Need Schematic to fix Sorensen/Xantrex XT series power supply - Page 1
Forum section: electronics / repair

author: cdev
author_rank: Super Contributor
timestamp: December 09, 2016, 05:07:45 am
content: I am going to be getting a Sorensen bench supply soon via the auction site, its partly broken, I figure it should be fixable, as it looks well documented., There are manuals and price lists and basic theory of operation, do people think I will need the schematic? As I understand it the first unit, the 7 volt 6 amp supply is broken, the other two 20 v and 3 amp are okay. The first unit registers 9.99 0.00. It would be nice to get all three working.Probably will be a week or so till it gets here, want to see how much documentation I can find to make it easier.Very much looking forward to putting it together.Edit- Ive now received it, its in good shape and built like a tank, and all three supplies appear to deliver adjustable power but the transformer? has got a loud hum and the leftmost supply's top LCD display is pinned at 999 - The leftmost 7 volt, 6 amp supply has this meter issue.The manufacturing date is listed as 1986. Its quite well built and I don't see any obvious signs of problems with the PCB visually except maybe the leftmost front panel pcb in the meter area is a tiny bit bent..Took these pictures yesterday evening- need to revisit it with better lighting - this was just done in ambient kitchen table lighting- so unit is in better focus.Edit: Found Schematics for this older high quality Sorensen (or Xantrex) XT Series power supply in a 2015 discussion. Scroll down for link.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: December 10, 2016, 02:05:45 pm
content: I like the bright red displays on those. How much did you pay?

author: cdev
author_rank: Super Contributor
timestamp: December 10, 2016, 10:15:34 pm
content: Around $110 including shipping. (Around a third of the cost was shipping. I dont remember the exact figure) It was "for parts" but the seller indicated that only the first of the three supplies (the XT 7-6 part ) was broken. (its a triple uint that also has two 20 volt three amp supplies in it. The manuals are online but there isnt any schematic with them, however the manuals I have found comtain an extremely good overview as manuals go, of the theory of operation. It appears to be a very popular supply thats also sold under several other names, and its clearly a quality product. The two working supplies can be put in series or parallel to double the current or voltage. It would be nice to have a schematic but hopefully with what I have I can figure out what if anything is wrong. the supply appears to not have any of the options because the back is competely devoid of any of the additional terminal blocks, etc.It will be a big step up from what I currently use, my main power supply is homebrewed from an ATX power supply and when I need an adjustable voltage I use an old HP 6217 adjustable supply that I got at an estate sale. If I can get three working supplies out of it I will be very happy. Even if the first one is unfixable, having the two working supplies will make it a worthwhile purchase.

author: eKretz
author_rank: Frequent Contributor
timestamp: December 13, 2016, 10:05:54 am
content: You might well be able to find a schematic. These are very high quality power supplies and seem to be fairly widely used. I've got a Sorensen 1200W supply on my bench; love it.

author: cdev
author_rank: Super Contributor
timestamp: December 15, 2016, 03:22:01 pm
content: So far it seems that all three supplies seem to be delivering adjustable voltage within the ranges they are supposed to, however the meter on the leftmost unit is showing an invalid value and something on the leftmost unit is buzzing, (perhaps the transformer) although nothing seems to be getting hot. Visually it all looks fine. Anyway, if I can get it fixed, it looks like the kind of power supply that I can use for a while, and never grow out of, especially if I replace the caps (although none appear to be bulging). It's good that it has a handle on the side, as it weighs a lot. Almost as much as my scope. This is definitely a linear power supply. But its perfect for the kinds of things I do, as I like to fool around with radio stuff.So far no luck on finding a schematic or service manual specific to this XT family of units, despite their popularity. The manuals refer to a schematic in Appendix A which describes the calibration assembly but the online PDFs Ive found so far doesnt contain it! - Just a blank page placeholder where it is supposed to be.One thing that is intriguing, there are multiple internal headers in each unit, which seems to me to indicate a lot of potential controllability/upgradability. Also, tested the two fully working units accuracy and they are both accurate as far as voltage goes. They have a 10 turn potentiometer for adjusting voltage to very fine accuracy but only a three digit readout for displaying it.It appears from peering through the space on the side that there are LEDs and a calibration pot under a little shim on the top left panel, but no obvious place to pull at it to remove that plastic.Looks like I may need to disassemble the panel.

author: pyroesp
author_rank: Regular Contributor
timestamp: December 15, 2016, 03:41:38 pm
content: Isn't it basically 3 times the same power supply?I know it's easier with a schematic but you could measure component values or voltages on the working channels and see if you can find something in the non-working unit that's not quite right.As others already mentioned, the power supply looks really good!

