On Sun, Sep 11, 2022 at 03:41 PM, Tom Lee wrote:

Linear vs. SMPS would not be expected to matter, in any case.

Sure, as to whether the devices fail. I was speculating that the instruments with linear supplies would need less high frequency filtering on the mains.? (but I have a fairly small sample size of instrument types to judge that on)

开云体育

Nearly all of my blown RIFA caps have been in instruments with purely linear supplies. Indeed, a fair fraction of them have been in linear supplies!

Linear vs. SMPS would not be expected to matter, in any case. The problem is one of moisture ingress. The encapsulant shrinks and cracks over time, letting moisture in. At some point the capacitor breaks down and you get a multimedia spectacular. None of those processes is particularly sensitive to what circuitry lies downstream.

--Cheers,
Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070

Following up...

I think it was a firewall issue, though it mysteriously went away after checking the settings without (consciously) changing anything. After that, the update completed successfully.

The only problem is that I appear to have lost cal constants as a result of the earlier update failure -- at power up I get a "no synthesizer cal coefficients -- using defaults" message. I would like to ignore that, but there is a strong spur at about +300 kHz from the center frequency that wasn't there before. Still scratching my head what to do about that.

John
----

On Sun, Sep 11, 2022 at 01:08 PM, Dave McGuire wrote:

Are you perhaps conflating the Rifa capacitor problem with the bad electrolyte formula problem?

Well no, since I asked the question in the first post. I may be off with the time frame though. No one seems to have answered that question yet. Presumably this is an issue with SMPS instruments. My 80's HP gear has (AFAIK) almost all linear supplies.?

If you can't be pretty, may as well be lucky!

All I can say is in 4 decades of designing, using,
and repairing electronic equipment, I haven't seen
a Schaffner filter blow up. Tomorrow may be the day
that I may see a dozen...

The goodness of the whole idea of putting several
safety caps, which are designed to blow without
catching the instrument on fire, in a can full of tar
eludes me.

-Chuck Harris


On Sun, 11 Sep 2022 12:40:50 -0400 "Dave McGuire"
<mcguire@...> wrote:

On 9/11/22 11:53, Chuck Harris wrote:

Mostly the failure rate of RIFA paper dielectric safety
capacitors, with clear (yellow) epoxy potting, is related
to how large the difference is between their design failure
voltage, and the voltage applied.

In other words, for older capacitors:
If you use a 250VAC RIFA cap on 240VAC mains, failure is
all but assured.

If you use a 250VAC RIFA cap on 120V mains, you will likely
never see a failure.

That's nowhere near true in the field, unfortunately. I've
replaced two 250VAC RIFA capacitors run on 120V in the past week
alone. These blow up *all the time*.

Storage in a humid environment dramatically accelerates the
failure of RIFAs.

Or so says my 40 years of experience as an engineer, with never
seeing a single RIFA capacitor failure on 120VAC.

You've been lucky.

-Dave

On 9/11/22 15:57, vk2bea via groups.io wrote:

HP 3403C
I would have thought that this was manufactured before these caps were used. It looks like a late 70s / early 80s device. As I understand it these bad caps were more a late 80s / early 90s problem.

Are you perhaps conflating the Rifa capacitor problem with the bad electrolyte formula problem? Most of the Rifas I've seen blown up have been from the early 1980s.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

On Sun, Sep 11, 2022 at 11:26 AM, Susan Parker wrote:

HP 3403C

I would have thought that this was manufactured before these caps were used. It looks like a late 70s / early 80s device. As I understand it these bad caps were more a late 80s / early 90s problem.

Manufacturers part number.

This may be different from the model number or NSN as diferrent companies can make the same model instrument.

I have had a Schaffner filter (on a Phillips counter) fail, and have had a few instruments where they had cracked but not failed explosively.?
But I've had two problems with domestic equipment - a fan and a sewing machine. The manufacturers may wish consumers would change devices more often but the truth of it is that they'll be changed for fashion or failure? : they can't generally claim the equipment is obsolete and no longer useful, like they might with commercial equipment.

Thanks Chuck. I guess I have both factors in my favor here; 120VAC and low humidity in high desert country.

My HP 3403C True RMS Voltmeter's cap went with a bang and a nasty smell some years ago - at 245 Vac we are right at the top end of the UK "nominal" 230 Vac line voltage in this part of West London UK though so not overly surprising.
At the moment it is bouncing up and down by several hundred mV and the frequency is also jiggering about too, which is not reassuring.

John Ackermann N8UR <jra@...> writes:

On 9/11/22 13:42, Sven Schnelle wrote:

I would think that this bootloader is very similar to the PA-RISC HP-UX
machines. Lan paths are only listed if there's a DHCP server returning
a ip + bootserver + bootfile, and the TFTP server is responding. So make
sure that the network setup is properly working.
Also enable the autosearch flag. I think you can also say 'search
lan'
which would query the network regardless of the autosearch flag setting.

Thanks, Sven! I was wondering about the autosearch, but since I had
no idea what it did, was hesitant to mess with it.

