agilent 54845A project ( REOPENED ) - Page 1
Forum section: electronics / repair

author: charlyd
author_rank: Frequent Contributor
timestamp: April 29, 2019, 11:34:02 am
content: Today my 54845A arrived. and after doing a quick inspection it was time to power on de dude.first i saw a failing bios time. 01-01-1999 so i checked the cr2025 and it had to be replaced. after replacing came the big question what are the actual optimal bios settings for the scope? some are in the manual. If the second IDE doesn t detect any drive, it is time to default the bios settings!!i booted the unit and i got the error. "Fine Interpolator handshake failed: Service is required".i did the self-test and many failed but also a lot passed. so from my opinion when the A13 has got the handshake ok we are back on track.. : later i found out that this input flat cable has nothing to do with the actual problem.did somebody have this error yet?and i still have issues after replacing the CR2025 in with the bios date...it is resetted to 1999 everytime. i have to look in the manual maybe the formal ownerplayed arround with the swithces and jumpers like he did with the wiring...1 wire on the A13 was stuck behind the power supply and not connected. after gettting it in place it was too easy to hope the unit would work.. because it doesnt.but looking at some youtube i discoverd i am missing an important flatcable W13 is totally gone.. see pictureWho can help me out?? with selling some parts? please PM mei am missing 5 screw in the AQ board / the flat cable / 2 screws from other board

author: charlyd
author_rank: Frequent Contributor
timestamp: April 29, 2019, 01:40:45 pm
content: and of course i still have the bios date time reset after power off -> on CR2025 being replaced

author: alpher
author_rank: Frequent Contributor
timestamp: April 29, 2019, 04:01:15 pm
content: I can try to unplug the cable on mine, to see if I can reproduce the error.Will try tonight, in the meantime can you see what's the software version yours running?

author: charlyd
author_rank: Frequent Contributor
timestamp: April 29, 2019, 07:25:17 pm
content: Thanks alpher, my software is 4.50 the latest version my unit was refurbished by keysight in 2014 … it is equipt with the VA-503Ahow can i get the lower input panel ( with the 4 ch inputs and 1 aux ) out. do i need to take the front off or is there a trick? i need to come get to the flat cable connector hidden behind the input panel.

author: alpher
author_rank: Frequent Contributor
timestamp: April 29, 2019, 09:51:43 pm
content: The panel is being held to the frame with 2 spring loaded clips, you have to push it from behind with something slim like thin long srewdriver for example.Here's a picture of panel removed, the clips fit in the two vertical slots, the horizontal openning is where you should be pushing from behind.It takes 5 seconds, really easy.

author: alpher
author_rank: Frequent Contributor
timestamp: April 29, 2019, 11:36:26 pm
content: Just checked the operation with the ribbon cable disconnected, as I thought no difference whatsoever, no error.

author: charlyd
author_rank: Frequent Contributor
timestamp: April 30, 2019, 08:26:22 pm
content: ahhh...so that mean i have problem with my board or pci card is that what it means? maybe you can try to pull so connectors and bot up to see when i am getting this error..btw my unit is VIN033. but i think that doesn t make sense with the error....but still i need the 30 pin flatcable.. PM wanted..

author: charlyd
author_rank: Frequent Contributor
timestamp: April 30, 2019, 08:29:48 pm
content: Hi alpher i also saw some power measure points in the right down corner [+8.5] & [-5.0] & [+5.0] ..are different in my unit from the picture from a guy project found on the web.how are yours alpher? and my channel 3,4 AD hybrids get quickly hot and channel 1,2 normal warm... ( last calibration ch 1,2 were passed)

author: charlyd
author_rank: Frequent Contributor
timestamp: April 30, 2019, 09:35:46 pm
content: btw these are my errors.

author: alpher
author_rank: Frequent Contributor
timestamp: May 01, 2019, 12:32:28 am
content: Here are a couple of pic of the acquisition board in my scope, hybrids stay just warm not hot at all.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 01, 2019, 06:29:33 pm
content: hi Alpher can you please check if you have the same values on those check points?This is a screen shot from matthews project (the web) with HIS voltages but are these the real values because my checkpoints are different and some voltages are not in place. ( pitty no schematic ) so i need other references..what is the total stretched length from the flat cable. so i can find it on ebay.. if nobody PM me.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 01, 2019, 08:39:56 pm
content: tonight i did some checks andin blue are my valuessee the difference with the above picture.and i have still te message defaults loaded - my cmos is defaulted everytime, even with the CR replaced..nearly everytime i get a NO screen when powering ………. the second time the picture shows up. ( many this is oin combination with the so called "default cmos error".

