherwise, I know I can get the necessary parts, just not completely sure where to start diagnosing what's going on.

Any suggestions, comments, etc. definitely welcomed!!

Thanks,
Bruce.
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Started with FreshRoast+, moved through a Cafe Rosto, two Alpenroasts, iRoast, managed to set a Behmor on fire, a couple of GeneCafes and now my shiny new Hottop
 
Randy G
Sounds like a failing control panel. But when you tear it down use "Deoxit-D5S" to clean all the terminals and connectors and make sure they are tight when reinstalling them. When cleaning the control panel, avoid getting any of the cleaner on or under the display. One user used painter's tape to protect it.

Life's too short to drink bad coffee.
 
chaff
Those high temperature readings could be a sign the on-board temperature sensor is hotter than the actual thermocouple cold junction, its connection terminals. Voltage regulator chips in power supplies, too, have thermal sensing and shutdown which could explain the display doing odd things.
Maybe look for blocked ventilation causing the logic to overheat ?
 
Randy G
I doubt that it is temperature related. I have seen Hottops which have had fires in them serious enough to melt much of the plastic outer case which still operate properly. They can be run, batch after batch, with the fan off and not exhibit this behavior. And I have seen them with amazing amounts of chaff built up and they still operate normally.

It is most likely either a failing control panel or (less likely) loose or dirty connections on the control panel. You can try this:

- Remove the control panel
- Unplug the ribbon cable from the back of the control panel
- Plug the roaster into mains power
- Using a short length (12" or so is plenty) of light gauge wire (like bell wire), create a jumper to temporarily short the BLACK wire to the ORANGE wire on the connector of the ribbon cable. This should cause the ejection door to open. If it does open, manipulate the ribbon cable to be sure it is not a damaged wire in the cable itself causing an intermittent open condition. The full list of possible activities that can be actuated in this manner are:

BLACK --> ORANGE = Eject Solenoid
BLACK --> YELLOW = Bean agitation Motor
BLACK --> GREEN = Main Motor
BLACK --> RED = Fans at 100% speed

If all those operate then the main circuit board is very likely OK and the control panel is the likely problem. The actual nature of that problem is beyond my scope of expertise.

Life's too short to drink bad coffee.
 
drllama
Thanks Randy,

This weekend was a write-off, but I'm going to get the cleaner you recommended for next weekend and then thorough cleaning, reassembly, see what happens.

If nothing obvious comes to light, I suspect I'll be availing myself of HotTop's Refurb service so it's looked at by people who know what they're doing (rather than trying to fully troubleshoot it myself).

Cheers,
Bruce.
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Started with FreshRoast+, moved through a Cafe Rosto, two Alpenroasts, iRoast, managed to set a Behmor on fire, a couple of GeneCafes and now my shiny new Hottop
 
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