HP 53310A - Power supply troubles

[TAMHAN]

Hello Folks,
my trust old MDO recently went puber on me - clearly a trouble in the switching mode PSU. As I needed the unit somewhat urgently and my father loves tinkering just as much as I do, we decided to bury grudges for now and get to work.

Our MDO had the PSU from Computer Products, who AFAIK bought up Boschert. Now, our problem is this. We managed to remove 17 caps which we considered suspect (the ERSA Nano was a bit to weak for it in fact), and found SIGNIFICANT electrolytic leakage under the two 2200uf caps and also the two groups of two 1000yF/35vF standing glued together to some other components with white silicone rubber.

Now, our problem is. The board is halfpopulated. How would you suggest to proceed cleaning, as not to damage the other components on the board? Or would you simply solder in new capacitors of higher quality?

[TAMHAN]

And, as someone else might need it, here is our parts list for the 17 caps we killed so far. All of the Elcos are RADIAL, so two pins on one side. No need to buy the expensive ones which look like
------|CCCCCCCC|---------

C26, 27 and 49 6800yF / 6v3 (no typo)
C40, C41 2200yF / 35V, one showed massive leakage

C7,8,9,10,11,12,13,14 were 1000yF/30V
C15, C16, C30, C31 also, but they showed massive leakage

[TAMHAN]

And finally, a pic of the goo so that you can maybe advise us on how to proceed re the repair.

Also, forgive the stupid question. Am I right in the assumption that the cable binders and the white silicone rubber glue are intended for suppressing oscillations?

[wn1fju]

The last one of these I fixed was cleaned simply by repeated hits of alcohol with a toothbrush.  You definitely should try to get the gunk off, not just solder in new caps.

Also, search the forums as there have been a few discussions about this power supply as it relates both to the 53310A and to many of the HP oscilloscopes that it was also used in.

[TAMHAN]

Hello,
and, to report success. Recapped it, and it works nicely again. Cleaning was done on a best effort basis, aka only where I could really see the electrolyte, with IPA and cotton swabs.

My father and I kept notes, if anyone ever needs them:

Caps used:
Hitano Low-ESR (the green ones) for all values except 220yF

Caps replaced
C35, C39, C34 - 220yF 50V
C32, C33 1000yF 35V
C50 220yF 50V
C42 2200yF 50V

and the ones listed above, ofc. The print of the PCB is very solid, we did not have any damaged traces as of yet. But we acted swiftly: after the MDO broke down, we ran it for less than 1h.



So far, we did not bother to replace the cable ties or the silicone glue. And the PSU still works flawlessly...no whining to notice either.

[Smith]

Ah, the crappy power supply we also know from the HP 5450x series. I know there is a schematic on the interweb, but it's not completely accurate. I heard about quite some people who where unable to fix the PSU.

Mine also had electrolyte covering the whole PCB. After the first problems it sat unused for about 6 years until I fixed it. The traces on the PCB where fine. but the green layer was quite bad on some places. I cleaned everything with IPA, and fixed the green layer with a conformal coating. I replaced all caps and a lot of other components because the electrolyte made most of them oxidizing. Now all is fine again.

[Tomorokoshi]

Good to know! I just got an HP 53310A. Once I work through some other projects I'll make inspecting the capacitors yet another project.

[TAMHAN]

Do it ASAP, brother. Fixing it while it still works is better than having to go over an array of totally fuxated components.

Oh, and be careful to clean any electrolyte from the three terminal regulators. That "bridging" can cause the voltage levels to wander off...

[kj7e]

I've been asked to provide a parts list I used to re-cap my 53310A power supply by more than one forum member, so posting all info I have here for reference.  The supply is made by Boeschert, HP part number 0950-1879.  The main problem I found with mine were with the 1000uF 35v and the 2200uF 35v caps near the center of the board near the rectifier diodes.  Since I had it out and it was only a few $ more I decided to replace every aluminum electrolytic on the board.  Attached is an excel spreadsheet from Digikey with the part numbers and quantity I ordered (includes a few extra spares).   All very high quality Rubycon ZLH 105C caps of proper size and fit.  Rather than use 2x 35v 2200uF and 1x 25v 2200uF, I used 3x 35v as fit was not an issue.  Also providing detailed photos of the cap layout for reference.

