Agilent 53132A Counter Repair (FIXED and Upgraded)

[HighVoltage]

The "upgrade" parts arrived from Poland and got installed today.
After turning on the instrument it gave the message "Not Calibrated", so it detected the 10 MHz OCXO alright.
The 3 GHz Pre-Scaler also seems to work.

Here are some pictures of the installed upgrades.
Next is to calibrate and check all specifications.

[WN1X]

 

[sorenkir]

Hi,

I have replaced the noisy fan of my HP53181A with the following:  Sunon A40201V4 (Super Silence Series  )
http://www.digikey.com/product-search/en?mpart=HA40201V4-000U-999&vendor=259

The fan is very quiet by itself  (12.8dB-A), but when installed, due to airflow & high rotation speed, it is still noticeable in a quiet environment.

Michel.

[HighVoltage]

Thanks for the Digikey link to the fan.
I found a similar fan in Germany and installed it.
It is very quiet and in the lab I do not hear the noise of this instrument.

Calibration was too easy with a good 10 MHz source.
Instrument is finish now.

All done now.
Thanks to all that helped me with this one.
 

[Vgkid]

Is that fan strong enough, 5.5 cfm is not much.

[HighVoltage]

Is that fan strong enough, 5.5 cfm is not much.

It seems very strong and blows very good and steady out of the back.
I also have a 53131A with double oven reference and still an original fan in there and it blows about the same.
So, I see no worries there.
It has been running for about 48 hours now and seems to be very stable.

[Nuno_pt]

Well, there is one mod i can do on my 53181A with Polish channel 2 option, will change the fan since it's very annoying.

I've found this two, I suppose the original it's 12Vdc fan, I don't have the schematic or manual on hand:

Ebmpapst 412/2H-048
12Vdc
100mA
7000rpm
12,5m3/h
25dB

and

Ebmpapst 412
12Vdc
0,9W
75mA
6000rpm
10m3/h
18dB

but this are more expensive about 9 to 14€

[HighVoltage]

Thanks for those fan part numbers.
The fan I installed works very well.

I had the counter officially calibrated and it passed all tests perfectly.
Here it is hooked up to my HP GPSDO and comparison to my 53230A
Seems right perfect.

[Nuno_pt]

HighVoltage,

Can you tell how the fan is attach to the board, solder wires or connector?
Can you confirm that the fan is 12Vdc?
I'm not at home till almost the end of the week, so no chance to look on the inside.

[soul40k]

Hey guys, wondering if you have any possible solutions to a Front End/Measurement self test fail on this?

I have all of my information on my laptop which I left at work unfortunately, but from what I remember, I have near perfect V's from the PSU, it had many issues on the logic side though, very hot MPU chip, which when replaced, fixed every self test issue I had except for Front End/Measurement test.

I bypassed the test screen and attached the reference out to both channels, and it will measure perfect 10MHZ, but if I take off the connections, it seems to float at any random amount with nothing being input. If I am not mistaken, I had a low VCC/GND ohmage (below 20ohms), and if I were to touch the board while running, it would stabilize the read out, but still not bring it to zero with nothing being input.

Sorry for this being my first post, just got into eev, literally starting from the beginning vids/pods, hope to be here more often!

[Orange]

HighVoltage,

Can you tell how the fan is attach to the board, solder wires or connector?
Can you confirm that the fan is 12Vdc?
I'm not at home till almost the end of the week, so no chance to look on the inside.

The fan is a 12 Volts type with solder leads. It's a 40x40x20mm

[Nuno_pt]

Thanks Orange.

[uncle_bob]

Hi

Just a comment from a latecomer to the thread. Based on a fleet of about a hundred 53131's 132's and 181's - they mostly die from a problem in the power supply. So far we have gotten by simply swapping supplies out of the 181's into the others (the 181's are no longer used). I'll take a look at a few supplies next time we have a pile of failures to go through.

Bob

[TheSteve]

I have a broken 53132A inbound, no idea what is wrong with it. If it is something simple I'll post it in this thread, if it turns into a big process I'll start a new thread.

[HighVoltage]

Lately I have been blessed with repairs that turned out to be simple. You just have to take the time and go step by step through the signal path and eventually the problem will emerge.

For many days no, I have this counter hooked up to my HP GPSDO and out of the 12 digits, only the last two are changing
It is quiet impressive, how stable the counter and the GPSDO is.
I calibrated it once against the "locked" GPSDO and since then the system has been extremely stable.

And yes, it was a 12V fan that was installed in this counter.

uncle_bob,
since we now have the schematics for the power supply, you should be easily figure out, what the problem is.
BTW, how come you have hundreds of these ?
What for?
Pictures?

[crispy_tofu]

I have a broken 53132A inbound, no idea what is wrong with it. If it is something simple I'll post it in this thread, if it turns into a big process I'll start a new thread.

Can't wait! 

[uncle_bob]

Lately I have been blessed with repairs that turned out to be simple. You just have to take the time and go step by step through the signal path and eventually the problem will emerge.