author: alpher
author_rank: Frequent Contributor
timestamp: May 02, 2019, 02:26:28 pm
content: Unfortunately I cannot power it up right now, I'm in the process of changing the motherboard.The i810 mobo that I bought of ebay finaly arrived and the scope is in pieces.Will have some time this weekend to put it together.Your problems seem to be motherboard related, can you try a different mobo?If I was desperate I may have tried a mini ATX mobo there, I think that the scope software will run on pretty much anything from the period ( socket 7 to 370 ).

author: charlyd
author_rank: Frequent Contributor
timestamp: May 02, 2019, 08:29:04 pm
content: hi alpher, following you close ;-) new motherboard… upgrade the W98 board ? i started again. last night i took of out the motherboard and i fixed the problem from the bios. so the motherboard is. ok. the problem was in cr2025 spring. i took the battery out and the bottom spring was bend so the the battery was not doing its work .. so. Problem 1 fixed.the second more difficult one the AQ board. i miss the 8.5 volt. as i told before i took the board out and checkt 6.3 volt next to the attentuator, in my case it is -12volt so.the side board also has a eprom and more on the board 4 of the iron coolpads measure the same value and the top 4 coolpad also the same value. 3v and 12v.@alpher what is the length of the flat cable. and the pitch of the pins. is is 30 pins if i counted well.

author: alpher
author_rank: Frequent Contributor
timestamp: May 03, 2019, 02:19:53 am
content: I don't know why that ribbon cable is so important to you, it only matters when you want to use special Agilent/HP probes that cost an arm a leg and then some.Nonetheless here it is, a simple 30 conductor flat ribbon cable , 1mm pitch, measured length ~32cm and there's plenty of room for longer cable.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 03, 2019, 04:39:22 pm
content: hi alpher thanks i understand it is not in the circuit but my feeling says that this one is difficult to get ( long time) in the end it is good to have one.. so that why i try to get it..as soon as possible.thanks very much… is your unit online again? if yes what about your voltages on in red in the picture.. and with the W11 disconnected?yesi meaned W11(small flate cable) is important W13 is only going to the end of the input circuitairy..W11 is in between the boards.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 04, 2019, 05:41:53 pm
content: I am also curious if there is anybody who booted up the unit with all ADC hybrid out? or with just only with channel 1 Hybrid in..this way i can test the hybrid one by one. and know what error i can expect when hybrid are out or broken. i mean to say is my error maybe related to 1 broken hybrid which distort my whole unit.i hope someone can tell me more about the repsons with and without...

author: alpher
author_rank: Frequent Contributor
timestamp: May 05, 2019, 01:54:08 am
content: I don't know if you know of a big thread going on here on the same subject.https://www.eevblog.com/forum/testgear/agilent-54835a-scope-(4-channel-1ghz-4gss)-repair-uphack/Check it out if you didn't already.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 05, 2019, 02:21:44 pm
content: @Alpher yes i saw it and it is really worth readding it, great topic..!!This afternoon i did a deeper dive.. to check the voltage "mathew project" is talking about but from what i saw in my unit they are different with his, i mean to say when looking in my pictures you see the measurment i did and like the 6.3 out and the -5 is not on the coolpad but on het output.. so do matthew pictures really match in real?again i took the hybrid out so i could take a closer look at CH 3 and from what i saw under the microscoop CH 3 is really BAD(lost). so the next step is the get a new one of ebay..but of course first i want to find out it the unit is 100% before i buy one. to check this i have to know a few things:can i bypass my " fine interpolator handshake error" by taking out hybrid(s) and try to get just 1 or 2 channels going. or maybe other tricks?It is really difficult to work on the board, so i took both attentuators out and i check if my voltages are present when both attentuators are out or does the unit go in a protect mode.At this point i am curious at what the real voltages are in the unit when both attenuators are out. (easy measering).and what would happen if hybrids are completly out, so if someone is intent to clean his hybrid for better trigger results please try powering on without 1,2,3 or all hybrids/attentuators out.. and see what error is cumming up.

author: TRN
author_rank: Unknown
timestamp: May 09, 2019, 10:12:06 am
content: You can measure voltages with the attentuators removed.See attached PDF

author: charlyd
author_rank: Frequent Contributor
timestamp: May 09, 2019, 08:53:03 pm
content: Hi thanks for you reply they are all ok on both attentuators. when i boot i hear them clicking (i think) like they should…my problem lies more arround the hybrid. what power supplies do i miss over there.. on the bottom side between each metal bracket is a yellow Tantalum cap i measure -5Volt over the tants.for the rest i can find any voltages arround those brackets on the bottom side.what voltages would be going ( and should be found ) to the hybrid brackets?

author: charlyd
author_rank: Frequent Contributor
timestamp: May 09, 2019, 08:59:57 pm
content: Here is an other thing which caught my eye and fingerwhat i found are 2 black big SMD resistors in the corner where the fan connectors are located on the bottom side of the board. Both these resistors coded " 201" are HOT HOT. is this normal ??

