Any better way to use a HP 6625A than dragging cables from the rear outputs? - Page 1
Forum section: electronics / testgear

author: Tony_G
author_rank: Super Contributor
timestamp: August 03, 2016, 11:38:31 pm
content: Hi All,While I was buying a 3458A at auction it came with a 6625A System DC Power Supply. I wasn't particularly interested in buying it or using it but it was part of the lot.Now that I look at it, it seems to be able to provide 1 uA and 0.5 mV level control of the output - It might be useful to use that at some time.The problem is that the outputs are on the back - Does anyone have a better solution that creating my own terminal block and just wiring it to the back of the supply?There doesn't seem to be a lot of information or desire for these things around - I got mine from a facility shutdown of a Western Digital plant, maybe they simply aren't much use outside of specific test scenarios.Thoughts?TonyG

author: edpalmer42
author_rank: Super Contributor
timestamp: August 04, 2016, 03:42:46 am
content: I have the 6622A dual-output member of the family.I wired the output and sense leads via a 2 - 3 meter cable set to a terminal box. I can take the terminal box over to my bench rather than trying to bring the equipment to the supply. For the power leads, I used 16 AWG (~4 mm squared) stranded cable. For the sense leads, my junk box coughed up a nice piece of two pair, twisted, stranded cable with each pair enclosed in a foil shield. I put a spiral wrap around the cables to make a neat bundle. I couldn't have come up with a better cable if I tried!

author: Berni
author_rank: Super Contributor
timestamp: August 04, 2016, 05:15:17 am
content: I have a 4 channel version of it and i modified it to have front panel binding posts.Its not as simple of a mod as on some other supplies as these ware never designed to have any sort of front panel connections. The front panel PCB just covers the button area, but there is some sheet metal bellow it that needs to be trimmed back a little to make room as well as the typical drill some holes in the front panel.I have some photos of it somewhere.

author: TAMHAN
author_rank: Frequent Contributor
timestamp: August 04, 2016, 09:35:30 am
content: Hello,actually, dragging the cables is not so bad if you "adapt" to your situation. My HP 6624A is below a "bumper" to protect it from chairs driven against its front panel. And I created two cables which can directly plug into the breadboard by soldering normal breadboard bridges (cut in half) to cables.Pics coming in a jiffy...

author: pelule
author_rank: Frequent Contributor
timestamp: October 10, 2016, 09:05:21 pm
content: QuoteJust seen this post by Berni.Never seen the photos, but I assume, Berni just mounted the supply outputs (+/-), means 8 the binding posts.If so, you have no access to the sense connectors (add. 8 bindig posts) and thus you limit the use of the 6624A for low current use.Thus I prefer to wire them from back of the suppy to my own terminal block.

author: Berni
author_rank: Super Contributor
timestamp: October 11, 2016, 06:02:35 pm
content: Here are the photos of the modification process of my HP 6624A. I know its not the prettiest of mods but it works. If you are using that 7V 5A range on it then yeah local sensing might be a good idea for for 3A and under sensing at the output terminals is more than good enough.Also for anyone replacing the loud fan in this thing. The CPU board on the side of the case has a underpopulated 12V header on it with lots of current behind it. Nice place to plug in a 12V computer fan to replace the original ridiculously powerful 110V AC fan.

author: pelule
author_rank: Frequent Contributor
timestamp: October 11, 2016, 09:02:38 pm
content: Hi Berni,many thanks for taking the time to share your mod and the pictures.When I have seen the front pictures I remembered to have seen the front already somewhere in another thread (I gues it was regaring 19" rack gears).I had same mod idea in mind, but refused, as I need also higher currents and thus need the sense lines.How about the "sound of silence"?Did you mode the FAN (i.e. with a quite PAPST)?I myself build a FAN-Temp-Control board, mounted above the Relay-Option board.That switches off the FAN as long as the temperature of each power modules is below 60°C (each is taken into account).Basicallly 4x OmAmp comparators each with a relay, each is sensing one of the in-side the modules temp-sensors (used for over-temp-sensing). The relays are OR-wired, thus any activated relay switches on the FAN.As long as the required output current is in the mA range the FAN is off (quite). That's the case in >90% of the time.For security I checked operation up to an ambient temp of 45° to ensure the tank gots not over-heated in hot summer days.Additional I logged the temperature inside the case for several month (recording the max temp only to not fill the disk to fast).Works fine - most of the time the tank is quite!BRPeLuLe

