EEVblog #281 - BK Precision 8500 Electronic Load Teardown

Featured Chips:

Teardown Tuesday.
What's inside BK Precision's 8500 300W 120V/30A DC Electronic Load?
It is also known as the Itech 8512.

Dave's DIY Simple Constant Current Dummy Load:

[insonicbloom]

I know why they laid out those DIP ICS the way they did, cause it looks more like a little town, when laying out PCBs I usually am not happy unless it looks cool, I will spend a day after laying a board out just trying to make it look nice
I love power supply stuff so this teardown was brilliant. thanks Dave.

[mariosliquid]

I agree. my point was that a DB9 connector is for RS232 that has around -15 +15 levels where in this machine they used TTL levels but with a DB9 connector.

[RVProject]

I believe the red stuff you are calling "locktite" is actually a varnish called "Glyptal". I remember the stuff way back when I used to work on aircraft communication gear to keep stuff from vibrating loose, and to QC each connection.

[PhattyMo]

SWAG: The TL084 DIP op-amps might be to drive the big MOSFET's, from the DAC? The DIP package might have higher dissipation, or something, so they went with that package. Just a guess!

[oldevil]

"it smells good" and "those thick inputs, love emm" Omg! Haha, u are an awesome geek who doesnt feel ashamed admitting it, gotta love this guy!

[EEVblog]

Yup! And most of the old stories are hard to share without photos or docs or whatever, both of which I kept very few of unfortunately.

[EEVblog]

And please share when done. There are plenty of DIY loads on the EEVblog forum.

[mjlorton]

Great video...nice useful piece of kit...need to add it to my wish list....
Look forward to the review.

[EEVblog]

Yeah, the x20 lens works great. Just need a stable mount for it because it has to get relatively close inside the gear to get those shots.

[CampKohler]

They might have put the xfmr up front to better balance the weight of the unit. The already have the heatsinks in the back, so if the xfrmr was there, too, it might have a clumsy, unbalanced feeling that could lead to dropping it (by we clumsy, unbalanced users).

[ddowlingau]

Got one of these about 3 months ago for some SLA charger testing and transient testing of a MOSFET switching circuit. It is a great unit and so much nicer than my home built MOSFET load.
The PC control works well. There is Python code for driving the unit so Linux support is no problem. The DB9 is TTL and not a regular pinout. I made up a cable using a FTDI TTL232 cable and DB9 plug. Not isolated but I will dig up pinout if anyone is interested.

[mikeselectricstuff]

The silicone guy went a bit nuts - even glued the white connectors that had latches!

[deathventure]

Yeah, it all depends on the system though. I've seen a documentary on a portion of the satellite tv wars that happened here in the States. Pretty interesting stuff that engineers were hired to do for corporate espionage. Acid that removed the plastic layers of a several hundred pin chip so he could figure out at the base layer and decode the chip's proprietary functions.

[EEVblog]

Could be. But I don't see a reason to measure that, the stability and tolerance are designed-in, and the cal takes care of the absolute value.

[ConradsStudio]

Can't believe I had a piece of kit before Dave did! :) I have this one's little brother (The 150W one). Very handy.

[ubuntututorials]

I've seen quite a few failed in monitors, but they are far better than say Capxon. In general, I think with the 1100 USD price tag, they could have used some better ones. Especially as a load tester gets very hot and is supposed to be reliable.

[EEVblog]

Yeah, seriously good value. The street price is $900, as little as $750 on ebay, and the 150W version is under $500 on ebay. Great value for such a niche bit of test gear.

[ginbot]

It bugs me so much when manufacturers etch out the labels on an IC...

[Whddee]

Thanks for sharing so much knowledge in such a casual, light manner. Very thankful. Great vid!!

[EEVblog]

You had to remove the front panel rubber to peel off the film.