Author Topic: My poor mans SMU - The Agilent 66311B  (Read 72586 times)

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Offline HighVoltage

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Re: My poor mans SMU - The Agilent 66311B
« Reply #175 on: November 10, 2016, 09:52:36 am »
- the thing is now spinning but noisy as h.. :) But very precise and works well.

If you add a 100 Ohm resistor in line with the fan supply, it gets much quieter and still has plenty of air flow.
Or you use an ultra quiet fan with built in temperature control.
I have two of these and they are both very quiet now.

There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline georgd

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Re: My poor mans SMU - The Agilent 66311B
« Reply #176 on: July 07, 2018, 07:16:05 am »
As owner of a 66311B unit with dim display finally decided to replace it with a new one. A seller on ebay offers many types of VFD
 replacement displays for HP power supplies.

The 1st one is for $130:
https://www.ebay.com/itm/HP-Agilent-Keysight-VFD-For-66311A-66312A-6632A-Vacuum-Fluorescence-Display/123034228542?hash=item1ca569573e:g:meYAAOSwhktas22x

The 2nd one is for $85:
https://www.ebay.com/itm/HP-Agilent-Keysight-VFD-For-6634B-Vacuum-Fluorescence-Display/122895199356?hash=item1c9d1fec7c:g:cy0AAOSw4PxaTZug

Only differences I observed is a tiny  bars under sign "OUTPUT AC +DC" in the rightmost lowest corner.
The 66311A version's sign "AC +DC" are underscored but on 6634 version I do not see it.

Do I have to pay 50% for dedicated display?

Georg

 
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Offline hakko

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Re: My poor mans SMU - The Agilent 66311B
« Reply #177 on: October 05, 2019, 02:06:03 pm »
Hi! Anyone knows a hack to enable rs232 interface on 66309D series?
 

Offline nctnico

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Re: My poor mans SMU - The Agilent 66311B
« Reply #178 on: December 25, 2019, 10:21:42 pm »
I finally did some hacking on my Agilent 66311B. The biggest let down is the loud fan but no binding posts on the front panel was also lowering the apeal of this otherwise very nice PSU. The PSU is just too good to leave it sitting unused in a corner so I decided to do some hacking to it. First I put some standard binding posts on the front panel and made a cable which connects the bindings posts to the front. I used seperate sense wires which connect at the binding posts.
896542-0
I used white braided sleeving (cheap from Ebay) and glue lined heatshrink tubing (also cheap from Ebay) to make a nice wire loom which I then snaked through the PSU. The green plug goes into the output header at the rear of the PSU.
896556-1

Last but not least I replaced the fan. I used a Noctua NF-A6x25 FLX (60x60x25mm) fan which has half the airflow and pressure compared to the original fan. But since my PSU only has 1 channel and HP/Agilent tends to oversize the fans anyway I'm sure it won't be a problem. The fan is a direct replacement which plugs in with the supplied cable.
896552-2
The original fan has a piece of FR4 sitting between the heatsink and the fan. My guess is that this is to protect the wires from the fan. The Noctua fan however has the wires deeper into the fan's housing to they can't touch the heatsink.

The end result is very good. The noise from the power supply went from obnoxious to almost whisper quiet. At full load the fan spins at the maximum RPM and at that point it becomes audible but the amount of noise is very low.
« Last Edit: December 25, 2019, 10:53:01 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline JxR

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Re: My poor mans SMU - The Agilent 66311B
« Reply #179 on: December 26, 2019, 07:41:20 am »
Last but not least I replaced the fan. I used a Noctua NF-A6x25 FLX (60x60x25mm) fan which has half the airflow and pressure compared to the original fan. But since my PSU only has 1 channel and HP/Agilent tends to oversize the fans anyway I'm sure it won't be a problem.

I have the same fan in my 66321B.  It is so quiet the first time I turned it on I thought it must have gotten disconnected during the reassembly.  It really does make a huge difference.  I never did an extended load test at 3A to see if it would overheat with the loss in airflow.  I did test it at 1.5A for about 15mins after I first installed it, and it performed fine.

Now if I could just find a solution to the fan in my Keithley 238.  All attempts to quiet that monster have failed.
« Last Edit: December 26, 2019, 07:43:37 am by JxR »
 

Offline JxR

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Re: My poor mans SMU - The Agilent 66311B
« Reply #180 on: December 26, 2019, 10:38:03 pm »
I took the 66321B up to a 30W load today with the Noctua NF-A6x25 FLX installed.  This was over the course of about 30mins, with a load of 30W for about 10mins.  The overtemp protection did not kick in.  So, it seems in a room at ~21C 30W is fine. 

I don't plan to test it up to the max @45W since it exceeds my personal needs for the supply.  This unit is not my main power supply and I rarely would need more than 15W out of it.  I think most people with a supply in the 663xx family would be very happy with this fan.
 

Offline mark03

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Re: My poor mans SMU - The Agilent 66311B
« Reply #181 on: December 27, 2019, 02:12:50 am »
I have a couple of this model's big brother, the 66332A (20V, 5A).  They are more of a pizza-box size but have the same wind-tunnel heat sink and deafening fan noise.

You have inspired me to investigate a slower/quieter fan.  I would definitely use them more if they weren't so loud.
 
