Author Topic: Hayward Maxflo VS Pool Pump Motor Drive Unit Repair  (Read 293 times)

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Offline jcrubinTopic starter

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Hayward Maxflo VS Pool Pump Motor Drive Unit Repair
« on: June 02, 2023, 09:47:55 pm »

While viewing the readings of my pool a day after adding salt, I had realized that the control panel was blank with no power indication. This happened after some bad weather though all power was secured during this event and we had no power issues at that time.  I will however cut off power to my main breaker as I prepare to open the cover of the unit to conduct some basic troubleshooting.

Most know from my previous video that my faceplate has been remoted, and the top of the pump has a blank faceplate.  The cover removal exposes my AC connection as well as my connections to the remote faceplate.  With the re-application of power a quick check on AC shows that the correct AC voltage is in fact making its way to the pump.  Sadly this is going to be a Pump issue and not a simple breaker issue.  A DC voltage check on the faceplate lines shows a strange low voltage fluctuation that is definitely not looking good.

With these findings it was time to cut power and disconnect the cables from the pump.  The water, seen in the water tight area where the cables were removed is a sign of things to come.  Id set everything up fr the pump to be easily removed, it took but two minutes to pull after the cabled were disconnected after all plugs pulled and everything drained. Since its coming inside, the pump was washed to remove all sorts of accumulated crud.

Set up inside the house the first order of business was the removal of the fan shroud.  One screw was rusted and snapped off.  The wife had complained it was loud and we found that the debris was causing it.    The motor itself was spun and felt really good.  Whatever is going on, its not a binding motor or bearing issue.

Unscrewing of the top cover begins, the center screw is dealt with very carefully as its filled with water and rust, cleaned and oiled for later.  T25 anti tamper is used for the cover bolts on the underside, allowing its removal.   Its a good idea to check the filter caps at this point before continuing because they can hold a considerable charge after an hour and ruin your day. Waiting is key.

Initial observation shows that a water leak has been going on for a very long time, its origin not yet known.  The oxidation on the aluminum is a tell tale sign.  While drying out the middle screw, soaking in oil, is carefully removed.  Two further screws on the side are removed that secure the drive unit.  Followed by T15 bolts that secure the board into the housing, 5 of those. A T10 removed the heat sink screws.  Even with all this, there are several components held on with mastic so it must be removed carefully.  Finally the board is separated by a four pin connector.

With the board removed the full extent of the damage inside can be seen, all on the left side where the caps are.  Also it is evident that Capacitor C6 has exploded and a note is made.  A determine is made from historical footage as to why only half of the unit filled with water.  Attempts are made to clean the destroyed capacitor to get a marking off of it but its too far gone.  The capacitor was then removed from the board, the are cleaned up.

Troubleshooting then begins working from mains back. Through a variety of components in a logical order making my way to the rectifier. Note that during testing I didn't need 240 volts but substantially less was used from my Variac , around 45VAC, low enough voltage to prove out the rectifier and basic filtration.   

Making my way to the IC TNY274 I was able to further analyze the switch mode power supply with the documentation as well as the inclusion of a temporary capacitor where the old one was ruined.  The drain and enable pin and DC output shows an artifact that demonstrates an over-current condition somewhere.  Taking a quality guess showed a particular rectifier that might be the culprit, pulling it off the rails removed the protect condition from the TNY274 so its a good indication.  The rails are checked and stable, this IC will need to be ordered and replaced.


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