author: TRN
author_rank: Unknown
timestamp: May 10, 2019, 11:27:25 am
content: Regarding the selftest errors; enable the "service extension option" and then run the individual selftests for the items which failed. (i.e. for:)Test Time TagTest Interpolator TagTest TimebaseMaybe this will narrow down the problem.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 10, 2019, 08:44:44 pm
content: ok here is my logging the scope file pasted and series attached.my feeling says i am missing some voltages/power line(s) but where??**Test Run** : Scope Self Tests Test --- 10 MAY 2019 22:17:45Self Test invoked cal executed.Test FAILED on channel 1Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 2Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 3Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 4Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 1Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 2Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 3Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 4Acquisition Error: Acq not completed in alloted timeTest FAILED on channel 1Acquisition Error:Test FAILED on channel 3Acquisition Error:Test FAILED on channel 1Acquisition Error:Test FAILED on channel 3Acquisition Error:Test A to D Converter FAILED.Self Test invoked cal executed.FISO test failed on channel 1FISO data bit error not correctable.FISO test failed on channel 2FISO data bit error not correctable.FISO test failed on channel 3FISO data bit error not correctable.FISO test failed on channel 4FISO data bit error not correctable.Test FISO FAILED.Self Test invoked cal executed.Acquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeHi Imped. Mode Offset Dac FAILED on channel 1Acquisition Error:Check A to D converter selftest.Hi Imped. Mode Offset Dac FAILED on channel 2Acquisition Error:Check A to D converter selftest.Hi Imped. Mode Offset Dac FAILED on channel 3Acquisition Error:Check A to D converter selftest.Hi Imped. Mode Offset Dac FAILED on channel 4Acquisition Error:Check A to D converter selftest.Self Test invoked cal executed.Acquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeLo Imped. Mode Offset Dac FAILED on channel 1Acquisition Error:Check A to D converter selftest.Lo Imped. Mode Offset Dac FAILED on channel 2Acquisition Error:Check A to D converter selftest.Lo Imped. Mode Offset Dac FAILED on channel 3Acquisition Error:Check A to D converter selftest.Lo Imped. Mode Offset Dac FAILED on channel 4Acquisition Error:Check A to D converter selftest.Test Offset Dac FAILED.Self Test invoked cal executed.Acquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeAcquisition Error: Acq not completed in alloted timeTest FAILED on channel 1Acquisition Error:Check A to D converter selftest.Test FAILED on channel 2Acquisition Error:Check A to D converter selftest.Test FAILED on channel 3Acquisition Error:Check A to D converter selftest.Test FAILED on channel 4Acquisition Error:Check A to D converter selftest.Test Gain FAILED.Test Probe Board PASSED.30.4deg.CTest Temperature Sense PASSED.Test Trigger Level PASSED.Test Logic Trigger PASSED.Test Pattern Trigger PASSED.Test State Trigger PASSED.Interpolator test failed.Interpolator test timed out.Interpolator test failed.Interpolator test timed out.Time Tag test failed.Time Tag Counter does not reset to zero.Time Tag test failed.Time Tag Counter fails lower limit. Counter = 6Expected value = > 19,500,000 < 20,500,000 .Test Time Tag FAILED.Interpolator test failed.Interpolator test timed out.Interpolator test failed.Average (long interval cnt - short interval cnt) = 0Expected value = > 910 and < 1113Test Interpolator FAILED.Arun not clear when post trigger cnt zero and FF Clk mode.50MHZ Clk mode.25MHZ Clk mode.10MHZ Clk mode.FF Clk mode.Test Timebase FAILED.Max. Chan 1 Relay actuations: = ÚÚÚ50001Max. Chan 2 Relay actuations: = ÚÚÚ45706Max. Chan 3 Relay actuations: = ÚÚÚ45311Max. Chan 4 Relay actuations: = ÚÚÚ44354Test Attenuator Contacts PASSED.Test Scroll Mode Counter PASSED.Test Non-Volatile SRAM PASSED.Test Video Ram PASSED.Test Video SRam PASSED.Test Tri-state Register PASSED.Test Timer PASSED.Test Video Control Register PASSED.Test Acquisition Status/Control Register PASSED.Test Scope Self Tests FAILED.

author: TRN
author_rank: Unknown
timestamp: May 11, 2019, 10:49:40 am
content: That is weird,None of the ADC tests passed, and it is very unlikely that all 4 ADC's are bad, so it looks indeed that one of the voltage rails supplying power to the ADC's failed.Today I don't have time, but tomorrow I will remove a hybrid from my scope and measure the DC voltages from the contact pins.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 12, 2019, 07:50:30 am
content: Hi TRN THX.!! that would be very helpfull, maybe a good idea to see how the test outputs it self with a Hybrid off. so NOT SEEN for the unit. When you run the logging maybe some puzzle pieces fall into place.