author: bitseeker
author_rank: Super Contributor
timestamp: October 12, 2016, 12:50:08 am
content: Quote from: Berni on October 11, 2016, 06:02:35 pmThat looks quite good, Berni. No one is going to look at the rear panel.QuoteAn 8-position panel-mounted Phoenix connector might be one way to save space while bringing the sense lines to the front. The green color, though.

author: Berni
author_rank: Super Contributor
timestamp: October 12, 2016, 05:41:31 am
content: My reasoning by wiring it in to the back terminals like that was that if you do want to use sense lines you can disconnect the front panel sense and run your own cable. While that phoenix connector might look ugly it is very useful since you can buy a bunch of screw terminal to female blocks that you can leave screwed on to the cables of your projects and just plug them in as needed.I been considering making a fan controller for it but i was a bit lazy and that HP pulse generator that you see it sitting on was waiting for repair. Once i got to it i found out it just needed a mains fuse and the power lamp just needed to be re-seated to light up(Yes lamp as in incandescent lamp not a LED). Its still a nice piece of gear despite how old it is, makes up to 250MHz square wave with 800ps rise times.With the fan i simply directly connected it to 12V over a resistor to reduce its speed. It made it pretty quiet so i didn't bother with a fan controller. Tested it with all channels shorted and set to max current and it didn't seam to get all that hot. Looks like the heatsinking on these is quite a bit overkill, but then again this was designed to run 24/7 in a hot factory inside a even hotter rack. Still having it run completely silent when not under load would be nice to have.I have some Agilent E3610A power supplies that are fanless for less demanding use. Really nice little PSU with no bells and whistles, multiturn pot for voltage multiturn, pot for current and away you go. You can also change a RC timing capacitor in the LED display board to make it update really fast, yet still stay stable.

author: bitseeker
author_rank: Super Contributor
timestamp: October 12, 2016, 04:44:01 pm
content: I didn't know that about the E3610A display update hack. Cool.

author: Berni
author_rank: Super Contributor
timestamp: October 12, 2016, 05:14:39 pm
content: Quote from: bitseeker on October 12, 2016, 04:44:01 pmHere is the display update hack for the E3610A.That C5 cap (Shown in red) has to be replaced with about 20pF to get roughly 10 Hz update rate. There are two Microchip TC7107 multimeter ICs driving it. But the clock pin on one is wired to the other so it is nececery to just change one RC circuit to speed up both.Opening these up can be a bit tricky since its not instantly obvious since there are no screws holding it together. All held by plastic clips. There are 4 clips holding the front bezel on and 4 clips holding the rear(2 on top 2 on bottom) They need to be pried up as shown. Care must be taken to use as little force as possible as the plastic becomes brittle with age.

author: bitseeker
author_rank: Super Contributor
timestamp: October 12, 2016, 05:22:59 pm
content: Thanks, Berni. I have an E3610A in my repair queue. I'll check this out. I also have an E3630A that I'll have to take a look at for a similar hack.

