hybridfree/eevblog-posts huggingface dataset:
[Solved]34401A Fuse drawer Advise. - Page 1
Forum section: electronics / repair

author: coldframe
author_rank: Regular Contributor
timestamp: December 18, 2019, 09:04:20 am
content: Hello Forum.I want to buy Fuse drawer.There were so many different types of item that I didn’ t know which to buy.http://www.farnell.com/datasheets/2020920.pdfI think I need some help.Edithttps://www.digikey.ch/product-detail/en/schurter-inc/4303.2014.01/486-1111-ND/641307UpdateThis is what I bought (Attatched Last Picture)Part# : 4303.2014.17, It’s 5.80USD plus tax paid.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 18, 2019, 12:04:56 pm
content: This part is orderalble, in my other threads about a 34401a i found out where you can buy the ac receptacle ....You need the one with the gray block in it, its for the different ac voltages around the world the "fingergrip one"I think it was this one, cant find my digikey orders ... It was for the Schurter z01 series receptacles if i recall correctly.https://www.digikey.ch/product-detail/en/schurter-inc/4303.2014.01/486-1111-ND/641307

author: coldframe
author_rank: Regular Contributor
timestamp: December 18, 2019, 03:08:24 pm
content: Hello coromonadalix.I ordered it!Thanx.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: December 18, 2019, 08:16:56 pm
content: Did you order only one?I have 34401A fuse related question as well... I'm missing the current fuse on the back of one of the meters, any chance somebody knows where to get one of those?

author: coromonadalix
author_rank: Super Contributor
timestamp: December 18, 2019, 11:27:56 pm
content: I ordered the 2 fuses sockets at digikey, the rear one and the internal one ...I think in some 34401a threads i left the part numbers

author: coldframe
author_rank: Regular Contributor
timestamp: January 04, 2020, 04:25:21 am
content: This is what I bought (Attatched Picture)Part# : 4303.2014.17, It’s 5.80USD plus tax paid.4303.2014.17https://www.chip1stop.com/USA/en/view/dispDetail/DispDetail?mpn=4303.2014.17&partId=SCHU-0007954&classCd=030799&keyword=4303.2014.17&partSameFlg=falseThanks coromonadalix.
34401a no display repair. How does one remove the power switch? - Page 1
Forum section: electronics / repair

author: BobRyan
author_rank: Contributor
timestamp: December 12, 2020, 09:45:17 pm
content: I've just purchased a 34401a "turns on" which has no display. I've checked voltages to the front panel and +/-18v are present. Filament voltage is 5.4vAC with ribbon cable removed and 4vAC with the ribbon cable in place. Resistance across the filament is 10 ohms.I'm suspecting a driver issue or perhaps a problem with the -13v regulation on the front panel but I can't get the damn thing off. I can't remove the display because the power switch is in the way and I'm afraid of breaking the front cover or the power switch prying at the edge.I'm hopeful the unit is functional as the continuity tester seems to work. I've tried to blindly put the unit into RS232 remote mode but haven't been successful.Can anyone give some advise on how to remove the long white pushrod? I have it disconnected from the switch at the rear of the unit but I don't see how to remove it.Bob

author: BobRyan
author_rank: Contributor
timestamp: December 13, 2020, 12:49:32 am
content: After findinghttps://www.eevblog.com/forum/repair/how-to-hpagilent-34401a-display/I was able to remove the power push rod. It required pushing the frame holding the transformer out a little bit but the front panel came off easily once the push rod was removed.I'm still trying to figure out the display problem. It doesn't seem to be power or logic related which makes me wonder if the VFD itself has completely failed. There are a few ominous specks of ash(?) floating around in the display. I probed all of the pins and see what looks like +/-18v logic on most and power rails or the AC filament voltage on the others. Two pins (highlighted in red) display what looks like garbage but I haven't figured out the pin numbering yet

author: Runco990
author_rank: Frequent Contributor
timestamp: December 13, 2020, 01:38:22 am
content: Stop troubleshooting.... the VFD tube is open to air. Replace it. Meter is probably fine.Look at the getter flash spots. That is your problem.

author: BobRyan
author_rank: Contributor
timestamp: December 13, 2020, 01:43:38 am
content: Thank you for the quick response. New VFD is on its way.

author: BobRyan
author_rank: Contributor
timestamp: December 27, 2020, 02:05:01 am
content: The replacement VFD I purchased off ebay fixed the issue. The unit I received looked brand new but the pins had obviously been soldered before.Thanks again Runco990!

author: Runco990
author_rank: Frequent Contributor
timestamp: December 27, 2020, 04:35:09 am
content: Sweet! You're welcome!
34410A firmware bug? - Page 1
Forum section: electronics / repair

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: May 20, 2020, 02:46:30 pm
content: Hello!I noticed on multimeter 34410A a bug?When I select resistance mode, automatically it says on display “AUTO RANGE” but when I measure resistor for example 50k it does not autorange it! If I press resistance key again, than it autoranges.The instrument pass all the tests btw.What could be a cause of this?Thanks!Hrvoje

author: HighVoltage
author_rank: Super Contributor
timestamp: May 20, 2020, 03:42:47 pm
content: What firmware is installed ?

