TEK 2445 (not A, not B) repair - U800, fan, etc. - Page 1
Forum section: electronics / repair

author: Skimask
author_rank: Super Contributor
timestamp: May 21, 2016, 06:00:13 pm
content: "Scored" a Tek 2445 off ebay. That was the cheap part. Pictures, video clips to come. Pulling them off the card now. USB2 sucks when you can't find the right USB3 cord.Bought the Tek 2445 knowing it had problems. Screen info only shows up on the right half of the screen. When the Horizontal Position knob is turned left, everything bunches up in the middle and stops. Turn it to the right, everything moves to the right like it should. Hooking the probe up to the CAL output shows a trace. Everything else seems to respond correctly. A couple of the smaller knobs were broke when I got it, and I broke a few more taking the front panel off. Add those to the shopping list.Following the schematics, for the voltages at the U800... The +Out and -Out from the U800 going to the horizontal deflection plates voltages pretty much match up to the voltages & waveforms in the service manual...sometimes. When the Horizontal Position knob is turned more to towards the right, the waveforms (#61 & #62 around page ~245ish of the 2445 service manual) match up. When the screen starts to collapse (eg. try to get something to display on the left half), the waveforms almost look like they fold back over themselves). Power and system voltages are within spec, +87v, +/-15v, +5v, and whatever else is in there. I went to the power subsystem schematic page and checked pretty much every voltage I could find on that page.The fan is, for all practical purposes...shot. Spins, but doesn't spin very fast. The bearings seem to be shot as I can move the motor shaft in and out about 1mm or so. Can get a replacement at Qservice Electronics for $35. Debating whether or not to go with that, or modify the whole thing to fit a PC fan, or both. Maybe put a couple of those really thin fans like they use on video cards in/around the U800 mounted to the outside of the case and tap off that +15Vunreg lead that feeds the main fan.Looks like I'll want to swap out a few of the caps on the power boards. No evidence of leakage, but the bottoms of a few of the larger electrolytics are blackened. Just swap them out and be done with it.

author: Skimask
author_rank: Super Contributor
timestamp: May 21, 2016, 06:27:57 pm
content: Just grabbed a screen shot of the Tek's display. Nothing displayed on the left half. Everything that's supposed to be on the left half is kinda "bunched up" into a single vertical line around the middle, and the right half of the screen looks normal-ish.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: May 22, 2016, 04:29:18 am
content: I have one of those. Great scope.I would start with the power supply. The low voltage power supply is known for capacitor failures, both electrolytics, and the yellow box line caps. Check all the voltages and the ripple. You will likely want to do a complete re-cap on the low voltage supply. The Tekscopes mailing list has a list of modern equivalent caps to use.Once you get the power sorted out then start looking at any other faults.

author: Skimask
author_rank: Super Contributor
timestamp: May 22, 2016, 05:29:44 am
content: Any thoughts on the fan swap?Can get a 'new'/refurb replacement at Qservice for ~$35, probably a few other places online as well. I've got this squirrel cage fan, 12V @ 1.1A. Blows a fair amount of air. Looks like it'll damn near bolt right up to the chassis.(This one to be exact:http://g01.a.alicdn.com/kf/HTB184xoIXXXXXXjXVXXq6xXFXXXh/AVC-F9733B12HP-12V-1-1A-97X97X33MM-server-cooling-fan.jpg_640x640.jpg)Searching around for complete recap kits for now. If that fails, I'll start over at Digikey and see what happens.Any idea what is supposed to be plugged into J110, J118, and J119 on the main PCB?

