Old Discovery Spa Needs Your Help

[danskelly]

Hi everybody, I'm been lurking and searching here for the last several weeks since I acquired an old hot tub off Craigslist for free.

Here is all the info I've gleaned off of it:
It's a Discovery Spa SL800 (Can't find that make anywhere!)

It has a Balboa ZX1000 control board

And this Topside controller:

The main recirc pump works great, both speeds. The secondary pump and blower don't work (not a problem right now.)

The heater tests out great, and does indeed heat the water.

When I first got it, I couldn't get it off ECON mode and thus couldn't get the water temp above 97F. But with enough button mashing, I found out how to turn that "feature" off.

It will often stop running and display FLO, but if I mash the Jets button enough, it'll start back up again. I know it's trying to tell me that the flow switch is malfunctioning, but I've tested it with my meter, and it seems to be working fine.

The other day, I came home and checked on it, and it displayed ILOC and nothing would work. I looked up that code, and found that it is an interlock for an open door panel or over-temp. There is no door-panel sensor/switch, so I guess I have to assume that it's an over-temp issue. I only set my temp to 102F, so I can't imagine that occurring unless the pump didn't start for some reason. Anyway, I cycled the breaker, and now we're back in business.

TODAY, I went in the tub, and the normal FLO was displaying, but when I mashed the buttons, the pump started, and then SN1 appeared on the display. Dang... So, I looked THAT up, and it seems that code is for Hi-Limit sensor malfunction. WTF... I'm not sure how to test the sensor (what the resistance range should be, etc)

Anyway, Sorry for the long post, but I was thinking that perhaps somebody might be able to shed some light on these issues. Could all of this indicate a bad board?

Thanks for any help you can provide. :-)

DAN

[Spa Board Doctor]

If you're having to "mash" the buttons then you may need a new spaside.

From the picture, the terminals on your heater element are leaking and element replacement is in your future.

Pressing temp up and temp down simultaneously switches heater modes between standard and economy.

If "FLO" alternates with water temperature then pressure switch is open when pump is on (dirty filter, obstruction in water line or pump impeller, bad pressure switch, or bad connection on pressure switch wire harness).

If "FLO" is solid on display then pressure switch is closed when pump is supposed to be off (bad pressure switch, stuck-on pump relay).

Here is the temperature v.s. resistance chart for Balboa probes. You must disconnect the probe harness and test each probe set individually with an ohmmeter. The probes should be within a couple ohms of each other in resistance.

BB

[danskelly]

Thanks Spokane,

I'll check the resistance of the probes later today.

As far as the "mashing," the buttons on the topside are actually quite responsive, I just meant trying multiple combinations of buttons to figure out which worked. BTW, are there other "hidden" features of this spa I should know about?

The FLO is steady in the display when it is present, so I can test the pressure switch to see if it's sticking on. (or just replace it, not too expensive)

There are 2 Dip Switches on the lower right of the circuit board where the silkscreen says "SW1 Filter Setting" Both are off, and I can't find anywhere to explain what they actually are or do.

I also noticed the corrosion around the heater terminals. I still see no water, so I'm gonna let it ride for a little longer to make sure I don't have to put in an incredible amount of money first.

[Spa Board Doctor]

No other hidden features on this spaside.

The dip switches are for filtration cycle duration.

Example:

off_off = 2hr

on_off = 3hr

off_on = 4hr

on_on = 5hr

There are two cycles per day.

BB

[danskelly]

Great! Thanks!

I've ordered the probe set and pressure sensor, and will replace as soon as they come in. I'll then post the results.

Also, do those gate valves fail on EVERY hot tub? Seems every hot tub I've worked on for friends and family, they always leak water when closed. Is there any sort of remedy short of replacing the whole valve? Doesn't look like they come apart to replace seals. (glued?)

DAN

[danskelly]

I got the new pressure sensor, and installed it yesterday. The old one was indeed stuck in the on (pressurized) position.

I think it's fixed at this point.

Thanks, Spokanespas!

[Spa_Guru]

Failed gate valves and corroded heater elements go hand-in-hand, and are caused by excessive sanitizer use or low PH.

Your spa is 19 years old, the odds of the valves surviving this long are less than slim.

I wouldn't delay replacing the element, you are talking about water dripping on 240v connections, a universally bad thing.

The new element for your heater runs around $75 list, you may find it for less with enough searching.

Process for element replacement;

Drain the spa.

Remove the two screws that are holding the copper strips just above the heater element, at this point you aren't going to get the element nuts off the strips in one piece, so you will end up removing the copper strips anyway.

Remove any sensors clamped to the heater.

Remove the clamps or bolts holding the heater to the aluminum box that houses the circuit board.

Remove the unions on each end of the heater pipe, as well as the union that goes to the discharge side of the pump, this will make reinstallation more feasible.

Now that you have the heater in your hand, take needle nose vice grips and clamp them to the nut on the back side of the copper strap, and try to remove the nut visible in the photo, it will either come off, or the post will snap in two, but you will end up with the copper straps intact.