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: May 20, 2020, 04:44:17 pm
content: Quote from: HighVoltage on May 20, 2020, 03:42:47 pmThe latest, 2.41.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 20, 2020, 06:11:29 pm
content: That is kind of strange behavior/I have several 34410A and they all stay in Autorage mode, after pressing the button once.I would try to remotely switch to resistance measurements and see if the problem persist.

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: May 20, 2020, 08:25:33 pm
content: Quote from: HighVoltage on May 20, 2020, 06:11:29 pmYes, strange.Actually, the FW is 2.43.You know what, try this:select diode test and than select resistance mode, try that several times and check if instrument behaves normally. I have noticed that when i move from diode test to resistance, than is that strange behaviour more frequent. On the display says auto range, but i really dont know why the relay inside does not click when i short probes when in resistance mode, well that happens from time to time.What do you think could be the cause of this behaviour?Btw., in the meantime i have found this post belowread this:https://community.keysight.com/thread/37599same issue that i have!Now i feel calmerI am almost 100% sure that is a F/W problem.Btw., do you maybe have 53131A counter? I have some issues with the counter. If you are experienced with repairing these units than you can maybe help me. Check my posts regarding 53131A.Anyway, thank you for your reply.Hrvoje

author: faraday
author_rank: Regular Contributor
timestamp: January 08, 2021, 04:48:45 pm
content: My 34410a does the same on FW 2.40.

author: ddcc
author_rank: Regular Contributor
timestamp: January 09, 2021, 12:06:08 am
content: I've also noticed that this occurs sometime on mine as well, v2.43.

author: faraday
author_rank: Regular Contributor
timestamp: January 10, 2021, 03:16:19 pm
content: Firmware upgrade to 2.43 and no change.
34410A Relay clicking when in resistance mode only if i touch probes - Page 1
Forum section: electronics / repair

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: June 11, 2023, 12:14:19 pm
content: Hello dear people!I have an issue/concern with my 2 34410A.When in resistance mode, if i touch the probes (insulated parts, not the tips!), relay inside clicks over and over.Please see a video, and sorry for potentially shaky video.https://easyupload.io/wllctrThank you in advance!

author: HighVoltage
author_rank: Super Contributor
timestamp: June 11, 2023, 01:58:05 pm
content: There are a few spots on the resistance scale of the 34410A and also the 34411A when the relay clicks between rages, since this instrument can measure in the G-ohm range.All my 34410A do the same, so no worries.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 11, 2023, 02:53:40 pm
content: Same here

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: June 11, 2023, 02:58:19 pm
content: Hmm, strange is how i didn't noticed this behaviour before.Whatsoever, thank you a lot!Oh yes, i almost forgot to mention, these instruments (34410A) are "buggy", they have a design flaw with autorange mode. Check this:https://community.keysight.com/s/question/0D52L00005IdprESAR/34410a-autorange-issue-when-selected-resistanceKind Regards,Hrvoje

author: HighVoltage
author_rank: Super Contributor
timestamp: June 11, 2023, 03:59:23 pm
content: Quote from: Hrvoje_CRO on June 11, 2023, 02:58:19 pmThese instruments are not buggy at all.Yes, this is a known small issue but easy to work around.These multimeters are considered to be the best 6 1/2 digit DMM ever built. (At least my opinion)They are just amazing when used correctly.

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: June 11, 2023, 04:08:35 pm
content: I must agree with you, this is why i did put buggy under quotation marks.
3458A - 210 Hardware failure - CAL VALUE OUT OF RANGE: 64 - Page 1
Forum section: electronics / repair

author: mimmus78
author_rank: Unknown
timestamp: September 19, 2019, 10:13:51 am
content: My 3458A started to trow out this error when is worm.Self test and acal all finish with ok when is cold ... but acal all trow this error when is few hours worm.Constant 64 is "dci zero rear 10 µA" from ACAL OHMS.I suppose this is zero point of the 10 µA range, so maybe some leakage in this part of the circuit when some component heat.Why this constant is only for rear? I suppose for front it's implicit in some other constant in the ohm range ... or what?My first step I think should be:1. turn on the meter and wait few minutes2. run acal ohm3. check/note the value of constant 644. set the meter in dci 10 µA with nothing connected and monitor drift if the zero offset5. wait a couple of hours6. run acal ohm again (at this point I should expect the error to appear)7. check what is value of constant 64 again to verify how much is drifted8. valuate the dataAny suggestion?

author: mimmus78
author_rank: Unknown
timestamp: September 23, 2019, 07:00:27 am
content: Ummm it seems since few days it's not failing anymore ...Can someone check what is value of cal 64?Mine after warmup is -1.9E-09.
3458A failing self test and ACAL ALL - Page 1
Forum section: electronics / repair

author: drhex
author_rank: Regular Contributor
timestamp: June 02, 2025, 05:07:26 pm
content: Hi,topic says it to a degree. My 3458A fails self test and ACAL ALL if 10V DC are connected to the input. Both work fine with open or shorted input, so I am thinking that one of the input relays aren't working properly (K1/3/7). Does anyone know if/when those should be active during self test or ACAL?I have another issue where the least three digits in current measurements stay the same independent of range and actual input, any ideas about that also welcome.Thanks,Florian

author: Kleinstein
author_rank: Super Contributor
timestamp: June 02, 2025, 05:47:33 pm
content: For testing it should work to set the meter to amps. This should have the relays to isolate the voltage input set to open and would allow a measurement there. Chances are this is a welded contact that does not open and thus a defect that is relatively easy to find. A driver that failed on is also possible, but less likely.The 2nd described error looks very odd. Probably first fix the relay issue (at least temporarily) and than run a full self test to see if other errors come up.The signal transmission from the analog to digital board should be in a binary format and the digital part is usually well separated from any input issue and hardly make a difference between voltage and current. Are the current ranges working at all ?