author: TRN
author_rank: Unknown
timestamp: May 12, 2019, 04:04:48 pm
content: I removed Hybrid#1, ran the Self Test, and measured all the DC voltages at the Hybrid socket.The attached PDF shows the self test results. The XLS sheet shows the DC values measured.rgds

author: charlyd
author_rank: Frequent Contributor
timestamp: May 13, 2019, 06:44:15 pm
content: @TRN: you did great work. Which was your reference point? one of the GND pins?? First thing when i am in the workbench i gonna check it.today i took my all 4 hybrids off so there is no heat problem. for this moment i want to figure out where my trigger signal is...

author: TRN
author_rank: Unknown
timestamp: May 14, 2019, 07:34:59 pm
content: Yes all voltages reference GND.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 15, 2019, 05:13:20 pm
content: this is with the attentuator on?

author: TRN
author_rank: Unknown
timestamp: May 15, 2019, 06:15:20 pm
content: Yes,Both attentuators installed; only Hybrid #1 removed

author: charlyd
author_rank: Frequent Contributor
timestamp: May 16, 2019, 08:06:01 pm
content: Hello everbody maybe it is good idea because there is not much info known about the acquisition boards. to collect all REVERSIONS of the board with the Original problem.username VIN# AcQ reversion Mobo version problemcharlyd 033 Rev. C VA-503 Fine Interpolator Handshake error; service required

author: Ashevil78
author_rank: Newbie
timestamp: May 16, 2019, 10:24:24 pm
content: Hello there I'm new to this blog I have a agilent 54845a myselfThe scope it self works perfectly all on board tests pass with no failures as well as on boot up no failures alsoI changed the cmos battery because it was deadThe only issue I have is when I start it up for the first time after being shut off for awhile it hangs in the windows boot up .So it usually takes about 3 or 4 power cycles to get it to boot completely once its booted it runs perfectly .Is there anything on the windows side that would cause this issue or maybe the ram is causing this .Any help would be great thanksBill

author: charlyd
author_rank: Frequent Contributor
timestamp: May 18, 2019, 07:01:41 am
content: i saw in some topics and even on the keysight website that reinstalll the unit sometimes does magic...as a quick win i will try that first ..:edit: re-install did not help me. on first reboot i got a calibration message, for a short while i hope to have fixed it.But after the second reboot the error was back visible.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 19, 2019, 05:28:12 pm
content: ok did a deep dive on component level.The interpolator is a circuit designed to measure the time from the input signal initiated trigger event to the next edge of the timebase post trigger delay clock. To measure the time interval, a capacitor will be charged rapidly through a constant current source. The charge on the capacitor will be directly proportional to the time interval during which the constant current is applied. The capacitor is then discharged through a stretcher circuit consisting of a constant current source which may be as much as one thousand times smaller than the constant current source used to charge the capacitor. Two voltage ramps are observed, a charging ramp and a discharge ramp. The discharge ramp is used to gate a counter on at start of the ramp and off at the end of the ramp. While gated on, the counter counts clocks of a known clock width to measure the time of the discharge ramp. If the ratio between the charge and discharge constant current sources is known then the time between the trigger event and first delay time post trigger delay clock can be calculated. The test of the interpolator circuit is a re-run of the calibration software for the interpolator. There are two time intervals measured in the interpolator calibration. A short interval of two periods of a known clock and a long interval of three periods of the same clock. The difference between the two time intervals will be an accurate measure of the clock period since fixed system errors will cancel out.Getting you startedError Symptom DiagnosisInterpolator Self Test fails Look for evidence of short and long ramps. Probe at base or emitter of Q36 or around zener diode VR1Check ramp control U127A pin 3 (MC 10H131)Check set line of D-flip flop U127A pin 7 (MC 10H131)Check start interp cal line U128C pin 17 (MC 10H116)Check interp cal control line U116A pin 8 (MC 10H131)Check interp cal width control line U124 pin 13 (MC 10H105)i probe arround Q36 (smd code : 1AM) and VR1 (smd code : Z11)can somebode help me out telling me what voltage is on the emitter and base in a good working 54845A.(Q36 is located on the topside in the corner where the flatcable from the computer card is connected to the AQ board.)