The nuts holding the heater element into the pipe may be so corroded to the element that the element will just break and spin, so be prepared to hacksaw the nut in half to get it off. Be careful to not damage the heater tube.

Once both nuts are off, the element can be pushed inside the tube and extracted from the end.

Clean the tube inside and out, especially near the two holes the element is attached thru.

The new element will likely come with two small O-rings which I typically remove and apply a small amount of silicon sealant to so they can better seal against a slightly irregular or eroded heater wall, then I reinstall them.

Now insert the heater element back into the tube, paying attention to which way it came out, (long end to the left in your case) I usually leave the small wire connector nuts on at this point to protect the threads on the posts.

Align the heater posts to the holes, and tilt the tube so they can drop out where you can grab them, then install both mounting nuts.

Because of clearance limitations in your specific system, at this point I would reinstall the copper strips, because you will need a 1/4" wrench to hold the heater element post from turning while you tighten the nut that holds the copper strip to the element, and doing that after the heater is installed could be problematic.

Now that the heater is reassembled, reinstall it reversing the procedures from above, and install new heater gaskets, using silicon sealant on them as well.

[Mountain Spa Idiot]

I just procured what seems to be the same spa. It was free from a friend with no manual. He moved into a new house and never turned it on. Previous owners said it worked, but he wanted to tear out the old deck and was just going to get rid of the tub. The fiberglass is in perfect condition. Got it wired in yesterday. It turned on immediately and flashed ECON>>>FLO>>>Temp. If I try and hit any buttons the display freezes and there is a clicking noise in the control board, everything shuts down. I have to turn the breaker off and back on to restart.

I let it go to see if it would heat and by morning it was at 100 degrees! Thought I was good to go, but then I tried to turn the jets on and again display goes haywire and everything shut down. I reset again after reading this post and tried hitting the up and down arrows to remove from ECON mode. This seemed to work, as the display then read the current temp only, but it still made a clicking noise in the control panel and all button would not work again.

Any troubleshooting ideas would be welcome.

[danskelly]

I am NOT an expert. Just a hobbyist with an basic knowledge of electricity, and its components. Hopefully a spa-expert will comment, too.

I was gonna suggest that you have one or more bad relays, but since you got it to temp that means that the circulation pump and heater relays are working. Well, at least the low-speed on the circ pump.

It's possible that the relay for the 2nd pump (do you have 2 pumps?) is shot, or the low-high speed relay for the 1st pump.

Basically, it sounds like a stuck/bad relay to me. Again... Not an expert. :-)

[Mountain Spa Idiot]

I do not have a second pump. I am not that good with electricity, but a friend and I pulled the covers off all the relays and could not identify any obvious issues. How would I check to see if they were "bad", because none of them seem like they are stuck?

The "FLO" indicator comes on upon reset about 3 times and then the tub runs fine if you don't push anything. For I while I was able to work the controls: I changed to standard mode, adjusted temp, and turned jets on and off. Then, somewhat randomly, it would start clicking and quit working. Part of me thinks it might be a bad pressure switch, or the entire control board is bad?

Any ideas on some more troubleshooting?

[danskelly]

I'm not entirely sure how to proceed with testing the relays. You might search this forum a little to see if anybody has a writeup on testing relays.

As for the FLO message. I also had it on mine when I got it. The pressure switch was bad for me. Replaced a $20 part and done. Other things that can cause the message are: filter needing replaced, gate valves closed, or scaling inside the heater tube. Basically anything that restricts the "flow" of water through the heater tube.

It is still possible that the whole board s bad, and finding just the board on these old tubs will prove to be challenging.

[nivek311]

Recently my roommates and I picked up one of the same Discovery Spas that you are working on. My dad has been wiring everything in and we haven't filled or tested anything as far as I know of, but my dad was concerned about a wire that he isn't sure where it goes or what it is for, so we were googling everything we could think of and couldn't find a manual to tell us what the wires go to exactly, so I am hoping that someone here could tell us.

First here is the box itself, same as yours:

The wire I'm holding below is the one that is bothering us:

My dad told me that he thinks that it looks the wire is bad and maybe someone replaced this wire with a new one without removing the old one somehow. Not sure how that's possible, but I'm no electrician.

The wire I'm holding in the picture below is the one that my dad believes is the new one replacing the wire above:

So if anyone could tell me what these wires go to and what you think is going on here, or give me a link to the information I am looking for please reply. I don't see the mystery wire on the OP's at all and my dad can't see where the wire would go except for where the other wire I mentioned is plugged in.

[danskelly]

Hello, sorry it took me so long to respond to this.

That appears(without seeing the other end of the wires) to be the pressure/temperature sensor wires which you can indeed see in my 2nd picture hugging the right side of the enclosure. small black ziptie holding the 2 cables together, same brown connector.

It does, indeed look as though yours has been replaced for whatever reason, and the wires have been abandoned.

If the tub gets up to temp (whatever you set it to) then I wouldn't worry about it. Coil it up, and leave it.