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: May 23, 2016, 05:46:23 am
content: My concern would be to make sure that fan has enough power. Not sure how much the power supply is designed to handle. Check the specs on the old fan.It is really easy to break the collet when you remove the fan. I SuperGlued mine and it worked fine.

author: Skimask
author_rank: Super Contributor
timestamp: May 23, 2016, 06:27:41 am
content: The old fan is that stupid looking stock brushless fan, Siemens I think. Looks a bit like the big ol' caps it sits next to.When I say "a fair amount of air", what I mean by that is, with a 12v input, the proposed replacement fan draws a little over an amp, and easily blows around a stack of papers about a foot away from the outlet.I'm 143% sure it'll push a lot more air than what that stock fan was moving.Re-cap parts on order. About 52 caps, plus a handful of diodes, resistors, etc. on order from Digikey, as well as replacement knobs from various other places. All the caps are 105C parts or better, higher voltage ratings, tighter tolerances, etc.etc. And only $80 for everything.All in all, if this works out right, short of a proper calibration, I'll have a practically pristine 2445 in a couple weeks. Roughly a total of $260 invested, along with a few hours of work.Sure, a guy can get a digital 'scope for a couple hundred more that's got a buttload more bells and whistles, takes up 1/4 of the space, half as noisy, uses 1/10 the electricity...but where's the fun in that?

author: Orange
author_rank: Frequent Contributor
timestamp: May 23, 2016, 08:22:50 am
content: You wrote that all powersupply rails are OK. That means you have a problem with U800.Before you do anything on this scope you better focus on this part. They are very difficult to find, and if you do find it, probably very expensive.

author: grumpydoc
author_rank: Super Contributor
timestamp: May 23, 2016, 08:41:40 am
content: Quote from: Orange on May 23, 2016, 08:22:50 amCould be U800 but that normally shows up as things driftingtothe left.Make sure both horizontal deflection plates are connected.

author: Skimask
author_rank: Super Contributor
timestamp: May 23, 2016, 11:32:48 am
content: Checked the rails.Already have a 'new' U800 installed.Checked the plate connections before I tore it down, measured/compared voltages, etc.Waiting anxiously on those new parts to come in.

author: Orange
author_rank: Frequent Contributor
timestamp: May 23, 2016, 12:39:04 pm
content: Quote from: Skimask on May 23, 2016, 11:32:48 amAnd did the new U800 fix the problem?

author: grumpydoc
author_rank: Super Contributor
timestamp: May 23, 2016, 01:05:27 pm
content: Quote from: Skimask on May 23, 2016, 11:32:48 amIn that case start with the final X amplifier.Do you have a 2nd 'scope?

author: Skimask
author_rank: Super Contributor
timestamp: May 23, 2016, 01:14:30 pm
content: Ya, I recorded some video of what the problem was before I tore it down. Don't have any time to get it edited and posted. Got a 2245 and an SDS7102 as well.The display bunched up in a vertical line about 1/4" to the right of center, almost as if the electrons were bunching up against a wall. You could see where the display should have been vertically, it just wasn't spread out like it should've been. If the horizontal position was turned to the right, the display would move to the right and look normal (using the built in cal test point for something to display). Move it back towards the left and anything that was displayed would bunch up.I've seen other videos of folks with roten U800's. It similar-ish, but not the same. In most of the videos I've seen, the display kinda rolls off in one direction or the other when the chip gets heated up. Mine is just plain stuck. Don't have any cold spray either to try out.Doesnt really matter much now anyways since as I mentioned, I already swapped the U800 and I'm going g to recap it later this week when parts show up.And I'll take another look at the schematics for that final X amp. Hope it isn't one of those hybrids...

author: siggi
author_rank: Regular Contributor
timestamp: May 23, 2016, 01:19:55 pm
content: Quote from: Skimask on May 22, 2016, 05:29:44 amThe old squirrel cage fan is wonderful when it works. It's temperature controlled and under normal conditions it runs pretty slow and quiet - you'd be hard put to hear it in an otherwise totally quiet room.I was able to recondition the fan motor in my 485 which uses the same gitup. The fan was in pretty rough shape in that there was a horrible rattle when I ran it.If you desolder the motor from the control board, you can get to an adjustment screw at the back of the motor. I pulled the screw all the way out and flushed the motor with IPA to get old gunky grease out. Soaking it, then blowing and drying it out is probably a good thing to do.After drying it, I put a drop or two of synthetic motor oil in it, and it works like a charm now.You can then tighten up the set screw a little bit to get rid of the slop, though I don't think a bit of slop is a problem.Beware that before all of this I tried putting a drop of 3-in-1 in there, and the fan didn't like that at all.

