Author Topic: An ugly but working HP6060B Electronic Load  (Read 5288 times)

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Offline Swake

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Re: An ugly but working HP6060B Electronic Load
« Reply #25 on: January 22, 2023, 09:39:07 pm »
Do I understand correctly that the L-shaped brackets that are used to connect the wires to the motherboard are actually original parts used by HP?

The pictures give the impression these brackets are made out of aluminium. I've always had the idea that because of the so rapidly forming oxidation layer on the aluminium it would be very difficult to create a good connection.
When it fits stop using the hammer
 

Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #26 on: January 22, 2023, 11:17:07 pm »
Do I understand correctly that the L-shaped brackets that are used to connect the wires to the motherboard are actually original parts used by HP?

The pictures give the impression these brackets are made out of aluminium. I've always had the idea that because of the so rapidly forming oxidation layer on the aluminium it would be very difficult to create a good connection.

I don't think they are made out of aluminum, that would have been not the best option in terms of conductivity given the 60Amp rating of the load, and I doubt HP would have made that strange choice. This besides the chance of electrolysis induced corrosion as you mention would have been I am sure very well considered. Those L brackets I would assume are plated copper if I am not mistaken. In any case something way better than aluminum.
 

Offline amc184

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Re: An ugly but working HP6060B Electronic Load
« Reply #27 on: January 23, 2023, 08:23:10 am »
The L-brackets are original.  When the binding posts are mounted on the rear panel they bolt directly into these brackets.

I'll have to look at them again, I'm not sure exactly what material they are made of, but it looks a lot like aluminium.
 

Offline Swake

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Re: An ugly but working HP6060B Electronic Load
« Reply #28 on: January 23, 2023, 08:25:59 am »
electrolysis induced corrosion
Wasn't thinking about electrolysis but indeed this might become a factor too.

I looked at that picture again and to be honest one will have a very hard time convincing me those brackets are not made out of aluminium.

Aluminium is a good electric conductor and it is used in many high current applications including wires.  That part I'm convinced it is ok. But the aluminium oxide layer that is formed so quickly when it is in contact with air is a very good insulator. Apparently bolting something on it is creating good enough conductivity.

Found several other pictures with the same brackets. Here is an example.
https://github.com/fivesixzero/hp-6060b-front-binding-post-mod/blob/main/images/binding-posts-installed-whole-device.jpeg
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Offline AVGresponding

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Re: An ugly but working HP6060B Electronic Load
« Reply #29 on: January 23, 2023, 10:41:28 am »
The brackets may well be aluminium, but the threaded inserts are going to be zinc plated steel.
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Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #30 on: January 23, 2023, 02:01:54 pm »
[I looked at that picture again and to be honest one will have a very hard time convincing me those brackets are not made out of aluminium.

By looking at the posted picture I have to agree. I did not have a picture of my unit of that area where they are mounted at the time of my earlier post, but will probably pull it from the rack sometime this week to replace the fan thermostat that I added with a lower temperature trip point one, so will have a chance to examine those brackets more closely.

Also agree that aluminum oxide (white powdery stuff) is non-conducting, so not a desirable compound to be present at electrical connections.
« Last Edit: January 23, 2023, 02:07:15 pm by AMR Labs »
 

Offline AVGresponding

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Re: An ugly but working HP6060B Electronic Load
« Reply #31 on: January 24, 2023, 10:13:33 am »
The oxide layer is pretty transparent at the few nanometres of thickness it has, and covers the whole surface. The only way to get a clean, pure surface, is to use a chemical cleaner, and it doesn't last very long. This is one reason that despite the much lower cost of aluminium, copper is still preferred for most electrical local supply installations (it is used for grid and supergrid, but that's a different story) because it's very troublesome to get a proper termination; you can't just make off an armoured cable and shove the ends into a connector block or crimp, you have to use special materials and techniques, and the connection is still more likely to cause problems over time.