On my tub, one of the 2-conductor cables goes to the temp sensor next to the light (through the spray foam) and the other cable goes to the pressure sensor on the top of the heater tube. I'm guessing the temp sensor went out since that is hard-wired to the connector, and the pressure sensor can be replaced without replacing the cables.

Good luck!

[DiscoveryUser]

It's good to see you guys are keeing these old Discovery Spas alive. I've been using mine for many, many years, and have been through it inside and out. After reading this thread, I see danskelly has become quite an expert too. Congrats!

I thought I would share a few of the repairs I've had to make to mine over the years, in case any of it might help someone else out there. As for the "button mashing" comments in the first few posts, if you press "temp up" and "temp down" at the same time, it will toggle between "econ" and "stnd" modes. My tub always power up in "econ" mode, at 100F.

A few years ago my display became unstable, resetting randomly, locking up, etc. I found the electrolytic capacitors on the main board were shot. I replaced them, it's been working great since.

The heater went out on it a few years ago, so I picked up a new element off eBay for $34 delivered. Installed it myself in the existing tube, back up and running in no time.

The high / low pump went out (disintegrated, black bits of plastic coming out of the jets), required replacing the impellor and pump seals, another low dollar repair (sorry, don't remember how much, but I seem to remember it wasn't much).

The high / low pump motor bearings went out (really just the one on the pump side, but did both anyway). I found mine uses common 6203 bearings (not sure if it's the original pump though). These bearings are used in many applications, including the hubs on my mower decks, and the front wheel of my old 98' Kawasaki. I bought a box of them for the mower some years ago (10 @ $2.40 each), so had them on hand. I always pull the seals and repack with synthetic grease, so I don't expect to be replacing them again for a long time.

Another thing I found with mine, the second jet pump (mine has 2) requires disconnecting the line to prime (let the air out) after filling the tub. For some reason, it will not prime without doing this. I mention this as a warning to others that may have the two pump model, so they don't run the second pump without water, and possibly cause damage to it.

I'm currently exploring a way to add wireless remote control to my tub. If anyone has any information about the 14 pin topside display interface cable (like the pinout), please post it here. I'm sure I'll figure it out soon enough, but just in case someone already knows this info, and posts it soon, it would save me some trouble.

Thanks, and if anyone has any questions about this particular spa, feel free to PM me. I don't normally hang out on forums.

Edit: Forgot one other thing. Several of the rotating heads on mine became loose, and started coming off by themselves. I fixed these by making a shim washer out of some clear plastic (like the kind used in "blister pack" packaging) to create a tighter fit between the tub wall and the jet body. These have held up great as well.

[Roger]

Yea I'm impressed. Considering it's age though I would likely not invest to much and sell it for the start to your bit more modern 5-8 year old tub. When you initially said you were having a flow issue. My first though was air bubbles gathering from cavitation or a blockage. Or needed to be bled.

[danskelly]

It's good to see you guys are keeing these old Discovery Spas alive. I've been using mine for many, many years, and have been through it inside and out. After reading this thread, I see danskelly has become quite an expert too. Congrats!

I thought I would share a few of the repairs I've had to make to mine over the years, in case any of it might help someone else out there. As for the "button mashing" comments in the first few posts, if you press "temp up" and "temp down" at the same time, it will toggle between "econ" and "stnd" modes. My tub always power up in "econ" mode, at 100F.

Thanks! I work in industrial controls for a living, so I can usually figure this stuff out... eventually.

I actually thought I tried the Temp Up and Temp Down at the same time when I first got it, but it didn't seem to work initially. Now, it works for me every time. Although I wish it didn't default to ECON mode after a power outage

The high / low pump went out (disintegrated, black bits of plastic coming out of the jets), required replacing the impellor and pump seals, another low dollar repair (sorry, don't remember how much, but I seem to remember it wasn't much).

My 2nd pump has siezed (before I got the tub). So, I took it out, and tried to break it loose, but it would not budge. So, I put it back in and am leaving it for when I have a spare $200 to replace it. Luckily, it's not required to heat the tub.

I'm currently exploring a way to add wireless remote control to my tub. If anyone has any information about the 14 pin topside display interface cable (like the pinout), please post it here. I'm sure I'll figure it out soon enough, but just in case someone already knows this info, and posts it soon, it would save me some trouble.

I am interested in this as well. So, if you find anything out, please PM me, (or post here.)

[kvnbdvs]

I have the same era hot tub and am not getting the iloc error code all the time. I have replaced the water pressure and water temp sensors. There is no door lock and it isn't heating above 96 degrees.

[AlaskaFire]

On the off chance that someone here still knows... I’ve got a question. I need to know what filter fits in this hot tub. I was recently given one of these old Discovery spas SL800 and I can’t figure out which filter it needs. It didn’t come with one and every hot tub store I’ve been to says they don’t know. Everything else seams, miraculously, to work fine with this 27 year old hot tub, that hadn’t been plugged in for at least 5 years. Any knowledge one of you could pass on would be greatly appreciated.