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MAS25 Lite Leader displaying Sn


Venomous Duck
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Ok, I have a Down East Spa Bar Harbor. Paperwork says it is a 2000 model but manufacture date on the control pack and serial numbers point to 1999. Anyway, it had a Balboa MAS25 Rev 1A, v/n 51999, model X300960, control board with a 2 button control panel. I had a heater relay stick and scorch the board beyond repair. The 51999 is no longer available and was replaced with the 52000. The standard 52000 is no longer available and was replaced with the 52000 Lite Leader. After installing and chasing down revised wiring diagrams I got it installed. After install, the top side controls did not work, couldn't change speeds, lights, or temp setting. It only showed temp and that it was heating, with low pump running with the heater. I figured I would let it go and heat up as the temps were supposed to get below freezing and deal with the top side later. I went out in the AM and it was shut down displaying OH (overheating). I reset the breaker and it ran through the standard blinking 0 a few seconds, then flashed 99 and went to Sn. The owners manual just states Sn means either hi limit or water temp sensor malfunctioning. Balboa manuals says Sn means sensors are more than 2 degrees out of sync, or one or both are bad. I tested the sensors and they are within 2 degrees of each other, and that is with the hi limit sensor put in the tub right next to the water temp sensor after a few hours. I plan on ordering new sensors since they are fairly cheap and are almost 20 years old. Any ideas other than the top side may not be compatible with the new board (although I tried it with the old MAS25 rev 1A chip in it with the same results)? I am considering jumping the sensor plugs with a couple of 22K resistors to trick the board into thinking it is at 46 degrees and see if it will start up so I can trouble shoot the top side.

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The fact that you got an SN error, added to the fact that your sensors are 20 years old, would certainly point to a need for new sensors.

The OH error usually points to a water flow problem.   If the tub was recently drained and refilled before the problem occurred, it could be an airlock restricting water flow.  It could also be dirty filters (take them out and see if that helps).  It could be a mechanical problem with the pump like a broken impeller or something stuck in the wet end.  If the OH was due to a flow problem, when you turn the spa on, you'd hear water boiling in the heater can and it would be too hot to touch.

If the  heater can is not hot when you get the OH error, than it's either a sensor or circuit board problem.  I think ordering sensors is the best means to troubleshoot the problem.

Your topside is probably either incompatible or not working properly.  If you start up a Balboa system without a topside, it will usually default to Standard Mode, 80 degrees.  If you need to get a new spaside, obviously make sure it's compatible with your new circuit board.

For the future, it's often less expensive to replace the entire pack with a Retrokit than to replace a circuit board.

Dave

 

 

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Thanks for the response Jersey. I located the problem. When I installed the new board it was initially working but the heater was popping the breaker and when investigating I noticed the wiring was quite warm so I put in all new wiring and upped the gauge. The larger gauge wires were not quite fitting right in the two hot junctions where two wires were coming out. That apparently was causing the board to get some funky voltages and interfering with it. Got it taken care of today as well as putting in a new transformer since the other one was a tad heat damaged. That and the wiring diagram the parts place sent was wrong. I ended up finding the right diagram buried on balboas web site. When I first fired it up it was taking for ever to get to temp but seems to be holding temp fine now. Also at first I kicked the pump up to high like I usually do to help build up heat when first filled and it tripped the breaker after about 15 minutes. I haven't ran high yet again to test it but probably will tonight.

I also had suspected flow problems too so removed the filter, and the impeller was replaced 3 months ago. Top side control problem turned out to be the jet button is just getting to be fickle, probably time for a new top side soon, I have one lying around but it is 6 wire instead of 7 and apparently not compatible as all it does is cycle set temp up to max, then back to min then repeat without touching anything.

I considered doing a retrofit pack. They were around $400, I picked up the board for $180. Of course if I end up replacing the topside down the road I will end up right around the same cost, but this way I didn't have to lay out all of it at once.

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The retrokit would also give you a new heater and sensors.

I'm wondering, what wires did you replace?  Do you mean from the breaker to the tub?  What size were you originally using?  I've never heard of thinner wiring causing a breaker to pop, but I have seen wires get hot.  As far as too-thin wiring causing voltage fluctuations, I've never heard of that either.  But that doesn't mean it couldn't happen, and if that's what you measured, it is what it is.  Was the voltage fluctuations at the 120 and 240 level, or at the low voltage on the other side of the transformer?

Just as a tidbit of info, a Balboa heating element should raise the temperature about 4-5 degrees per hour.  Depends on the age of the element, the wattage, and how heavily coated it is with minerals.  I've seen elements completely encased in a calcium shell that barely heated at all.

Dave

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I replaced everything from the gfci with 8, same as it was before. The other wiring I replaced was the internal wiring for the relays and heater from the terminal block to the fuse blocks and board and to the pump molex connector. They were originally 14 ga and I upped them to 12. The fluctuation was the 120 feed to the board, caused by a poor connection in the terminal block. All is up and running good now.

 Only issue left is the temp is way off. I originally purchased the tub in 2000. We used it for about 10 years and then sold it. We got back a few years ago after the flow switch failed and it froze. I repaired the plumbing and put in a new heater and flow switch. After getting it back up and running the topside control displayed the temp 4 degrees cooler than what I confirmed with 3 different floating type thermometers anchored at the steps next to the thermostat sensor location. Now with the new board it seems to be off even more, although I haven't yet confirmed it with a thermometer. What would cause that? The heater looked clean when I had the pack out.  I first suspected one of the sensors going bad, but now i know the tub has a fail safe between the 2 sensors of one goes bad and it is highly unlikely they both are going bad at the same exact rate and the same exact time. I wouldn't think it would be the topside since all it does is display what the ROM is reporting from the sensors. I previously thought maybe the ROM was corrupted with the old board causing it to be off or corroded connections but the new board is even worse. I plan on swapping ROMs and seeing if the problem returns to only 4 degrees off. That is if the new board will operate with MAS25 rev 1A software. The chip it came with is 1B, but it is also able to be set for a 4 button topside where as my old one wasn't. 

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