Agilent U1253B internal and what about the OLED display...... - Page 1
Forum section: electronics / general

author: Achilles
author_rank: Regular Contributor
timestamp: October 13, 2011, 01:38:49 pm
content: So, I said I will have a look inside of the U1253B and I have taken some time today to open it up..... well, I take photos not videos, so you may be stuck with static insights.First of all, the Display. I was really concerned because Dave and others told it's nice on the Bench, but a no-go when working outside. So when the sun came up today I tried it a bit in the sun. Well, I partly agree... In direct sunlight it is really very hard to see anything. So putting it next to you and work with you Probes may become a mess. You can see a little bit, but the contrast is really low then. Very hard to work with that.Well, if you work with it in shade it's not that much of a Problem. You can read the display quite good then. So it may be OK for "Bad Weather" workers/Europeans. The dots of the OLED are quite big, but that's fine. It still has some nice resolution. Maybe technology evolved a bit and we get something like the Fluke 287/289 or Metrix MTX328x Series with graphical representation of the logged data some day by Agilent. You can have a look on the pictures below (sunlight and shade and resolution). I didn't have a tripod so the shutter time has been a bit fast for a sharp shot. It actually has full working digits. Just because of the refreshing OLED in combination with the fast shutter it didn't take a fully lit display. So that's some bug by me, not the DMM.....As far as I remember, Dave mentioned some rattling when shaking the DMM. That may have been the Battery (anything else wouldn't make sense to me). They seem to have found a solution for that. Maybe Dave can tell if the foam inside of the battery lit has been there before or not. This foam presses against the 9V Block and keeps it in position. Sadly that has the disadvantage that the lid needs to be pressed on tight to slide in position. The locking mechanism of the lid seems to work fine and isn't to stiff. I can move it with my fingernails, so I don't need to take a coin or sth. to open/close the lid(lid.jpg).So let's have a surgery and take a look on the inside.First of the solder joints. They looked quite nice all in all (sockets_solder), but I don't like the joints of the capacitors and resistor like shown on the RLC.jpg. For my taste the remaining ends are a bit too long. It looks more like an array of cannons than an pcb there. Another thing I didn't like was the mounting of the piezo buzzer (piezo.jpg). There must be a more elegant solution than smashing on the plastic with a soldering iron....at least in this price Range.All in all the Layout looks nice, but I think there really didn't change much since the A Version. You may have look on the boards. It seems that a lot of parts are really common between the U125xB Models. Actually most PCBs are just labeled as U1251B.It would be really interesting to try and switch some parts like Display Board and so between the models and see what happens.... I think the difference between U1253B and U1252B really is just the Display, but I don't know how about the firmware. Some PCB pictures are also attached.Some points about working with it. Well, the case is nice and tight, but the rubber armored parts could have more of a sticky rubber feel that actually glues to your hands. It feels more like some kind of elastomeric plastic. I have quite small hands, so I have to hold it tight, what isn't that relaxing when you hold it a while...The probes which come with it are really nice. The are sharp and it's nice to have changeable tips for different work. I have taken a shot with a 0805 Resistor for comparison.The battery runtime, at least for me, doesn't seem to be that much of an issue. It seems to be around 9 hours. I yet didn't empty it when working, but as usual I keep a spare alkaline with me.....The functionality is great. The response is quite fast and autorange, apart form resistance measurements, seem to work quite nice. In resistance it needs a while to settle. I bought it to use from some basic diy electronics which it should handle more than well, calibrating some of our euipment (we had the field calibrator talk already somewhere else) and some automotive troubleshooting, but mostly the old funny things

author: Achilles
author_rank: Regular Contributor
timestamp: November 05, 2011, 11:20:38 am
content: So...an Update!After a bit of using it (nothing fancy) I want to show some problems. The First one:-The U1253B has a thermocouple type K readout. When I use the dual display and get the Temperature in Deg Celsius on the primary and Deg Fahrenheit on the secondary display, both show me the temperature in Deg. Celsius....a 1:1 conversion would be nice and easy, but it isn't right-In the Custom Functions you can setup the tone-frequency of the signal tone. I used 1200Hz, because I like a deep tone more than an little screamer. As I don't work in very loud areas usually that is fine. From time to time it happens that the signals are given with the highest (4800Hz) tone. When I look in the setup it is still set to 1200Hz. After switching of and on (you have to do to get out of the custom functions) it's fine again.-The biggest issue. I tried it on the mains (we have 230V in Germany) and it shows me about 85V?!?!?! What the...... That can't be. I tried my old TRMS and it gives me 235V, which I really put more believe in. Put it in again and the Agilent says roughly 85V again!. Apart from a false reading, it is very dangerous I would say. A difference of roughly -65%. I checked that there is no filtering or anything applied...and well, I used the same probes on both meters.Restoring the factory defaults shows the same result....I have written an email to Agilent and let's see what they say. Maybe someone with a U1252B or U1253A/B could have a check for the T-Couple issue. I have Firmware 2.19 on my meter.Cheers, Achilles

