Author Topic: My poor mans SMU - The Agilent 66311B  (Read 49572 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

 

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?
 

Online 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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