mountainguy Posted February 19 Report Share Posted February 19 (edited) Certa 780 with 2 pumps... Woke up one to day to find no power to the hot tub (display is dark). Breaker was not tripped. Turned it off and opened the control board box to find the two black wires going from the outside power connector(TB1) to J8 and the SC-30 fuse melted and burned out right after the connector. Shockingly the fuse appears good - could not test under load but tested continuity with fuse removed. After the shock that 2 10ga wires managed to melt and burn without tripping the breaker or the SC-30 fuse wore off, I looked at the board more closely and do not see any other obvious/visible damage. Looking at the circuit diagram, it appears the wire from TB1 to J8 is bypassing the fuse - am I looking at this wrong? Leads me to think that the problem was on that side of the wiring... What is J8 powering? Outside of the control panel box, I see the flow sensor was likely dripping as it is right over one of the pumps and I see some corrosion on the box where the power goes into the pump assembly. I wonder if the pump shorted and led to the short in the panel box. Apart from the idiotic design decision to place the pump power box right under the flow switch, the other ridiculous thing is that right about a year ago we had a problem with the flow switch and I thought of replacing it myself but since we were just inside the 5yr warranty we called the authorized dealer to repair under warranty and it appears they did not screw the flow switch tight and it was dripping... Just blows my mind to think about the lack of attention or competence... Anyways, I am wondering where to event start with this thing now...Should I even bother replacing the two burned wires? It is hard to imagine that these wires melted without damaging the board? Since I probably have some wire laying around in my work shop, I am wondering if it is worth disconnecting the power from the pump, replacing the two burned wires at the control panel, and powering up to see if anything is still operational. Any help is greatly appreciated! Edited February 20 by mountainguy fixed pictures Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted February 19 Report Share Posted February 19 no pics Quote Link to comment Share on other sites More sharing options...
mountainguy Posted February 20 Author Report Share Posted February 20 my bad, fixed the pictures - thanks for letting me know Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted February 20 Report Share Posted February 20 I would be pulling the board and having a look on the back for damage. Only takes a few minutes to remove. Cleaning and Re-doing any damaged wires. Can't really see what's going on on the left side where the incoming power is. Looking at where the wires that burnt connect I can see some pitting and corrosion. Test the blue snubber for continuity and make sure it was not also damaged. 15 hours ago, mountainguy said: it appears the wire from TB1 to J8 is bypassing the fuse - am I looking at this wrong? Leads me to think that the problem was on that side of the wiring... What is J8 powering? J8 is sending power to the heater relays. Power goes into the relay above J8 and then comes out to the heater connections next to J8 (J10 I think). Check the back of the board, make new wires, Inspect and clean up everything else. Test the snubber and then see what happens. Would also remove the back cover of the pump motor and check to see if the water dripping has corroded any wires going to the pump. Post pics so we can see the entire board and also the schematic on the inside cover Quote Link to comment Share on other sites More sharing options...
mountainguy Posted February 20 Author Report Share Posted February 20 Thanks for the reply - posting a few more pics here... In looking further at pics I think you are exactly right about J8 - it looks to be heater in. At least that might mean the water pump MAY not have been the culprit. The incoming power wires can be seen on one of the pics below - the black is burnt a bit from the fire on the other side, I will cut a few inches and strip fresh wire. I have plenty of length available. Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted February 20 Report Share Posted February 20 8 minutes ago, mountainguy said: At least that might mean the water pump MAY not have been the culprit. If the screw holding the incoming power wires are not tight they can arc. The screw has to compress the copper strand and can loosen over time if it wasn't cranked down on install. Is one possibility. Any recent power outs/surge? Quote Link to comment Share on other sites More sharing options...
mountainguy Posted February 21 Author Report Share Posted February 21 nothing that was notable enough to remember. I was also thinking whether this could have been a defect with the black wires, you scenario of possible screw loosing over time fits the bill. I will check the tightness of the screw when i get to the tub again but it may be welded from the short so not sure if that will give me a definitive answer. What blows my mind still is that two 10ga wires melted together and burned off and that did not trip the breaker or blow the fuse on the control panel. It seems to me that the protections that are supposed to catch that sort of thing are not really working... Quote Link to comment Share on other sites More sharing options...
mountainguy Posted March 8 Author Report Share Posted March 8 Hi folks, just a quick note that i have not forgotten about this thread but was not at the location of the hot tub for a while. I hope to be able to replace the burnt wires this weekend, weather permitting, and will update after that... Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted March 9 Report Share Posted March 9 On 2/20/2024 at 8:24 PM, mountainguy said: did not trip the breaker I am no where near being an electrician but would guess that it was not a ground fault issue causing the breaker to trip like when water and electricity come together. Replace the blue snubber where the incoming power wires are. Google... Electrical snubber Snubbers are frequently used in electrical systems with an inductive load where the sudden interruption of current flow leads to a large counter-electromotive force: a rise in voltage across the current switching device that opposes the change in current, in accordance with Faraday's law. @mountainguy See this post... https://www.poolspaforum.com/forum/index.php?/topic/52358-2015-jacuzzi-j365-circuit-board-question/ Quote Link to comment Share on other sites More sharing options...
