Hi @jolugo, sorry you’ve had such an unfortunate experience with your power supply, 220V has quite a punch doesn’t it?
Since you seem to have access to an ac volt meter, I would check the voltage between SC and SP terminals while using the AC to AC transformer (with unit misbehaving). I would also test a DC voltage between the same terminals.
If you are getting only half your expected AC voltage on these terminals and there is some DC voltage on the meter, then you may have an issue with a bridge rectifier and would need to send the unit in for repair (or take it apart and repair it yourself).
Cheers,
Gene
P.S. In case you are using Gen 1 controller, thus missing “SC / SP” terminals, you should measure the AC voltage between the Right White Common Terminal and the Top most Yellow sensor terminal (not the one immediately adjacent to the right white terminal).
This is probably tempting fate but I’m in the UK using a 240v to 24v 50hz 1.0A AC transformer on my gen2 unit with no problems. Originally I looked into using the original 110/24 transformer and just adding a 240/110 converter but what was available for sale seemed to be advertised with caveats saying that they should only be used for short periods at a time (I guess they were meant for electric shavers etc) which clearly would not be suitable to be plugged into a rachio which needs 24/7 supply. Implication was that long term use could cause the transformer to blow (and the resulting transients could fry rachio circuits).
Do you by any chance have a model number of the AC supply your are using? Seems like it has some sort of protection circuit / current limiter, maybe it is just underrated.
I would like to ask you to take a picture showing the Rocchio’s original power jack’s inner opening next to the one you are using. It is possible that the inner hole of the power jack (into which you have inserted the black meter probe on the first picture) is not making a good contact with the Rachio’s socket (it may be too large). According to @franz’s post (link), the inner diameter of the power plug should be 2.1mm.
Good point regarding the transformer,I just read the the information about the transformer and its designed for internment service like door bells, albeit when I connect directly to the water pump solenoid they work perfectly.
Transfomer
I am using the original rachio jack, Have cut it out of the poor toasted transformer.
40VA = 1.67A @ 24VAC which should be more than enough for Rachio’s 1A requirement.
Original plug is also a good move. Since you have already “spliced” the original plug onto the new transformer, I would like to ask you to disconnect one of the leads between the transformer and the plug into rachio and measure the current by switching the meter to 10A first (and lower if the Amp draw is not too large) and placing the meter in series with one of the leads.
You can also try connecting the transformer directly to the SC / SP terminals (bypassing the original power plug).
Thanks,
Gene
P.S. By the way what do you mean by “water pump solenoid”? Are you talking about a power replay for the water pump or a water solenoid for one of the zones?
I guess this thread can now be a caution story, and it seems whatever protection Rachio put on the power socket is working even when the unit is otherwise inoperational. rachio
I was hoping that at the end the issue would be with the transformer and/or something minor on the power side, it should not have normally blown up with connection to SC / SP terminals.
Keep us updated if Rachio will be unable to do anything for you (they are usually pretty great at supporting their customers in unfortunate circumstances). If you take the unit apart and take some post mortem pictures, maybe it can still be repaired (if you are willing to use a soldering iron).
Is there any damage visible on the back side? From the initial observation it seems that the “new” damage is limited to a ferrite bead (which is a filter, something like this). Looks like it couldn’t handle the load and melted / exploded.
The good news is that it’s a cheap part (less than a $1) and if you don’t plan to use SC / SP terminals any time soon, you could simply remove it with a soldering iron in order to get back to where things were this morning.
As far as the rest of the circuit, MV10 (which is probably a MOV, overvoltage protector) near the power plug, seems a bit suspicious (not sure what the smudge on top of it is). Would be nice if you could take a close up picture of this part.
An overvoltage could have caused it to degrade and start conducting at lower voltages, or it is possible that 30V AC supply is simply too high to begin with (maybe someone from Rachio could clarify what these MOVs are rated for).
The more I think about it, the more it’s becoming apparent that 30V AC should be considered an overvoltage for this design. MOVs are probably rated for something like 25VAC (like these), which equates to about 35V at the peak voltage. 30V AC on the other hand has a peak voltage of 42V+. If the MOVs on the rachio are anything close to being rated for 25VAC, they would pretty much short anything over 39V.
Well, the good news is that the main capacitors (C8 and C9) are rated for 50V, so 30VAC supply should be within the Rachio’s tolerance. Without knowing what the other MOVs (MV9 through MV18) are rated for you may need to replace them all in order to guarantee that 30V supply will not trigger them all.
If this is the case, MOVs are rated at less than 30V. and it would be a good idea to replace all of them.
From the looks of it, the size of MOVs are 1210, in which case 30V mov would be this one (link), I would not go higher due to 50V rating of the capacitors.
Size of the ferrite bead is harder to judge, it is probably either 0603 or 0805. 0603 is a safer bet and should fit into 0805 footprint as well if need be. In this case this (link) would be one of the acceptable parts.
If you are using less than 8 zones, you could try moving one of the good MOVs to replace the damaged one.
For example Moving MV11 over to replace MV10 would remove the surge protection from zone 8, not an issue if you are not using that zone.
Alternative to buying a ferrite bead filter, is to simply remove the damaged FB1 part and shorting the footprint with a piece of wire. SC / SP terminals will work again for majority of possible needs.
So, in summary, you may need to buy these (or similar) parts:
10 of these: 399-13766-1-ND (to upgrade MOVs to 30V to work with your supply)
2 of these: 1276-6387-1-ND (to replace the damaged filter on SP terminal)
Oups…
rachio 