author: charlyd
author_rank: Frequent Contributor
timestamp: May 20, 2019, 03:44:09 pm
content: today i went into the faults again i have 3 failed situations in my tests so i decided to drill down into there to see if there is a common component.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 20, 2019, 08:36:16 pm
content: ;EDITTED:i think i am in the need of some dump parts. Who can help me out with a hybridplease PM me if you have parts like a hybrid 1NB7-8348 or the mylar flat cable which goes to the input panel.[ this message is not relevant anymore]

author: free_electron
author_rank: Super Contributor
timestamp: May 20, 2019, 09:53:00 pm
content: i may have that flatcable. i need to delve in my parts bin.i don't have donor boards for the 845.the fact that you have so many errors leads me to believe you have a bigger isssue.your relay clicks for example are nonsense. which leads me to believe the calibration ram is corrupted or empty.take that cr2450 battery off the scope adapter card and install a fresh one. then attempt to run the self calibration. that will reset the cal ram.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 21, 2019, 05:01:27 pm
content: @free_electron: hello thanks for you reply i for sure keep the flat cable in mind but first fix...but does the battery create a "Fine Interpolator Handshake error" ? did you even see that error with the solution of the battery. my batterij measures ok if i am right. but will check as soon as i am at work.pitty no donor board. so my question stays openWho can help me with a donor board?

author: free_electron
author_rank: Super Contributor
timestamp: May 21, 2019, 09:23:23 pm
content: if the calibration ram gets corrupted there is no telling what the machine will do. it may load wrong constants.disconnecting that battery and reconnecting will erase the ram. the scope will detect that and load factory defaults and then ask to perform a calibration. this will bring the machine to a known state.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 22, 2019, 07:46:44 pm
content: meanwhile i arrived at component level U133 there should be some clocks…-> no clocks at all...U133 is a Actel A1010B PL44C FPGA. thats why i was looking for a donor part board.also discovered [closeup pictures are taking under a microscope]dirty solder work arround the U121 (pins 19 and 20 were shorted) and on some neighbour chip also dirty solder work, chips like U120 & U133 .. Somebody must have been in a terrible haste !Or was it a matter of "shotgun trouble shooting" at the service centre?

author: charlyd
author_rank: Frequent Contributor
timestamp: May 24, 2019, 10:01:55 pm
content: @free_electron: i tried the battery trick from the pci-card without any succes.so i decided to probe arround for a while again last night. My conclusion for now: i miss the clock on U133 so the U130 is next to look at the so called clock manager.i can t find any datasheet from this guySC64031FN so datasheet wanted / donor chip wanted[parked for now]Interpolator error says: U127 [check pin 3 and 7] but what about the power supply on this chip it has as power pins 1,16 & 8 what should they be?one of the pins show -1.8v (measured to GND) i would say not ok.the 100Mhz crystal on the other corner/side of the board is checked and ok.

author: TRN
author_rank: Unknown
timestamp: May 26, 2019, 04:51:42 pm
content: charlyd, the pinout from the datasheet of U127 is for a 16-DIL package. Pinouts for 20-PLLC are different.See the attached conversion sheet.So pinout is as follows:VCC1 = pin 2 =0VDCVCC2= pin 20 =0VDCVEE = pin 10 = -5.1VDCI measured the following voltages over VR1:Between Kathode & Anode: 2.45VDCBetween Kathode and ground: 2.92VDC

author: charlyd
author_rank: Frequent Contributor
timestamp: May 26, 2019, 10:06:04 pm
content: Ah this is a good point special thanks to @TRN for the conversion sheet. Apart from i was missing the pins of course nothing was written in my datasheets....but this makes sensean update is on its way, and also about the other power supplies and on the pins in that area ….

author: charlyd
author_rank: Frequent Contributor
timestamp: May 29, 2019, 08:07:13 pm
content: After spending hours searching for something to holdon. i took the attachments again and looked for a general thing..Let s see if there is a steady 100Mhz on the PLCC chips and on U130 pin 2 it should give a 100Mhz in. Probing arround with the Tektronix i discovered the 100Mhz is not like it should be. sometimes visible sometimes not.100Mhz were does that come from..Ok looking for crystal Oscillators on the board i found 100Mhz were does that come from.. I found a 2 Oscillators a big Vectron 2Ghz en NEL HS2810. - 100Mhz on the otherside of the board. checked over and over again and then went to "the NEL HS2810 corner" is this Crystal failing from time to time.. or more failing then working.i decided to take it out and build a test circuit. it is a negative powered Oscillator so -5.1v is powered. see picture.and i didn t get any output...

author: charlyd
author_rank: Frequent Contributor
timestamp: May 29, 2019, 08:32:26 pm
content: For my feeling the NEL is not ok.A few things kept spinning in my mind and bringing the 100Mhz from one side of the board to the complete otherside is really weird.The U121 with the shorted pin 19, 20 from dirty solder work made way back in time before i got the unit.and some not responding PLCC chips. Let find the datasheet from the big vectron 2Ghz Oscillator.mmmm difficult to find a datasheet from this bigboy but i found something what cleared things for me..this is a Double Crystal Oscillator pin A = 100Mhz and pin B = 2Ghz and this one is located next to the PLCC chips. so i pulled the bigboy andit is powered with +15v to GND. see picture.i took the Double Crystal Oscillator out and after feeding 15 volt i got nothing out.. on this one also..this is really strange a failed Double Crystal Oscillator. If that is the case where does the pin A (100Mhz) lead to.Exactly to the U121, the 10H116 with the dirty solder work so it looks like the Double Crystal Oscillator has been shorted for a longer time and died??the Double Crystal Oscillator is on its way. together with a 10H116.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 29, 2019, 08:39:10 pm
content: on the bottomside in the neighbourhood of the NEL HS2810 there is a 14 pin ACT14 ( 74ACT14 - 6 Hex Schmitt-Triggered Inverters)they also past this chip a while back with the "Art of soldering" i checked it, it was ok but it needed resoldering to be fitted good.so now it is waiting for the parts…… and the NEL HS2810 is added to list of wanted parts from a donor board.@tony_g you were right this unit was a MULE.

