HP 6632B failed on me. - Page 1
Forum section: electronics / repair

author: fchk
author_rank: Frequent Contributor
timestamp: April 30, 2025, 09:52:07 am
content: Hello world;A few days ago my HP 6632B power supply suddenly failed on me while powered on. I couldn't turn on the output again. I turned it off completely and on again, and now it displays the PROT and ERR indicators.Pressing the PROTECT button shows "-- OT OV -- --". SHIFT CLEAR PROT does nothing.Pressing SHIFT ERROR shows errors 1, 2, 3, 4, 5, 80, 11 in this order.I haven't opened the device yet - its the very bottom of the stack.What's wrong here?

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: April 30, 2025, 11:11:27 am
content: Hello fchk,Quote from: fchk on April 30, 2025, 09:52:07 am....you need a rack. (I got some to spare) ;-))Get the service-manual.Good luck

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: April 30, 2025, 12:04:00 pm
content: Hi,here are the error-codes:Error CodeDescriptionProbable CauseE1Checksum in Read-only Non-volatile ROMA2 Interface BdE2Checksum in Config Non-volatile ROMA2 Interface BdE3Checksum in Cal Non-volatile ROMA2 Interface BdE4Checksum in State Non-volatile ROMA2 Interface BdE5Checksum in RST Non-volatile ROMA2 Interface BdE10RAM test failedA2 Interface BdE1112 bit DAC test failed, 0 is written to DAC U241A and B,ADC U242 is checked for 133 +/- 7 countsA2 Interface BdE1212 bit DAC test failed, 4095 is written to DAC U241Aand 0 to B, ADC U242 is checked for 71 +/- 7 countsA2 Interface BdE1312 bit DAC test failed, 0 is written to DAC U241A and4095 to B, ADC U242 is checked for 71 +/- 7 countsA2 Interface BdE1412 bit DAC test failed, 4095 is written to DAC U241Aand B, ADC U242 is checked for 10 +/- 7 countsA2 Interface BdE158 bit DAC test failed, 10 and 240 are written to DACU244, ADC U242 is checked for 10 and 240 +/- 7 countsA2 Interface BdE80Dig I/O test failed, SEC_PCLR written low and high,read back through XilinxA2 Interface BdE213RS-232 input buffer overrunA2 Interface BdE216RS-232 framing errorA2 Interface BdE217RS-232 parity errorA2 Interface BdE218RS-232 UART input overrunA2 Interface BdE220Front Panel comm UART input overrunA3 Front Panel/Display BdE221Front Panel comm UART framing errorA3 Front Panel/Display BdE222Front Panel comm UART parity errorA3 Front Panel/Display BdE223Front Panel firmware input buffer overrunA3 Front Panel/Display BdGood luck

author: bingo600
author_rank: Super Contributor
timestamp: April 30, 2025, 12:23:06 pm
content: Quote from: fchk on April 30, 2025, 09:52:07 amSame as Dr. Frank ??https://www.eevblog.com/forum/repair/agilent-6632b-fault-repair-and-several-design-flaws/

author: fchk
author_rank: Frequent Contributor
timestamp: April 30, 2025, 06:07:48 pm
content: Quote from: bingo600 on April 30, 2025, 12:23:06 pmMaybe. The fuses are blown, but the capacitors are not shorted. It also seems that they used ceramic caps in my unit. I checked all tantal caps, but found no shorted one. No visible signs, either.

author: Dr. Frank
author_rank: Super Contributor
timestamp: April 30, 2025, 08:35:37 pm
content: Quote from: fchk on April 30, 2025, 06:07:48 pmProbably.Please provide pictures of the fuses, these capacitors in doubt and the junction of the solder side of the board.Frank

author: DrijSkij
author_rank: Contributor
timestamp: May 01, 2025, 10:14:56 am
content: Quote from: Roehrenonkel on April 30, 2025, 11:11:27 amBrutal.

author: fchk
author_rank: Frequent Contributor
timestamp: May 01, 2025, 10:50:54 am
content: Quote from: Roehrenonkel on April 30, 2025, 11:11:27 amI need space. for that.

author: fchk
author_rank: Frequent Contributor
timestamp: May 01, 2025, 10:57:12 am
content: Quote from: Dr. Frank on April 30, 2025, 08:35:37 pmHere they are. The caps seem to be tantals as it seems now. The freen fuses are blown, bothing shorted, diodes tested ok.

author: Dr. Frank
author_rank: Super Contributor
timestamp: May 02, 2025, 05:04:18 pm
content: Yes, your instrument has the very same schematic error, i.e. these yellow tantalums are not connected to ground, therefore they see 2x overvoltage.They really blew up the 2nd time I powered up, before there was only the same malfunction like your 6632B, i.e. blown fuses.I suggest to replace fuses and tantalums, and see what happens.Mine is working properly ever after.Frank

author: fchk
author_rank: Frequent Contributor
timestamp: May 03, 2025, 09:11:12 am
content: Parts should arrive next week. Did you replace the fuses with resettable PTC fuses or with traditional one-time fuses?

author: Dr. Frank
author_rank: Super Contributor
timestamp: May 03, 2025, 12:53:08 pm
content: Quote from: fchk on May 03, 2025, 09:11:12 amI have used resettable fuses, as I got them on stock.The selection of the nominal current is critical.Frank

author: fchk
author_rank: Frequent Contributor
timestamp: May 05, 2025, 05:51:25 pm
content: Success! My 6632B works again, at least for now. I swapped the fuses, the caps and applied the mod.

author: Dr. Frank
author_rank: Super Contributor
timestamp: May 05, 2025, 10:26:56 pm
content: Quote from: fchk on May 05, 2025, 05:51:25 pmHave you checked the Tantalums for excess leakage currents, or short?Frank