Agilent 33220A Generator, FPGA not repairable - Page 1
Forum section: electronics / repair

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 02:03:37 pm
content: This Agilent 33220A was bought used and broken and now I am trying to repair it.Error message: "Reference phase-lock loop is UNLOCKED"Like usual, I checked all the rails and the -15V rail only has -13.1 VSo, I suspected the evil yellow tantalum caps, but they are not the culprits.If I remove the 0 Ohm resistor right at the output of the -15V regulator, I have perfect -15VIt seems that some component is pulling too much current from the -15V regulator.But nothing is getting hot to an usual level.Any suggestions would be appreciated.The manual can be found here:http://cp.literature.agilent.com/litweb/pdf/33220-90012.pdf

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 05, 2015, 02:24:23 pm
content: So you suspect the tantalums but you know they are not the problem how?And how much current is too much current? Have you measured it and is it below the 1A specified for the 7915?

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 02:53:00 pm
content: Quote from: Quarlo Klobrigney on September 05, 2015, 02:24:23 pmBecause I removed them and replaced the temporarily with some electrolytic caps.QuoteThis is the weird thing.If I use my DC load, I can pull 450 mA out of the 7915 and the voltage stays at -15.0VThe instrument is pulling "only" 200 mA from the 7915 and the voltage drops to -13.1 V.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 05, 2015, 02:58:47 pm
content: By: "The instrument is pulling "only" 200 mA from the 7915 and the voltage drops to -13.1 V."You mean the actual circuit that the regulator is mounted or supplying to.I would change the 7915, the 2 series diodes, the electrolytics need to be checked or replaced.When I was talking about the tantalums, I was assuming there were more on the external circuit at the IC's on the board. Are there any near the IC's?Also the rectangular SMD ones are usually OK, it's the dipped ones that are crap.

author: AF6LJ
author_rank: Unknown
timestamp: September 05, 2015, 03:20:53 pm
content: Have you looked at the 7915's output on a scope, almost sounds like the regulator is oscillating.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 03:29:51 pm
content: Quote from: AF6LJ on September 05, 2015, 03:20:53 pmYes, I did and the output of the 7915 is very smooth.OK, after some more checking, it seems the -15V rail is only a symptom and not the reason for failure.I injected -15V manually from an external PSU and still have the very same problem and error messageThe external PSU supplies about 200 mA to the circuit and stays stable.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 03:59:21 pm
content: OK, I did not notice this right away, but after I injected the -15V from an external PSU, I am getting a new Error 606, which is explained in the service manual as:This error indicates that the cross-isolation interface between the mainprocessor (U101) and Synthesis IC (U501) has failed, or that thesynthesis IC itself has failed.It seems this is beyond repair, because the U501 is the main FPGA.Thanks for all your help, but I am now giving up on this repair.

author: AF6LJ
author_rank: Unknown
timestamp: September 05, 2015, 04:02:50 pm
content: One quick thing you might try.Put 10MHZ into the timebase input in the back of the unit.The manual says it will automatically switch to the external 10MHZ timebase.Run the signal in there power up the unit and see if the error clears.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 05, 2015, 04:07:27 pm
content: EP1C6Q240C8

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 04:10:52 pm
content: Quote from: AF6LJ on September 05, 2015, 04:02:50 pmDid not work!I also tried to get it started through GPIB but the same problem stays.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 04:16:53 pm
content: Quote from: Quarlo Klobrigney on September 05, 2015, 04:07:27 pmThanks.It seems, U501 is available and it will probably work.But this is too much for me, since I do not have the tools to solder such a part in correctly.I will leave this to someone else and offer this Agilent Generator for sale in the "Sell/Buy' section of this forum.

author: plesa
author_rank: Frequent Contributor
timestamp: September 05, 2015, 04:22:06 pm
content: replace the this size is possible with piece of kapton tape and heat gun or contact some repair center they can do it for you for 20-40 EUR.

author: vaualbus
author_rank: Frequent Contributor
timestamp: September 05, 2015, 05:04:49 pm
content: Could be also somethingh else. I think if the main FPGA is broken the instrument won't turn on.Does it output a signal?I would ceck for short component before call it a unrepair!

author: AF6LJ
author_rank: Unknown
timestamp: September 05, 2015, 05:09:57 pm
content: From The Potentially Stupid Question Department...If you buy this FPGA, how do you get it programmed or for that matter do you need to have it programmed??