author: charlyd
author_rank: Frequent Contributor
timestamp: June 13, 2019, 08:35:52 pm
content: some weeks past before the parts arrived.. I replaced the U121 and the 100Mhz osc. and when powering on i fell into the next problem….the LCD went white after moving the Long white flat cable a bit the picture was back and gone.. so that cable needs also be to replaced but no problem…let s connect a External monitor and yes the picture was there...ok now fingers crossed and boot the Mule.after booting i got a message like needs calibration …..my"Fine Interpolator handshake failed: Service is required". was gone.. so that is a real positive step forward..! but i still have all 4 my ADC of the board and my both Attentuators are also not connected.. so no triggered signal..ok let first find the flat cables which i need so my LCD is also working again. and then easy build the mule together with one channel.. ans see what happens.

author: dzseki
author_rank: Frequent Contributor
timestamp: June 14, 2019, 01:19:48 pm
content: Sligthly off topic, but I was just reading the October 1993 issue of the HP Journal, where they go into detail with the interpolator of the HP 54720 from page 24, which is of course a different model than yours, but I believe they are based on the same concept, they also give specs on the 2GHz oscillator, although it might be a different model, but sure looks similar enough. It should be a good read for those who are interested in the art.

author: charlyd
author_rank: Frequent Contributor
timestamp: June 17, 2019, 07:12:43 pm
content: so today i spended an other day again at the 54845A project.i decided to have a look at the display to see if there is the reson from my flickering LCD and yes ...1 very small connector was not connected on the LCD side. So pulled apart the front and see if it is fixable...ah reconnect and see if the LCD is working. Yes strange but ok.. fixed.Time to build the mule back together.. and see what happens with the selftest and when that shows many "PASSED" i can go on to the Calibration part and see what is happening there.i decided to put all Hybrids back in and then bring it to life…so after a while when the mule looked a bit like a scope again...it is time for power on and selftest. I long while ago i already decided to disconnect the Original harddrive because i don t want to damage or delete usefull history data.So already on het start of this project i took a 20GB maxtor drive and restored the 4.3 software version using a extra CDROM drive connected to the second IDE port from the VA-503A which i needed to load bios defaults to get the second IDE back to life again. Ater that i restored like the procedure explained howto reinstall the scope. with the #VIN033 first restore was software version 4.3 and then upgrade to version 4.5. so i ended up with a new installed drive leaving the Original in tact.after booting i got the calibration needed message .. and as i told 2 posts back my error was definitely gone. i connected a keyboard and mouse and now it is time for the selftest… with all hybrids reinstalled again…after powering on first thing i saw was i got 3 good triggered signals ch2/ch3/ch4 and my channel 1 trigger signal was gone..next step "the selftest"...A to D convertor and FISO error. all errors were in the first few tests and somewhere a warning that the Attentuators contacts were totally out limited…Attentuators needs to be replaced...of course why should the mule would work already in one time. of course not...

author: charlyd
author_rank: Frequent Contributor
timestamp: June 17, 2019, 08:04:41 pm
content: so i think my Hybrid in ch1 looks broken… in the selftest...let see what the Calibration does... and see how the hybrids respond.vertical triggerCh1 failed failedCh2 failed failedCh3 failed failedCh4 failed failedof course this is like a real MULE is..back to the selftest i got ch1 bitstuck in hybrid and also some warning from the attentuators. the contact value were really out limited. 4 very long numbers..? really strange..So status: ch1 no signal (it was somewhere out of LCD). and all calls are failling.yeah and what is the next step...i decided to look if it is possible to reset the attentuators because the restored image 4.3 doesn t have my contact count ( fingers crossed if the attentuators are also not mule parts..)But first i take the hybrid from ch4 and put it on socket ch1 so when i do the call again it could go for 6x passed before crashing..Meanwhile i do ask here for 1 hybrid for sale 1NB7-8348 .. (please PM )then i can go through the selftest withour errors anymore, i hope.next step was to reset the contact count and see what happens.i missed the ATT SET in the extension service menu so i remember when you start the scope and change the /autostart in the shortcut to /service you get some extra option and are able to reset the count.after that i went back to the call menu. to see what happens.vertical triggerCh1 failed PASSEDCh2 PASSED PASSEDCh3 failed PASSEDCh4 ------ -------[not installed]so it is time to figure out what causes the vertical cals to fail…? assuming that 4 ch will also pass the trigger site after being installed.

