EEVblog #667 - Agilent 6643A Power Supply Binding Post Hack

[miguelvp]

I wonder what Agilent's design is?

I believe the picture in reply #5 from Monittosan:

https://www.eevblog.com/forum/blog/eevblog-667-agilent-6643a-power-supply-binding-post-hack/msg520401/#msg520401

Shows the Agilent's options:



Edit: But Dave's mod also gives you mains earth as well.

[EEVblog]

This is an example of when having a basic, even "less than basic" mechanical shop facility would come in handy.  (mentioned when Dave was considering re-locating)

Yes. At present I don't even have a drill in the lab.

[SeanB]

Not even a cordless one? I had so many I resorted to giving the least loved 4 away, so that I only have around 5 basic drills and a rotary hammer now. One was still new in box, it came as a kit with a planer and a tool soft case for no more than the planer itself. I wanted the tool case and the planer, power planing is a lot better than sitting with a Skil saw and a plane to fit doors, especially if you have to trim 5mm off each side.

[phamuc]

Hello Dave,

I have made this mod to my HP power supply, that I picked up off ebay.
The banana binding post I also picked up from ebay from a Chinese company. These binding post are standard dual binding post.
I did not have to mod the panel, (no drilling), only cut the thin plastic cover foil. These post fit like a glove. No I have not added the mod to the sense lines, but could add a second set of posts, to give me front panel access to output and sense and still have room for a ground post. HP seems to used a generic base front panel for bench power supplies and Multimeters, just stick the right custom foil on. The post have the standard spacing, the same as a DMM. (and strangely the same spacing as an Euro plug!)
I have crimped and then soldered the lugs on, not solder then crimped, you are only asking for trouble  . Dave, why do you not like soldered lugs? I have experienced that just crimp lugs, the wire can and does sometimes come loose, but not crimped and soldered lugs. In my HP supply, the connector on the PCB, for the front panel assy.  was already mounted, I just had to add the cable harness with the correct plug for the PCB connector.

Oh, and the Fluke meters and HP power supply I bought on a buying spree on ebay, after watching some of  Dave's excellence videos on YouTube. My wife thanks you very much Dave 

The Dummy loads are H4 car headlights. What else do you with blowen normal beam light but the Hi-Beam light part is still good?
Throw them away...NOooo.

Dave are going to be at electronica this year?

-Paul

[mgebha]

About a year ago I also added binding posts to my HP6632Bs: They now do have 5 connectors (+/-, sense +/-, mains earth) and a little switch for directly connecting the sense wires to the output: http://www.jave.de/blog2/wp-content/uploads/2014/09/front_diagonal.jpg

In order not to completely destroy the decent look of the front panel, I also have designed a label. It can be printed using any photo printing service as 10cm x 15cm photo: http://www.jave.de/blog2/wp-content/uploads/2014/09/10x15_hp6632b.jpg.

You can read the complete report of this hack in my little blog at http://www.jave.de/blog2/?p=199.

[AndyC_772]

I didn't fancy punching holes in the equipment at all, so I mounted the binding posts in a separate box and attached it to the rack mount ears.

[hammy]

What about some scrap pcb then drill and epoxy it to the back of the front panel it would give you a solid base to work with.

I was shouting that out when Dave was going at the panel with the scissors...  Dave, good job you did not show how the back of the posts in the unit. 

Me too! 
Especially because he owns a 3D printer and it is easy possible to print a matching carrier material to hold these posts ... 

But it is his HP unit. He can do whatever he want ... 

[Riotpack]

It does the job, no need for it to be perfect. I would have a LED near the front binding posts to show when remote sense was switched on rather than have to look around the back or measure under a load to be sure.

[EEVblog]

It does the job, no need for it to be perfect. I would have a LED near the front binding posts to show when remote sense was switched on rather than have to look around the back or measure under a load to be sure.

Yeah, good point.

[djacobow]

Despite his protestations about not being bothered, Halfway through the video I was 100% sure there was no chance Dave was actually going to re-assemble that power supply without bringing the sense line to the front.

There were just too many digits of voltage accuracy goodness to let drop on the floor!

[SArepairman]

I did a binding post hack on mine recently.



My approach was a bit different (I'm using glue, I don't have any serious tools in my house). And I had no binding posts on hand.

