Agilent 66332A Dynamic DC Source 20V/5A Repair and mods

[nctnico]

As written in the text above a electrolytic capacitor has too much leakage so the current readback won't be accurate down to the uA level.

[OP27]

Hi all,
I am currently repair the device HP66332A.
The my device has a broken front cover.  (transparent display cover, VFD it is OK)
Where i can buy parts? I need the whole front cover.

I found the part number (service manual agilent): "5063-3426" Front Panel Assy, Std unit.
Nowhere can not find this part

The part can also be used. Thank you for any help.

[little.tesla]

Hello,
I know this is an old topic but I'm trying to get a copy of the original file which was located at http://helmut-singer.de/pdf/hp66312a.pdf
Unfortunately the company switched off their website and removed all files. I'm interested in particular regarding the custom mod J02 and I think there should be actually more mods described.
Can anybody help out?
Thanks in advance.

Best regards,
Dimce

[Berni]

What is the PDF supposed to contain?

[little.tesla]

mark03 with its "Reply #47" posted a text snippet describing the custom option "J02" of the 66312A. I'm hoping the other options (like J03 J04) are described in this document as well. I'm unable to find any information on the internet regarding this options. The newer manuals from Agilent don't mention them at all.

[korlatos]

I have the PDF file but couldn't upload it due to size limitations (>1MB). So I created a split ZIP file - part 1 is attached.

[korlatos]

Part 2 of the ZIP file. Please rename it to file.z01 before you attempt to combine them (eevblog doesn't allow upload of a file with a z01 extension).

[little.tesla]

Thank you very much for the file. I really appreciate it!

[Dwaine]

I just bought a Agilent 66332A and looking forward to the suggestions of putting front connectors with sensor wires.   

[Berni]

I might also need to get a broken one of these because it appears to use the same front panel as another instrument i'm working on (N3300A Load mainframe).

The problem is that a lot of the time something that is sold broken for parts is often easily fixable and then i feel bad stripping it for parts and am motivated to try and get a more broken parts unit.

[Dwaine]

I have a 6632B as well, from the pics they do look the same, likely just a firmware change. I also added front mounted binding posts.

My Agilent 66332A serial number MY4300xxxx has firmware version A.01.03 in an M27C202-70K6 OTP EPROM (2-Mbit, 128Kx16) with the part number 5080-2513 etched on it.

Attached is a binary dump of my 66332A firmware version A.01.03 if you are curious enough to try loading it on your 6632B. I also have a couple of 6632B and haven't gotten around to trying that myself yet.

My device has firmware A.00.08....   Looks like it was used once.  Just after it was unboxed from its initial purchase.

[beanflying]

I just bought a Agilent 66332A and looking forward to the suggestions of putting front connectors with sensor wires.

Should be much the same as what I did on my 6632B as per the photo below. I should have used some more upmarket Jacks I guess I used what I had at the time. The Gold plated link bars are modified audio ones.

[Dwaine]

I just bought a Agilent 66332A and looking forward to the suggestions of putting front connectors with sensor wires.

Should be much the same as what I did on my 6632B as per the photo below. I should have used some more upmarket Jacks I guess I used what I had at the time. The Gold plated link bars are modified audio ones.

I think they look great.  I really like the link bars!

[beanflying]

The Bars came from these guys. https://meniscusaudio.com/product/gold-shorting-barspr/ There online site doesn't love overseas transactions but you may do better at least being in the area.

Standard 19mm 3/4" spacings between the sockets as I sometimes use dual Pamona style jacks.

[matches]

Hi and a happy new year.
I'm new to this forum. Recently I picked up a 66332A and found usefull intel here. Immediatley I installed a third bodge (2 were already there) with the two ta caps not beeing ground referenced as Dr. Frank found and reported.
Thank you very much. The caps on mine seemed fine so I left them in. I think it does not have seen a lot of usage.

So I'd like to share some intel and quirks with you.
Attached you find foto of the inside. If you look really closely, you may spot two bodges on the interface board.

As some stated, the fan is a littla on the noisy side. On mine it had dust accumulated unevenly which leads to more vibration (see the dusty picture).
Papst has added a very small weight to balance it out, so I think this dust is noticable. After a clean it is better but still too noisy for my taste.

It's a Type 612 with rated 40 dBA with 24 cfm of max. airflow. Found a data sheet on dogo key (https://media.digikey.com/pdf/Data%20Sheets/ebm-papst%20Industries%20PDFs/600.pdf)

When switched on, it is run at approx. 8 V, so it is regulated. In the schematics there is a HS_Therm signal wired to pin 14 going to the interface board.
Yet I cannot find any sensor at the heat sink.

[matches]

So here is detailed view of the interface board.
On the back it says HP, the label on the front says Agilent, but looks like slaped on.
And, despite the very good condition, the knob was a little loose as well.

[Berni]

Yeah depending on the period its from you can get mixed HP and Agilent branding at times. The dark gray plate you got peeling off is actually one of the standard "nameplate" formats that are also used on other gear they make, so its possible the older ones that say HP are also glued on. For some gear all they do is swap the tiny silver HP bade with the Agilent star logo without it actually saying Agilent anywhere on the front.