author: charlyd
author_rank: Frequent Contributor
timestamp: June 20, 2019, 06:28:17 pm
content: Hello ok i will post a picture from the hybrid i am looking for.so if you have 1 hybrid for sale please PM me.as soon as i have one then i can go on with the Mule project and see if all my selftests will pass...to start with.any suggestion about the failing vertical Cal.why they are failing on CH1 and CH3 ?

author: dzseki
author_rank: Frequent Contributor
timestamp: June 20, 2019, 07:24:26 pm
content: Previously you mentioned that the relay counters were way over the top. Perhaps those really need some care?

author: charlyd
author_rank: Frequent Contributor
timestamp: June 20, 2019, 08:16:57 pm
content: those were over the top because on the earlier restored image they were way to high.. for a reason. ( maybe because on the init moment of that image my scope was half dead. )but on the Original disk the count were way under the limits.. but i will check this soon by feeding the output from the attentuators 2 to hybrid 1 with the sma jumper pigtail.but i doubt that is the problem but i will come back on this one.

author: charlyd
author_rank: Frequent Contributor
timestamp: July 10, 2019, 05:33:48 pm
content: hi ok the Mule project continues….i got a new Hybrid because my hybrid in channel 1 gave me a triggered line in the bottom of the screen...( not in the middle ) and from what i saw it is a hybrid thing..meanwhile a i resetted the contact count already of the attentuators (who are installed swapped at this moment ) and place my hybrid 4 to channel 1.i placed the new received hybrid on ch 4. and now i can do the selftest.most of this was passed..except:i got Self Test invoked cal executed.Error in self test invoked cal - DLL cal.Error in self test invoked cal - Clk 100Mhz cal.Error in self test invoked cal - Data Acq cal.Error in self test invoked cal - Fiso Redundancy cal.Test FAILED on channel 1Fiso data bit error not correctablelet start a CalibrationVERTICAL TRIGGERCH1 FAILED PASSEDCH2 PASSED PASSEDCH3 PASSED PASSEDCH4 PASSED PASSEDmmmmm this looks good. but ok a CH1 problem. bit stuck error( will copy the exact error later here).but it looks like it can by dangeres to put my new received hybrid on CH1 and kill it maybe… no way..!uuh what can i do.... because all my triggers are passed in the CAL i got all channels a nice colored line in the centre.NEXT STEP:let s put back the ( broken ) hybrid with the failed trigger line back on CH1 and put the CH4 hybrid back in its empty place on Ch4. and swap both attentuators back to its Original place…RESULT:calibration…VERTICAL TRIGGERCH1 FAILED FAILEDCH2 FAILED FAILEDCH3 FAILED FAILEDCH4 FAILED FAILEDpfffffffff………tonight i rollback to the ch2,ch3,ch4 working situation. and move one by one. see what happens when...

author: charlyd
author_rank: Frequent Contributor
timestamp: July 15, 2019, 05:17:19 pm
content: ok..... the story continues……after rollback the hybrids and went back to the working config. it was again in the ch1 with result…. vertical fail… trigger pass. (like in the post above)lets start from here:selftest fails with both hybrids placed on ch 1 same error.....i know from one hybrid it is really failing but the last one were the trigger shows passed i would say the hybrid was the ch 4 hybrid..i managed to test the hybrid on a different channel and 2 times passed… So the mule still has a channel one issue.this looks like i still having an error in the channel 1 circuit.i will come back on this one after the deep dive into channel 1.when i calibrate in the end when you look at details your are pointed to the error section. if you turn it arround if all channels fail on both vertical en trigger. you will see nearly all section from the repair diagram shown in details.that will point you to the solution one way or another...i also did a deeper dive into the hidden options of the scope and went in with the commandlines :just create 2 batch files with a command from below in the c:\scope\bin directoryFor scopes that use the hp5484X.exe executable:hp5484X.exe scope /scope /hpib /service (for service mode) i did not see anything yet apart from ATT SET in the selftest menu for resetting the contacts.hp5484X.exe scope /scope /hpib /internal (for some very interesting stuff) for this option it gives you an extra option at the bottom of the CALIBRATION /SELFTEST dropdown menu. where you can choose different options.ok what can this error all mean: in the selftest with service extension checked.--------------------------------------------Self Test invoked executedError in self test invoked cal - DLL cal.Error in self test invoked cal - Clk 100Mhz cal.Error in self test invoked cal - Data Acq cal.Error in self test invoked cal - Fiso Redundancy cal.FISO test failed on channel 1FISO data bit error not correctable.Test FISO FAILED.---------------------------------------------It is all pointing to a sort of cal. or pre-cal state which is not in place, knowing the hybrid used on CH1 is working 100% . The attentuators swapped also doesn t make any difference..-> it has to be with CH1.clicking on details after calibration it only says: "FISO REDUND" for the rest nothing.does anybody know what i could diagnose extra by connecting the scope to my laptop with GPIB/HPIB.new update i think the last time the FISO was not really seated ok. because channel 1 is working after i swapped ch4 <-> ch1 ch4 has the failed error. really strange. because i saw it working…..but one way or an other the FISO needs to be replaced it think. so i am looking for a second FISO.. for this real mule.just a tip before putting the connection pipe between the attentuators and the FISO. be aware to fit and tighten the FISO first completely with out the cooler then put the connection in between en tighten the screws and at last place the cooler on the FISO. that way the contact are 100% ok to the FISO and not a bit lifted.