author: German_Engineer
author_rank: Newbie
timestamp: April 20, 2021, 12:06:42 am
content: Hi Berni,thank you for the inspiration. I did the same modification on a 6626A including binding posts for the sense leads.The front panel labels are "film free waterslide decals" from sunnyscopa (ppt and pdf attached). The look is nice and the durability ok. A low-noise "Noctua NF-A12x25 PWM" replaced the original fan. It is wired directly to header P210 on the GPIB board leaving the PWM input open. The fan has about half the througput of the original one but is sufficient for the 6626A. The heat sinks of the 50W outputs did not raise above 40°C at 22°C ambient temperature with all four outputs shorted and delivering the maximum current.Regards and all the bestHans

author: Berni
author_rank: Super Contributor
timestamp: April 20, 2021, 06:13:59 am
content: Now that is one hell of a clean looking mod.Those stickers look pretty much factory, as well as the very HP looking binding posts.

author: SMB784
author_rank: Frequent Contributor
timestamp: April 20, 2021, 06:01:58 pm
content: Quote from: German_Engineer on April 20, 2021, 12:06:42 amWow, where do you get those binding posts? I need some for my E3631A, my old ones are all cracked and broken!

author: German_Engineer
author_rank: Newbie
timestamp: April 20, 2021, 08:04:31 pm
content: I got them from aliexpress, search e.g. for ELEABC store.

author: Marsupilami
author_rank: Frequent Contributor
timestamp: May 26, 2021, 04:33:51 am
content: Aww maaan, I did mine a few months ago but now looking at yours I'm all jealous.There will be soon enough here for a 662x beauty contest tho.

author: DC1MC
author_rank: Super Contributor
timestamp: May 26, 2021, 06:57:33 pm
content: Hey @German_Engineer mod inspired me as well to order the posts and I'll do the modification on my 6627A if the ever present Deutsche Adler will not confiscate them. The question is, does anybody know of a suitable silent fan because the always-on on, maximum speed, one is making way to much noise.Also I want to add temperature drive speed control and eventually the output on/off switch (Option 750, see the attached PDF.Also @German_Engineer, can I bribe youto print me a set of decals, if so, kindly please PM me.Cheers,DC1MCLink to posts, they really loon nice:https://www.aliexpress.com/item/32871905530.html?spm=a2g0o.store_pc_groupList.8148356.63.6c305068emoWQL

author: coppercone2
author_rank: Super Contributor
timestamp: May 27, 2021, 01:57:46 am
content: Did dave jones not do this mod ? I think he wired the system supply with front panel jacks many years ago. maybe i am mistaken.

author: james_s
author_rank: Super Contributor
timestamp: May 27, 2021, 03:02:23 am
content: I really hate drilling holes in nice equipment, I've passed up gear more than once because some former owner had drilled holes in the front panel for some modification. How about just make a box that sits under, on top or next to the thing that has binding posts? You could even have the PSU up out of the way on a shelf above the bench with a little remote panel on or under the bench with binding posts in a convenient place.

author: Berni
author_rank: Super Contributor
timestamp: May 27, 2021, 05:27:50 am
content: Quote from: DC1MC on May 26, 2021, 06:57:33 pmI just used a generic Corsair 12V PC case fan.The fan that is originally in there is way overkill for the amount of cooling this thing needs in a typical lab environment (Its designed to run 24/7 packed in a hot rack on a hot factory floor). So due to the huge heatsinks you can get away with much less powerful of a fan. Id avoid the really silent low rpm PC fans, but any regular fan where you can feel a decent amount of airflow with your hand should be fine. Yet no need to go for those special high CFM fans since those tend to be ridiculously powerful and make a lot of noise.Quote from: james_s on May 27, 2021, 03:02:23 amThese large rack mount PSUs are not really all that high valued pieces of gear. They sell so cheap that shipping one cross country costs more in shipping than they are even sold for. They are bulky and don't really provide that much power compared to there size, so they are not all that desirable. So i don't really care if i made it even less desirable. Certainly wouldn't do this to a more high valued piece of gear.My solution for rear connectors on gear is to put bulkhead feedtrough connectors on the rails of my server rack (i keep all the big boatanchors in there). I often don't properly rackmont my gear and instead use rackmount shelves. So this leaves lots of the square mounting holes down the side rails free and they are large enough to fit things like SMA connectors trough them. So i just bought some SMA to BNC bulkhead connectors and screwed them into these square holes, then ran a SMA cable out the back to the back of the gear. Never looked into any high power versions of this, for something like the 50A PSU in that rack i just ran a big fat cable from the back and fold it together on top of the PSU when not in use.