When you stick your DMM probe on an exposed bit of aluminium frame or bracket, your probe tip breaks through the oxide layer. When inserts are crimped into an Al part, the electrical connection relies on displacing material to ensure a mating surface that is not exposed to atmosphere. It's still just a matter of time before they fail, and it won't necessarily be visually obvious, unlike with say, a rusty steel or iron part.
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Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #32 on: January 24, 2023, 02:31:45 pm »
I think for aluminum to oxidize the environment has to be quite damp (possibly even wet), probably not the case inside this instrument unless it is being stored somewhere humid enough, and then aluminum oxide forming would be the least of the worries. Most of the aluminum oxide I've seen in general  is usually caused by electrolysis (aided by dampness) for example between a stainless steel screw driven into aluminum. In those cases most times the screw is so tight that it will not turn so that for removal one usually needs to shear it off and drill a new hole for the next screw. But I diverge.
« Last Edit: January 24, 2023, 02:34:34 pm by AMR Labs »
 

Offline Bud

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Re: An ugly but working HP6060B Electronic Load
« Reply #33 on: January 24, 2023, 02:42:30 pm »
It's still just a matter of time before they fail, and it won't necessarily be visually obvious, unlike with say, a rusty steel or iron part.
I once had a factory made 100W RF amplifier, about 30 years old. The input and output connectors were riveted to the rear aluminum panel, yet none of them made electrical contact with the panel  :scared:
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Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #34 on: January 24, 2023, 03:56:36 pm »
It's still just a matter of time before they fail, and it won't necessarily be visually obvious, unlike with say, a rusty steel or iron part.
I once had a factory made 100W RF amplifier, about 30 years old. The input and output connectors were riveted to the rear aluminum panel, yet none of them made electrical contact with the panel  :scared:

The probably anodized aluminum panel, as many similar radio equipment of their time used, and on which those connectors where mounted, did surely not help much with proper contact either. By using rivets instead of proper screws/nuts with star washers obviously points to that manufacturer wanting to skimp on costs and not really caring much about long term reliability.
 

Offline AVGresponding

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Re: An ugly but working HP6060B Electronic Load
« Reply #35 on: January 25, 2023, 06:40:35 am »
Al oxidises very aggressively, hence its use as the "fuel" in thermite. It does not need to be damp; that's only a factor in galvanic corrosion.
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Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #36 on: January 25, 2023, 02:20:40 pm »
Al oxidises very aggressively, hence its use as the "fuel" in thermite. It does not need to be damp; that's only a factor in galvanic corrosion.

Yes I agree its a product of galvanic corrosion, but damp or wet surfaces are better conductors than dry, so the galvanic process is accelerated which in itself at the end is a flow of electrons between two dissimilar metals, hence electrical current.
 

Offline AVGresponding

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Re: An ugly but working HP6060B Electronic Load
« Reply #37 on: January 26, 2023, 09:31:05 am »
Al oxidises very aggressively, hence its use as the "fuel" in thermite. It does not need to be damp; that's only a factor in galvanic corrosion.

Yes I agree its a product of galvanic corrosion, but damp or wet surfaces are better conductors than dry, so the galvanic process is accelerated which in itself at the end is a flow of electrons between two dissimilar metals, hence electrical current.

Yes, but my point is that Al will oxidise in a completely dry environment.
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Offline jwrodgers

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Re: An ugly but working HP6060B Electronic Load
« Reply #38 on: February 14, 2023, 02:04:44 am »
(UK electricity distribution referenced...)
I have experience in electricity distribution systems, particularly in low-voltage power at 400/240 V. In modern systems, most cables are made of aluminium and have a cross-section of 300 mm2. These cables are terminated at low-voltage fuse panels and down the feeder near properties have service joints that connect them to copper or Al cables to take the power into houses.

Connections at the source end are usually made using clamps with a bolt that shears at a specific torque. Based on my experience, these clamps are more than capable of carrying 400 A without causing issues. Any oxidation or resistance buildup could generate significant heat. Therefore, aluminium as a conductor is suitable, as long as the contacts and terminations are clean and bright during connection.

btw... all good conversation :)
 

Offline AVGresponding

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Re: An ugly but working HP6060B Electronic Load
« Reply #39 on: February 14, 2023, 06:11:18 am »
The only Al conductors I've seen in mains supply have been ones we're ripping out, that were fitted decades ago   :-//

Though I'll grant you, the biggest supply I've worked on was 270mm2 4C Cu x2, fused at 1250A/ph before we replaced the panel board, and incomer from the substation.