At least they put more effort into it back then. If you get gear from just the right at the Keysight transition period you can get a scope where they simply put a little Keysight sticker on top of the exiting nameplate where the Agilent logo is. Naturally that sticker quickly found its way into the trash can. Tho upon updating the software there was suddenly Keysight logos in every possible place (On windows based scopes they even change the Win 7 login screen background and the desktop background to a giant full screen logo). By now i got a bit more used to the Keysight branding, but when they announced it i found it being the stupidest name ever.

As for the fan. Well if you put some engineering effort into it you could fit a blower cage style fan in here that could provide the same airflow with much less noise. You probably just need a 3d printed adapter to be able to mount it on. But then again even without the fan, then the transformer hum in this thing would then start to becoming the noisy part. Im guessing there is so much audible hum due to the strangely very flat E core transformer leaking a lot of field and vibrating the top and bottom covers panels.

I found a higher power alternative to my Agilent 66332A in the form of a Agilent 6050A (DC Electronic load mainframe), but you should hear the fans in that thing! There are two 120mm all metal casting fans running from 110V AC and use 20W each. Luckily the thing is so heavy that it doesn't end up flying off the bench when the fans turn on. I seen these huge 110V AC fans in other gear too so i plan on making a 110V speed controller board for them.

[matches]

As for the front terminals. In the servica manual it is stated to cut some jumper resistors (R456 to R459).
If all of the 4 pins of the connector for the FP option is used, the current flows to the front and back to the rear if the load is connected there.
If the load is connected at the front, two of the 4 wires carry the voltage back to the rear, so the sense terminals at the back can be used and they read the voltage at the front terminals.

One interesting thing: the service manual also has a schematic of the board for the front terminals.
They have included some caps a 4700 pF, 250 V and a 220 pF, 1 kV in parallel from each terminal to mains earth.
I wonder why that is. Some compensation for the additional cunductor and its inductance? Just capacitive coupling to earth?

If I were to add them should I use ceramics like X7R or NPO, or should I rather use foil caps?

As for the binding pist and the shorting links.
Pomona has the nice binding posts Model 3760 https://www.pomonaelectronics.com/products/hardware/binding-post-tin-plated
They have also the shorting links Model 4115 https://www.pomonaelectronics.com/products/hardware/shorting-link-binding-posts

The posts are available gold plated as well as Model 3750. They even have a low thermal EMF version, Model 3770. But I think thats not needed here.
Although in the metal case there is only a small cutout, the binding posts shhould fit. There is enough clearance.
Especially when using a mounting base. Which I'd prefer because of the pre cut front panel. I think it then gives more stability.
The base: https://www.pomonaelectronics.com/products/hardware/mounting-base-double-binding-post

[matches]

Haha I can imagine the meeting where they decided to change the name.
"Hey we haven't changed our name in a while. Lets change it to Keysight."
"Ouh yes, good Idea! "

Haha.. but as long as the performance and quality is there.

Funny, I've never seen a sticker as a label. They could have sold it as Agilent anyways.

I have checked with some older Pomona binding posts. They do fit. No interference with the metal casing.
There is like 1/4"  clearance.

[Berni]

Here is what the stickers look like (Photo found on google).


Well in this case they didn't put it over the Agilent logo. But they put this sticker on when the instrument was sent in for a calibration.

[beanflying]

As for the front terminals. In the servica manual it is stated to cut some jumper resistors (R456 to R459).
If all of the 4 pins of the connector for the FP option is used, the current flows to the front and back to the rear if the load is connected there.
If the load is connected at the front, two of the 4 wires carry the voltage back to the rear, so the sense terminals at the back can be used and they read the voltage at the front terminals.

One interesting thing: the service manual also has a schematic of the board for the front terminals.
They have included some caps a 4700 pF, 250 V and a 220 pF, 1 kV in parallel from each terminal to mains earth.
I wonder why that is. Some compensation for the additional cunductor and its inductance? Just capacitive coupling to earth?

If I were to add them should I use ceramics like X7R or NPO, or should I rather use foil caps?

I did see that on the schematic too but as I am as from the bush I just hacked into the back of the rear terminals and used 16AWG wire for the sense lines to minimize any voltage drop.  The Caps to Earth might be worth adding to mine so I will load it up and have a proper look for any stray signals on the output. Since I did that I also now have some plated copper shield I should put around the run with an outer of heatshrink as it passes close to the AC end.

Also need to look at doing the Mods as per Dr Franks thread that I hadn't seen before https://www.eevblog.com/forum/repair/agilent-6632b-fault-repair-and-several-design-flaws/msg1018796/#msg1018796 Death to the Tanty

Photo of my butchery 

[Berni]

Ah them darn tantalums again. Much like my repair of a blown tantalum on the digital board.

Then again at least they tend to be a easy fix. A shorted power rail is easy to notice and usually the caps catch fire so its easy to spot the black charred mess on the board so that you know exactly what capacitor to replace.

If they all look fine then just Ohm it out, or my method where i get annoyed and i just hook up a high current power supply to the shorted rail and let it push a ton of current in. At some point something gets hot, or catches fire to point me where the problem is.

[Ussovak]

The User manual clearly explains the difference between using the front posts and rear terminals.

See attached.