author: drhex
author_rank: Regular Contributor
timestamp: June 03, 2025, 04:00:07 pm
content: @kleinstein Danke! Will try that.Here're a few pics of the other problem, I input .1 mA and just change the range. Observe the least significant digits. And working otherwise - self test doesn't show any issues if there is no DC connected. Maybe the broken relay is somehow injecting a spurious signal from the DC side into the DCI end...

author: drhex
author_rank: Regular Contributor
timestamp: June 03, 2025, 04:01:58 pm
content: More ranges...

author: Kleinstein
author_rank: Super Contributor
timestamp: July 01, 2025, 06:49:36 pm
content: It is somewhat normal that the higher current ranges get less accurate. If there is a defect and error reported during ACAL it may not run correct and get the scale factor between the shunts wrong. It should start with the reference 40 K resistor and thus about a 100 µA internal test current, maybe the 10 µA.Instead of a series of pictures a table with numbers would be easier to read.A question would be if the error is a wrong scale factor, or some offset. An offset voltage to the current ranges would give a similar picture.Are the reading in AZ mode or with a proper zero in non AZ mode ?K1 and K7 should isolate the input when in self test and ACAL. The realy K2 should operate during some test and CAL steps.The relay K5 would seprate the current part from the voltage input. So this relay would also be suspect. If K5 is bad, I would also suspect the protection of the ohms source, as this would otherwise limit the current through K5.
34901A repair - Page 1
Forum section: electronics / repair

author: strawberry
author_rank: Super Contributor
timestamp: February 22, 2022, 03:34:55 pm
content: Is it possible to replace MCU ?blown temp sensor. temp sensor SDA SCL 100.. 700ohm . seems all 3 card ID ports are 5..7ohm

author: m k
author_rank: Super Contributor
timestamp: February 22, 2022, 06:56:04 pm
content: What is it?My guess from picture is ATmega.For the question I'd say that hardly.Manufacturer can of course give you a filled one, or sell for nominal fee since you're so good customer.

author: DeepLink
author_rank: Regular Contributor
timestamp: February 22, 2022, 07:15:06 pm
content: It's a 8051 with internal programGuess that you cant buy a spare from HPThere are loads of counterfeits on the marked of these modules

author: strawberry
author_rank: Super Contributor
timestamp: February 22, 2022, 08:15:13 pm
content: intel N87C521some made front panelscould be possible to read serial and make on something like 328

author: madao
author_rank: Frequent Contributor
timestamp: August 02, 2025, 03:53:07 am
content: Quote from: strawberry on February 22, 2022, 03:34:55 pmOld theard, but i must make posting.Yes, i have reading MCU from working card. Lucky not locked.https://www.eevblog.com/forum/testgear/diy-scan-card-for-keysight-34970a/msg5996381/#msg5996381Pull image and burn into 87C52 or 89C52 or 89S52.Damage seems like: overcurrent via ground..I have here 3 dead 34901A, two has burned pcb trace to ground, all DS75 SCL/SDA is not 1k (100-700 Ohm )

author: madao
author_rank: Frequent Contributor
timestamp: August 16, 2025, 04:31:46 am
content: I have four dead 34901A here, one is added since short time ago.two cards have burned PCB-trace , two card have no damage pcb.1xground /low wire between Input and Terminal is blow1x ground pcb trace between relay driver and mcu is burn downAll four has dead MCU, dead DS75,two cards have survived FRAM, two is missed (preowner..)Also 74ACT132 (reset generation/ control) is always dead.Only one Card has dead 74ACT138cards with damaged PCB has also blowed transistor & diode for relay (Q301-Q303 (?))I have replaced dead MCU with Atmel 89C52 /89S52 with firmware (previous posting has link to firmware dump, (Rev 2.0 and 2.3 works)Finally, i am fixing successful three cards.Last card with blowed ground between relay driver and MCU, it make still ERROR 916 (wrong Firmware, but ID on MCU is correct.. )
34970a bootloop - Page 1
Forum section: electronics / repair

author: f14
author_rank: Regular Contributor
timestamp: October 18, 2020, 11:06:50 am
content: Hi Guys,After fix the error code 625 by replace MCU 89s52 with fw from other 34970s . I get new problem. my 34970a keep restart over and over (bootloop) when I install the 34902a card ( this card working good in other 34970a ). 3 slot have same issue .but when power on without card it can boot up and pass the self test without any error codehave any idea?thank you

author: alm
author_rank: Super Contributor
timestamp: October 18, 2020, 04:19:59 pm
content: Did you check for ripple the power rails, especially with a card installed? I'm thinking it might be dried electrolytics. The increased current draw by the card might cause the ripple to increase.

author: f14
author_rank: Regular Contributor
timestamp: October 18, 2020, 04:38:44 pm
content: I'm checked all supply voltage from P302 connector . and seem very normal with/without card (double check with other 34970a). after that I'm try to replace two 2200uf 35v by one 4700uf 35v but nothing happensmaybe problem come frome reset signal from u305 or u304?.