I had already removed 8 of the 1000uF 35v caps here, but this can be used an a reference;


Some of the leaky caps, clean up the residue with IPA.  C15, C16, C30, C31;


As I removed the caps, I laid them out in a map;




Caps replaced;


Take note of the blue potentiometer on the edge of the board next to the 20 pin output connector, this is the 5.1v adjustment, the 5.1v test points are the black dmm lead receptacle jacks just to the left of this pot.







Once done, adjust the 5.1v rail and you should be good to go;


Probrabbly not a bad idea to run the self test in a loop for a while to verify everything is okay and stable;


See the attached xls spreadsheet for a Digikey shopping list, about $35 in parts.

[maxwell3e10]

I also started to have trouble with the power supply in the HP53310 analyzer. The symptom was that interpolator calibration started to fail occasionally. The problem was with the -12V power supply, which went down to -10 V and would drift around. Among the capacitors, only the 220 muF, 50 V ones showed leakage. I replaced just those 7 capacitors. It didn't however immediately solve the problem. The actual problem was that some of the electrolyte leaked across R28-R45 resistors and was messing the voltage regulation of the -12V supply. After I cleaned it, everything seems to work fine.

Interestingly, this improved the noise performance of the  HP53310 measured before there were any obvious problems. So, even if it doesn't show any problems and passes all self-tests its a good idea to check the voltages on the test points of the power supply.

[SoundTech-LG]

Had mine for a few days. All options except oven, but I'll use a GPSDO or Rubidium Ref. Cleaned it out thoroughly. Today I took the PS apart, pulled the board, and inspected carefully for any signs of leakage around the caps. None showing, but I still need to check the supplies. There seems to be a few different threads for this analyzer.  Quite a handy piece. Saw someone used 2 MeanWell supplies to fit inside the case, rather than the labor of changing all those caps, and saving some current waste at the same time.

[kj7e]

Had mine for a few days. All options except oven, but I'll use a GPSDO or Rubidium Ref. Cleaned it out thoroughly. Today I took the PS apart, pulled the board, and inspected carefully for any signs of leakage around the caps. None showing, but I still need to check the supplies. There seems to be a few different threads for this analyzer.  Quite a handy piece. Saw someone used 2 MeanWell supplies to fit inside the case, rather than the labor of changing all those caps, and saving some current waste at the same time.

You will need to pull a few caps to see if they are leaking, at that point may as well just replace them.  Its really not that big of a job, I fully re-capped two of them recently.  I saw the post where the computer supplies were used, that looked like more work than just re-capping the original supply.

[wn1fju]

"Saw someone used 2 MeanWell supplies to fit inside the case...."

I was the guy who did this and I unfortunately must conclude that I don't recommend this solution.  Indeed, the Meanwell supplies exhibit some sort
of switching noise which was easily picked up by the 53310A circuitry, despite my attempts to shield the supplies.  I don't remember the exact frequencies,
but it was in the 0-100kHz range as expected.

Ultimately, I went back to the original Boeschert supply - after I fixed it, of course!

[SoundTech-LG]

Well that is certainly useful information.  I won't be going down that road then. I checked carefully around all caps, and don't see any evidence of leakage, and the unit operates flawlessly, passing all self tests as well. I hate to tear it down to board level again. I'll check the supplies for voltage, and ripple, and give it more thought.

[maxwell3e10]

I suspect it depends on the history of the instrument. At work we have 3 of them and none had problems so far. They are  powered on nearly continuously. Electrolytic capacitors start to fail if not used for a long time. So if your unit was in storage previously, its more likely to start failing once turned on again.