author: KhronX
author_rank: Frequent Contributor
timestamp: December 15, 2016, 03:49:31 pm
content: Good call on the comparison idea. It's a reeeeeeally safe bet that all the three front-panel boards are (damn near) identical anywayThat being said, i did pay a wee bit more than that on my TTi PL330QMT earlier this year

author: cdev
author_rank: Super Contributor
timestamp: December 15, 2016, 04:38:44 pm
content: Quote from: pyroesp onTodayat 10:41:38>Isn't it basically 3 times the same power supply?Yup, it is, with some differences that are spelled out to a substantial degree in a document Idohave!!I know it's easier with a schematic but you could measure component values or voltages on the working channels and see if you can find something in the non-working unit that's not quite right.That sounds like a plan!Good suggestion!As others already mentioned, the power supply looks really good!My guess is a cap about to fail or some problem in the meter or calibration area.. we'll see.I will take some better pictures just so you follks can see how pretty the construction is. Its really overbuilt.One strange thing about this unit is, all of the documentation for the product lists it as having a 4 screw terminal barrier block (positive and negative output and sense wire connections) on the back of each unit, and there is also a vertical knockout which on units that have an internal interface is used for whatever that interface's external interconnects are (GPIB, DB9 for an RS232, etc.)My unit has nothing there on any of the three units. Which is odd. Maybe they added the terminal strip at some point so its only on the newer units.It'sSOunusual for an electronic device manufactured in 1986 (as this power supply was) to still be a currently offered model!Offhand I cant think of anything else that I own thats like that or even remotely close.Edit: Foundrevision 4.1 of the manual, which contains a theory of operation (but the schematics are missing) Its from 2001.Hopefully will have time to get in there again today.

author: KhronX
author_rank: Frequent Contributor
timestamp: December 15, 2016, 05:13:25 pm
content: Unlike the "pedestrian" consumer world, i guess "serious" gear manufacturers tend to stick to the old "if it ain't broke, don't fix it" adageFortunately for some of us...

author: cdev
author_rank: Super Contributor
timestamp: December 28, 2016, 04:56:36 am
content: This is posted for anybody who like me was looking forthe older revision of the XT Series schematics. (which are not in the newer documentation)Thank you Liv!

author: arlo_g
author_rank: Contributor
timestamp: December 29, 2016, 03:27:37 am
content: By all means check the internal supply rails, but the symptoms that you describe in your initial post sound a lot like a Xantrex supply of mine that had one bad display when I bought it at auction. Swapping the pertinent ICL7107 fixed my display. On two vintages of these supplies that I own, the ICL7107's are all socketed, so the hardest part of my repair was bending the leads of the DIP IC to fit into the socket.

author: cdev
author_rank: Super Contributor
timestamp: December 29, 2016, 03:40:22 am
content: That would make sense. Indeed, they are socketed. All the ICs in it are, so easy to replace.Thank you for the suggestion, I'll give it a shot tomorrow morning.EDIT: That was it, the replacement chip arrived today and its working like a charm. What a nice power supply! Definitely not portable though, despite the handle on the side.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 11, 2018, 03:43:30 pm
content: FYI, I just picked up five of these and I've been tinkering on one of them. They use a pair of Microchip TC 7107CPL ICs to operate the displays. If you have one with a bad display then I would pick up a copy of the Datasheet for the 7107 and start from there. The 7101s do need a second, separate power source to operate so if both displays are bad I would check that first. The display ICs in mine are HDSP 5601. Those are available in red, high effiecentcy red, yellow and green if anyone wants to change the color of their display. Each digit in mine is a separate IC and there are five pins along the top of the IC and five more along the bottom so they're not hard to get out.None of mine came with binding posts on the front panel but I found that the pads were already on the display board and the holes for the binding post were already in the front plastic panel. The front of the unit is actually a sticker so I punch through it with a small Phillips screw driver and then trimmer out the sticker around the holes. The circuit has two pieces of copper tubing that form the sockets for the sense inputs so nothing else needs to be done there. I had to slightly ream out the holes for the + Output and the Return and the Earth Ground for the binding posts that I used (Superior 30 Amp type). I also had to slightly ream out the hole in the circuit board for the Earth Ground connection. For some reason it was smaller than the others. I left the front collar on the binding post and installed it in the plastic panel and secured it with a nut (no washer) of the back of the plastic. Then installed the circuit board and secured the binding posts with flat washer, tooth washer and nut and the spacing between the circuit board and panel was exactly right. (I discarded the rear collar from the binding posts.)One word of caution, the front panel is connected to the main chassis via two 9 pin cables and all four of the connectors are identical and the cables could be easily swapped. Mark the cables (upper and Lower) and left and right before you unplug them.Getting the power supply apart the first time was tricky. If anyone needs instructions let me know.Picture of the type binding post that I used is attached.

author: cdev
author_rank: Super Contributor
timestamp: August 22, 2018, 03:36:03 am
content: Indeed the 7107 was what was broken and replacing it fixed it.