author: alm
author_rank: Super Contributor
timestamp: October 19, 2020, 08:46:01 am
content: Thanks for posting the solution, and congratulations on the fix!
3D printing knobs? - Page 1
Forum section: electronics / repair

author: Axtman
author_rank: Regular Contributor
timestamp: January 26, 2022, 06:56:08 am
content: Does anyone here 3D print items? I am interested having someone print me about a dozen knobs for an old Univox guitar amplifier. Thanks.

author: Swainster
author_rank: Frequent Contributor
timestamp: January 26, 2022, 02:34:50 pm
content: I do, but I'm based in Singapore. If you have no luck here then you could probably find someone closer on Reddit

author: mag_therm
author_rank: Frequent Contributor
timestamp: January 27, 2022, 03:50:35 am
content: Did you do a search for "NOS" knobs etc or try search generic "guitar amp knobs"?I recently restored an old Bogen amp and found the original skirted knobs available from more than one supplier.like here:https://www.surplussales.com/ShaftHardware/Knobs-10.html(there are other pages)

author: george.b
author_rank: Frequent Contributor
timestamp: January 27, 2022, 04:12:12 am
content: In the US you could try Shapeways or something, I guess?
42lv5400-ub no pic or sound help. - Page 1
Forum section: electronics / repair

author: Serge125
author_rank: Regular Contributor
timestamp: January 18, 2022, 09:43:12 am
content: Hi all!!!Ok my 42lv5400-ub just decided that it doesn't show any picture and yes I have done the flashlight test and don't see any thing on screen as for sound I don't know. It was working just a few mins ago and now nothing. I did noticed that when I turn it on I get a red led then I get 2 white flashing BUT the thing is that I found out that the TV is on because I can turn it off and I get the normal white led that turns on and off when the tv shuts down. So I didn't get the chance to test anything it happened late last night but I did took the time to take the back off for later today after work to check things out. I will try my T-CON power test thing to see if my lcd works with red, green, blue and white screen appearing. Still I'm asking anyone here for any advice so when I get back from work to test some of your suggestions and yes I do have the repair manual for it too. I do have a meter and a LED back light tester too. So thanks for any advice!!!!THANKS in advanceSerge
465B X-Y Horizontal Shift - Page 1
Forum section: electronics / repair

author: awesomechapro
author_rank: Contributor
timestamp: November 26, 2024, 04:31:42 am
content: Hi all,I've recently been restoring an old Tektronix 465B oscilloscope. I've gotten it mostly working, but am having trouble with the X-Y mode. The normal sweep is positioned in the right spot horizontally. (in the center of the horizontal adjustment knob) But when I switch the oscilloscope into X-Y mode the dot is significantly shifted to the left. Is there an adjustment somewhere that can adjust the default horizontal position in the X-Y mode without interfering with the horizontal position of the sweep? I have already had a look throughout the service manual, the calibration procedure and the schematics to no avail.Thanks in advance.

author: tggzzz
author_rank: Super Contributor
timestamp: November 26, 2024, 09:27:22 am
content: What do you mean by "significantly"?How does the issue change when you change the X-channel control settings?

author: awesomechapro
author_rank: Contributor
timestamp: November 26, 2024, 10:26:35 am
content: as in when both channels a GND coupled, and the horizontal position control is at it's right most position, the dot is still to the left of the center line

author: ondraN
author_rank: Regular Contributor
timestamp: November 26, 2024, 01:21:47 pm
content: The X position can be affected by the correct setting of the trimmer R1126 "CH1 TRIG DC BALLANCE" on the CH1 preamp board. (1)
47PFT5609/12  Philips (/LG) TV repair - 12v becomes 8.6v after power on. - Page 1
Forum section: electronics / repair

author: Odd
author_rank: Regular Contributor
timestamp: April 28, 2022, 04:48:19 pm
content: This TV appears just black when power is applied.The 12v PSU output is 12v and 24V- all good... the TOSLINK led is on. PSU on signal is 3,3v.A long press, and the TV switches on sometimes displaying "Philips" for less than 1/3second - then dies.The 12V output from the main power supply is now 8.6v and the 24v output is zero.I have found the service manual:https://tel-spb.ru/files/philips_chassis_tpm14-1e_la.rarI tried to start it up with all load 12v + 24v connector disconnected - and the 12v rail is then 8.66v.When the ON signal is left floating, it's 0v.How can I know what the PSU is supposed to provide when it has no load? right now I am not sure whatever a floating PS_ON is the problem - or not..is the 8.6v an fault, or just stnadby/poweroff voltage?...and why does it die (apparently because the power_on signal goes low? - or does it go low due to power loss (back to 8.6v?)- how to troubleshoot further?

author: Harvinder Singh
author_rank: Newbie
timestamp: June 10, 2022, 05:54:12 am
content: The PSU should have a minimum of 12V output (12V nominal) if it's a good quality unit. If it doesn't then that's a sign that something is wrong with your PSU. You may need to replace it.If it does have a load connected to it then the PSU should supply at least 6-8V under load.You could try connecting a multimeter between the +ve and -ve terminals of the PSU and measure the voltage across them while the PSU is supplying power to the system. That way you'll know whether the PSU is providing enough power to the system.If the PSU isn't providing enough power then you might want to consider replacing it.

