Author Topic: My poor mans SMU - The Agilent 66311B  (Read 49430 times)

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Offline TheSteve

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Re: My poor mans SMU - The Agilent 66311B
« Reply #125 on: March 10, 2016, 09:36:00 pm »
ve7xen - nice job on the repair, and the power jack install. If you have hot air to remove a PLCC device they are quite nice to work with. Installing them can be a bit of a pain if you don't have a fine enough tip or can't get the soldering iron angle needed.

I just got an Agilent 6632A which uses the same controller board as the 66311B, but it allows for full control over current sinking. I dream of finding a firmware rev that allows the same for the 66311B.
VE7FM
 

Offline edavid

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Re: My poor mans SMU - The Agilent 66311B
« Reply #126 on: March 10, 2016, 09:48:06 pm »
My choice was to bring the 'remote' sense lines from the connector to the front panel and short them directly to the output there. Without adding a switch, this means I won't have remote sense capability, but that was a feature I was unlikely to ever use anyway.

It's usual to connect the front panel jacks to the sense lines through "small" resistors - then you can still hook up remote sense wires, which apply the real remote load voltage to the sense inputs.

Depending on the design, it can be tricky to figure out an appropriate value of small.
 

Offline ve7xen

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Re: My poor mans SMU - The Agilent 66311B
« Reply #127 on: March 11, 2016, 05:52:01 am »
I noticed this in reading the user manual:
Quote
Although the dc source can operate in either mode, it is designed as a constant voltage source. This means that the unit turns on in constant voltage mode with the output voltage rising to its Vset value. There is no command for constant current operation. The only way to turn the unit on in constant current mode is by placing a short across the output and then enabling or turning the output on.

So I decided to do some captures of the turn on behaviour, which might be of interest here. All measurements are done with a 1X probe, and all done with the output enable switch. I don't think that will cause any measurement issues for these, but let me know if I'm wrong about that.

Let's start with unloaded 15V:



Hmm curious glitch there before the supply comes online. I wonder if it's related to the program voltage or load, and if it might be a problem powering very sensitive...stuff that can't handle a ~2.5Vpp 100us spike.



Nope, doesn't seem to be. Very similar with a 50R load and 100mV program voltage. Looks to be almost exactly 8ms before the main loop starts, during which time the output goes negative, and looks the same regardless of parameters or load (I assume subject to the supply's drive capability). It seems to be related to the output enable/disable switching, as it doesn't appear when going from 0V to 5V with the output enabled. The overshoot also seems to be much more prominent here compared to with a higher output voltage, though it's not quite constant.

On to the 'start in constant current mode' tests. First I decided to test a capacitor directly hooked up to the supply, figuring this would be a challenge for the output amplifier. I selected a nice beefy 6800uF cap from the junk box and set the supply to 14V / 100mA:



So with this load, it looks like it takes 6-7ms for the current loop to kick in and regulate to a constant current. Not shown is charging, which looks nice and linear, and the switch back to CV mode after charging the cap also looks nice and clean, no hint of oscillation or ringing.

Next up is intended to simulate a high-power LED, as 4 1N4007 in series across the supply at 100mA and a 5V set point:



This one is very similar, as it takes 6ms for the current loop to kick in. Then we get what looks like a discharge curve down to the constant current. I guess this might be related to diode capacitance or maybe Vf changing as I goes down when we go into CC mode.

Finally the supply into a purely resistive 50R load, first in constant current configuration set for 100mA @ 14V:



Wow it's really slow to kick into CC mode with a resistive load! 220ms. My hypothesis is that the loads above would appear as nearly a dead short to the supply, pulling enough current to hit the 'peak' current limiter, and then ending up in CC mode after that. With the resistor, 14V/50R is only 280mA, so it runs that way for a while before the regular loop notices.

Finally a close up of CV mode into 50R, set to 5V/1A (the filenames are wrong on these, oops):



There are a couple more captures with my repair photos at http://gotroot.ca/66311b/
« Last Edit: March 11, 2016, 05:55:43 am by ve7xen »
73 de VE7XEN
 

Offline TheSteve

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Re: My poor mans SMU - The Agilent 66311B
« Reply #128 on: March 13, 2016, 01:07:33 am »
Finally received my banana jacks from china. Did a quick install this afternoon, so far I am pleased with them for $1.48 shipped. I ran the 4 wires and soldered them directly to the back of the banana jacks. Because of the depth of the front plastic face I used a pair of larger washers on the back side along with lock washers and one set of nuts instead of the backing plate included with the banana jacks. The jacks I bought were from ebay # 321513366620 but the price has since gone up. Removing the main board is quick and easy, just make a note/take pics of where all of the connectors plug in.
VE7FM
 

Offline stuartk

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Re: My poor mans SMU - The Agilent 66311B
« Reply #129 on: March 13, 2016, 02:09:15 am »
Hi Steve,

Nice banana jacks for the output. Where did you route the sense wires to?
 