author: tautech
author_rank: Super Contributor
timestamp: May 23, 2016, 01:24:20 pm
content: Quote from: siggi on May 23, 2016, 01:19:55 pmThat's a good trick to know, thanks for sharing.

author: Skimask
author_rank: Super Contributor
timestamp: May 24, 2016, 03:20:42 am
content: Quote from: siggi on May 23, 2016, 01:19:55 pmThat little 'slot' in the shaft that doesn't spin is actually a screw?Huh...Gotta go have another look...

author: siggi
author_rank: Regular Contributor
timestamp: May 24, 2016, 11:09:49 am
content: Matthew D'Asaro did a full rebuild of one of thosehttp://www.antiqueradios.com/forums/viewtopic.php?f=8&t=235478fan motors.Sent from my iPad using Tapatalk

author: Skimask
author_rank: Super Contributor
timestamp: May 24, 2016, 07:04:22 pm
content: Quote from: siggi on May 24, 2016, 11:09:49 amHad a look at the above page. Ya, I'm not gonna play that game.I've got a couple of squirrel cage fans of various sizes here that'll just about fit in that shrouded area in the back of the 'scope. Maybe add a PCB with a regulator, filter caps, and a couple of ferrite beads along the wiring, and put it all in that little bowl where the original fan motor used to sit.But for grins, I got the motor in the cleaner now, and I'll try the synth motor oil as described earlier. Put 15v across the PCB and see what happens.

author: tautech
author_rank: Super Contributor
timestamp: May 24, 2016, 09:31:08 pm
content: Quote from: Skimask on May 24, 2016, 07:04:22 pmWith a current limited PSU or a light bulb in series I hope.

author: siggi
author_rank: Regular Contributor
timestamp: May 24, 2016, 11:55:47 pm
content: Quote from: Skimask on May 24, 2016, 07:04:22 pmYeah - I wouldn't attempt that either, but at least you get great pics of the motor's construction.Quote from: Skimask on May 24, 2016, 07:04:22 pmGood luck, I hope it works for you. I modded my 2465 with a 60mm case fan, but I hated the fan noise so much I eventually snagged a NOS fan motor on eBay and fixed'er back.Now of course I mostly use the 2467 and a TDS784D - so much for a quiet lab :/.My 485 fan with the impeller mounted on the bench consumed about 85mA, standalone on the bench after a drop of oil. Any interfering with the airflow dropped the current usage - putting my hand in front of the center of the impeller dropped it to ~65mA, so I suspect it runs at even lower currents in-place.

author: Skimask
author_rank: Super Contributor
timestamp: May 25, 2016, 04:12:13 am
content: Well, I didn't take the motor apart completely, but I did remove that rear screw, and dunked the whole thing into my cheap ultrasonic cleaner for a half dozen 3 minute cycles. Shook it up a bit, blew it dry, put a drop of Mobil 1 (should be good for 15,000 miles right?) , put the set screw back in and tightened it down until there wasn't any axial play in the main shaft, resoldered it to the circuit board (more on that later), and it worked just fine. Wasn't noisy, was smooth, etc.And I didn't just throw 15v across it. I used my DP832 and ramped up the current slowly until I was sure it was dead shorted or anything...8v @ 50mA9v @ 53mA10v @ 58mA11v @ 61mA12v @ 67mA13v @ 74mA14v @ 80mA15v @ 89mA16v @ 100mA17v @ 112mA18v @ 127mA19v @ 149mA20v @ 173mASchematic shows it being connected to the +15V-Unreg rail, but also shows a test point with 19.2V on it.Hell with it. I'll reinstalled the original part and keep an eye on it.However, I am going to tap off that same +15V-Unreg rail and install something like a 50mm or 70mm on the bottom/outside of the case, blowing directly on the U800. Maybe throw an inline 7805 or 7808 to keep the noise down a bit, if I have to, I'll run it off a separate supply. Small hassle/price to pay to keep that U800 alive.