author: fzabkar
author_rank: Super Contributor
timestamp: June 10, 2022, 06:54:59 pm
content: The 12V supply has two possible states depending on the state of the DV5 control signal (page 70 of PDF).When DV5 is high, Q9341 is switched on and R9345 is shunted in parallel with R9344. The potential divider consisting of R9343, R9344 and R9345 then sets the supply voltage to 12.3V.When DV5 is low, Q9341 is switched off and the potential divider consisting of R9343 and R9344 then sets the supply voltage to 8.04V.DV5 is 12V when PS_ON is high, and 0V when PS_ON is low.Therefore it would appear that 8V is the normal state of the 12V rail in standby mode.
5 band resistor identification (SILVER third band) - Page 1
Forum section: electronics / repair

author: fudmuffin
author_rank: Contributor
timestamp: September 14, 2019, 04:52:19 am
content: Hello, I didn't expect to need help identifying a blown resistor, but thought it's better safe than sorry.Bands are:RED, RED, SILVER, GOLD, BLACKIs it a .22R? (assuming it reads left to right) What's stumped me is that it is a 5 band resistor but with SILVER as the third band. If the GOLD represents tolerance, then what does the BLACK signify?Any tips to identify? Photo attached. Many thanks!

author: timgiles
author_rank: Regular Contributor
timestamp: September 14, 2019, 06:57:01 am
content: https://en.wikipedia.org/wiki/Electronic_color_codeAn old British Standard. Your resistor looks to have a tolerance and temp. co efficient as well.
5-pin SOT Voltage regulator TRDEC - Page 1
Forum section: electronics / repair

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 28, 2022, 08:11:19 am
content: I know there are some website where you can look up those 3 and 5 letter codes, seen them before, but I cannot find them anywhere (should have book marked them)Anyone knows which voltage regulator this is, or where to find those reference list websites?Many thanks.Additional info:- Probably regulates from 5V to 3.3V- It burns when you feed it 12V- 1.5mm x 2.5mm in size (those stripes are half mm)

author: Audiorepair
author_rank: Frequent Contributor
timestamp: January 28, 2022, 12:37:07 pm
content: fzabkar provided me this link a couple of days ago, seems a good resource.http://www.smdmark.com/en-US/search/code?id=DEC

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 28, 2022, 12:47:55 pm
content: Thanks yes, sort of like that.Though the one I remember, you could filter on both package (pins) and the 3-letter code.And was not specific to a supply house. If only I had bookmarked it.Anyway, thanks. Alas, I could find it on that list.

author: fzabkar
author_rank: Super Contributor
timestamp: January 29, 2022, 06:20:08 am
content: These appear to be pin compatible step-down converters. You need to match the feedback voltage, switching frequency, and max Vin. The size of the inductor would be a guide to the switching frequency and output current. Compare it against the inductors in the application circuits in the datasheets.http://file2.dzsc.com/product/17/10/16/1129211_103315937.pdfhttps://www.maxlinear.com/Files/Documents/SP6669_DS_RevC.pdfhttps://datasheet.lcsc.com/szlcsc/1903011605_JoulWatt-Tech-JW5222_C371424.pdfhttp://www.broadchip.com/Public/Uploads/uploadfile/files/20210402/BCT1814.pdfhttp://www.broadchip.com/Public/Uploads/uploadfile/files/20210402/BCT1812.pdfThere are plenty of other possible candidates:https://ipv4.google.com/search?q=filetype%3Adoc+OR+filetype%3Apdf+%22absolute+maximum%22+%22sot23-5%22+converter+%22step+down%22+OR+stepdownI would look for a compatible part from makers such as Monolithic Power, TI, On Semiconductor, STMicroelectronics, Vishay, Richtek. The pinout seems to be very common.If you can determine the values of feedback resistors R39 and R40, then you should be able to calculate the feedback voltage, assuming that Vout is +3.3V.
53131A OCXO timebase cal failures - simple fix. - Page 1
Forum section: electronics / repair

author: naimns
author_rank: Newbie
timestamp: September 14, 2024, 07:00:58 pm
content: I've had an Agilent (MYxxxxxxx) 3CH 53131A sitting on my bench for a while needing attention. Working fine with the failed OCXO disconnected. OCXO p/n 10811-60160 (OPTION 010) .Problems with the OCXO were located down to a blown E1 ferrite and blown L2 inductor. Both easily replaced. Not sure how this was caused.The next issue was a little confusing. The unit wouldnt pass the timebase cal. 10MHz signals looked fine. I used a standard GPSDO and waited for 24H for the 53131A OCXO to stabilize.After several fails, I checked the OCXO DAC serial port on a LA and monitored the DAC vout, all fine and no problems with the interface. While checking the DAC, I noticed that the cal always failed when the DAC output was at max (+5v). You can watch the vout shift as the unit tries to trim the OCXO.The problem was located to the OCXO internal trim (labelled FREQ. ADJ.) being too far off for the DAC to compensate. A few attempts at shifting the trim resolved the issue (several turns).The timebase cal does pass without the OCXO having being run for long (a few hours).Generally quite some noise on the +5v/-12v/+12v, possibly needs some caps replacing.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 15, 2024, 11:47:06 am
content: if something as blow up sure you have or had problems, and yes others here would say check all you caps and redo them if needed,your ocxo section was at fault, and maybe it's a matter of time before the same problem happens again ? maybe some spikes in it's supply ??