[SoundTech-LG]

I have a different theory now. Having acquired another 53310A, as well as a 54501A for parts (PS in particular), I now can see 3 different Revision PS boards J, L, & E. They do not seem to correlate chronologically with the age of the instrument. I think maybe HP had a huge stockpile of these supplies, and used them, in no particular order. My original 53310A is of the first generation (Made in U.S.A.) circa 1988, (Rev J PS). The latest one, from what I can tell, Made in Korea, 1997 date code marked on the Lithium backed NVRAM (Rev E PS). The scope, was mfg'd early 90's if I remember correctly, and using a (Rev L PS) . I do not know what changes were made in each Rev.
The latest manufactured 53310A came to me with the earliest Rev PS. (Rev E)

So the Rev E supply has no signs of leakage, smell, or corrosion.
The Rev J supply has no signs of leakage, smell, or corrosion.
The Rev L supply from the scope is basically a swamp of sticky, stinky cat pee smell, and corrosion to the screw heads, some circuitry corrosion around the smaller components. It appears it was stored on it's left side (CRT side down), because the swamp was draining out that side, even down the 20 pin connector and cable. The L Rev board also had a look of a shiny coat to it everywhere, and a darker green appearance. Possibly some kind of conformal coat.

Considering all this it makes me think, there may have been some bad production run/s on these caps.
Wouldn't be the first time. It would be interesting to know the Rev levels of other PS boards in these instruments, and the conditions of the boards.

[Tomorokoshi]

Data on my power supply:

HP silkscreen:
Hewlett Packard P/N 0950-1879

Manufacturer's part label:
Computer Products
XL131-3604E
115/230VAC
3.0/1.5A
50/60HZ
CSA LR50913

Manufacturer's serial label:
P/N: 700040-01
S/N: HPQ S173
REV: S
DATE: HD36S

Agency label:
"TUV Product Service"

Written on PCB:
"790019 REV. S"

PCB information:
"COMPUTER PRODUCTS BOSCHERT INC"

Date code 9301 on Q3 transistor in power supply.

No RIFA yellow capacitors. No observed leakage or bulging capacitors.

[syau]

Data on my power supply:

HP silkscreen:
Hewlett Packard P/N 0950-1879

Manufacturer's part label:
Computer Products
XL131-3604E
115/230VAC
3.0/1.5A
50/60HZ
CSA LR50913

Manufacturer's serial label:
P/N: 700040-01
S/N: HZW 0195
REV: S
DATE: HE36S

Agency label:
"TUV Product Service"

Written on PCB:
"790019 REV. S"

PCB information:
"COMPUTER PRODUCTS BOSCHERT INC"

No RIFA yellow capacitors.
Few 1000uF capacitors show sign of leakage on removal.

[SoundTech-LG]

Thank you for the info...

Once I dipped the 54501A PS board in 99% IPA overnight, it lifted a considerable amount of gooey stinky slime. Pulled all 14  1000uF 35V caps. A bit of goo under there.  Rather than clean off 1/4 pound of solder I twisted the caps off, after pulling all the bent over leads, heated the mounds of solder and pushed a small drill bit through. Saved considerable time. I had a whole bag of 50V Panasonic caps. They were fatter, and shorter, but made them fit, and NO, I did not bend over each lead, like Boschert did. Simply inserted, soldered, and clipped off the the leads. Works good now. I also found a corroded meter Pin jack at the 5.1V PS test point next to the pot, that corroded right off. This was supposed to be a parts item, now working...  oops not so fast...  it also needs a NVRAM/battery combo Dallas. Well it can still be parts. Most of the case parts, CRT, CRT board, PS, all in common with 53310A. This scope also came with the nice HP Rack mount with 4 BNC Front Panel connectors. Immediately came off, and went to the 53310A.

[m3vuv]

any idea what caps c32 and c34 are?

[kj7e]

any idea what caps c32 and c34 are?

Look at the bottom of my post above;
https://www.eevblog.com/forum/repair/hp-53310a-power-supply-troubles/msg2365593/#msg2365593

There is BOM attached and lists the parts, including C32 and C34.

[Tomorokoshi]

Here is information on repairing a similar power supply:
https://www.eevblog.com/forum/repair/hp-54520a-psu-repair/

[m3vuv]

hi,any idea what value C37 is,its the one ar the rear of the reg board?,cheers m3vuv.

[m3vuv]

dont you think im already doing that?,how about you read the question i asked before posting FFS!!

[abdulbadii]

just grab replacements with same/higher specs rate from good brand:
- Rubycon.
- United Chemi-Con (or Nippon Chemi-Con)
- Nichicon.
- Sanyo/Suncon