Mastertemp 200 - Display completely blank and no LEDs

[johnnybravojr]

Hello,
Had a few storms recently (although not sure it is what caused the damage). I have a Mastertemp 200 pool heater and the display is blank and no LEDs illuminate. I saw that the fuse was blown. Got a replacement fuse and turned back on the breaker and the new fuse blew instantly. I'm thinking it is either the control board or transformer. Does anyone know how to properly root cause which is the issue (or something else?) I have a fluke multimeter so I can take simple measurements.

Thanks in advance!

 

[ajw22]

Welcome to TFP.

If your MasterTemp connected to automation through the "firemans switch"?

Is the fuse you replaced by the firemans switch connection?

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

See pages 40-41 for the electrical diagram for where you can poke around with your multimeter - https://www.pentair.com/content/dam...stertemp/Manual-MasterTemp-472592-English.pdf

I would first take a careful look at all the wiring and see if there are any signs of rodents chewing on the wires.

@swamprat69

 

[johnnybravojr]

Hi @ajw22 ! Thanks for the response. Yes, it connects through the firemans switch. The fuse I replaced is right next to it. I was able to find the pentair replacement (1.25A - fast blow). I was going to start investigating in the morning for any chewed wires. We do get a lot of mice and chipmunks in the area where the pool heater is located. We also had some wicked storms the last few weeks (around the time we noticed it stopped working).

 

[ajw22]

First thing I would do is disconnect the wire to the automation and jumper the firemans switch so the heater runs in local mode. If the fuse still blows then the short is internal to the heater.

I suspect that you will find a 24V wire that has chafed or been chewed and is touching metal and shorting to ground.

 

[johnnybravojr]

First thing I would do is disconnect the wire to the automation and jumper the firemans switch so the heater runs in local mode. If the fuse still blows then the short is internal to the heater.

I suspect that you will find a 24V wire that has chafed or been chewed and is touching metal and shorting to ground.

Sorry, I'm an electrical engineer but new to the Mastertemp 200 system. When you say jumper the fireman's switch, do you mean connect the fuse (bottom) to the top of the fireman's switch (bypassing it)? Right now the bottom of the fuse holder is connected to the bottom of the firemans switch which then goes up to the control board.

 

[ajw22]

Sorry, I'm an electrical engineer but new to the Mastertemp 200 system. When you say jumper the fireman's switch, do you mean connect the fuse (bottom) to the top of the fireman's switch (bypassing it)? Right now the bottom of the fuse holder is connected to the bottom of the firemans switch which then goes up to the control board.

In this pic you would disconnect the blue wire nuts and the wire and then twist the ends of the yellow wires together and put a wire nut on the end.

Wire the two terminals the arrows point to together.

Post a pic of this area in your heater if you need more guidance.

 

[johnnybravojr]

In this pic you would disconnect the blue wire nuts and the wire and then twist the ends of the yellow wires together and put a wire nut on the end.

Wire the two terminals the arrows point to together.

Post a pic of this area in your heater if you need more guidance.

Got it, thank you Sir! Will take a look in the morning and get back to you.

 

[johnnybravojr]

@ajw22 I was able to take apart the whole heater unit (top, front and back panels). Couldn't find any chewed or damaged wires. Right now I'm leaning to the board potentially being damaged, there are two pads that have some potential damage (circled in the attached photo). Trying to figure out what type of component it is. Thinking about ordering a replacement board on amazon. The only other idea I have is the transformer (since it died when we had some storms/power outages) although it looks like it is in good shape. The only time I've seen a transformer fail, it had visible evidence although it isn't always the case.

Any ideas that I might be missing?

Thanks again for all your help!

 

[Poolbreh]

I would check voltage from breaker, just to confirm it isn’t missing a phase. I agree with you, transformers are less likely to go out. In my experience fuses blowing are usually defective boards. The only way to be certain is checking the vac from transformer.

 

[ajw22]

Let’s see what @ps0303 thinks

 

[swamprat69]

If the latest set of photos is of your heater, then the heater is not being controlled remotely and the firemans switch connection is already jumpered by the yellow wire connecting the bottom of the fuse holder ( I assume that this is the fuse that you are blowing) to the terminal on the left. This is the 24V circuit and it would tend to indicate a direct short to ground in the circuit or a transformer winding short if it blows right away. The connection at J7 has 24V to the board on the 2 left wires and the passthrough from the firemans switch on the 2 right wires. The sequence of operation should be 24V through the water pressure switch to prove that the pump is running. 24V to start the blower motor and then 24V through the air pressure switch to confirm blower has started. Then ignitor warm up time folowed by power to gas valve. Kill power to the heater when you remove or replace connections at the heater board. Kill power to the heater and remove the 4 wire harness connectors from the circuit board (leave the membrane pad connected). At this time you might want to dismount the circuit board and inspect the back of the board around the area that you suspect might have a problem. Does it look OK? If so remount the circuit board. Power the heater (with the 4 wire harness connections still not connected) and you should measure 24V on the 2 left wires of the harness that was connected to J7. Kill power, reconnect the J7 wire harness to the board and power up again. Did the fuse blow? No? Kill power, reconnect the wire harness that was attached to J1 and power up again. Did the fuse blow? You can repeat this for both the upper left and lower left safety wiring harnesses if the fuse did not blow. This should help isolate where in the circuit the problem is occuring and you can then isolate further from that point.

 

[swamprat69]

As you are testing the wire harness connections you can run the temperature set point from below to above the water temperature to see if the problem occurs only when the board is calling for the heater to heat.

 

[johnnybravojr]

Thanks everyone for your input.

I ordered a new board off Amazon. Once swapped, if the fuse blows instantly I'll get a new transformer. Hopefully it is one of the two.

I did check the breaker, looks good. Back side of the board looks good, can't find any visual damage.

 

[ps0303]

Most likely the transformer is what is causing the fuse to pop. I replace many transformers that look perfectly good visually. The board issue you show, can you use a tooth brush and wipe that off? Doesn't look like that would be the issue here.

 

[johnnybravojr]

Most likely the transformer is what is causing the fuse to pop. I replace many transformers that look perfectly good visually. The board issue you show, can you use a tooth brush and wipe that off? Doesn't look like that would be the issue here.

Thanks for your input. I ordered a transformer too. I have a 42007-0107, but I noticed there was a 42007-0107s. Do you know the difference between the two? I was thinking maybe it is a newer revision. Since both the board and transformer have free returns, I figured no harm. The transformer is easier to swap when the top is off the heater so maybe I'll try that first.

 

[ps0303]

The "s" one is for units made after 2003.

 

[johnnybravojr]

Hi Everyone. Just wanted to provide an update. I swapped the transformer -- still blew the fuse. Put the original transformer back in and swapped the control board. The heater now powers up with no blown fuse. Was looking at the "damaged" board closer and the only guess I have now is the component on pad L10 (I believe it is an inductor) appears to be swelled slightly (like when a capacitor is damaged) compared to the L10 component on the new board. By any chance anyone know what this is? The board part number is 42002-0007s. I was thinking about trying to repair the board (solder in a new component) to have as a backup. I've only had the heater two years and since the board already failed once, I feel like I will be in this same situation again.

Thanks again for everyones help!

 

[ps0303]

There should be markings on the L10 item. Not sure what it is but if you can get the same part and are good at soldering, it's worth a try. Hopefully the rest of the board is good.