author: naimns
author_rank: Newbie
timestamp: September 17, 2024, 07:04:43 am
content: yes, possibly some past life issue. power supplies measure fine, min/max/rms as expected.
53131A strange behaviour update - Page 1
Forum section: electronics / repair

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: May 18, 2020, 06:54:49 pm
content: Hello!Ok this is quite strange and i am confused. I need old experienced electronics guru who can explain me why this is happening.So i connected my 53131A to Siglent SDG2042X, 100mVpp, 1kHz. The display on 53131 does not update (except if i push RUN key on the 53131A). Ok, so i tried old Stanford Research with same settings and voila! The counter has worked normally. I have filmed this. You can see it herehttps://easyupload.io/myvo5g. But i am still not sure if everything is ok with my 53131A because of thishttps://easyupload.io/3sckkj. This happened today even when i did connected 53131A to the Stanford Research generator, but after i tested 53131A on the Siglent first. Strange, huh?Thank you in advance!Hrvoje

author: awallin
author_rank: Frequent Contributor
timestamp: May 18, 2020, 07:00:41 pm
content: what are your trigger settings and trigger level?

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: May 18, 2020, 07:12:39 pm
content: Quote from: awallin on May 18, 2020, 07:00:41 pmon my 53131A? Default, i am not sure what exact values. But under trigger sensitivity i didn't change anything if you mean that. Few moments ago i have tested the 53131A, had misbehaving issue with siglent, as i connected counter to the siglent the values on display of the counter had misbehaving, and as i changed the frequency from 1kHz to 10kHz the counter did not the followed accurately frequency update, so i tried the same on other signal generator, had same issue but after few moments the counter had stabilised the readings. Also one important thing: if i connect counter to the 10MHz rear output or rubidium i get stabilised readings with no any issues.

author: Dr. Frank
author_rank: Super Contributor
timestamp: May 18, 2020, 07:31:41 pm
content: check your trigger levels, and AC/DC coupling, please.Unpleasant shaky video, btw.Also check this BNC cable, and the other channel on your 54131, i.e. BNC connectors may be shaky alike.Frank

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: May 18, 2020, 07:48:42 pm
content: Quote from: Dr. Frank on May 18, 2020, 07:31:41 pmSorry for the shaky video. It was only for demonstration.
53132a ROM checksum failure - Page 1
Forum section: electronics / repair

author: martinr33
author_rank: Frequent Contributor
timestamp: March 04, 2019, 05:34:24 am
content: I picked up a unit with this failure. Easily fixed by reflashing the memory. Seems to be a problem for 20+ year old units.The parts are AMD 29F010 in a PLCC package. They are reprogrammable, so you don't need spares.The HP sockets don't seem to fit a standard extractor, so you need care and some jeweler's screwdrivers (risk of cracking the socket).You will need a PLCC adapter for your programmer. Fixed socket versions are available on Amazon Prime, or on eBay from China for a bit less money. ZIF sockets are also available, but you don't really need them.In my case, it was one bit in one memory at the very end of the address space.It is worth reflashing all four devices. You can also upgrade to the latest code, but this update requires a recalibration.Then you can do all the upgrades...

author: wn1fju
author_rank: Frequent Contributor
timestamp: September 03, 2021, 08:10:56 pm
content: Exactly the same experience here. Turned out to be a single bit at address 130022 in U8. Should have been FF, but was EF. These bytes were at the end of the ROM in a big block of FF's, and the error didn't seem to degrade the 53132A, so perhaps the counter wasn't reading those addresses. It only threw the ROM error at startup, but otherwise worked fine. New set of AM29F010 with the (version 3944) binaries from KO4BB's site fixed all.

author: Cyclotron
author_rank: Unknown
timestamp: August 06, 2024, 09:29:49 pm
content: Thanks for the hints. I also found a bit flipped in the lower region of U8, which caused my ROM FAIL issue.Now I have a nice 53132a ready for me to build and add an Ultra stable oscillator.

author: wraper
author_rank: Unknown
timestamp: August 06, 2024, 10:05:37 pm
content: Quote from: wn1fju on September 03, 2021, 08:10:56 pmStrange, I'd expect opposite, Flash losing the charge. Not unprogrammed bit reading as programmed. So it looks more like accidental programming due to some glitch rather than retention issue.
5333h 1xha - CPS533 Voltage Regulator Info or Substitute   - Page 1
Forum section: electronics / repair

author: Hundleton1
author_rank: Contributor
timestamp: September 27, 2022, 09:53:02 am
content: Hi everyone, I hope it’s ok to post this here, if not I apologise and please tell me where would be best.I am trying to find any info on a voltage regulator that’s labelled 5333h 1xha that we believe is a CPS533 5v regulator.I can find nothing on this part at all. Not even a data sheet.If anyone has any data sheets, info on supply or an alternative I and the FPV community would massively appreciate it .