author: Skimask
author_rank: Super Contributor
timestamp: May 26, 2016, 07:15:26 am
content: New parts showed up. ~40+ caps, a few resistors, etc. Swapped them all out, and tested the pulled parts for grins.1 250uF cap on the main input showed completely open, 2 other 100uF caps showed stupid high ESR, >50ohm. Another 7 caps showed higher ESR's than their replacements by 1 or 2 orders of magnitude.4 1N5821's on the input, pulled them for grins and replaced them. 3 of 4 of them were just a bit leaky, about 1K reverse leakage on 3 of them, 4th one was solid. Replaced them all anyways.All caps replaced with Nichicon or Panasonic, except for the film caps which were either KEMET or Vishay. Most of the pulled parts were 85C, replaced with either 105C or 135C parts. Also upped the voltage rating on all replacement caps by a step or two.EXCEPT...the two big fat 290UF on the tray next to the cooling fan motor. I got 2 new ones in...and the leads aren't long enough to reach from that tray down to the PCB. WTF!!!The old cap's are Sprague 290UF/200DC, measure out at ~290UF and < .1ohm ESR.New ones are Nichicon 330UF/300DC @ 85C (couldn't find 105C parts), measure out at ~330UF and < .2ohm ESR.Old ones aren't bulged, discolored, just a bit dusty and cleaned up with a douching of a bit of IPA.I think I'm good to go.Tomorrow's job will be to remember where all these nuts, bolts, washer, connectors go.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: May 26, 2016, 03:41:07 pm
content: Yeah, those bulk capacitors will require some extra wiring (with a decent gauge wire to handle the inrush). I ended up leaving my bulk caps alone. According to the guys on Tekscopes they rarely fail. If I had had the wire to hook them up at the time I would have replaced them when I had the instrument open, though.Reminds me... I should open her up for an annual inspection

author: Skimask
author_rank: Super Contributor
timestamp: May 26, 2016, 04:23:41 pm
content: Gonna have look around later today. I'll bet I've got some fairly big gauge pins that could easily get stuck in the holes, then stuff the cap wires into the pin where the wire should be.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: May 26, 2016, 05:02:17 pm
content: My plan was to use some 20 or 22 gauge solid wire and run them up to the holder. Then pad the holder with something like foam, etc. It would be a good idea to have them insulated or heat shrunk, or both. I think some guy shows his on YouTube if you search for it.Like I said, I bought the filter caps, but the ripple was fine so I just left them as they were.

author: Skimask
author_rank: Super Contributor
timestamp: May 26, 2016, 10:09:07 pm
content: Possibly overthinking this again...haven't put it back together yet...haven't had the time to do it yet...Read above and you'll find the description of this 'scope's original problem...the display STOPS at about mid-screen, only shows up on the right side, if the horizontal position knob is turned, it stops at mid-screen, and the picture/data that is supposed to be on the left is basically bunched up in a line in the middle of the screen.If one of the horizontal plates in the CRT was broken/disconnected/shot/etc, what would that do to the display on the CRT? I guess the real question is, if one deflection plate is broke, would that cause the beam to only be deflected in the other direction? Does a CRT require both deflection plates to move a beam, for instance one positive, one negative to go one direction, and vice-versa. Or does a CRT only require voltage on one plate to move the beam in any particular plane?Just attempting to wrap my head around how the horizontal beam deflection could hit such a hard-limit/brick-wall with a handful of rotten transistors and cap's as mine was showing...

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: May 26, 2016, 10:53:00 pm
content: I have not studied the circuit in question closely enough to know for sure, but I have repaired other, much simpler, scopes. I seem to recall two transistors driving the horizontal deflection, one positive and one negative. It would seem like one of those is perhaps not working.Not positive, but possibly a power supply issue could do this if you had only a positive voltage, but the negative voltage rail was not working.Again, just thinking out loud, with very little actual knowledge of the circuit at hand. So could be crazy wrong.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: May 26, 2016, 10:54:04 pm
content: I seem to recall the service manual having some troubleshooting procedures. Have you checked it out?

