Circuit board, Tank Levels, 1991 Thor

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
richardhufford

richardhufford

Well-known member
Joined
Apr 11, 2016
Posts
77
Location
San Jose, AZ
The circuit board that shows tank levels went dead on my 1991 Thor Establishment. It's located behind a panel in my range hood, and it looks to me like the board is burned or corroded near an 8 v. voltage regulator. I'm trying to figure out the best way to deal with the problem. I could try to repair the original board, but all the components are 30 years old, so it might make more sense to make a new board, which I believe I can do. I assume the original is no longer made. Is there an easy replacement circuit board? If I made a new board, would other RVers with old RVs want one too?

The photos show the panel and the circuit board. The board has the characters 5079 and CKT near the main plug, and REV A on the other end.20220122CircuitBoard1.JPG20220122CircuitBoard2.JPG20220122CircuitBoard3.JPG
 
As long as it's a single layer board on each side, I think it can be saved. You may have to run a few wires over burnt traces. I doubt there would be any problem replacing the 8V regulator if that is what shorted out and burned the board. Finding 30-year-old common parts shouldn't be a major problem. Will probably be easier than finding another board.

-Don- DeRidder, LA
 
Consider an upgrade. NOTE Link provided for information only. Never done business with vendor

www.rvupgradestore.com

Garnet 709-P3 SeeLevel II Tank Monitoring System

The Garnet 709-P3 SeeLevel II Tank Monitoring System is designed for accurate level measurement of motorhomes and trailers with three holding tanks. This system monitors battery voltage, fresh, grey, and black water levels. The level in percent is shown on a three digit LED display.
www.rvupgradestore.com
 
That panel does more than tank levels, though. Installing a SeeLevel is a good idea, but only solves 75% the problem. However, the fan and water pump switching is probably very easy to do.
 
I have always been successful when looking for old board components. What will determine your success is troubleshooting. This will be heavily dependent on the physical inspection. I guess if you have the time, replace the components that look to be the problem and maybe a few more that are associated. Should be cheap enough online and check in with your local electronic parts store if you have one. Usually, one can be found and if it's a good one, the folks there can save you lots of time.

Making your own board is a large project but certainly possible. It would seem maybe a little too much but if you have the time, why not. If you cannot find a schematic for the board, physically following the paths of components can become awfully time consuming and if something is missed along the way, add that time to your project.

My suggestion would be to do without or replace. My system is 2001 and none of the tank sensors have ever been reliable so I do not use them. They light up and look great, but the information offered is meaningless. The other functions on my panel are needed and I see you have other functions that you need on your control panel too. That makes things a little more difficult. You could just replace the tank side of things maybe mount a new tank monitor panel somewhere else and leave the stock as is without the tank functions or just redesign the entire system using new stuff.
 
Gary RV_Wizard said:
That panel does more than tank levels, though. Installing a SeeLevel is a good idea, but only solves 75% the problem. However, the fan and water pump switching is probably very easy to do.
Click to expand...
SeeLevel has panel models that include a pump switch and a water heater switch. If the existing switches no longer work, the water heater switch could be repurposed to operate the fan.
 
Last edited:
If you replace the voltage regulator you may want to replace the capacitor as well. Cap failure is often the cause of regulators letting out the magic smoke.
 
I went ahead and ordered a new capacitor and voltage regulator from Digi-Key. (Actually, I ordered two of each, because I can break anything!) I'll spend a day or two and see if I can make the old board work. If I have my act together, I'll post whether it works.
 
The one that you have looks identical to the one that we had in a 1987 Allegro but different from the hood mounted monitor panel that we had in our 1998 Cruise Master and both were made by KIB RV Electronics, which is a division of KIB Enterprises, located in Elkhart, IN. They are still listed on Dun & Bradstreet and I'm sure that they are still in business and I did locate a URL for them on Linked-in but did not visit it as they now require you to go through a security check to go on their pages.
KIB Enterprises Corp. It is possible that you might find parts if you visit them.

As to a market for a replacement board if you make one, I doubt that there would be much demand for them as they seem to have a very low failure rate and that version isn't used any longer.
 
NY_Dutch said:
Oops!

They have a variety of models to fit different requirements. I installed the 709-HP3W panel in both my previous and current motorhomes.

RV Holding Tank Monitor Store | Garnet Instruments

www.garnetinstruments.com www.garnetinstruments.com
Click to expand...

You might try calling either the company that makes seeLevel or RV Upgrades. (Or another respected dealer) as I said I've not done business with RVUpgrades but I've not heard bad things eitehr.
 
I think he's talking to me. My parts are arriving today or tomorrow, so I'll see if I can repair the board. If that doesn't work, I'll try making my own because it looks like fun. The place I send my design to makes 3 copies of the circuit board, so I'd have another 2 to pass along to someone else, if they'd want it. I don't see any reason to try to make a profit on this. (Things like this always look like fun, before I start them.)
 
The regulator works or it don't. 3 pin regulators like that are usually pretty tough, being able to withstand a wide input voltage range and continuous direct short. I would suspect the cap before I would the device but in the grand scheme this is a couple bucks worth of parts so why argue with it. A minute with a DMM would show where the problem is in any case. On that note, the IC's there are common comparators and prolly a buck or so apiece so even if you shotgunned every active part on the board you're into it for a few bucks, so I would see no reason why this board couldn't be repaired even if the whole thing was zapped. I can see the zorch mark there by the regulator, hard to say if that's an arc or corrosion by the photo but a few seconds with a solder sucker or some wick will clean that up. For extra credit one could come up with a bench supply or a pot to exercise the analog inputs to the comparators and see the LED's play but it would be my bet it will work again once the regulator issue is resolved.

Mark B.
Albuquerque, NM
 
Well, my parts arrived and it turns out I didn't need them. There was one broken trace, and when I soldered a wire in its place, the board started working. Thank you for your help!
 
You must log in or register to reply here.

Latest posts

Members online

Total: 1,120 (members: 30, guests: 1,090)

Forum statistics

Threads
131,930
Posts
1,387,710
Members
137,681
Latest member
skidsteerpilot
Back
Top Bottom