author: German_Engineer
author_rank: Newbie
timestamp: May 27, 2021, 09:34:08 am
content: Hi DC1MC, have fun with the mod.The stickers are a bit tricky and I needed three loops until I got them right. I used "Film Free Waterslide Decal Paper Type M" (USD 8.90 for 10 sheets) and glue W2 (USD 6.00). I ordered the items directly from sunnyscopa in KR. Their website is perfect, Paypal, and the delivery took just a few days - much faster than aliexpress. They have some youtube videos describing the application. Unlike other waterslide decals, the film is removed at the end. Only the toner and the glue remains on the front panel. The result is very similar to the original print/silk screen. I think they are unique and are also good to repair front panels with rubbed-off markings.Site:https://sunnyscopa.com/Paper:https://sunnyscopa.com/collections/waterslide-decal-paper/products/filmfree-waterslide-decal-paper?variant=36426713727142Glue:https://sunnyscopa.com/products/glue-w1-w2?variant=36426927734950Tricky items: The paper needs to be printed mirrored on a laser printer. I managed this with ppt and a pdf printer driver from the "PDF-Xchange" toolset which has a mirror option. The printer driver did change the scaling slightly and I had to adjust it to preserve the holy 19mm spacing between the posts. Tip: Print first on paper and measure the distance between two posts. Grey color (some black pixels on white background) rubs off. It is better to print as much toner as possible (Black or any other saturated color, heavy paper, high quality setting of the printer). The stickers should be aligned with the bottom edge of the front panel. The rest is dexterity and patience for placing them at the correct position, wipe out the excess glue, heat with a hair dryer and let them dry. After a few trials they will be good. You can remove them with isopropanol and some ellbow grease without damaging the equipment. I did not dare to use acetone as the company recommends. I attach a ppt file with the stickers, so you can modify the labels to fit the 6627A. Just download and rename the extension to pptx (no virus, I hope).Fan: I am happy with the noctua fan I mentioned in my post. Temperatures in the 6626A (150W total) are good. The 6627A has 160W , I believe, and should be OK as well. Sound level: 45dBA 50cm in front of the device and no disturbing resonances or harmonics. The 12V header can be located in the service manual. I bought a fan controllerhttps://de.aliexpress.com/item/32973504131.html?spm=a2g0s.9042311.0.0.31a44c4d3LPhRubut did not try it since i need a good idea where to place the temp sensor. Anyhow, the power supply shuts down when it overheats and displays an error message according to the manual - so it is safe to experiment.The next move in the beauty contest would be a backlight for the LCDanyone?

author: DC1MC
author_rank: Super Contributor
timestamp: May 27, 2021, 10:57:17 am
content: Quote from: German_Engineer on May 27, 2021, 09:34:08 amWell, if I can't convince you to print some for me for a cost, I have to suffer with my ancient Epson Acculaser, but I'll try my best, approximately what distance from the panel bottom line did you use ? I now use some of those distribution boxes with posts as some other member mentioned, but they are occupying space on my little desk and a bit painful to drag around, so this mod is most welcome if it will succeed. any special precaution that I should take while disassembling ? What is the size of the fan ?Cheers,DC1MC

author: German_Engineer
author_rank: Newbie
timestamp: May 27, 2021, 10:00:02 pm
content: Here the decals for the 6627A. The pdf contains the mirrored version for printing the decal at 100% scaling or "no scaling". Use the highest resolution. The posts must be 19mm apart. The other file is a pptx (download and change the extension from txt to pptx). It contains the drawing (1st slide) and a picture with the positioning of the decals (2nd slide).