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2015, 05:26:30 pm
content: Quote from: vaualbus on September 05, 2015, 05:04:49 pmYou might be right, but I leave this to someone else to find out.I can switch the frequencies white the error message stays on the screen and it has a good response to pushing the buttons but NO output can be detected.

author: Andy Watson
author_rank: Super Contributor
timestamp: September 05, 2015, 05:27:31 pm
content: Quote from: HighVoltage on September 05, 2015, 03:59:21 pmAt least hang a scope on the isolation optos (U304-A and U305-A) and check that they are attempting to communicate.

author: free_electron
author_rank: Super Contributor
timestamp: September 05, 2015, 05:30:33 pm
content: it's dead jim ...the fpga is loaded through a serial link from the main flash memory. so swapping it is not a problem.i had one of these with a similar fault. the negative rail would sag after like 1 or 2 seconds after power up.if i remember correctly there are 0 ohm resistors in all the supply rails. or they were big filter coils from coilcraft. they sit in the centre of the board , kind of alone ..simply remove the ones going to the +15 and -15 rail. and start up.if you get a comms error the fpga is dead.there is a dpak regulator right next to the fpga . that one should be running very hot...the fpga draws way more current than normal and pulls down the power supplies.

author: plesa
author_rank: Frequent Contributor
timestamp: September 05, 2015, 05:51:38 pm
content: The last try check following in menu:1 Turn on the menu. A: MOD MENU2 Move across to the PHASE MENU choice on this level. G:PHASE MENU3 Move down a level and then across to the UNLOCK ERR command.4:UNLOCK ERR4 Move down a level and disable the unlock error. DISABLE5 Save the change and turn off the menu.The unlock error setting is stored in non-volatile memory, and does not change when power has been off or after a remote-interface resetI found this in option menu manual, so give a try.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 05, 2015, 05:58:23 pm
content: U501 1822-1342 1 IC PLD FPGA-SRAM UNPRGMD CMOS 240-PQFP 12880 EP1C6Q240C8from the parts list, however it looks like you have a different part there...I also wondered that also, even with a config EEPROM you still have to do up the FPGA.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 06, 2015, 10:46:54 am
content: Quote from: plesa on September 05, 2015, 05:51:38 pmI think you are mixing this up with the older Agilent 33120A that had the vacuum fluorescent display (VFD)This one is the 33220A with LCD and graphics display that does not have this menuOr I am mistaken?

author: HighVoltage
author_rank: Super Contributor
timestamp: September 06, 2015, 10:48:39 am
content: The generator is now soldhttps://www.eevblog.com/forum/buysellwanted/agilent-33220a-arbitrary-waveform-generator-%28needs-repair%29/May be we will hear from the buyer, how he fixed this instrument.

author: plesa
author_rank: Frequent Contributor
timestamp: September 06, 2015, 12:00:16 pm
content: Quote from: HighVoltage on September 06, 2015, 10:46:54 amYou are right, so if this menu is not available you can try it by SCPI.It is not fix, but can be used like bypass to enable output.PHASe:UNLock:ERRor:STATe {OFF|ON}PHASe:UNLock:ERRor:STATe?Disable or enable the function generator from generating an error ifthe phase-lock is ever lost. The default is OFF. If the phase-lock is lostand the error is enabled, a “Reference phase-locked loop is unlocked”error is generated. The unlock error setting is not stored in non-volatilememory. That is, the setting will be lost when the power is cycled. The:STAT? query returns “0” (OFF) or “1” (ON)Reference phase-locked loop is unlockedThe PHAS:UNL:ERR:STAT has been enabled (“on”) and the internalphase-locked loop that controls the frequency is currently unlocked.This error is most likely to occur when the external reference is out oflock range.

