No power on Jandy LX400 Heater

[rsabouri]

I have no power to my Jandy LX400 heater. had a pool technician come over to tell me that my heater needed to be replaced and he quote me $4000 but he also told me he thinks the Power distribution board is burned out and my issue could also be a the transformer. I ordered a new power distribution board and before I install it I made sure the board is set for 240v since incoming power is 240v. as soon as I turned on the pump the board blew up. any idea what might be the issue here? red and black connectors on the board shows 240v . Should I replace transformer along with the power dist board?
Thanks for your feedback.

 

[ajw22]

Welcome to TFP.

Shotgunning replacing parts is never a good diagnostic technique.

Do you have a multimeter? You check the voltage output on the transformer?

See page 14 in https://www.fwwebb.com/docs/gas/JandyPoolHeaterTroubleshootingGuides.pdf

Is there a history to this heater? Transformers and boards don’t usually fail. Has the inside of the heater been visited and chewed on by rats?

Post pics of the inside of the heater.

@swamprat69 may have ideas.

 

[swamprat69]

Photos of the individual electrical components and overall photos of the of the electrical components would be helpful. Especially of the part which was burnt as I do not see a separate power distribution board in the manual, but only a power terminal block with a 15 pin connector in and distribution out to electrical components. Burning out of any power component is usually an indication of a direct short or a short to ground of one of the components or the wiring. A multimeter and some knowledge of troubleshooting is needed to isolate the cause of the problem ( other than labeling and disconnecting components and then reconnecting one at a time in the order of the sequence of operation until it burns out again). Knowing the sequence of operation would also be very helpful. This seems to be the manual for your heater? https://edc.poolsupplyworld.com/wpdf/jandylxltpoolheater-manual.pdf Would be able to help more with addtional information

 

[rsabouri]

@swamprat69, Thanks for your reply. yes I have a multimeter and have checked input voltage to the PDB which showed 240v. Should I check the output voltage from the PDB to the transformer (blue and white cables) or output from transformer (red and yellow cables, see attached diagram. an no, there're no sign of any cables been showed.... no prior issues with is heater and it is been working fine until now. adding photos of the heater. PDB is to the right with burn mark visible

 

[ajw22]

@setsailsoon Just want to call your attention to this thread since I know you have been inside the Jandy heaters.

 

[swamprat69]

I am obviously looking at the wrong wiring diagram (LX, not LXi Pro). You do appear to have a separate power distribution board that seems to conform to a Jandy/Zodiac LXi Pro like this Jandy | LXi Heater Your 120/240 V card will vary the distribution to the line voltage components ( Transformer, Blower and Hot Surface Ignitor ). You should check to make sure that the power distribution board 3 and 5 pin connectors (transformer and blower) are not damaged and make a good connection. You can check that the line voltage loads (Transformer, Blower and Ignitor) have resistance wire to wire (not 0 ohms) and also do not show 0 ohms from any wire to case ground. I can't see the tracing on the back of the power distribution board, but it appears that it has blown across the blower tracing or possibly the transformer tracing.

 

[swamprat69]

Power distribution board date code seems to indicate mid 2006 or about 15 years old.

 

[rsabouri]

the PDB shows burn marks on Transformer tracing. This is a new board I just installed but my heater is about 8 years old. checked the connections to both transformer and blower and they are good. Does PDB provides power to the transformer though D,E,F (Blue,White,Black) connectors, right? so PDB sends 240 v to the transformer, correct? or is that incoming voltage to the PDB from transformer?

 

[swamprat69]

Yes, power to transformer from PDB through blue, white and black. Does transformer show a positive resistance (ohms) from blue to white, blue to black and black to white (not 0 ohms or infinite ohms {open})? Also does it show infinite resistance ( not 0 or a positive number... no continuity) from blue, black and white to case ground? Transformer takes line voltage 120/240 and steps it down to 24V for control voltage. Transformer primary (120/240) is not fused separately, transformer secondary (24V) has one leg grounded and second leg fused.

 

[swamprat69]

PDP seems to be burnt out from the L2 connection across the board. May not necessarily be the transformer. Should also check ohms for blower motor just like transformer ( wire to wire and also each wire to case ground ). Readings that you get when checking continuity would help.

 

[setsailsoon]

r,

Sounds like you definitely have a dead short to ground on the 240 v side. Can you tell us anything unusual that may have happened when it just stopped working? Did the breaker trip? Did you have a lightning storm recently? There are only 3 components that use high voltage. They actually are 110 v that come from the transformer. Seems the transformer uses a floating neutral that is obtained from the 240 connection to the primary when you set the board to 240v. The 110v devices are the igniter, blower motor, and the transformer itself. 110v is also passed through the Fenwal when conditions call for ignition. Everything else is powered by 24vac including the display. I would check the power connector to each of the 110 v devices and check for a dead short or a short to ground. If this is the case for any of these it would probably blow the PDB. The only other way to do this I can think of is the dumb mistake I made. I left the electrical raceway out and exposed during a brief down pour and threw a tarp over it that had collected water. The pdb popped immediately and violently. The igniter doesn't get power until over a minute after you start the unit and all the safety tests are successful so it's not likely. You should also be able to make a 110v jumper to the blower to test it independently. Before doing this does the blower rotate freely? A small twig or something could jam the motor which would cause the unit to trip but not cause the panel to be dead. There's a small glass fuse on the secondary side of the transformer that's very sensitive. Unfortunately in my case the fuse didn't blow at the right level so it burned up the transformer. This is all secondary to the high voltage problem you have but once you find the high voltage problem you may find something shorted in the 24vac circuit.

@swamprat69 is a real expert on this stuff. I'm just an OP that had the heater fried by a severe lightning strike, then fixed that (very frustrating when I learned all about flame sense control) and then fried it again myself with the rain event after initial repairs. In the process I literally took everything apart and learned a lot with a LOT of help from swamprat. The good news is that persistence pays off if you approach with logical diagnostics instead of random replacement. A dead short shouldn't be that hard to find. In my case the lightning strike did a lot of damage and I did even more with my dumb water dump move but I was still able to fix it for under $1000. Less than half the price of a new unit and a quarter the cost of a professional installation. That was a couple years ago and my heater is still going strong on its 8th year.

I hope this helps.

Chris