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  1. #1
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    Robertshaw 300-225 battery replacement

    Ok, I know the Robertshaw 300-225 doesn't use a battery but it has some way of storing energy to save the time when the power is disconnected. The circuit board looks like a pretty basic design but I'm still quite new to electronics and I'm still learning to determine the purpose of specific components, I'm getting there but it's still just a hobby for me so my progress is hindered by life's other obligations. I'm wondering if anyone has determined exactly what component is being used to store the energy? I wouldn't mind trying my hand at soldering on some new components if someone here has an idea as to what component it Is that would be required.

    This is more or less a curiosity thing and a personal interest thing because I see a bunch of these thermostats fail in this manor and I'm really curious what it would actually take to get it going again. It would also give me more practice with my soldering, which I'm always looking for an excuse to do. It is a marrage of two interests




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  2. #2
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    Prolly uses a capacitor to power the flash memory. Finding which capacitor is the tricky part!

  3. #3
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    Thread Starter
    That's my assumption. I'm guessing I'll be pulling each one off and replacing them individually until I see the results I'm expecting. It's so far beyond what we do in this trade that I suspect it's a bit of a reach to find an answer on this here, but you never know what people's interests are until you ask, and who knows perhaps someone has tried this before...


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  4. #4
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    These days, boards are replaced rather than a repair attempted. When it comes down to the numbers, its cheaper to replace.

    I recently helped a friend with his home furnace. Board failed, factory replacement $150....generic replacement $55.00. For $55, theres no way its worth my time to Troubleshoot and repair a PCB.

    A few years ago, I had to assist troubleshooting a several thousand volt motor starter. I was only helping on the control voltage side. (Less than 600v). We got to the point of testing diodes on a control board. I remember talking to one of the 30+ year electricians. He said, Ive forgotten all that stuff.....these days its voltage in voltage out....no voltage out, the board is bad.

    I applaud you for wanting to learn that side....I really do....but the nowledge gained may or may not be applied to real world scenarios. The question is....how much geek do you want to apply on something that you may never use?.....when there are much more applicable things to fill the Grey matter with....

  5. #5
    Join Date
    Dec 2006
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    Thread Starter

    Robertshaw 300-225 battery replacement

    Quote Originally Posted by 71CHOPS View Post

    I applaud you for wanting to learn that side....I really do....but the nowledge gained may or may not be applied to real world scenarios. The question is....how much geek do you want to apply on something that you may never use?.....when there are much more applicable things to fill the Grey matter with....
    Ive built boards and assembled controllers to control my Christmas lights to synchronize them to music so this is right up there with my other interests. Similar to your experiences though, there was one time that I looked into having an obsolete board repaired but in the end we just ripped out all the controls and built a new controller box controlled by DDC rather than this obsolete companies original controllers. It works better now than it ever did so the additional money the customer had to pay for the upgrade was well worth it for them and they are happy they didn't end up having us send the board off for repair. I wouldn't waste my time on a thermostat for a customer it wouldn't be worth the money. I'm more curious about figuring out their design because I didn't think those small capacitors would be sufficient to maintain the clock circuit and the display for at least 2 hours.

    Although taking an electronics course would be great I unfortunately don't have the time to put aside for that so little projects like this is the next best thing. Unfortunately I don't need any more controllers for my lights otherwise I would just keep building those... Or could I use more... Well Maybe, but if I do that then I'm changing my whole setup to a different type of light and I'm not able to make controllers to control the lights that I eventually want to work towards.


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    Last edited by thatguy; 10-10-2018 at 10:16 PM.
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