As soon as everything sets I will install it on the front panel. I love that this hack was brought up, my 6643 was collecting dust.

Andy_C, I don't like your mod. It is easy to knock it off, it is a potential safety issue, the wire could get snagged.

edit: glue is set, it works great, can hold banana plug just fine.

[poundy]

What about some scrap pcb then drill and epoxy it to the back of the front panel it would give you a solid base to work with.

I was shouting that out when Dave was going at the panel with the scissors...  Dave, good job you did not show how the back of the posts in the unit. 

Me too! 
Especially because he owns a 3D printer and it is easy possible to print a matching carrier material to hold these posts ... 

But it is his HP unit. He can do whatever he want ... 

The 3d printer was what I first yelled at the screen hoping he'd hear.  Print some dinky inserts and that'd be 86.4% better than a random hole like that

[RupertGo]

It's standard irregular verb conjugation, in this case of the verb 'to mod'.

I implement an appropriate engineering solution given time and resources
You bodge that one up a bit, you do know epoxy isn't a liquid bolt, right?
They make a real how-ya-doin' pig's ear of an arse of that one. Shocking.

[wreeve]

Apparently you can use these PSU's as a DC programmable load (to sink current) to 25% of their rated current. Might be worth a quick video to demo this Dave? I am awaiting my eBay purchase of the 20v 10amp version to use for this purpose!

[simingx]

Apparently you can use these PSU's as a DC programmable load (to sink current) to 25% of their rated current. Might be worth a quick video to demo this Dave? I am awaiting my eBay purchase of the 20v 10amp version to use for this purpose!

Simply set the output voltage to something below your expected input (or just 0V), and set the current limit to whatever you want to sink from the external source...

[sprocket]

Just picked up the Agilent 6653A from an auction of surplus equipment from Cobham satcom. Paid a tad over 600dollars which was a bit more then what I wanted too, but equipment like this very very seldom gets put up for sale here in Denmark, and when they do, it is very overpriced.   People are still trying to flog off old phillips 50Mhz analog scopes for +500 bucks on our local version of Ebay.. bloody insane. And further more I can pick it up in my home town, I really dislike buying expensive stuff over ze interwebs. Too many scammers around.

I will definitely be doing this modification to this PSU.

[lausvi]

I didn't fancy punching holes in the equipment at all, so I mounted the binding posts in a separate box and attached it to the rack mount ears.

I didn't either.
As I have no rack to mount my 6632B, I 3D-modeled the rack mount ear and put the posts into there. Cables are routed to the back of the unit. Looks pretty nice and is completely reversible. I made a version with 3-posts (mains earth on the panel) too but ended up using the two-post version as the posts would block access to the mounting scews and I didn't want to make a too close fit to get all stuffed in.

This was my first serious attempt to model and 3D-print anything actually usable so it took at least seven revisions and several fails to make the final product 

It doesn't show in the pics, but there are also sense-wires going behing the thick wires.

EDIT: now uploaded to thingiverse: https://www.thingiverse.com/thing:4563144

[kjn4685]

Great job on the deck. Looks professional and well constructed.  Again good job

[The_Parp]

Hi Everybody,

I know this topic is old. I took the idea from the video that is old too. Just finished mine.

 

I decided to port the sensor on the front too.

There is one thing I don't understand,
I wonder why only the " - " sensor terminal is required to obtain accuracy? When I unplug the "+" sensor terminal from the load, no change in voltage.

[TizianoHV]

Nice work!

It could be a wiring error, try measuring the resistance between S+ and + (it shouldn't be a short circuit). You could also try applying a load and see if you get good load regulation (connect a multimeter across the sense posts and see if there's a voltage drop after applying a load).

I don't get how you connected the binding posts, I would expect:
S+    +
S-     -
none  Ground

But they seem to be connected like this:
+    +
-     -
S+  S-

A bit weird but if you prefer them that way ok.


PS: Just a sidenote, it would be better to twist the sense wires.

[TizianoHV]

You could do it this way:
Sense and source side by side, ground and if you want you can use a 2 contact switch to choose between internal/external sense without need to to use jumpers.

[The_Parp]

Yes, I wanted 2 sets of posts on the output. Custom Style!
The regulation is perfect but affected by "-" lead only.

PS: Just a sidenote, it would be better to twist the sense wires.

Thanks for the tip!