author: tautech
author_rank: Super Contributor
timestamp: May 26, 2016, 11:11:32 pm
content: Quote from: Skimask on May 26, 2016, 10:09:07 pmSwap the plate connections for a quick sanity check.Yes, there must beequalplate voltage to both plates for a centered display. IIRC this can be checked in XY mode and adjustment made to center the dot. (when the scope is working correctly)Normally it's just under half the plate output amplifierssupplyvoltage.I haven't hunted out the SM but look forDC voltages valueson the schematic that help one troubleshoot with only a DMM. Note, for these DC voltages to be valid it is usual to set the scopes controls in a specific way.RTFM.

author: siggi
author_rank: Regular Contributor
timestamp: May 27, 2016, 12:14:13 am
content: Quote from: Skimask on May 26, 2016, 10:09:07 pmHere's a video of a deflection problemhttps://youtu.be/IVYGzsuLV6Y?t=128. This is pretty long-winded, but this turns out to be a disconnected deflection plate lead. Your problem does look very much like that to my eye, though it's hard to tell from your picture - square waves don't highlight nonlinearities particularly well.If it's not U800, and it's not a disconnected deflection lead, it has to be either the CRT or R804 or R809.You note that you measured the deflection plate voltages, but you never gave us the values you found.

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 12:59:51 am
content: Quote from: FlyingHacker on May 26, 2016, 10:54:04 pmYep, sure did. Kinda vauge.It says, and I don't quote exactly...but..."if there is a problem with the horizontal on the CRT, check out the horizontal driver section".Well, ya, no shit right?I say "Hey Doc, it hurts when I do this."Doc says "Don't do that."

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 01:07:42 am
content: Quote from: tautech on May 26, 2016, 11:11:32 pmDOH! That would've been quick and easy.QuoteDid thatas much as I could decipher anyways.Found all the voltages, +87, +/-15v, +5, etc. All of them were close if not dead on. BUT, one thing I didn't check for was any AC component (I know better now). As noted earlier, one of the main filter caps was completely open and a handful of other caps on the power supply boards had very high ESR values, not to mention most of them looked "burned"/overheated/scorched/old/poached/fried/baked/swimming/what... and they've all been replaced now.

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 01:11:48 am
content: Quote from: siggi on May 27, 2016, 12:14:13 amYa, I measured the voltages, and they were equal-ish. Didn't write down the values but I did get it on recorded video with my other 'scope scoping the deflection plate connections. I'll look thru that again and see what's what.With any luck this thing will be back together tonight or tomorrow and I can lay this issue to rest.I guess one of the main reasons I'm doubting the U800 fix is because the video's I've seen with bad U800's show the display drifting off to one side or the other and none of the videos show my issue exactly (the bunching up in the middle).I am, by no means, a 100% know-it-all-electronics-expert-in-everything-possible-on-any-given-day-of-the-week. I think I know just enough to be dangerous on every given day of the week

author: tautech
author_rank: Super Contributor
timestamp: May 27, 2016, 01:25:26 am
content: Quote from: Skimask on May 27, 2016, 01:07:42 amQuick tip: don't use thisit hurts.You're getting there, take your time and put all the snippets of info/help offered together.Like any CRO get the PSU right first.Do you have this from Tek:http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 03:26:23 am
content: Quote from: tautech on May 27, 2016, 01:25:26 amI do now...and I'm beating on that video file I took the other night before I tore it down, trying to find a chunk of the clip with the 'scope's output.

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 03:47:17 am
content: Short video of the horizontal failure (I think I had that problem one time back in high school...but that's another story for another time...)

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 04:05:36 am
content: Quote from: siggi on May 27, 2016, 12:14:13 amJust finished watching the above linked video...I would shoot myself in the nuts if the problem was a disconnected lead...which it wasn't since I had to disconnect each lead using a long tipped hemostat.And 150ohms from each lead thru R804/R809 to pin#4/#9 on the U800 respectively.