author: fzabkar
author_rank: Super Contributor
timestamp: September 27, 2022, 07:49:16 pm
content: I found a reference to CPS5333 in this teardown:https://view.inews.qq.com/k/20201019A02MJH00?web_channel=wap&openApp=falseThe part marking is 5333, not 5333H.There is also a CPS8100GQ part in the same teardown. Its logo belongs to Convenient Power Semiconductor, also known as Convenient Power Systems.Their web site is basically useless:https://convenientpower.com/home/I did find a totally unrelated datasheet which confirms the identity of the company and logo:https://edit.wpgdadawant.com/uploads/news_file/program/2022/36980/tech_files/program_36980_suggest_other_file.pdfHere is another reference to a CPS5333 buck converter:http://www.icsmart.cn/53387/Edit:I'm getting closer:https://convenientpower.com/home/power-management/(CPS5303/5/7)
54522a Battery repair/relocation - Page 1
Forum section: electronics / repair

author: SometimestheDragonWins
author_rank: Newbie
timestamp: July 06, 2022, 07:40:50 pm
content: I have a 54522a purchased from an auction a few years back and it had the typical failure mode that the whole 545** series has when the internal 17450 (3v) battery goes flat. I am just wondering if my fix of soldering wires to the PCB and running them outside of the scope to an 18650 (3.7v) battery holder is going to end up giving me problems down the line. So far it seems to have worked and i got the scope to accept the newest firmware from keysight.

author: wn1fju
author_rank: Frequent Contributor
timestamp: July 07, 2022, 11:42:18 am
content: I did the external battery trick on my 54522A a few years ago and have had no problems whatsoever.In fact, I have had many pieces with internal RAM backup batteries that died. What I usually do is to replace them with two alkaline AA batteries in one of those cheap sealed plastic battery holders. Usually there is enough space inside the piece to mount the holder internally. I've never had any problems doing that except, of course, that the batteries will eventually leak. But that's the purpose of the holder - to contain the leak. When the original battery was a rechargeable type, I simply put a diode in series with my AAs to prevent charging.My only regret is that I didn't put some sort of label on the pieces that I put new batteries in, so I have no idea when looking at a piece whether or not I ought to check on the batteries every couple of years. Oh well, live and learn.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: July 07, 2022, 02:19:10 pm
content: just identify lin. reg, ie. its property specs, beside it if it's ok for 3.7V
54622D Boot data error occured? - Page 1
Forum section: electronics / repair

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: March 29, 2020, 02:06:54 pm
content: Hello,I have updated few days ago my scope with newest firmware.Everything was ok until today when i powered it on i've get one new system concern which was not previously seen.It was boot data error occured.See the pictureHow to fix that? Is this due to low battery?Otherwise, scope pass all the tests and it is working normally.Thank you in advance!

author: JFJ
author_rank: Regular Contributor
timestamp: March 29, 2020, 03:56:41 pm
content: Quote from: Hrvoje_CRO on March 29, 2020, 02:06:54 pmReplace the lithium cell and reset the oscilloscope:NB You will need to access the underside of the system board to unsolder the battery.

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: March 29, 2020, 05:04:16 pm
content: Quote from: JFJ on March 29, 2020, 03:56:41 pmHello JFJ,So if i change the battery and reset the scope, will boot data error dissapear? I am so concerned about that error, i hope it is not HW problem because scope works fine.Thank you!

author: JFJ
author_rank: Regular Contributor
timestamp: March 29, 2020, 05:56:45 pm
content: You should be able to test that the errors will disappear by doing a power-on reset now. The boot data that was lost is only non-critical information, such as the oscilloscope's settings (Volts/div, Time/div, etc.) before it was last powered down.

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: March 29, 2020, 06:06:12 pm
content: Quote from: JFJ on March 29, 2020, 05:56:45 pmI tried that! Pushed softkey during power up and display came wihout any errors.So this is a good news?Yuk! Battery replacement is sensitive but i will change it.

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: March 30, 2020, 01:01:16 pm
content: Quote from: JFJ on March 29, 2020, 05:56:45 pmI forgot to mention, i did as you wrote and errors did disappear, but at the second power-up it is the same error list.Thank you!
HP 54645A megazoom Firmware - Page 1
Forum section: electronics / repair

author: atwork
author_rank: Newbie
timestamp: May 21, 2022, 07:06:23 pm
content: HelloI have HP 54645A megazoom. After power on, oscilloscope show normal screen with message address error, and any key doesn't work. I think it is problem with firmware.i need firmware A.02.0x. to repalce old one.Regards

author: free_electron
author_rank: Super Contributor
timestamp: May 22, 2022, 04:46:55 am
content: clean the rotary encoders first. if the scope start then firmware is ok. you can't flash that scope. the firmware sit in UV eprom.

author: atwork
author_rank: Newbie
timestamp: May 22, 2022, 04:23:33 pm
content: without conection keyboard is the same address error.I know that, firmware is on UV EPROM. I need 2 hex file to reprogram EPROM.Do you have the same equipment? Are to able to dump firmware chips?

author: oPossum
author_rank: Super Contributor
timestamp: May 22, 2022, 05:41:15 pm
content: 54645D attached.I don't know if that will work in the 54645A

author: xavier60
author_rank: Super Contributor
timestamp: May 22, 2022, 08:13:33 pm
content: This is what I saved 11 years ago from one of mine.

author: atwork
author_rank: Newbie
timestamp: May 23, 2022, 05:19:07 pm
content: thank's for firmware.
54831 Oscilloscope Cover - Page 1
Forum section: electronics / repair

author: bostonman
author_rank: Super Contributor
timestamp: May 31, 2024, 03:14:23 pm
content: Not sure if this is "repair" related, but I'm wondering if anyone knows where to locate 54831 oscilloscope face covers to protect the front.Does anyone know where to find these and/or alternatives?