The biggest Al cables I've seen, probably a decade ago, were no bigger than 120mm2 or so, one particularly ugly one being a 2C quadrant cable, with half-moon cross sections. No way you're terminating that into a regular crimp, which means, as you say, an adapter with a shear bolt for each conductor. All that adds size as well, which in todays penny-pinching boards that are ever reducing in size to save on materials, is yet another disadvantage. These were used to supply various DBs from a main panel board at a municipal swimming pool, and were all replaced with nice Cu cables.
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Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #40 on: February 14, 2023, 12:27:47 pm »

Once I've received the new aluminium backed PCB panels I've ordered I'll check they work, and if so I'll post the gerbers up here for anyone to use.


Just curious if you might have received the PCB panels and how did they end up working out.
 

Offline amc184

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Re: An ugly but working HP6060B Electronic Load
« Reply #41 on: May 14, 2023, 12:20:02 am »
I finally got around to adding those front panel boards added to a PCB order, and got them back last week.  This weekend I got them assembled onto the three units I had in mind, a 6060B, a 6632A and a 6644A.

All three worked well:


What they look like on their own:


I also made a blanking plate for the rear of the 6060B:


I've attached archives for each panel:
  • 6060B FSP A1 GBR.zip - front panel for 6060B, should suit 6060A, 6063A and 6063B as well.
  • 6060B RSP A1 GBR.zip - rear blanking panel, suits same as above.
  • 6632A FSP A1 GBR.zip - front panel for 6632A, should also suit 6633A and 6634A.  Might also suit 663XB series and others as well.
  • 6644A FSP A1 GBR.zip - front panel for 6644A, should suit 6641A, 6642A, 6643A and 6645A.  Might also suit 654XA series and others as well.

Each of these ZIP archives contains the following files; GOL (board outline), GTL (gerber top layer), GTO (gerber top silscreen), GTS (gerber top soldermask) and TXT (NC drill).  The GTL file is empty in each, but I included it because if it's included you do get a preview with JLC PCB.

The panel for the 6644A includes a ground and the 6632A doesn't because that's what's moulded into the front panel.  You'd have to ask HP why this is inconsistent.  The connector openings are 12mm in diameter and 19mm in pitch, except for the 6060B where they're customized to suit the original binding posts.  Note that because of the nature of the front panel moulding of the 6644A (which is made to take multiple binding post styles) two of the panel are needed for each unit.
« Last Edit: May 14, 2023, 12:31:12 am by amc184 »
 
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Offline amc184

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Re: An ugly but working HP6060B Electronic Load
« Reply #42 on: May 14, 2023, 12:29:37 am »
Also, while I was installing the new panel on the 6060B I rotated the binding posts as someone suggested to me.  The front panel has notches in all four directions, so they can be set to preference.

I used 4mm safety banana sockets on the 6632A and 6644A for a few reasons:
  • They don't sick out beyond the panel.  Binding posts feel very vulnerable sticking out from the front of one of these heavy linear power supplies, though I guess the knobs on the 6644A are just as bad.
  • I use a few cables with these that are terminated in safety banana plugs, so I like the compatibility.
  • Safety banana sockets seem to be higher quality.  I've never really come across a non-safety 4mm banana socket that I've really liked.

I've attached the 6060B panel ZIP archives here, they seem to have dropped off my last post.
 

Offline AMR LabsTopic starter

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Re: An ugly but working HP6060B Electronic Load
« Reply #43 on: May 14, 2023, 12:31:17 pm »
Very nice indeed. Can you please remind us where did you have these boards made? Thanks for posting the zip files.
 

Offline DavidAlfa

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Re: An ugly but working HP6060B Electronic Load
« Reply #44 on: May 14, 2023, 03:25:11 pm »
Any cheap PCB maker could do this nicely.
It's just the substrate (Without any copper on it) and the silkscreen.
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Offline amc184

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Re: An ugly but working HP6060B Electronic Load
« Reply #45 on: May 14, 2023, 06:55:11 pm »
That's right, these are just the substrate, soldermask and silkscreen, with no actual copper layer.  I had these made by JLCPCB, but others will do this fine as well.
 

Offline Ordinaryman1971

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Re: An ugly but working HP6060B Electronic Load
« Reply #46 on: October 27, 2023, 07:26:46 pm »
Did anybody make those panels 3D printed by any chance?
 


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