author: charlyd
author_rank: Frequent Contributor
timestamp: August 02, 2019, 05:42:06 pm
content: to finish the Scope i need 3x spacers/standoffs set like in the picture below.containing:3 PROTECTOR CAP .234 ID .3125 DEPTH3 BOLT M3X.05MM 35 MM LG PANHD3 SPACER M3X25 MM and still looking for a FISO as well.EDIT: Got these 3 parts already...

author: charlyd
author_rank: Frequent Contributor
timestamp: September 22, 2019, 06:18:31 pm
content: to finish the project i ordered the last FISO this weekend i will close the complete topic with a picture of the result as soon as it arrives and the calibration is done.

author: analogRF
author_rank: Super Contributor
timestamp: September 25, 2019, 01:09:11 pm
content: Quote from: charlyd on May 20, 2019, 03:44:09 pmHi charlydwhere did you get these attached documents in post #35?

author: charlyd
author_rank: Frequent Contributor
timestamp: October 05, 2019, 08:08:28 am
content: a good tip for anybody who is struggling arround with the Hybrid & failed calibration. This weekend i received a just bought FISO to finish the job but this FISO was not ok.It failed both on vertical and trigger, after placement i did a new calibration. This time even the CH2 FiSO advertised as complete failed. So what i mean to say is the channel 1&2 and 3&4 a sort of go together. after the newly bought broken Fiso was taken out, CH2 was ok again.So take in mind: If for CH1&2 / CH3&4 one of the FISO fail it can also take down the companion as a false positive.Still looking for a working Agilent 1NB7 - 8348

author: analogRF
author_rank: Super Contributor
timestamp: October 05, 2019, 11:08:40 am
content: Quote from: charlyd on October 05, 2019, 08:08:28 amHi charlydwhere did you get these attached documents in post #35?

author: charlyd
author_rank: Frequent Contributor
timestamp: October 07, 2019, 08:10:39 am
content: Hi analogRF in the scope itself look for a file named: HP4XS.HLP and open it in the W98 machine because it is an version help format, for sure not recognized extension in WIN10 or so.you could try win7 if i remember well.

author: rickells
author_rank: Regular Contributor
timestamp: December 28, 2020, 03:45:55 am
content: hi Charlyd,I was told by TRN(?) that you are an HP 54845a expert:I have continued Trigger Self-Test Failures( All Trigger self-tests fail for all 4 Ch's) in an otherwise working HP 54845a scope ( VIN 33, latest).Since I cannot pass the Trigger self-tests, I can Not preform a Cal. Otherwise, The scope works fine on all 4 CH's !!See: for the details.https://www.eevblog.com/forum/repair/agilent-hp-54845a-1-5-ghz-scope-trigger-self-test-failures/msg2346717/#msg2346717Wondering if you have any insight ?thank you,rikels

author: charlyd
author_rank: Frequent Contributor
timestamp: December 04, 2023, 06:49:52 pm
content: It is time to reopen this post.after a long time i got the last hybrid. for a reasonable price.so today i thought lets place this last hybrid in CH1 the one which had a vertical "failed".so hybrid swap and test again. and at this point the lights went out. CH1 passed passed. But now CH4 has the vertical "failed" as if the error is moved from CH1 >> CH4.anybody here who recognizes this behaviour. next weekend i will investigste further why this happens.For my feeling i have 5 100% working hybrids but still an issue in the vertical part. unless i am wrong.

author: charlyd
author_rank: Frequent Contributor
timestamp: December 11, 2023, 02:15:49 pm
content: i did a full self-test after i clear the logs and that was passed on all steps.then i did a calibration which failed on channel 4 with a detailed message: "muxing 1x mux ofst"so what could be part of this last step?still really weird that with the other hybrid in CH1. CH4. was 100% passed. ?