Hottop B control panel failed

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
paul49
Posts: 5
Joined: 12 years ago

#1: Post by paul49 »

Hi All,

My Hottop B (4 years old) has developed a fault which I presume is in the control panel. Yesterday, it ejected the beans (with no input from me) about 5 minutes into the roast. Today after the preheat period, it beeped once, turned off the heater and only responded to the Power button.

Replacement panels are over $200 here in Australia.

The Hottop already has a thermocouple in the bean chamber connected to a PC so I don't need to worry about that side of things. I've been a programmer for a very long time, have a drawer full of various kinds of Arduinos and AVRs and plenty of experience writing robotics/interfacing software. I've been thinking of "doing my own thing" with the Hottop for some time, and I guess that this has forced me to get serious.

A couple of years ago, I remember seeing an explanation of the function of the connections on the main board but I can't seem to find it any more. The Hottop website has a photo showing which connection does what but it doesn't explain how the fan speed and heater settings are controlled or how to drive the connections electrically.

Can anyone point me to some information to allow me to get started?

Thanks,
Paul.

paul49 (original poster)
Posts: 5
Joined: 12 years ago

#2: Post by paul49 (original poster) »

Now that I've calmed down a little from the shock of my impending lack of roasted beans, an educated guess would be that the control panel uses PWM to control fan and motor speed and just possibly also the heater?

AngerManagement
Posts: 167
Joined: 18 years ago

#3: Post by AngerManagement »

Paul

I fixed one for a mate the other day... He now has the original LCD display / control board back in and has a spare LCD and control board; as he purchased a replacement and now finds he does not need it after my work and service on his system.....

What is the exact model of yours; as it could be a number of things...

PM me with you details and after some off the record chats; maybe we can update all on how it progresses..

Mark
Ability is nothing without opportunity. - Napoleon Bonaparte

rgrosz
Posts: 331
Joined: 14 years ago

#4: Post by rgrosz »

Jim Galt has the hardware available to actually control the HotTop via an arduino (HTSHIELD, plus a TC4 shield):
http://www.mlgp-llc.com/htri/index.html

I ordered mine a few weeks ago, but haven't set it up yet. If you want more information on how the HotTop is controlled, check these pages:
http://www.homeroasters.org/php/forum/v ... rum_id=133
http://artisan-roasterscope.blogspot.co ... ottop.html
http://homepage.ntlworld.com/green_bean ... -ctrl.html
LMWDP #556
Life is too short to drink bad wine - or bad coffee

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rama
Posts: 344
Joined: 15 years ago

#5: Post by rama »

If the panel works fine at the start of a roast, there's a good change its not the panel that's at fault.

Before you start replacing expensive parts, reach out to Hottop support. They are very responsive and helpful in debugging these sorts of situations.

JimG
Posts: 659
Joined: 18 years ago

#6: Post by JimG »

Two things to add to previous comments:
  • The HTRI boards (HTC or HTShield) supplement the OEM board and only control the fan and heater. You still need a properly functioning OEM control board and power board.
  • Just for grins, disconnect the rear fan and see if the problems resolve. Lately I've been hearing of odd behaviors that are in some way related to the fan.
Jim

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Randy G.
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#7: Post by Randy G. »

JimG wrote:Two things to add to previous comments:
  • Just for grins, disconnect the rear fan and see if the problems resolve. Lately I've been hearing of odd behaviors that are in some way related to the fan.
Jim
+1
Also:
- a good main filter
- check all connections on main board
EspressoMyEspresso.com - 2000-2023 - a good run, its time is done

paul49 (original poster)
Posts: 5
Joined: 12 years ago

#8: Post by paul49 (original poster) »

Thanks very much everyone for your fast responses. Plenty to think about.

I replaced the main filter and selected Ad3 instead of Ad1 which I normally use. (Just for something to try. I've never saved a profile - just control it manually). I loaded a batch of Robusta to save risking any "good" beans and it worked normally. Oh well. I might even grind some up and see what 100% Robusta tastes like.

Since my gut feeling tells me that it isn't really magically cured, I'll pull it down and give all the contacts a good clean with DeOxit, as per your suggestion, Randy. It's a pretty harsh environment for electronics so it could stand some TLC. While I'm in there, I'll get out the multimeter and 'scope and see how the panel talks to the main board so I can emulate it if need be.

Thanks for all the links to good information.

Mark, Thanks for your kind offer. If all else fails, I'll be in touch.

Paul.

AngerManagement
Posts: 167
Joined: 18 years ago

#9: Post by AngerManagement »

I could upload a photo but not so clear....

If you remove the LCD / front panel - give it a good clean and use a spray can of Air to make sure there is no crap caught in the pins to the LCD.

1: Have pics of one where there was so much chaff and oil build up that it was causing led segments to fail and other strange behaviours.

2: Also use a the air can to clean the main power board and a 15mm wide paint brush (I usually chop a bit off the bristles so that it is a tad stiffer) to also make sure any loose or possible electrical tracking is removed.

I do have special board cleaners that I use (with caution) and then usually after testing and all OK; then apply a couple of coats of a heavy duty electrical cct board lacquer. While these boards tend not to have high impedance input FET's, I still find that being able to restrict any chance of stray signals is worthwhile.

In particular where there are the chance of oils or moisture ingress...
Ability is nothing without opportunity. - Napoleon Bonaparte

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drgary
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#10: Post by drgary »

paul49 wrote: I might even grind some up and see what 100% Robusta tastes like.
I'm told better Robustas can taste okay but you'll be slamming so much caffeine you'll look like this all night... :shock:
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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