Offline TheSteve

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Re: My poor mans SMU - The Agilent 66311B
« Reply #130 on: March 13, 2016, 02:12:41 am »
Hi Steve,

Nice banana jacks for the output. Where did you route the sense wires to?

The sense wires and main current wires are both connected to the banana jacks. So any voltage loss after the jacks will not be compensated for which is fine with me. I used much smaller gauge wire for the sense leads.
VE7FM
 

Offline mtdoc

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Re: My poor mans SMU - The Agilent 66311B
« Reply #131 on: March 13, 2016, 06:25:21 am »
Ve7xen and TheSteve -Excellent mods!. 

I'd decided not to add front panel jacks but now I'm tempted.

I especially like the recessed Pomona Jacks. Any ideas of a good source for these?
 

Offline TheSteve

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Re: My poor mans SMU - The Agilent 66311B
« Reply #132 on: March 13, 2016, 06:54:05 am »
You can buy a chinese 10 pack no noname ones for 3.89, ebay # 262238741920
Of course they might be decent, they might be total crap.
VE7FM
 

Offline mtdoc

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Re: My poor mans SMU - The Agilent 66311B
« Reply #133 on: March 13, 2016, 08:21:54 am »
You can buy a chinese 10 pack no noname ones for 3.89, ebay # 262238741920
Of course they might be decent, they might be total crap.
Thanks for the link. For that price they are surely low quality. On the other hand, how bad can it be given the very simple function?

I was able to find genuine Pomonas on Digikey for 2.60 each. I think I'll throw a couple in with my next Digikey order.
 

Offline TheSteve

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Re: My poor mans SMU - The Agilent 66311B
« Reply #134 on: March 13, 2016, 08:49:28 am »
At that price I'd go for the real Pomona's too.
VE7FM
 

Offline SKPang

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Re: My poor mans SMU - The Agilent 66311B
« Reply #135 on: March 13, 2016, 10:02:23 am »
Quote
I was able to find genuine Pomonas on Digikey for 2.60 each. I think I'll throw a couple in with my next Digikey order.

The problem with the Pomonas one is you can't attach bare wire to it. For a PSU I would prefer a version that allows bare wire.
 

Offline mtdoc

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Re: My poor mans SMU - The Agilent 66311B
« Reply #136 on: March 13, 2016, 08:02:40 pm »
Quote
I was able to find genuine Pomonas on Digikey for 2.60 each. I think I'll throw a couple in with my next Digikey order.

The problem with the Pomonas one is you can't attach bare wire to it. For a PSU I would prefer a version that allows bare wire.

That's a good point I hadn't considered. I suppose a short banana alligator lead would solve the issue but is less elegant. There's still the Phoenix connector on the back as well.
 

Offline timb

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Re: My poor mans SMU - The Agilent 66311B
« Reply #137 on: March 14, 2016, 01:28:20 am »

Quote
I was able to find genuine Pomonas on Digikey for 2.60 each. I think I'll throw a couple in with my next Digikey order.

The problem with the Pomonas one is you can't attach bare wire to it. For a PSU I would prefer a version that allows bare wire.

Sure you can! Just grab one of these: Pomona MDP Double Banana Plug

Simply insert wire and tighten screw. I use them with a few of my power supplies that have banana jacks instead of binding posts. They work great!
Any sufficiently advanced technology is indistinguishable from magic; e.g., Cheez Whiz, Hot Dogs and RF.
 

Online nctnico

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Re: My poor mans SMU - The Agilent 66311B
« Reply #138 on: March 14, 2016, 03:12:24 pm »
Quote
I was able to find genuine Pomonas on Digikey for 2.60 each. I think I'll throw a couple in with my next Digikey order.
The problem with the Pomonas one is you can't attach bare wire to it. For a PSU I would prefer a version that allows bare wire.
Sure you can! Just grab one of these: Pomona MDP Double Banana Plug
I don't like these at all. I rather have proper binding posts which take bare wire and 4mm banana. I have modified various pieces of equipment to have such binding posts.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline SKPang

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Re: My poor mans SMU - The Agilent 66311B
« Reply #139 on: March 14, 2016, 03:37:19 pm »
Some of the binding post I've seen doesn't have the hole for the bare wire. I'm tempted to drill a small hole through the thread for the wire myself.
 