author: Andy Watson
author_rank: Super Contributor
timestamp: September 06, 2015, 12:29:42 pm
content: Quote from: HighVoltage on September 06, 2015, 10:48:39 amMay be! But don't hold your breathI like a challenge but I think I might have bitten-off more than I can chew with this one. The board shown in your original photo appears to be an early version. If it is the FPGA at fault, as free_electron confirms, it might be beyond economic repair. It looks as if HP/Agilent re-spun the design because the 20k200 FPGA became obsolete. The only sources I've found for the original FPGA are asking silly prices.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 06, 2015, 02:25:52 pm
content: Well good luck to whomever has possession of the unit, hopefully all will be repaired in due course.

author: MadTux
author_rank: Frequent Contributor
timestamp: September 06, 2015, 02:30:51 pm
content: Quote from: Andy Watson on September 06, 2015, 12:29:42 pmWhy that, I found one that seems to fit for $32 on ebay. Might be worth a try,since that box is probably worth more than $250 when working.http://www.ebay.com/itm/Brand-New-FPGA-IC-Chip-Altera-EP20K200RC240-3-Field-Programmable-Gate-Array-/331326657509?hash=item4d249b93e5It's a faster version, but other than that I don't see why it woiuldn't work

author: Andy Watson
author_rank: Super Contributor
timestamp: September 06, 2015, 02:42:59 pm
content: Thanks, I'll keep that in mind. I was looking for the exact part number. I will have to study the datasheets

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 06, 2015, 09:29:05 pm
content: The replacement part still would have to be programmed and where is that file? I wouldn't necessarily condemn the part until it is verified as bad. The first thing I do is to reflow (resolder) all the stuff in the area especially if it is lead free. You'd be suprised how many faults can be repaired in that way. Nothing like a nice dull joint when you're done if using lead free or shiny for us leaded folks. That chip could be easily drag soldered in under a minute or so.Quote from: Andy Watson on September 06, 2015, 02:42:59 pm

author: Andy Watson
author_rank: Super Contributor
timestamp: September 07, 2015, 05:31:05 pm
content: Quote from: Quarlo Klobrigney on September 06, 2015, 09:29:05 pmI believe that, as is often the case with FPGAs, the "programme" is loaded from an external device. The datasheet says:"APEX 20K devices are configured at system power-up with data stored in an Altera serial configuration device [I think that means serial EEPROM] or provided by a system controller."The 33220A appears to use the latter option, i.e. the programme is supplied via the system processor every time the unit is powered-up. I assume the programme is in the firmware of the system processor.

author: AF6LJ
author_rank: Unknown
timestamp: September 07, 2015, 05:52:07 pm
content: Quote from: Andy Watson on September 07, 2015, 05:31:05 pmNow that makes a gob and a bunch of sense; stock one part, usit in twenty different products, Just add firmware.....Makes its own sauce.Like two way radio equipment of the late 80s a dozen models would use the same logic board, only the firmware, and a zero ohm resistor or two would change.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 07, 2015, 06:31:48 pm
content: I was speaking in terms of a replacement device in a refit of the original, i.e. the new part number pin for pin or one on a daughter board to replace the unobtainium part.Sorry for the confoosion.

author: Andy Watson
author_rank: Super Contributor
timestamp: September 07, 2015, 06:56:23 pm
content: Ah, I see. That would be a tricky problem! However, if substituting a different part is the only option my first line of attack would be to use the FPGA that is in the current revision of the PCB. HP/Agilent provide two versions of firmware updates for these devices - I'm guessing these corresponds to the two different FPGAs. I've not determined what other modifications might be necessary.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 07, 2015, 07:05:20 pm
content: Well in your case (I haven't looked) they still provide support for it. Your very lucky.They've orphaned my HP spectrum analyser for the sake of emailing or providing a link to the ROM files to which I can do up the EPROMs myself.I will be forever stuck at revision x instead of the latest on their last run for the 8591A.Also Dave is out in left field for that piece of equipment that he gave up on for lack of a service manual etc.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 07, 2015, 07:08:59 pm
content: I believe there are some more hardware differences.The change was made from the MY43... to MY44... serial numbers and the later one should have been called 33220B but somehow that was missed, I guess.I was looking for the option board for the 10 MHz input /output and noticed that there are two different boards, depending on the serial before or after MY44...More interesting, the option board for the earlier models can be ordered from a distributor as an option but the same board for the later one is not sold through distribution, but instead a "repair" part from Keysight directly.So, it is probably more that just the FPGA