HOPI HP-9800 Power Meter – Australia mods

*** Note that this information describes the changes to and modifiction of 240 AC equipment which can be lethal if mistakes are made. If you are not knowlegeable please do not attempt any modifications you may put yourself or others in peril. I am not available to guide or advise in this area. ***

Note also that I can be pretty slack in posting or checking my website.. it is free to look at though! Don’t expect follow up or responses to questions but I will help if I can. – Mister Meaargee.

I recently obtained a HOPI meter after seeing Big Clive use one for quite a while now. I recommend you watch his video – (https://www.youtube.com/watch?v=2HQGXZU2d4I&t=618s).

I like the meter, it seems quite accurate for what it is but I had a few concerns…
1. The AC outlet was a ‘one size fits all’ power outlet, which I wanted to convert to an Australian three pin GPO (General Purpose Outlet). I understand that this is the same outlet that’s used in China (although inverted), which led me to the next issu..
2. The AC inpiut lead ended in a three pin plug that, although works, is inverted here and fouls most power switches. The AC lead itself seems robust enough with decent conductor diameters.
3. The ‘Auxiliary output’ through a set of speaker terminals, this is not fit for purpose in my view and the terminals are only suitable for low voltage or audio uses. It is easy to touch active conductors on these terminals.

The biggest job is to replace the AC receptacle on the meter. This socket is also a little dangerous as you can access unprotected live terminals via a removeable plastic cover.
I found a flush GPO socket at Jaycar Electronics (as of Jan 2021 – https://www.jaycar.com.au/mains-panel-socket/p/PS4094) which should do the job.
I wanted to make as few mods to the actual case as possible and I figured this might fit.

It would fit but not without some help, I then designed a mounting block for the socket and 3D printed it (https://www.thingiverse.com/thing:4744289). After several iterations of design, I finally had a design I was comfortable with. The design was done in Sketchup, exported as an STL, then sliced with Cura before printing at 2mm layer height, with supports, in PLA.
Note that when the ‘Universal’ socket is replaced the Active and Neutral terminals are swapped around physically and the short lengths of copper connecting to the original socket will need to be replaced. I did so with more robust wiring. The new socket is less likely to cause an electric shock from the rear as the terminals are recessed.

I will change the power plug in the future and I’m also thinking of putting a high current IEC power socket to replace the lead but I cannot find a ‘keyed’ IEC socket righ now. This would ensure that the power lead used is up to the current carrying erequirements (I hope). A standard IEC would let me use any cheap, poorly made, aluminium cinductor IEC lead.
The speaker socket holes need blocking but I might have another idea for them…

Here is the pictorial … enjoy!

The HOPI disassembled with the GPO socket installed and the universal socket and speaker quick connectors removed to the left.

The adaptor I designed to fit the new socket in place

The socket in place, the front cap holds it all together OK but I did add mounting screws that are obviously missing in the photo

The socket installed and wired up. The two red wires to the left are the original socket wire connections.

‘Just like a bought one’ – the meter in use. The holes below the socket are from the speaker connector and I’ll fill them later.