Offline FrankE

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Re: My poor mans SMU - The Agilent 66311B
« Reply #140 on: March 26, 2016, 10:50:47 am »
I was looking at those earlier for cellphone test and repair and as a general PSU. I found one at £170. I logged in here to look for opinions on the kit and I've saved half of that.

Nice one, thanks
 

Offline SKPang

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Re: My poor mans SMU - The Agilent 66311B
« Reply #141 on: April 06, 2016, 07:11:52 pm »
Got some binding post but it didn't have a hole for the bare wire so I drilled a hole myself.

Didn't want to solder the wires to the PCB so I routed it to the outside. Not as neat but it will do.

 

Offline rrinker

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Re: My poor mans SMU - The Agilent 66311B
« Reply #142 on: April 06, 2016, 08:12:42 pm »
 Are those actual HP binding posts or are they the look-alikes that were posted a few posts back? Now seen on the unit itself, if those are the fakes, they sure seem to have the right look and color to match the rest of the design.
 

Offline SKPang

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Offline FrankE

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Re: My poor mans SMU - The Agilent 66311B
« Reply #144 on: April 06, 2016, 08:32:37 pm »
Good grief! How many tracking numbers can one package have. It cleared customs at CDG (Paris) on Monday.

Tomorrow, maybe.
I've got the missing Phoenix terminals. My one is also missing a front panel.
I had binding posts in my RS order but I took them out to put in my Digikey order but I'm not quite at £50 threshold for  free delivery yet.
I hope there's not too much wrong with it electronically or if there is, it's something I can handle.
 

Offline TheSteve

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Re: My poor mans SMU - The Agilent 66311B
« Reply #145 on: April 06, 2016, 08:40:22 pm »
I like the look of the binding posts as well, very much a factory look to them.
VE7FM
 
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Offline macboy

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Re: My poor mans SMU - The Agilent 66311B
« Reply #146 on: April 07, 2016, 12:40:12 pm »
Got some binding post but it didn't have a hole for the bare wire so I drilled a hole myself.

Didn't want to solder the wires to the PCB so I routed it to the outside. Not as neat but it will do.

...

...
Your sense wires should twist around each other, not around the current-carrying wires. Likewise, the current carrying wires should also be twisted with each other. They way you have done this, current fluctuations will induce voltages in the sense wires, messing with voltage regulation and possibly even causing stability issues.
 

Offline SKPang

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Re: My poor mans SMU - The Agilent 66311B
« Reply #147 on: April 07, 2016, 12:44:17 pm »
Thank you macboy, good point. I will take it apart and re do the wiring.

 

Offline FrankE

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Re: My poor mans SMU - The Agilent 66311B
« Reply #148 on: April 08, 2016, 11:33:57 pm »
Got mine today. No front panel, no knob. I already had ordered the Phoenix connectors
I've no supply rails. +15V -15V. The 5V rails are fine, front display.

F308 (5AM), F310 (5AM)  F303 (5AM) F306 (5AM) seem to have blown. I blew the chassis fuse with my DMM lead, d'oh but at least it was at the mains switch so I won't have blown anything in the DC stages  I've put Littelfuse axial fuses on my next RS order  What do they mean by M suffix on their fuse ratings?
Fuse speed is rated on RS by either T  (time delay), F (fast), FF (very fast)

I think I might have 15V, 5V and +15V regulators somewhere, just in case.

Table 3.3 p32 states to use the R431-4 on A1 board as a common. It's not evident which pin that is because there's no pinout marking on the component or board.

The fan is quite loud isn't it? The Papst is rated at 33m3/h 20CFM. Similar sized case fans are up to 16, so I wonder if the volume is a function of the pitch of the  impeller blades or if a lower air change fan would be sufficient.
 
 

Offline FrankE

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Re: My poor mans SMU - The Agilent 66311B
« Reply #149 on: April 10, 2016, 07:07:38 am »
I like the look of the binding posts as well, very much a factory look to them.
Yeah, me too. I don't mind a trailing lead from the back but there isn't strain relief unless one cable ties the test lead to the fan grille.
I found 'binding posts' [they are not binding posts just sockets] , that take shrouded leads Hirschmann SAB 2600 series (M4 thread), 2630 (solder pin), 2640 (solder bucket) , Multi Contact XUB (?M4)  Probably others, though I couldn't see Pomona ones Hope they are a proper 5 way and have the transverse hole for hook up wire.
[EDIT: No they are only sockets, i.e no threading to secure spaded leads, or bind hook up wire, no transverse hole for on the fly hook up wire.
If they can't take binding they ain't binding posts.]

If so, saves having duplicate sets of shrouded and bare leads
Seems odd that these have to be hunted down, I would have thought these would be the norm these days, not the exception.
« Last Edit: April 14, 2016, 08:06:15 pm by FrankE »
 


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