For many days no, I have this counter hooked up to my HP GPSDO and out of the 12 digits, only the last two are changing
It is quiet impressive, how stable the counter and the GPSDO is.
I calibrated it once against the "locked" GPSDO and since then the system has been extremely stable.

And yes, it was a 12V fan that was installed in this counter.

uncle_bob,
since we now have the schematics for the power supply, you should be easily figure out, what the problem is.
BTW, how come you have hundreds of these ?
What for?
Pictures?

Hi

Needless to say, the counters are not mine. We use them at work. To avoid the whole "disclaimer" thing I don't post pictures of work. I'd rather not become their spokesman ...  That said, they are in the frequency products / timing industry.

Bob

[TheSteve]

Received my "parts/repair" 53132A that was supposedly missing parts. The only part I know is missing is the back plastic bracket. I plugged it in and absolutely nothing happened. OK, lets take a closer look. The line and neutral wires were desoldered from the IEC connector. I looked over the supply and didn't see anything that looked bad so I reconnected them. The power supply seems fine and tests ok, the fan is dead of course. The counter itself fails the front end test and measure tests. I also see all of the HP branded PLCC chips near the front end have been resoldered or possibly changed. So perhaps this will be a bit of a challenge afterall. Looking at the schematic I should be able to feed a signal in and follow it through. I also have a 100% working 53132A to compare to so hopefully that will narrow things down pretty quick. Being both channels fail I am thinking the problem is a portion they have in common.

[HighVoltage]

It looks like you have a much larger repair job than I had. Looking forward to your progress.

I really don't like it, when some instruments are sold as defect and then when you get them, you find out that someone has tried to fix it and usually caused more damage.

You are probably right that the fault has something to do, that is common to both input channels.
Is the self test showing any error numbers?

[uncle_bob]

Hi

Be careful of the HP custom ASIC chips in these counters. About the only way I have ever seen to get them is to buy an entire board. You do *not* want to pay HP prices on those boards.

Bob

[TheSteve]

We shall see what the problem is. The front ends are totally fine. It looks to be something just after that. I may be buying a parts board in the future! The whole thing was $165.00 so I have a budget for parts.

[soul40k]

 

We shall see what the problem is. The front ends are totally fine. It looks to be something just after that. I may be buying a parts board in the future! The whole thing was $165.00 so I have a budget for parts.

That is where I sit right now, the front looks fine, really weird actions with just a completely spastic display with nothing connected, but I touch it when live, on the bottom, and it stops. This is going to be the death of me, probably something really simple that I am just missing.

[HighVoltage]

Can you show us in the schematic where you have to touch to make the display stable?

[TheSteve]

Spent some time last night working on my 53132A. The entire time I just kept hearing Shahriar in my head saying "Follow the signal path" lol.

Anyway, some progress was made and I know I'm close. While following the signal flow between the front end and the FPGA I kept getting that feeling something obvious was wrong yet I couldn't see it. I briefly thought maybe the FPGA was bad as it was not generating any reset signals but then it occurred to me that it probably had to detect some sort of signal before it would reset the count circuitry. This proved to be true as selecting input two and then going back to input one would generate 2 or 3 reset pulses that could be traced through the logic.  At this point I looked at why I was getting no LED indication showing the selected input or gate samples. So I focused on U50. I had previously gone through all of the logic chips and verified +5, -5 and ground but I thought I'd do it again on U50. The -5 was nice and steady on my 34461A but the +5 was only steady for the first 3 digits. A quick hit with the soldering iron solved that problem and I now had input and gate indications. I still received the failed front end and failed measure errors at boot but it correctly measured the frequency being input which it had never done before. I should also mention at this point I had removed U44 which is a buffer opamp to set the trigger levels as it just didn't look right comparing its in and out voltages. I gave channel 1 a fixed trigger level with a resistor. After seeing it count the frequency properly I reinstalled the original U44. At this point it will not count anything at all and still gives the same errors. I get the feeling I am now at the point of the original failure which started the previous owner resoldering everything. The bad solder connection on U50 was caused by the previous rework as nearly all of the logic chips in the front end have been removed and resoldered(maybe replaced, I'll never know). It was late so  I had to pack it in for the evening. I will take a very close look at U44 tonight though. Unless I can say 100% for certain it is good I will order a replacement from Digikey, it's in stock for 5 to 6 bucks and may be all that is really wrong with the unit. I know it can count a frequency correctly so there there can't be much else wrong right?

btw, the previous person that did the rework has some skill but not really enough to do a proper job. The soldering they did is far from excellent and they removed a part or two that there was clearly no need to remove as they can easily be verified 100% good in circuit. They also left the signature amateur calling card in the top of one of the relays in the form of soldering iron melt marks.

[soul40k]

Can you show us in the schematic where you have to touch to make the display stable?

It is literally anywhere near the front end, no specific point, I got busy with another job,  so I haven't tried other places yet, have to get back to it soon though.