author: Unknown
author_rank: Unknown
timestamp: November 05, 2011, 12:10:52 pm
content: Quote from: Achilles on November 05, 2011, 11:20:38 amSounds to me like the meter is either broken or the calibration constants are corrupted. Can't imagine a firmware bug causing this making it past QA. The other points you mention are mere annoyances. One might even assume that a 85V reading is due to capacitive coupling with other wires, and that the wire is not energized, although they should really use a lower impedance instrument to confirm this.

author: Achilles
author_rank: Regular Contributor
timestamp: November 05, 2011, 12:51:39 pm
content: Quote from: alm on November 05, 2011, 12:10:52 pmYeah, sure...the wrong readings are more a problem of wrong calibration I think. I haven't changed the firmware or so.....so that has been an QC failure or soAnd to the wrong probes. Honestly, if you can't measure with the supplied (or another normal set of Probs I had) on the mains, then there is no reason to put in an AC Mode...... nice to print it on, but if you can't use it without special probes to buy separate (they don't offer anyway) ->worthless.I really think more it's a problem with somebody have done a mistake at calibration or an technical issue due calibration. The other two errors are minor and don't bother me much. I told them to Agilent, because there are people who really might put big value in the dual Temperature display or the changing beeping let's you assume a lower quality..... Think about a changing sound of your car while you lock the doors...it would keep you from putting trust in that system, too

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: November 05, 2011, 04:29:52 pm
content: Achilles how this unit ended at your hands ? Greek curiosity !

author: Achilles
author_rank: Regular Contributor
timestamp: November 05, 2011, 04:45:59 pm
content: A German reseller hat them on sale for 279Euro plus VAT as month's special, so I had taken the chance and bought it about three weeks ago.I tried a bit and it is rather interesting when I switch through the Ranges now :5V->OL, 50V->OL that's what I expected, after that it's getting interesting. 500V->bouncing about 75V, 1000V->40V. So the displayed Voltage is roughly split to it's half. It is the same behavior in ~V and in ~=V.I may take a Video with my cellphone tomorrow (grrrrr, hate those sh*tty cellphone cameras).

author: Amarbir[Lynx-India]
author_rank: Frequent Contributor
timestamp: October 07, 2013, 06:45:10 pm
content: SirDid this get solved .got a u1253a off ebay

author: Sylwerdragon
author_rank: Newbie
timestamp: October 07, 2013, 07:39:23 pm
content: I think this voltage issue must be technical problem. There is still chance it is calibration thing..but i;m not sure about it. I would change it for new one if possible..asap...

author: VK5RC
author_rank: Unknown
timestamp: November 15, 2013, 11:45:50 am
content: I have had a U1253B for about 2 years now, the worst thing is the NiCad slowly loses its ability to hold charge and needs replacement but an exact replacement was easily found.Software V2.19Mine reads mains voltage here in Oz (nom230V) correctly and within its error of a Fluke 87 V and a HP desk top 6 1/2 DVM 34401A.The leads themselves are really nice, gutsy but nice and flexible far nicer than the default Fluke 87s.I have had one of the clip covers go hard and crack after a year but the replacement was cheap (AUD11)I have not had a problem using it out in the sun but inside the OLED screen is to me far more readable than a standard LCD, esp when the desk is cluttered with a project in a million bits, wires going everywhere and the DVM on the other side of the desk pointing slightly the wrong way!The most annoying thing was the silly default start up screen and tones but this can be deprogrammed.I like the 2 stage stand that can be reversed into a hanger, it has spent a fair period of its life in all three positions.If it died tomorrow I would buy another ASAP and I tend to reach for it first over the Fluke as the display to me is a winner.Agilents great data base of manuals (both user and service) and upgrades is also for me a plus for their gear.