TBF Inverter Teardowns

In this page, we will have a look at:
TBF 500W 500W pure sine wave inverter
TBF 2000W 2000W pure sine wave inverter
TBF 6000W 6000W pure sine wave inverter

       Up for teardown are three TBF branded low cost pure sine wave inverters. Check out the pics for what I saw.

       We start with the TBF 500W. The smallest of the bunch. It is pretty small and cheap especially for a pure sine wave output inverter. Let's see how it was built.

Inverter packaging as received. Let's see what we have here.

Here it is. It is pretty cute and it fits in my hand.

DC input side. Binding posts are the cheap plastic kind but are metal thread sleeved.

Fuses are two 20A blade fuses.

Output connector. Typical "one size fits all" outlet.

LEDs are "flapping in the breeze".

Who needs plastic spacers to properly support the indicator LEDs!

With the bottom plate removed, we have an overview of the main board.

Fuse holder connections and power input binding post backsides.

HP300? Does this mean this is a 300W inverter?

There you go. The inverter's true rating is 300W.

Input bulk caps are no name "chong" branded caps.

Output filter cap appears to be a genuine Nippon chemi con capacitor.

PIC16F716. It appears to control the main DC-DC converter and its protection system.

Output H-bridge driver board is the common EG8010 based SPWM controller.

EG8010 based driver board. With some messy rework done.

Bottom side of PCB is a little messy with some flux residue but is not as bad as others I have seen before.

The main output filter inductor. They put glue on it to keep it from moving but it was not enough. I can still move it around a bit.

Output rectifiers are pretty small for the power rating. These are rated not more than 1A so I don't think the inverter can supply more than 1A (220W) of output power continuously without these overheating.

USB5V power is taken from an UNHEATSINKED! 7805 regulator. I don't recommend using the USB charger for devices drawing more than 100mA!

Someone laying out the PCB forgot to turn it around so it mounts to the heatsink!

There is a connection on the PCB for the earth ground pin but it was not connected. The filter caps (blue) are installed so it should have been connected.

I think they've thought about adding the ground lead but opted not to...

Four primary switchers are MXP6004CTS N Channel MOSFETs, two per phase.

214A 60V rated devices. Plenty for this application.

Output H-bridge MOSFET is marked JCS18N50.

This appears to be an 18A 500V rated N channel MOSFET.

Idle current is about 670mA at 12.5V input.

A bit high for my liking but typical of Pure sine wave inverters.

       Update: Went to use this and it suddenly stopped working. So, no, it didn't last long.

Back to top of page

       Now, for the bigger TBF 2000W. Let's see if this one is any better.

Here is the box as received.

A little bigger but rather small for a true 2000W inverter.

DC input connectors have nice covers.

DC input side with the covers removed.

Externally fused with four 40A blade fuses.

3x 40A = 120A which is about 1440W.

I don't think this can do 2000W continuous.

AC output side. The end plates are plastic. With a matte velvety finish. From the countless stuff I had coated with this, it became a sticky gunk after a while.

Like the smaller one, they also did not want to use plastic LED supports. It is rather fiddly to put it back together aiming for the front panel LED holes.

I see the common EG8010 based SPWM control board.

What is this? Do I see 1000W?

Sliding the bottom plate off, we get a look under the main board.

There is a generous amount of solder used to beef up the high current traces.

Flux residue is not cleaned off.

There is also a clear plastic insulator covering the whole underside.

"YOYO LIGHTING & POWER R&R" I wonder what that is....

A quick google search gave this YOYO Lighting & Power Technology (Dongguan) Co., Ltd

Another look at the SPWM driver board.

SPWM driver board pins are labeled. Nice.

I don't like the way they wired the fuse holders. Looks messy, but hey, if it works.

Connection to the DC input terminal is nice.

It's a 1000W inverter!

Internal heatsinks removed for better view.

Main board overview.

Looks like it's true rating is a 1000W inverter. The design version appears to be fairly old.

Main DC-DC converter controller board. Different from others I've seen but still based on SG3525 and a quad op amp.

Back of the DC-DC controller sub board.

Input bulk caps are no name chinese caps.

Output bulk caps appear to be genuine Nippon chemi con caps but they can counterfeit anything so...

Primary switchers are MXP6004CTS N Channel MOSFETs, four per transformer.

214A 60V rated devices.

Output rectifiers are MUR1660CT diodes.

Output H-bridge MOSFETs are FDA28N50.

28A 500V rated parts.

Protection LED glows a little dim even on normal operation.

That could be an issue when someone unfamiliar looks at it and wonders if the protection is really triggered or not.

Idle current is pretty low at 400mA. I like this. It should be not much of a problem leaving this on 24/7 on a moderately sized RE setup.

Back to top of page

       Now for the big one. This one is a TBF 6000W but it is a 24V input so I was not able to power it up. I just took a peek inside.

Inverter packaging.

Here it is. It is rather large.

Popping the front plate off, I see a large internal heatsink.

With the bottom plate slid off. There appears to be a bunch of rework and a bodge wire but I don't see solder covered traces for the high current paths.

Overview of the main board.

DC input terminals are bolted directly to the PCB.

The inverter is internally fused with six 35A fuses.

Hmmm. Interesting.

I guess there was no heatshrink tube available so they taped it. Ugh.

Silpad insulators appear to be a little mangled. No, I did not do that.

The internal heatsink for the H-bridge and output rectifiers is pretty big.

Heatsinks removed.

Front area of the main board. We see the main control circuitry.

Lots of optocouplers and a PIC microcontroller. Looks like the main power management control.

PIC18F22K

Another PIC. PIC16F1937. This one appears to be for driving the display and communicating through the RJ45 connector.

Smaller caps are the cheapie Chong caps.

Output bulk caps appear to be genuine Nippon Chemi Con caps.

These appear to be the drivers for the primary switchers.

Input primary switchers are FTP11N08 MOSFETs.

100A 75V rated parts.

And there's a lot of them!

Output rectifiers are MUR3060CT.

30A 600V rated, pretty beefy parts.

Four pairs of output H-bridge MOSFETs.

Output H-bridge MOSFETs are FDA28N50.

28A 500V rated parts.

Output noise filtering is populated.

Interesting, that the output current is sensed by a current transformer. Not a cheap resistor.

There is a snap in ferrite for the AC output leads.

Snap in ferrite filter and local regulators underneath.

like I was expecting. The LED leads broke!

Solder splatter on the LCD board!

       There's a lot to be desired in the build quality but it seems to do the job albeit marginally. The sticker is overrated but if it is run within half the sticker rating then I guess it should do fine. With the price, you can't complain!

Page created and copyright R.Quan © 11 May 2015.