mountainguy Posted April 15 Author Report Share Posted April 15 Thank you CanadianSpaTech - the thread you referenced seems to be covering the same or very similar problem that I am dealing with... apparently is not an isolated incident. After much delay I finally was able to get to the hot tub this weekend and did some further dismantling/trouble shooting: - Removed and inspected the board - looks fine to me and I did not see any obvious shorts/issues/damage. Pics attached, let me know if you see anything that looks unusual or problematic - Removed the snubber - looks ok visibly but based on testing per YouTube instructions it appears to be blown. I was planning to replace it anyways because it does not pass my smell test - I had a short that melted 10ga wire at the same spot where the snubber was attached... no way in my book it is still good. I will try to source one from the thread in the post above, hopefully they still have 'em. - The wire terminal/connector where the main power line connects to the board is bad due to the short. Not sure if you can see well from the pics below but the terminal is a two piece design with a rivet. I presume when the short occurred, the plastic attachment point on the terminal body melted and allowed the 2 metal pieces to come apart a bit... or it could be that that attachment point was loose and actually caused the short. Anyways, it is bad and need replacing - any ideas if that part is available to purchase or do I need to get a generic terminal piece? - Lastly, I also checked the pump where the flow sensor was dripping - under the cover everything looked fine so it appears the only damage is on the outside. I plan on disconnecting that pump when I first turn on the hot tub after i repair it, just in case. If anyone has a suggestion on sourcing a terminal replacement please let me know - the part number is GP GPT53000021 but my initial search is coming up empty for that number... As always - thank you very much for your help! Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted April 15 Report Share Posted April 15 See page 32 here for both the blue snubber(Varistor) and the terminal block: https://www.guillens.com/images/JAC/Pdf/JPS/2014-1 Parts Catalog.pdf Quote Link to comment Share on other sites More sharing options...
mountainguy Posted April 15 Author Report Share Posted April 15 perfect, thank you! Ordering now... 1 Quote Link to comment Share on other sites More sharing options...
mountainguy Posted April 26 Author Report Share Posted April 26 Partial progress... replaced the terminal block, snubber and the burned wires today and fired it up. The display turned on, both pumps work... Thank you CanadianSpaTech for your help to get me running again! Now, the partial part - I have a FL1 error on the display and the heater does not turn on. All I had time to do was clean the filter, which did not help... will do some more trouble shooting and will try to purge air over the weekend. I only know FL1 is switch stuck open or dirty filter/air pocket so need to research a little more. 1 Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted April 26 Report Share Posted April 26 Ensure the circ or heating/filtering related pump is running and has good flow. Check the flow switch housing and ensure that the toggle is pushed up against the post and making contact. Sometimes holding a flashlight behind the housing will make it easier to see. If it is making contact with the post but you have the flo error still then try and jumper the 2 flow switch wires together and bypass the switch. I recommend disconnecting the heater to do this test so if there is a flow related issue the heater does not engage and quickly overheat/melt down. The flow switch protects the heater from firing when there is not enough flow. If you jump the wires and the flo goes away replace flow switch. Quote Link to comment Share on other sites More sharing options...
mountainguy Posted April 26 Author Report Share Posted April 26 Thank you for the great trouble shooting guidance. I will do that over the weekend. The circ pump seems to be working and I suspect it is the flow switch but will see how it turns out... Thanks! 1 Quote Link to comment Share on other sites More sharing options...
mountainguy Posted April 27 Author Report Share Posted April 27 Fixed... everything works now. The FL1 was a problem of my own making - when I originally opened the tub a couple of months ago i was so angry with the leaking flow switch that was "professionally" repaired that i tightened it by hand 1/4 turn and screwed the direction of the flapper thingy. I figured this out even before opening the hot tub, I remembered that episode when i went to pick up some plumber tape to redo the switch. The "professionals" had used just a couple of turns of thin tape and it was not working...(random thought - HF has MUCH better tape than HD, it is much thicker). So I removed the flow switch, re-taped it and put it back on, pointing in the correct direction. FL1 is gone, heater working, etc. I will let it run for 48 hrs and then do a deep clean with Ahhsome and replace the water. CanadianSpaTech - I cannot thank you enough for your help and advice... I really appreciate it! 1 Quote Link to comment Share on other sites More sharing options...
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