author: German_Engineer
author_rank: Newbie
timestamp: June 21, 2021, 02:14:07 pm
content: Last and final mod for this one (The nerd-factor is already too high): An EL strip as backlighthttps://www.ebay.de/itm/263120517911.The idea came from other posts in the forum showing this mod on a 3468A multimeter. The EL strips have a limited lifetime, so the beauty will fade. The mod is not difficult and I made just two mistakes:(1) I cut an EL strip with scissors and the layers delaminated. This led to an uneven brightness (Can be fixed with a flattening iron, someone said). Then I tried a paper cutter on the next strip and it turned out good.(2) On the back of the LCD glass sandwich is a polariser film and a mteal plated reflective tape. The reflective tape needs to be removed and replaced by the EL-strip. I took a razor scraper and boldly removed both of them. Later I had to separate the reflective tape and the polarizer to fix the problem. It would have been better to insert the scraper between the polarizer and the reflective tape... BTW, the glue came off after applying plenty ethanol and let it soak for 10 minutes. A microfibre cloth did the rest. Have fun.

author: Berni
author_rank: Super Contributor
timestamp: June 21, 2021, 02:21:09 pm
content: Now that looks rather pretty indeed.You could probably get a similar effect without lifespan liminations by cutting down a LED based LCD backlight to the right dimensions and sticking that behind it. But the tricky part is that you can only easily trim it on the sides that don't have LEDs. So it would probably mean you have to find a LCD that is the same width and then trim down the height. I might dig trough the junk pile at work since a lot of damaged LCDs get thrown out, but i don't really use my PSU enough to warrant taking it apart again and installing that.

author: MRiddickW
author_rank: Contributor
timestamp: June 25, 2021, 04:42:31 am
content: Wow, these are all incredibly impressive!That's good to hear about the fan. I was quite disheartened when I fired up my 6626A for the first time to find that I had actually bought a jet engine, and that's after buying a slightly lower dB fan to replace the bad noisy fan it came with.It makes sense about the 24/7-in-hot-rack expectation, but I guess I never fully considered it! I actually considered a Noctua when replacing my fan, but got scared off by the way lower CFM.Anybody rigged up a temperature sensor to make the fan spin up as the heat sinks get hot or anything fun like that? Any kind of noise considerations you need to take into account when futzing around and adding fans and wires to the inside of the PSU, especially in high-precision units such as these?

author: Marsupilami
author_rank: Frequent Contributor
timestamp: June 25, 2021, 04:48:24 am
content: Quote from: German_Engineer on June 21, 2021, 02:14:07 pmThis is amazing.

author: MRiddickW
author_rank: Contributor
timestamp: June 25, 2021, 05:04:48 am
content: Quote from: pelule on October 11, 2016, 09:02:38 pmOh yeah... I thought the idea was familliar.

author: hansaya
author_rank: Newbie
timestamp: March 30, 2023, 05:24:34 am
content: Where did you guys found the binding post bridges? I cannot find any other than audio related stuff.

author: German_Engineer
author_rank: Newbie
timestamp: March 30, 2023, 08:50:26 am
content: I had the same problem and ended at DigiKey with Mullerhttps://www.digikey.com/en/products/detail/mueller-electric-co/BU-P4115/4073613or Pomonahttps://www.digikey.com/en/products/detail/pomona-electronics/4115/736747. Keywords are "Binding post shorting link" or ".... shorting bar". Maybe drilling down banggood or aliexpress reveals something more cost effective these days.

author: hansaya
author_rank: Newbie
timestamp: April 07, 2023, 04:29:12 pm
content: I ended up finishing my mod. Thanks for all the help

author: German_Engineer
author_rank: Newbie
timestamp: April 11, 2023, 07:57:56 am
content: Nice! What type of fan did you use? Can you recommend it?