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Offline kirill_ka

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Re: My poor mans SMU - The Agilent 66311B
« Reply #182 on: September 25, 2020, 09:43:12 pm »
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.
I know that post is 4.5 years old... I've bought an older version of 66311B (which is called "through hole pcb" in the service manual). Initially I thought that slow switching to CC mode is a fault of my unit. Especially after the seller confirmed that his 66311B is faster. Then it appeared that he was using a newer revision for the test.
While trying to solve the "issue" I found that the main analogue PCB is identical to the HP 66312B. And it does have schematics in the service manual! It looks like HP engineers deliberately sacrificed CC mode  in favor of peak current performance. The attached picture shows the main differences in current control circuit.
 
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Offline Shannon

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Re: My poor mans SMU - The Agilent 66311B
« Reply #183 on: January 30, 2021, 04:04:59 pm »
Could we use those part of this broken 66311B to build a higher power DC supply?

Maybe we can parallel the main power Mosfet or BJT, and modify voltage feedback and current shunt resistors, using higher power transiformer

if somebody has done this work, please give me some advise.

sounds like it's not hard to upgrade, and to get much more powful.

the drawback is we should be clear about those value on display is fake  ;D
Nature and Nature's laws lay hid in night:
God said, Let Newton be! and all was light.
 
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Offline vaualbus

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Re: My poor mans SMU - The Agilent 66311B
« Reply #184 on: September 09, 2023, 12:18:00 am »
I know this blog is olddd
But I need some help. I got my hands on the 66309D model of this supply with some eeprom corruption problem (The DVM measure were not accessible) so I clean the EEPROM loosing calibration but that is not a problem for me. Unfortunaly doing so I also lost my SN and option.
I see in this video of keysight around 1:49 there is a DIAG:SN option to set the SN via GPIB.
I try to write a script but is failing saying it is not liking the serial number format. Apparently it expect something that is not text for parameter?
I am new at pyvisa so maybe I am doing a stupid mistake?  :-DD

 First enable calibration
    foundInst.write(":CAL:STAT 1")
    # Send the serial number, it must be sent as ascii
    foundInst.write(f":DIAG:SN US39071080")
    # Save calibration
    foundInst.write(":CAL:SAVE")
    # Disable Calibration
    foundInst.write(":CAL:STAT 0")
    # Close the instrument.
    foundInst.close()

Returned error is -148 that for the user manual is: -148: Character data not allowed

Now are there a way to also enable option?
Because I lost both output as I have the option 521 installed so the output are switched using mechanical relays and of course now the isntrument things it has no option so it never turn on the output. (I verify with a multimeter following the SM that the output rails have the correct voltage!)
 

Offline Hydron

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Re: My poor mans SMU - The Agilent 66311B
« Reply #185 on: January 13, 2024, 04:16:24 pm »
If anyone is interested, see attached FW image for 663(19/21)(B/D) version 3.01. This is the firmware which supports datalogging as per some other threads, e.g. https://www.eevblog.com/forum/testgear/66319b-firmware-image/.

This came from my 66309D, which was sold "as-is" as a 66319D, with the 66319D firmware, front label and FAKE rear serial number sticker (the real one saying 66309D was still underneath). The price however wasn't high even for what I got vs what it was sold as (about 90 GBP shipped) and it wasn't obviously broken other than lying about the model name so I didn't make a fuss. Some observations about changing firmware and other oddities on my unit:
- The hardware clearly isn't that of a 66319D, as it is missing the extra PCB with analogue multipliers etc used for the output resistance control function.
- Running 66319D FW on a 66309D seems to work for the most part - the 1A range (unique to this model) is broken and resistance setting does nothing. I didn't test the fast datalogging capability but I suspect it will work given there is no difference in the logic/ADC board. This may be of use to those who want the fast datalogging on a model which doesn't support it otherwise, and are happy with losing current autoranging capability (manual range set is still OK if you avoid 1A).
- The EEPROM holding calibration etc is not necessarily compatible between the different FW types (in my case trying 66309 and 66319) - I had to put either a 66309D EEPROM image (thanks "TheSteve" for helping with this) or blank it totally to run the correct 66309D FW, otherwise I was seeing issues like the fan not running.
- After changing the FW or EEPROM image you need to do the initialisation procedure and calibration, and for a blank EEPROM also set the SN as noted here: https://www.eevblog.com/forum/repair/hp-66309d-issues
- My unit had a zero ohm link fitted at R427 (with flux everywhere - clearly not factory), which broke the 20mA range, DVM and 2nd output measurements by stopping the analogue mux which switched these into the ADC input from selecting the right channel. Major WTF as to why this was done, removing the 0R link fixed all this.
- It also had U327 obviously removed - this is a LM311 used for overvoltage detection; replacing it restored this function (another WTF)
 
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Online TheSteveTopic starter

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Re: My poor mans SMU - The Agilent 66311B
« Reply #186 on: January 13, 2024, 11:43:08 pm »
You have to wonder what the previous owner was trying to do to the poor thing.
VE7FM
 

Offline vaualbus

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Re: My poor mans SMU - The Agilent 66311B
« Reply #187 on: March 20, 2024, 09:06:28 pm »
I am wondering If having an image of both a 66319D and 66309D, patch the 309D fw to enable the logging stuff! I suspect the supplies use the same code base, also imaging be able to reproduce the analog mux board and add an option to have the resistance also on the 66309D!

Also I think I was going to buy your instruments (if you get it on ebay), I guess I am lucky I didn't at the end  :-DD :-DD
 


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