Maxxfan 7000K voltage regulator

[tdf-texas]

Parts List:
LTC3780 14A High Power Auto Step Up Down Voltage Regulator 5-32V to 2-24V DC Adjustable Converter Transformer
https://www.amazon.com/gp/product/B017SM1O98/ref=ppx_yo_dt_b_asin_title_o03__o00_s00?ie=UTF8&psc=1

VELCRO 2-Pack 3-in White Fastener
https://www.lowes.com/pd/VELCRO-2-Pack-3-in-White-Fastener/3043265

Procedure:
1. Turn off battery disconnect switch.
2. Rotate screen tabs 180 deg and remove screen.
3. Remove screws as marked and lower bottom housing.
4. Disconnect trailer wires from Maxxfan power wires, connect trailer wires to LTC3780 as shown, turn on battery disconnect switch, and adjust the potentiometer for an output voltage of 12.0 volts
NOTE: do not attach wiring to Maxxfan until voltage has been adjusted - the LTC3780 can output up to 24VDC which will make the Maxxfan control board very unhappy.
5. After verifying that the LTC3780 is set for 12.0 volts, turn off battery disconnect switch and connect Maxxfan power wires to output of LTC3780.
6. Attach velcro to back of LTC3780. It will need to be trimmed a little to make it flush with the edges.
7. Attach LTC3780 in the corner of the upper housing as shown.
8. Put everything back together the reverse of how you took it apart.
9. Turn battery disconnect switch on and test fan.

Congratulations, your Maxxfan can now operate with supply voltages from 5-32v.

 

[stephen99]

Thanks for the detailed instructions. I just ordered the regulator from Amazon.

 

[cpaharley2008]

2 questions, how do you know what the voltage is set ? do you hook up a meter or what and where do you measure. Is there a wiring diagram, I see 4 wires on one side and I assume the power lead on the other? thank for posting the upgrade. Perhaps the instructions that come with the board explains this? Thanks again.

 

[tdf-texas]

2 questions, how do you know what the voltage is set ? do you hook up a meter or what and where do you measure. Is there a wiring diagram, I see 4 wires on one side and I assume the power lead on the other? thank for posting the upgrade. Perhaps the instructions that come with the board explains this? Thanks again.

I measured the output voltage with a voltmeter across the output terminals of the board. To adjust the voltage - turn the potentiometer (see pic - it's circled) counterclockwise to increase - clockwise to decrease the voltage. If you don't have a voltmeter - maybe borrow one or they are fairly cheap to buy.

https://www.amazon.com/Etekcity-Mul...&qid=1548627954&sr=1-4-acs&keywords=voltmeter

On my trailer, the power wires to the Maxxfan were daisy chained off the LED light next to it and then continued across the ceiling to the next LED light. The LTC3780 has connections for two power leads that are common on the board which makes it convenient for connecting both sets of wires.
Look at the attached pic - the two positive wires are connected to the far left and then the negative wires on the next two terminals. If your trailer has only one power lead going to the Maxxfan, then the positive lead goes to terminal 1 and the negative lead goes to terminal 3. The terminal wiring info is stenciled on the board next to the potentiometer.

Power to the Maxxfan is on the other side of the board from the power input terminals. The terminal wiring info is stenciled next to the terminals. In the pic, the output is connected to terminals 3 &4 - 3 is positive, 4 is negative.

 

[cpaharley2008]

Thanks Tom, I think I got it. I'll be doing this as soon as we get home from the rally on the new 21.

 

[War Eagle]

Just curious - are those heat dissipation fins in the middle of the voltage regulator? And if so, is there any worry about excess heat buildup in the small enclosed framing space once it's all put back together and the fan is running? I know nothing about these these things, so again, just curious...

 

[tdf-texas]

Just curious - are those heat dissipation fins in the middle of the voltage regulator? And if so, is there any worry about excess heat buildup in the small enclosed framing space once it's all put back together and the fan is running? I know nothing about these these things, so again, just curious...

It's a 14 amp regulator that's running at 4 1/2 amps - it doesn't even get warm. I ran it continuous overnight and I had to hold my finger on it for a while to tell if it had even gone up in temp.

Also, it is mounted right next to the outside vent opening - good place for heat dispersion.