I'm not sure just what the procedure is, but the "manual" process with
the HP E4406A firmware updater is to enter the MAC address in the
program, then tell the E4406A to boot from LAN; from that I would
gather that the updater program on the PC sets itself up as a TFTP
server listening for the MAC of the VSA.

Ah, ok. Yes, than it's very likely that the Updater program provides
DHCP + TFTP. Have you check your Windows firewall settings/logs, maybe
the packets get dropped?

'boot lan' should also be possible to explicitely trigger a boot from lan.

On 9/11/22 13:42, Sven Schnelle wrote:

I would think that this bootloader is very similar to the PA-RISC HP-UX
machines. Lan paths are only listed if there's a DHCP server returning
a ip + bootserver + bootfile, and the TFTP server is responding. So make
sure that the network setup is properly working.
Also enable the autosearch flag. I think you can also say 'search lan'
which would query the network regardless of the autosearch flag setting.

Thanks, Sven! I was wondering about the autosearch, but since I had no idea what it did, was hesitant to mess with it.

I'm not sure just what the procedure is, but the "manual" process with the HP E4406A firmware updater is to enter the MAC address in the program, then tell the E4406A to boot from LAN; from that I would gather that the updater program on the PC sets itself up as a TFTP server listening for the MAC of the VSA.

I'll give the autosearch option a try when I get a chance to get back downstairs.

Thanks!
John

"John Ackermann N8UR" <jra@...> writes:

I was attempting to update my E4406A from an earlier firmware version
and the process failed. I think it was due to the firewall on the
Windows XP virtual machine I was using. After the update, the system
goes through the entire boot process and brings up the X windows
background then stops with:

Exec: load error: 8. Process killed.
/users/arcturus/.xinitrc: 68 killed
Hostname is VSA
Firmware Exit, cycle power

The OS seems to be OK because it gets as far as the arcturus login
before exiting.

I got my hands on an actual, physical WinXP machine and tried the
manual update process per the instructions using a hub between the two
devices. I can't complete that because the SEA command returns only:

Path Number Device Path
P0 FLASH

I would think that this bootloader is very similar to the PA-RISC HP-UX
machines. Lan paths are only listed if there's a DHCP server returning
a ip + bootserver + bootfile, and the TFTP server is responding. So make
sure that the network setup is properly working.

Also enable the autosearch flag. I think you can also say 'search lan'
which would query the network regardless of the autosearch flag setting.

(I also posted this to the eevblog test equipment group because there's been E4406A discussion there. I hope that doesn't result in too many of you seeing it twice.)

Hi --

I was attempting to update my E4406A from an earlier firmware version and the process failed. I think it was due to the firewall on the Windows XP virtual machine I was using. After the update, the system goes through the entire boot process and brings up the X windows background then stops with:

Exec: load error: 8. Process killed.
/users/arcturus/.xinitrc: 68 killed
Hostname is VSA
Firmware Exit, cycle power

The OS seems to be OK because it gets as far as the arcturus login before exiting.

I got my hands on an actual, physical WinXP machine and tried the manual update process per the instructions using a hub between the two devices. I can't complete that because the SEA command returns only:

Path Number Device Path
P0 FLASH

So there is no LAN path to boot to.

The "boot information" screen shows primary boot path as "255.0" and alternate boot path as "SESCSI .6.0". The IO information screen shows the LAN device is present. The machine address info shows what seems to be a valid MAC address, which is what I used for the manual update attempt. The memory command shows 4 64MB units, total 256MB. The Warnings screen shows no errors other than that fastboot is enabled.

In the BOOT INFORMATION screen the top 3 options (Autoboot, Autosearch, Autostart) are all turned off. Could the "Autosearch" setting be related to finding a network boot host?

Is there something I need to do to get the firmware updater and the E4406A to talk to each other? Or is it possible to get to a shell that would allow me to configure the network via ifconfig or /etc/network?

I'm stumped; any help would be appreciated.

Thanks,
John

I have seen a handful fail between work (4 hospital IT group) and home.? All had been in 120 volt service.? If I see any cracking, that cap is removed and replaced.? If there is no cracking I have been known to risk it for a while.??

--
Thanks,
Randy
randy.ab9go@...

On 9/11/22 11:53, Chuck Harris wrote:

Mostly the failure rate of RIFA paper dielectric safety
capacitors, with clear (yellow) epoxy potting, is related
to how large the difference is between their design failure
voltage, and the voltage applied.
In other words, for older capacitors:
If you use a 250VAC RIFA cap on 240VAC mains, failure is
all but assured.
If you use a 250VAC RIFA cap on 120V mains, you will likely
never see a failure.

That's nowhere near true in the field, unfortunately. I've replaced two 250VAC RIFA capacitors run on 120V in the past week alone. These blow up *all the time*.

Storage in a humid environment dramatically accelerates the failure of RIFAs.

Or so says my 40 years of experience as an engineer, with never
seeing a single RIFA capacitor failure on 120VAC.

You've been lucky.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Reminder that the brand new CRT for the 141T is still available.

Double-boxed and ready to ship or pick up locally in San Diego, CA or Los Angeles. (contact me off list for local pickup)

US$167.00 plus shipping. PayPal, check (must clear before shipping), or cash okay for local pickup.

More details and pictures here: