HP 6114A Precision Power Supply (56K warning) - Page 1
Forum section: electronics / testgear

author: PedroDaGr8
author_rank: Super Contributor
timestamp: May 05, 2013, 05:17:41 am
content: Well look what wandered in the front door.Why its another precision power supply. It appears similar in rating to the another beloved line, the Power Designs Precision, specificlly the 5020 (though the PD goes to 50V in the second range). Lets see how it compares in a few stats:Front meter accuracy:PD: +/- 3% of full scaleHP: +/- 2% of full scaleLine Regulation:PD: 0.001%+100uVHP: 0.0005% + 100uVLoad Regulation:PD: 0.001% + 100uVHP: 0.0005% + 40uVRipple:PD: 100uVp-p (up to 10MHz)HP: 40uVrms/100uVp-p (up to 20MHz)Output Voltage Accuracy:(basically how does the output match the set value)PD: 0.1% + 0.5mVHP: 0.025% + 1mV (any where in the spec range after a 5 min warm-up)Transient Recovery Time:PD:< 50uSec to recover to within 20mV of set value (for a change of load of 80%)HP:<50uSec to recover to within 10mV of set value (for a change of load of 100%)Constant Current regulation:PD: Doesn't address thisHP: 0.01% + 500uAActually, PD doesn't address the specs for their current feature at all, while the HP goes into a detailed break down of ALL of the aspects.Now we get to the ones people on here love:Drift:PD: 0.001% + 100uV over 8 hours, 1mV per week.HP: 0.0015% + 15uV over 8 hours (after 30 min warm-up), no per week ratingTemperature Coefficient:PD: 0.001% + 50uV per oC (0-45oC) and 0.002% or 100uV whichever is greater from 45oC to 60oCHP: 0.001% + 15uV per oC (0-55oC)So it looks like we have a heck of a slug fest between these two bad boys. Though one stark difference is despite similar drift and temp coeff, the HP does not use an ovenized voltage reference. Hard to believe both are over 40 years old, well PD released their first precision lines in 69-70 I think (the 5020 wasn't released until 79) while HP released this in 72.Now for the fun stuff.First, let me say the fit and finish on this thinking is very nice. Brushed aluminum, textured side panels, enameled front. The only plastic comes in the display, the voltage selector and a few knobs and switches. Everything feels very solid and the damn thing weighs a bloody ton. It's things like this that they get the monicker boat anchor.This is HP's version of digital, no knobs to turn. Just push the upper button to increment up one and the down button to increment down one.The 10-turn current setting pot.The beautiful insides. All of the traces that I can see are gold flashed and the gold is still shiny. Look at those 490uF 85V Sprague capacitors (Made in USA). The grey box is a small transformer (not sure what for). The large power transformer has 17 taps on it. A variety of canned resistors and other odds and ends. A bunch of film and disc caps. Oddly, for some reason, most of the large resistors are inserted into standoffs (as seen in the second image). What you can't see are the transistors mounted to the HUGE heatsink. They are hidden by that ribbon cable which is VERY stiff, so I couldn't move it to get a good pic of them. They are your typical TO-3 metal can power transistors. Also, note those large screws, they aren't for mounting the board to the case. So what could they be for?Yep, they are for mounting the screw terminal capacitors directly to the board. Which by the way are 40000uF 45V Sprague 'lytics, which the manual incorrectly lists as 4000uF. These things are about the same diameter as a can of RedBull if I had to compare it to something.The bottom, not much interesting going on here.The voltage regulator board in all its glory. Look at that gold shine. I also like the through-hole tantalums on board. Don't see those too often.A close up of part of the voltage regulator board. Everything on this board is top notch. Precision resistors from micro ohm(a variety of tolerances 1%, 0.1%, 0.05%), larger resistors from Dale, capacitors from Sangamo and Sprague, Zener diodes and transistors from Motorola, potentiometer from Allen-Bradly, Bourns and Vishay, op-amps from Analog Devices. The manual says the op-amps are from Sprague electric but they clearly have the AD logo on them (I'm really surprised my cellphone could pull off this pic). It's like a who's who of American electronic components companies. Sad to see the current state of affairs when you look at this.Behind the front panel, the large pot on the bottom right is the 10-turn one for setting the current limit. Let's take a closer look at that cluster of resistors under the voltage selector.Well I'll be, we have a trove of ultra precision resistors. 0.01%, 0.025% and some 0.1% to round out the mix. Basically, a voltage divider of some sort through these precision resistors to select the voltages.Lastly, we have the back side. First, you can see the huge freaking heat sink which is why it weighs so much and also why it is entirely passively cooled. The we have the simple warning message. No warning about how you will be killed, your dog will be maimed and how a swarm of locusts will descend on your house if you open the back panel. Just a common sense Hey look out, read the manual before messing with this thing. Now what's under this? Why your sense output and a whole bunch of other connectors which help in remote programming of voltages, paralleling supplies, hooking up supplies in series, setting various current features, etc. etc.Quite frankly, being as this device is roughly a decade older than I am, it out right amazes me. Not only for its features at the time. You look at today's supplies and especially the cheap ones don't come near to the qualities of this one. Hell you would think with the schematic being printed directly in the manual someone would have made a knock-off but nope. What also amazes me is that not only is this device made in the USA but ALMOST all of the components are as well. The only ones that I could see that aren't appear to be the Dale resistors which are made in Mexico.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: May 05, 2013, 05:19:09 am
content: Doh, hit post instead of preview. I will finish this up within the next 30min. Just know its a bit incomplete.And now it's done!

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 05, 2013, 06:54:43 am
content: As Dave would have put it, it's pornographic!! It looks brand new! Where and for how much did you score it?

author: PedroDaGr8
author_rank: Super Contributor
timestamp: May 05, 2013, 07:04:53 am
content: Quote from: iloveelectronics on May 05, 2013, 06:54:43 amYeah, I was REALLY pleasantly surprised at the condition. I picked it up on ebay, from a company in New Jersey. It looked pretty bad in the images. It looked almost grungy, turns out there was a lot of sticker residue on it when I got it but dirt wise basically nothing. I think the sticker residue helped keep the price down. As you and I know, sticker residue comes off easily with the right cleaner and some elbow grease. A few small nicks in the enamel here and there (almost all look like they were caused by the person removing the cal. stickers). No major dents, scrapes, etc. Internally, I can't see any repairs (no flux left over, no odd looking parts, no bodge wires). I paid a smidge under $100 for it shipped, ($59 for the item and $38 for cross-country shipping). It was VERY well packed, though the shipper did their best to try and damage it.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 05, 2013, 07:13:44 am
content: $100 shipped!? That sounds almost illegal!! Congrats!!

author: Kevin.D
author_rank: Frequent Contributor
timestamp: May 05, 2013, 09:18:23 am
content: Nice post.I wish you could get those old precision supplies over here but they very rarely appear on any european ebay sites.I see them regularly on ebay US. But the postage to europe for that weight is huge .

author: SeanB
author_rank: Super Contributor
timestamp: May 05, 2013, 09:35:06 am
content: Try postage to me, that $38 will be $700 for me, unless I select sea shipping, where it will be only $300. Lovely unit though, nice calibrated wire links there on the board for R19 on the current shunt.

author: free_electron
author_rank: Super Contributor
timestamp: May 05, 2013, 02:38:37 pm
content: I still have two in the lab at work. In daily use. These beasts are rock solid and produce an absolutely clean output.Part of the trickery lies in the metal can opamps. I did an experiment once with a simple lm723 ( which is a good regulator chip). The same board . One with dil package , one with to5 metal can. 60mv noise difference ! Why ? Because the metal can is connected to the ground terminal and shields the die from picking up crap.

author: Fsck
author_rank: Super Contributor
timestamp: May 05, 2013, 04:14:08 pm
content: Quote from: iloveelectronics on May 05, 2013, 07:13:44 amyeah, love the shots of the psu. hate you and your luck.

author: KJDS
author_rank: Super Contributor
timestamp: May 05, 2013, 05:23:55 pm
content: That is a great bargain

author: don.r
author_rank: Frequent Contributor
timestamp: May 05, 2013, 06:15:20 pm
content: Heck of a deal! They are usually $300-$400 in working condition. The PD still has the killer looks with those dials but the specs of the HP are better. The 10 turn vernier is an option, I believe.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: July 31, 2014, 03:52:14 am
content: Yes I am bumping my old post. We all know these things are good (0.025%+1mV) but check these numbers. I just recently came into possession of an HP 34401A (sometimes trades work out great for both parties, though monetarily I came out way ahead!). Decided to test out the 6114A and put it through its paces a bit more. Keep in mind, this is completely unadjusted, all of the settings are as it was when I received it. Both instruments were allowed to warm up for 30+ min. Allowed each reading to settle a while before measuring.Setting - Reading - % Error1V - 1.000169 - +0.0169%5V - 04.99970 - -0.006%10V - 09.99994 - -0.0006%15V - 015.0006 - +0.004%20V - 020.0002 - +0.001%25V - 025.0010 - +0.004%30V - 029.9998 - -0.0006735V - 035.0001 - +0.000286%40V - 039.9977 - -0.00575%Mind you all of these except 40V have the potentiometer set to zero. For forty volts you set the dials to 39.99 and turn the pot to 10. It's in no way a guarantee of how these perform. For all I know, it could be the inaccuracy in my meter almost entirely cancels out any errors in the power supply. Just this was interesting enough to share.Robrenz had somewhat similar results inthis thread

author: BravoV
author_rank: Super Contributor
timestamp: July 31, 2014, 08:01:20 am
content: Please, stop promoting this gems, cause its getting harder to get em cheap.lolGreat results there Pedro, another proofs of these HP 611xA series amazing performances.At the enthusiasts crowd, I think we should categorize it into a high power adjustable voltage reference instead of a bench psu.My 6115A, since I only have 5.5 digits DMM, once its heated and stabilized, even with dynamic load, its basically spot on at every scale with perfect linearity from 0 to 100 V, for me actually its quite scary to think about it's accuracy especially they were made at almost half century ago, and not even calibrated for decades.I guess this is a perfect example of a well aged & cooked precision components inside like the vref, precision resistors etc.

author: vtp
author_rank: Regular Contributor
timestamp: July 31, 2014, 11:46:24 am
content: Quote from: PedroDaGr8 on May 05, 2013, 05:17:41 amYes, indeed, take a good look at those capacitors while they still look nice to you. If you are into restoring older equipment you will learn to hate those caps.They have exactly two states they are in: failing or failed.Common reason is the thin aluminium (I guess it's alu) tab that connects the wet roll to soldering tabs at the sealing area (wider section at the bottom of the can) corrodes away. So they fail open. It's really sad as the construction is otherwise very nice and all the rolls I have removed from those have been in perfect condition. Also, sealing has been done very nicely. But that corrosion inside, whatever the reason...They can be restuffed with modern smaller capacitors but it takes quite a lot of work, especially if you would like to retain asthetics.I have a HP 6115A hidden somewhere and now that I have seen it contains those caps I think I'll rather turn it into a boat anchor. The weight is about right.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: July 31, 2014, 12:38:29 pm
content: IQuote from: vtp on July 31, 2014, 11:46:24 amYou can send to me instead.I didn't know that about those caps. So far there are no reports of that on these instruments. That being said, I'll keep my eyes on it. Thanks for the heads up.

author: linux-works
author_rank: Super Contributor
timestamp: July 31, 2014, 01:28:06 pm
content: got mine for free (damaged in shipping, seller just refunded me 100%). can't beat free and it was bendable back to mostly-ok condition:I have the PD precision supplies, too (4 of them) and they compare about the same on my scope for noise and the accuracy is dead-on for all of them. as a collector (and user) I did want both brands since they are excellent examples of old school engineering.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: August 01, 2014, 01:49:23 am
content: Quote from: linux-works on July 31, 2014, 01:28:06 pmWow when I see that scope I automatically think Chris Tucker from Friday.Glad to see that you were able to get it back together, amazing it works so well after being that messed up. Great job.As for the comment about the performance. Yeah I think truthfully for voltage ability these and the PD Precision supplies are neck and neck. These are slightly better specs wise, though both blow their specs out of the water. Quite honestly, it would take a metrology nut to figure out which one is truly better.Though even more amazing about these: the PDP uses an ovenized voltage reference to achieve that stability and accuracy. This supply used a locked loop, no ovens or any other sort of magic. Quite impressive. To think that both the PDP and the HPP supplies were designed decades ago, without computer CAD or simulation. Just good ol fashioned ingenuity.

author: HiTech
author_rank: Regular Contributor
timestamp: August 01, 2014, 08:40:29 pm
content: I've got two of the HP big boys -- 19" rack mount units-- 0-40v 0-5 amps and they are virtually bullet proof. They are my go-to PSUs.

author: schopi68
author_rank: Regular Contributor
timestamp: July 29, 2015, 11:43:48 am
content: Quote from: PedroDaGr8 on May 05, 2013, 05:17:41 amstrange to see - your device has been built after 1991. Almost 19 years after the first hp 6114a went into production. The 6114a did not have any big changes (at least i don't know about any) in it's circuitry during this timespan. The only changes i can see are design changes in the front-panel.