 

[Ian and Sue]

Thanks so much! Just placed my order too! Now to get a new board from max fan.

 

[rotorbudd]

Thanks

This is very helpful for those of us wanting to protect our Maxxfans from overvoltages.
Just ordered the voltage regulator myself! ;D

 

[sclifrickson]

Thanks, Tom!

 

[tdf-texas]

I forgot one step in the procedure - there is a Philips head screw holding the vent knob on - it has to be removed before you can remove the bottom housing.

Also, when connecting the input power to the LTC3780, make absolutely sure polarity is observed - the LTC3780 cannot handle reversed voltage on the input.

 

[EdColorado]

"... make absolutely sure polarity is observed "

Just how do I do that?

Ed
An electrical novice.
With a multi-meter.

 

[tdf-texas]

"... make absolutely sure polarity is observed "

Just how do I do that?

Ed
An electrical novice.
With a multi-meter.

Positive (red) wire goes to positive terminals 1 or 2 - Negative (black) wire goes to negative terminals 3 or 4. If your not sure, check with your voltmeter before connecting the wiring.

Take a look at the hookup pics I have in the procedure - if your wiring matches - it's good.

 

[sclifrickson]

I measured the output voltage with a voltmeter across the output terminals of the board. To adjust the voltage - turn the potentiometer (see pic - it's circled) counterclockwise to increase - clockwise to decrease the voltage. If you don't have a voltmeter - maybe borrow one or they are fairly cheap to buy.

https://www.amazon.com/Etekcity-Mul...&qid=1548627954&sr=1-4-acs&keywords=voltmeter

On my trailer, the power wires to the Maxxfan were daisy chained off the LED light next to it and then continued across the ceiling to the next LED light. The LTC3780 has connections for two power leads that are common on the board which makes it convenient for connecting both sets of wires.
Look at the attached pic - the two positive wires are connected to the far left and then the negative wires on the next two terminals. If your trailer has only one power lead going to the Maxxfan, then the positive lead goes to terminal 1 and the negative lead goes to terminal 3. The terminal wiring info is stenciled on the board next to the potentiometer.

Power to the Maxxfan is on the other side of the board from the power input terminals. The terminal wiring info is stenciled next to the terminals. In the pic, the output is connected to terminals 3 &4 - 3 is positive, 4 is negative.

Tom, question: Why did you choose to hook up the downstream light on the input/upstream side of the regulator instead of the output/downstream side, thereby not regulating the rest of the circuit run? Or am I seeing things wrong?

 

[EdColorado]

Positive (red) wire goes to positive terminals 1 or 2 - Negative (black) wire goes to negative terminals 3 or 4. If your not sure, check with your voltmeter before connecting the wiring.

Take a look at the hookup pics I have in the procedure - if your wiring matches - it's good.

Thank you

Ed

 

[tdf-texas]

Tom, question: Why did you choose to hook up the downstream light on the input/upstream side of the regulator instead of the output/downstream side, thereby not regulating the rest of the circuit run? Or am I seeing things wrong?

I am adding voltage regulator circuits using LM2940cT-12 to all the LED lights. I prefer to have each device have it's own protection as it modulizes the failure modes. One voltage regulator - one device. If a voltage regulator fails, it takes out only one device.

Also, the mod becomes universal - not everyone on the board needs to have voltage regulation on their lighting (just 2017-2018).

But if you wanted to - the LTC3780 is a 14 amp device and could protect any one of 12v circuits in the trailer.

I plan on installing one on all the devices that require protection from high voltage. I ordered 3 more from Ebay.
https://www.ebay.com/itm/DC-DC-Conv...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[rotorbudd]

Wow! good find!
Think I'll order a couple of more too.
At that price I think I'll add one to the light circuits.

 

[vermilye]

Any problem with RFI on AM / FM?

 

[tdf-texas]

Any problem with RFI on AM / FM?

I just went out to check. AM/FM/over the air TV - no noise.

Below is attached the datasheet for it. The datasheet has some errors - it's made in China.

 

[richardr]

Wow! good find!
Think I'll order a couple of more too.
At that price I think I'll add one to the light circuits.

If you install them in your lighting circuits, please post how and where you installed them. I'm also considering installing them.