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: June 01, 2024, 06:14:06 am
content: you could potentially take measurements and 3D print one yourself.

author: bostonman
author_rank: Super Contributor
timestamp: June 01, 2024, 06:38:36 am
content: I thought of that, but it’s a large piece and I don’t see anywhere it would clip onto.I’m thinking more like a foam mold.

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: June 01, 2024, 05:10:13 pm
content: If you have a foam cutter or a hot knife, you could cut a block of foam to fit over the front to protect it. It won't be exactly pretty but it should do the job. This is what I do when I ship oscilloscopes.You can also use velcro stickers to keep the foam cover on.

author: bostonman
author_rank: Super Contributor
timestamp: June 01, 2024, 11:44:22 pm
content: I’ll give some thought to that as it’s the best option.
55" Philips Smart TV blinks 2 times - Page 1
Forum section: electronics / repair

author: anton74
author_rank: Contributor
timestamp: July 30, 2021, 08:22:35 pm
content: Hello,I am trying to repair the 55" Philips Smart TV (model 55PFL6008K/12). The red led blinks twice. With the power supply connected to the mainboard, I measured the +3.3V and +12V on the output connector of the PS board. When the power supply is disconnected from the mainboard, the +3.3V is present while the +12V is absent. I suppose it is normal since no standby signal was applied. However, in the "hot" side of the PS board, I noticed the black, discolored diode D501 (please see attached). This diode is marked as "T2D 23". When unsoldered and tested with a multimeter, the diode reads open in both directions. The diode is connected across the primary of the SMPS transformer and to the drain output (pins 6, 7, and 8 ) of the U501 IC (FSB127H). I did not find too much information about this diode. I have read on some forums that it could be the TVS diode, while the datasheet of the FSB127H refers to the regular 1N4007 connected in the same manner. For example:https://www.eevblog.com/forum/repair/trying-to-fix-broken-psu-in-a-philips-46pfl8008s12-tv/.Other discussions about this (or similar) diode:https://www.avforums.com/threads/philips-46pfl8007t-12-diode.2237949/https://www.mikrocontroller.net/topic/465167https://forums.futura-sciences.com/depannage/828713-identification-diode.htmlIt seems that nobody identified this diode.So, I am not sure whether this diode is bad. So, I have the following questions:1) what kind of diode it is and is it bad or good;2) since I have measured both +3+3V and 12V, and despite the discoloration of the diode, the power supply is probably OK. Then, the fault is probably on the mainboard. I have read that the reflow of the main processor or replacement of the entire mainboard is required. How can I check the mainboard? I started to measure the voltages on different voltage regulators; however, there are about 10 different voltage regulators on the mainboard. Any information would be appreciated.Anton.

author: anton74
author_rank: Contributor
timestamp: July 30, 2021, 10:37:44 pm
content: Well, it seems that I 've found an answer on my own question regarding the diode - it seems that this is a transient voltage suppressing (TVS) diode and a fast recovery diode (FRD) in one package; probably ST02-170. Here is a datasheet:https://www.tme.eu/Document/430c98e056b0292bfda740fe9659b265/ST02D-170.pdfIt should measure open in both directions, and a discoloration is not a problem. So, the power supply is probably OK. That means the mainboard is defected, most likely the main processor needs to be reballed.
FLUKE 5520A starting up problem - Page 1
Forum section: electronics / repair

author: david123
author_rank: Newbie
timestamp: September 21, 2023, 07:26:22 pm
content: HiI have a FLUKE 5520A which due to a problem with the power button (stuck button), I disconnected it before not completed warm up time.then when I turn it on again it shows me the following message " starting up " and it remains in a permanent loop

author: Meowww
author_rank: Newbie
timestamp: July 30, 2024, 04:38:47 pm
content: hi ,problem is generated by dds board , check cmos ic's.
555 timer, no output - Page 1
Forum section: electronics / repair

author: nus
author_rank: Contributor
timestamp: May 12, 2019, 03:46:07 pm
content: ok so i have a 555 timer with no output, however it seems to make sense.

author: nus
author_rank: Contributor
timestamp: May 12, 2019, 04:06:32 pm
content: so on the threshold i have 3.75v. so in a discharge state.On the trigger i have 5v,on the oscilloscope it shows me a switching that is someting like 7v to 2.5v before c32 it is switching between 0 and 5ishreset is high 5vso im a bit stuck here, is the issue the dc offset caused by c32, since it never drops below 1.66. do i even count the dc offset caused by c32Also is there a way to calculate the resistance of the transistor according to the the signal its receiving. want to know this to understand why the voltage is highsincer22 is 33kq5 is 37k i measured this while it was offso the divider = 2.64 which would be enough to turn off the discharge, which might be grounding my output. however i think that is not ever turning on because of the dc offsetthis is a williams system 6 mpu

author: nus
author_rank: Contributor
timestamp: May 12, 2019, 04:07:19 pm
content: i need the output to be high

author: nus
author_rank: Contributor
timestamp: May 12, 2019, 04:50:50 pm
content: a is before c32 and b is trigger on pin 8

author: nus
author_rank: Contributor
timestamp: May 12, 2019, 04:57:27 pm
content: ok i just shorted the cap and now it works

author: nus
author_rank: Contributor
timestamp: May 12, 2019, 05:10:12 pm
content: what are the issues with this. the cap measures the right amount 46nf, it has 473 marking on it. i dont understand why stock cap at correct value would be doing this. any ideas on what i should do