This is a faulty Honeywell heating controller sent by Dr Pipe, who's channel is linked below.
It's exhibiting a common fault with these units where they keep resetting, preventing the heating systems from running.
The usual fix is to swap the entire front unit or replace it with a new controller, but as with many of these devices, the fault can usually be fixed by replacing one or two components.
For a professional heating engineer where time is money, it's going to be faster and easier just to swap the unit. But if you have one of these in your own home then it's viable to fix it yourself, either by loosening the two screws at the bottom of the unit and plugging in a new one or doing a small repair on the PCB.
Be aware that when the unit is lifted off its backplate there are exposed live connections. Turn the heating system off completely and always assume that contacts are live until proven otherwise.
Here's Dr Pipe's channel:-
https://www.youtube.com/channel/UC0hk5bxzJjD_vyA5qHs93uQ
I'll probably make another short video showing just the fix on its own. I tried desoldering the faulty surface mount capacitors, but even by SMD standards they are not easy to remove. They're not glued, but the solder connections extend underneath for far enough that it would require heat on both pins simultaneously to remove. There are also other smaller surface mount components in close vicinity that make hot air removal harder. They're probably best left in place, as attempting to remove them can easily result in track damage.
The easiest fix is to add a standard through-hole 47uF 63V capacitor to the spare SMD capacitor position closest to the dropper capacitor, and laid flat over both the capacitor positions.
I'll also test the dropper capacitor to see how low the value can go before it causes excessive voltage drop off. The dropper capacitor value can be tested in circuit due to its position in the circuitry. Despite its age, this one had held its value very well.
This unit was old enough to have very brittle plastic. Be careful when separating the back from it. There are four clips that can be gently released with a thin screwdriver. Using excessive force may snap them off and prevent the unit being reinstalled in a safe manner.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
It's exhibiting a common fault with these units where they keep resetting, preventing the heating systems from running.
The usual fix is to swap the entire front unit or replace it with a new controller, but as with many of these devices, the fault can usually be fixed by replacing one or two components.
For a professional heating engineer where time is money, it's going to be faster and easier just to swap the unit. But if you have one of these in your own home then it's viable to fix it yourself, either by loosening the two screws at the bottom of the unit and plugging in a new one or doing a small repair on the PCB.
Be aware that when the unit is lifted off its backplate there are exposed live connections. Turn the heating system off completely and always assume that contacts are live until proven otherwise.
Here's Dr Pipe's channel:-
https://www.youtube.com/channel/UC0hk5bxzJjD_vyA5qHs93uQ
I'll probably make another short video showing just the fix on its own. I tried desoldering the faulty surface mount capacitors, but even by SMD standards they are not easy to remove. They're not glued, but the solder connections extend underneath for far enough that it would require heat on both pins simultaneously to remove. There are also other smaller surface mount components in close vicinity that make hot air removal harder. They're probably best left in place, as attempting to remove them can easily result in track damage.
The easiest fix is to add a standard through-hole 47uF 63V capacitor to the spare SMD capacitor position closest to the dropper capacitor, and laid flat over both the capacitor positions.
I'll also test the dropper capacitor to see how low the value can go before it causes excessive voltage drop off. The dropper capacitor value can be tested in circuit due to its position in the circuitry. Despite its age, this one had held its value very well.
This unit was old enough to have very brittle plastic. Be careful when separating the back from it. There are four clips that can be gently released with a thin screwdriver. Using excessive force may snap them off and prevent the unit being reinstalled in a safe manner.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
Useful. I don't know why everyone uses toasters though…seems a bit extreme to me. I've just fixed for 2nd time using a hair dryer. Give it a good 10 min on full heat (screen goes darker) and full lcd function obtained.
Hi all, can someone please answer this question. If you remove the control unit from the back plate will the boiler still work as the controller perhaps only controls off and on etc. We have a problem where although the control unit says off the boiler is still operating and heating the radiators, also in auto mode when the should be clearly off due to the time the boiler also still stays on?
Thanks for posting, add the small capacitor and all working
Thanks for your many really instructive videos. I saw very similar on-off symptoms with our earlier version of the same type of Honeywell heating controller. (Ours has a NiMH battery and a smaller display.) A check of AC ripple on the 47uF 63V smoothing capacitor showed approximately 12V. In this earlier version of the board there is a single through-hole capacitor, which was easy to replace temporarily with a 100uF 100V component salvaged from a dead compact fluorescent bulb. Although larger the capacitor fitted in the case. The controller is now working fine and I have ordered a replacement capacitor of the original type.
Why not fit new capacitors, put wet paint on top, fit back, mark paint spots and drill a hole for each?
Great video thanks. What is the value of capacitor I need to add? 63V and 100uF?
My brother had the same issue with his unit. I ended up laying the radial caps with a tack of hot glue next to the 680uf to the left and shrink tubed small diameter wire over to the connections and it is still working today. These are poopular controllers, but they use inferior components. The only difference between what I did and you, I removed the 2 defective caps. Nice job sir!
Thanks for the video. I have a nice Honeywell with wireless remote T-stat. It has the same symptoms. Maybe there's hope !
I hate surface mount electrolytics. I would just kluge in some polymer caps in a 7343 package
Interesting and educational as always BCDC 👍
Interesting, i had this exact type of controller with the same fault when i moved into my flat
Oh wow, I've got one of these! Maybe I should be concerned…
Worked for me. Sourced a capacitor from a broken tv. I could only find 50v 47 micro farad but it’s going good up to now. Thanks for the advice.
Hi Clive, what component tester would you suggest for a novice getting into simple electronic circuits?
Flavor for the last 600 months. These things are prolific in the states.