author: eas
author_rank: Frequent Contributor
timestamp: July 29, 2015, 05:18:31 pm
content: Quote from: schopi68 on July 29, 2015, 11:43:48 amYeah, now that you mention it, most of the component date codes I can read in the photos look like they are the latter-half of 1990.Power Designs revved their precision supplies at some point to move from their own ovenized reference to using commercial ovenized vrefs.

author: schopi68
author_rank: Regular Contributor
timestamp: July 30, 2015, 02:35:26 pm
content: Quote from: linux-works on July 31, 2014, 01:28:06 pmquite interesting to see these Binding Posts on your Picture. They look exactly the same as the ones on one of my 6114a's (and they really do not look original).The serial of my device is 1349A003xx (last two digits hidden for privacy) - is your's from the same batch or did some third-party people do rework on this devices?

author: schopi68
author_rank: Regular Contributor
timestamp: July 30, 2015, 02:42:43 pm
content: In the meanwhile i had a more detailed look on some pictures in the service-manual and the hewlett-packard journal Nov. 1972. It looks like this binding posts were the ones in production at the beginning. Quite interesting to see.(Just keep in mind... the serial no. of my device decodes to the first 300 devices that has been built.)

author: linux-works
author_rank: Super Contributor
timestamp: July 30, 2015, 02:43:12 pm
content: they are very common generic banana plug jacks, from many places. I remember buying them as a kid, at radio shack, in the 1980's. they have been available as cheap connectors for that long or even longer.if you had to choose between $20 connectors from hp and $1 ones from radio shack that did basically the same thing, what would YOU do?

author: schopi68
author_rank: Regular Contributor
timestamp: July 30, 2015, 02:50:04 pm
content: Quote from: linux-works on July 30, 2015, 02:43:12 pmI would use the ones from HP.Because of the design... and because i know that from hp i can expect parts that last forever.The copper surface of the binding posts from the device in the picture shows heavy sign of corrosion. The binding posts on my other - somewhat jounger - device do not show any corrosion. Well i know, both devices have their own stories of history...But as mentioned in my previous post - it looks like these posts are the original ones. So i will not change them.

author: linux-works
author_rank: Super Contributor
timestamp: July 30, 2015, 03:18:40 pm
content: well, if the 'quality' hp parts last forever, why do so many of the used hp boxes have replaced posts on them? lol!these are not sent down from god. they are just posts. I would not obsess over them, personally. if I care to this level, I would not be using used gear, then, would I?hp's knobs also fall apart. you see so many hp boxes with broken knobs and plastic parts that yellow with age and fall apart. no vendor makes things that are always 100% pure quality. of course, the post problems could all be from equipment abuse by users. maybe the hp posts are well built and if treated well they'll last a long time. but again, if I'm buying used, I am probably not made of money and my application is probably not critical enough to justify 10x or more of the cost of common parts.

author: schopi68
author_rank: Regular Contributor
timestamp: July 30, 2015, 04:03:48 pm
content: Hmmm... i did not see many used hp boxes with replaced posts.Well - i am using used gear from hp. Because i know, it is not made by compaq-hp and has a higher quality than many of the brand-new today's devices, especially when comparing the price.On old HP-Boxes (and the ones from other manufacturers) i see dents and cracks on the knobs very often. Dents are the result of bumping something onto the device. Well, it's quite normal that something that sticks out of the device is more suspectible to be broken.There are some - in detail visible - advantages of the hp-posts compared to cheap ones (this does not mean that there are no other good ones on the market, but these are not cheap too). Longer lasting materials, terminal plates even on the screw-handle and so on. On old devices with cheap posts you will get contact problems very often.

author: linux-works
author_rank: Super Contributor
timestamp: July 30, 2015, 05:10:02 pm
content: buy some new pomona brand posts, then. they will be high quality, affordable (sort of) and if you buy real parts they will last.

author: schopi68
author_rank: Regular Contributor
timestamp: July 31, 2015, 12:16:11 pm
content: Nope, Material quality seems to be finde on ne Pomona posts - but i can see that have the same grip-area than all the others. One of the differences to the hp-ones. The typical hp parts have a slightly larger diameter and grooves that give more grip. This makes a feelable difference in screwing. And: a device with this posts still looks like a self-made repair.

author: eas
author_rank: Frequent Contributor
timestamp: August 21, 2015, 07:03:46 pm
content: I've started towork on my own new old HP 6114a precision power supply.So far I've just done some cleanup and body work, and check for any damaged components. I plan to put it back together and do some power tests this weekend and post an update then.

