Good morning everyone!

I've been hunting around online to try and solve a problem we have with our generic/Chinese brand K9 water treadmill. Most of my searches over the past year have given me some results from this forum, so I decided to join and see if anyone here can help me out with an issue that just came up.

We bought the unit from a warehouse in the area years ago. We wanted something for our dogs for hydrotherapy at home (my wife is certified in canine rehab), but didn't want to pay $50k. The unit had been working fine for years, but eventually the control panel stopped working. I bought a 3rd party panel and control board online and swapped everything out. Everything was working fine for about 18 months.

And then yesterday, when we turned on the unit, the countdown started on the screen, and instead of starting at speed 1 like it said on the screen, it IMMEDIATELY shot to maximum speed. The panel still read 1, but the belt was at max. All the research I've done suggests SOMETHING on the board is bad.

Here's a picture of the internals (with the board removed). It's very simple - power to the breaker which connects to the control board which then connects to the motor and control panel:




Here's the specs on the motor (sorry, just now realized it's upside down):




Here's a picture of the ORIGINAL board (before the panel died and I replaced it):









And here's the board I bought to replace it - note that I replaced the board because it came WITH the panel. I assumed the two were meant to work together:









The unit we have is not an inclining one - just a variable speed unit.

What I'm trying to do is two things. First, I'd like to figure out if the new board or the motor is bad. The speed control mechanism is clearly not working, but I don't quite know how I would diagnose that. Second, if I need to replace items, I would love some assistance on finding or identifying replacements.

That said, I would love to learn a bit more about what I'm doing. I'm a structural engineer by trade, not a mechanical or electrical. But I do want to learn about the process here since this type of unit is not exactly something I can call a tech to help diagnose! I also enjoy the tinkering and tweaking of it all.

 

I am not familiar with that board, but I would look first at the semi conductors mounted to the heatsink, invariably these are the problem causing your symptoms.

 

Commercial DC-Motor-Controllers are notoriously poor designs,
because a bullet-proof design can get very expensive, very fast.

One of the biggest problems is keeping the Power-Transistors cool.
This requires a large, expensive Aluminum-Heat-Sink and a Cooling-Fan arrangement.

If / when You get something working,
the most important thing that You can do is to purchase a small, continuous-duty, cooling-Fan
and aim it directly at the cheezy Heat-Sink that has been provided by the manufacturer.
.
.
.

 

This is good info. We've been running it more lately, so it DOES make sense that it could have overheated!

A few educational questions:

• What's the purpose of transistors on the MCB? I'm assuming it regulates the amount of electricity going to certain parts of the board? So if that's the case, it having failed means I can't regulate how much power is being fed into the motor?
• How do you test if one has failed?
• Assuming it has failed, is it better to replace the transistor or to replace the board? Given that it's a Chinese board, finding the right replacement might be a challenge.

That said, I've seen a few specific boards recommended here (by MaxHeadRoom even) such as the MC-2100. Does it make more sense to buy something like that, hook up my control panel, and just replace the board, add some cooling, and call it a day?

 

The MC2100 I believe is built the best, also there is the reverse-engineered schematic out there, although there are a few variations of the board.
What does the present unit have for speed monitoring, if at all?
This board most likely could be used on its own for this application without the console, !?

 

The way it's setup currently is that I'm using this control interface with the 1-2 hP non-incline control board:

https://www.aliexpress.us/item/3256802616038566.html?gatewayAdapt=glo2usa4itemAdapt

If there's a way to bypass everything with a new board and just have a dial pot I can manually hookup, I can 3D print a housing and a fan holder for everything.

I'm still unsure how to check the existing transistor though.

 

Check the part numbers of the IC;s fixed to the back aluminum heat sink and post, in order to pick a likely culprit.

 

So I was able to check the transistors on the dead board with my multimeter, and wouldn't you know, one of them wasn't responding to the diode test. So it looks like that's exactly what happened.

I was able to put the old board back in and confirm that the motor works. The old control panel was just REALLY finicky and on it's last legs.

So now, I need to buy a new board and control panel. Whatever I do, I 100% intend to figure out how to hook up a small cooling fan. Is that why transistors fail - overheating??

 

Is that why transistors fail - overheating??

Can be the source of one problem.