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 07:22:53 am
content: SUCCESS!!!kinda...I cut a quicky video of the first power up after getting it back together far enough for testing.Will upload it tomorrow, this weekend, sometime.SUCCESS!!! I got a sweep all the way across the screen...AND, bonus point, when I turn the vertical position up, the trace goes down. When I turn the cursors up, they go down.Dumbass me put the vertical deflection plate wires on backwards!Everything is a bit fuzzy at the moment, readouts aren't the right spots, etc. I'm sure that's just a matter of tweaking all the pots.But, SUCCESS!!! That's all that matters. And I'm about giggling like a little 8 year old.

author: tautech
author_rank: Super Contributor
timestamp: May 27, 2016, 08:19:24 am
content: Well done.Have you been up all night working on it?My US clock shows it's late/early over there.Now you've got this one under your belt, when's the next fixup starting?

author: grumpydoc
author_rank: Super Contributor
timestamp: May 27, 2016, 08:43:34 am
content: Quote from: Skimask on May 27, 2016, 07:22:53 amWell doneHave you figured out exactly what you did which fixed the horizontal problem?

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 03:46:08 pm
content: Ya, it was getting pretty late, but that's standard fare for me. I knocked off at about 3AM.The real fix?Probably the U800. The rotten cap's surely didn't help anything. Don't know 100% for sure.Either way, every part that got replaced had to be replaced.Digging thru the service manual now to plan out how to best go about tweaking it all. I don't have any known good verifiable references. Got a bunch of things I could probably throw together and make work half-ass, but that's about it.

author: tautech
author_rank: Super Contributor
timestamp: May 27, 2016, 08:14:10 pm
content: Not sure that you can do ahalf-assedcal on these, I think it's anall or nothing. (step by step)However the basic PSU and CRT adjustments could be made, then it's just verification of some sort ofreasonableaccuracy. In most usage that's all that's needed and as you have other scopes it shouldn't be hard to do some sort of comparison check or even use those when more accuracy might be needed.There may even be members not far from you that have the cal gear and are willing to assist.Road trip?

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 09:26:04 pm
content: Quote from: tautech on May 27, 2016, 08:14:10 pmI'm everything is inter-twined and inter-linked in some way, shape, or form.QuoteThat's a better way of putting it. Get a tight trace, centered, sharp, etc. Worry about the rest later.QuoteOh I'm all about a road trip.Just gotta talk the wife into it...be right back

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 11:01:11 pm
content: Dug thru the service manual, looking at the calibration procedures, this that and the other thing. Main thing was the data display (not the traces) was buried at the bottom, in general nothing was centered. Got all that taken care of (V-Gain, V-Center, and H-Center), easy enough, played with the focus adjustments (astig, focus, the high voltage box adjustments). A lot of them seem to be at or near their respective limits before I get a halfway decent display. I'm going to open it back up and see if there is anything I missed.And oh boy...Nope, I ain't got that kind of gear for a decent calibration. Time to hit up the local HAM club and see what somebody/anybody around here has...Other than a bit of a muddy display, seems to be working ok other than fan noise. Work on that later. The 'scope is still naked on the bench with a fan blowing on the whole thing.Measures the cal freq's and voltages "in the ballpark" when compared to my semi-known-good-but-as-of-yet-not-calibrated-just-very-well-used 2246.

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2016, 11:24:33 pm
content: One more thing...What say the masses about filing a small flat in the shafts of the V/DIV and Sec/Div know shafts to help those little grub screws stay in place?Nothing too deep obviously...I'm having a helluva time keeping the time base knob to stay put.

author: tautech
author_rank: Super Contributor
timestamp: May 27, 2016, 11:33:20 pm
content: Won't they stay put in the original marks?Is the rotational force needed for s/div more than your other 224* series?

author: siggi
author_rank: Regular Contributor
timestamp: May 28, 2016, 01:03:52 am
content: Quote from: Skimask on May 27, 2016, 11:01:11 pmYeah, unfortunately the cal procedure on the 2465 is pretty intimate with the gear specified. I'd be surprised, however, if it doesn't mostly drop into spec once you've been through the CRT adjustments.NB: Congrats on fixing the horizontal sweeps, must have been U800. I've heard that you'll fry the output stage if you (even momentarily) short the deflection leads to the chassis. Looks like maybe that's what befell your old U800...