author: bitseeker
author_rank: Super Contributor
timestamp: September 18, 2015, 06:18:52 am
content: Hey, eas. I recognize that 6114a. It was on my watch list.You're doing great work on it.

author: wade salt
author_rank: Newbie
timestamp: April 07, 2016, 08:44:21 pm
content: Hi, I'm a newbie to the group and our beloved HP6114A, SN 2650A-04940 is starting to misbehave.It has been rock solid forever but now the output voltage is wanders around the set-point +/-50mv.Does anyone have a suggestion what the problem might be or would someone qualified be interested in servicing it for us?Thank You!Wade

author: Vgkid
author_rank: Super Contributor
timestamp: April 07, 2016, 09:14:19 pm
content: Quote from: wade salt on April 07, 2016, 08:44:21 pmTry scoping the output, though I do think that 50mV is a bit much for a capacitor issue. So it could even be a pass transistor.i think that the pnp pass transistor is not working correctly in mine.Interestingly I was talking to a guy named Wade (in Hampton) on Saturday.Edit: Is this 50mv in a few finutes, or a couple hours. If the latter, could be a power supply issue. Especially since I believe thereference has its own supply.

author: wade salt
author_rank: Newbie
timestamp: April 08, 2016, 05:15:34 am
content: Quote from: Vgkid on April 07, 2016, 09:14:19 pmVgkid, Were you by chance in Hampton buying a UPS system for your gear?

author: Vgkid
author_rank: Super Contributor
timestamp: April 08, 2016, 05:35:27 am
content: Quote from: wade salt on April 08, 2016, 05:15:34 amYes. Same Wade then, small world.

author: wade salt
author_rank: Newbie
timestamp: April 08, 2016, 09:01:48 am
content: Quote from: Vgkid on April 08, 2016, 05:35:27 amSmall world Indeed!!!Would you like a repair project?Soldering must be to NASA standards and we will pay for the repair.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 08, 2016, 12:07:41 pm
content: Nice score! Looks like it had an easy life.Quote from: PedroDaGr8 on May 05, 2013, 05:17:41 am

author: PaulAm
author_rank: Frequent Contributor
timestamp: April 08, 2016, 01:19:00 pm
content: When I was fixing the paint on the tens digit switch on mine, I took the zero off entirely. Now I have leading zero suppression

author: mtdoc
author_rank: Super Contributor
timestamp: June 10, 2016, 08:21:33 pm
content: Three of these have shown up on eBay recently.The first 2 from the same seller for $47.95 are listed as "for parts or not working". He's gouging on the shipping ($54!). But still not a bad price considering he gives you 14 days to return it (sans shipping). For some reason he has an ITAR disclaimer in the description (WTF?) but then doesn't ship internationally anyways...The third one looks the best for $100 and $22 shipping. Very clean and listed as used, "tested under load", and with 30 day return policy.If I didn't already have one of these excellent supplies - I'd be buying this one

author: bitseeker
author_rank: Super Contributor
timestamp: June 10, 2016, 08:54:15 pm
content: On eBay, it's best to ignore the term "Shipping". The proper label for that field is "Buyer's Premium".e.g.,Condition: For parts, not workingPrice: $47.95Buyer's Premium: $51.16Total: $99.11Condition: UsedPrice: $99.99Buyer's Premium: $16.44Total: $116.43See, now there's no gouging on "shipping". The former listing is just an expensive parts unit.

author: Vgkid
author_rank: Super Contributor
timestamp: June 10, 2016, 09:51:03 pm
content: If the shipping was around 30, then it would be reasonable. 50 is almost 2x to much.

author: mtdoc
author_rank: Super Contributor
timestamp: June 10, 2016, 09:58:53 pm
content: Quote from: Vgkid on June 10, 2016, 09:51:03 pmYeah - the other seller is shipping for $22 and I'm sure they're not losing money on it. I think that is about what mine was to ship as well.

author: bitseeker
author_rank: Super Contributor
timestamp: October 08, 2016, 12:26:09 am
content: Well, I couldn't resist any longer. I got the one with the 30-day warranty. It appears that seller has sold several of these since the last post in this thread. The one I got was as described, but still better than I was expecting.Cosmetically, it has a few minor scratches, but no dents to the heatsink fins and it still has the rear cover over the programming terminals.All the voltage decades work well and are spot on. Relative to my calibrated U1252B, it's at most 1mV off. The analog gauge is spot on as well for both voltage and current. Noise is 600-700uVrms. It's rather refreshing to buy something that I don't have to fix for a change.Actually there is one thing that could use a tweak. The positive binding post is a bit loose.