Re: Leaking alkaline cells
On Thu, Sep 5, 2024 at 09:28 AM, Richard Knoppow wrote:
Duracell, especially AA size ... seem to have cured that, now have a 12 year guarantee
yes.
but there is a lot of bs and confusion... online... about whether the date code (on the cell) is the 'expiry date' or the 'manufactured date' ... so when does the 12 years start?
?
Anyway... AFAICT ... it's a 12 year 'shelf life' ... stored under optimum conditions... and AFAIK there's nothing in the guarantee/warranty about 'storage' in a 'device'
?
I don't know... but the electrolyte in alkaline batteries is KOH, and the anode is zinc... and high molarity KOH will react with zinc to produce hydrogen.... slowly... but it does happen.
Just to speculate... maybe over time, and over 'long over discharge conditions' enough of the gas builds up to cause the battery seals to fail sufficiently...? to let the electrolyte leak out.
And, maybe not.
|
Re: 8566B attenuator removal
... I could always just bypass the faulty attenuator internally, replace the top and bottom cases and just use any high-quality adjustable RF attenuator in series with a 10dB fixed attenuator permanently attached to the RF input at the front panel. So it wouldn't be the end of the world I guess. <shrug>
Jinxie, that is not a good idea. The input attenuator setting is coordinated with various gain stages in the IF to give an accurate amplitude reading regardless of attenuator setting. This is the reason you were so easily able to test the hypothesis that the attenuator may be bad. If you use an external attenuator, it will have no way of communicating with the processor. Each time you change the reference level, you will have to manually enter the expected attenuation.
?
On very rare occasions, the attenuator may limber up with repeated exercise if there isn't a problem with either the o-rings or the "Y-contacts". Depending on the age of the attenuator, it either has these mechanical Y-contacts, or a circuit board with solid state logic inside. You will have to open the attenuator to see which it is. Replacing o-rings requires some manual dexterity, but it's not like watch repair. Somebody just posted a link to a pdf file with instructions on this forum.
?
If a section is burned out, you can possibly make one good attenuator out of two bad ones. What do you know about the history of this 8566?
?
Vladan
|
Re: Keysight customer support policy
My current personal experience:
- Duracells will always leak.
- Energizers will leak 50% of the time during normal lifetime inside hp calculators such as HP71B, flashlights and such,
? so I check them monthly.
Any info on GP batteries?
Carlos Murillo.
Larry McDavid wrote:
toggle quoted message
Show quoted text
You believe currently manufactured Duracell AA and AAA cells now no longer leak? Does anyone have any evidence to support that? What is the current experience? I'd like to believe that...
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
On 9/5/2024 7:57 AM, Robert G8RPI via groups.io wrote:
The Alkaline cell leakage problem in premtium brands like Duracell and Energiser is not entirely down to cost cutting by the manufacturers. The root cause was the mandated (rightly) elimination of Mercury by governments. It turned out that the small amount of Hg alloed the re-absorbsion of hydrogen generated by the cell even when not suppling current. This lead to a period of production of cells the were prone to leakage. They now seem to have fixed the chemistry and more recent cells don't suffer this problem.
Robert.
|
Re: Leaking alkaline cells
Duracell / Duraleak has been owned by Warren Buffett since 2014, or so. Before that Procter & Gamble made sure the quality went way down. About a year ago, I had enough of seeing damaged appliances, so in a moment of particular annoyance I sent Mr. Buffett a letter asking him to look into it.
?
The brand¡¯s reputation is in my mind permanently damaged, but I am happy to hear that you see some improvement. The warranty however is useless, no matter how many years they offer. It may still be contingent on ¡°removing batteries from the device when not in use¡±. I agree that the old Duracells from way back were good.
?
Vladan
|
Re: HP 141T Power Supply Help Needed
Mike,? I now get a rather high impedance?at the output of the regulator, think it was ~50k.? ? ?The previous issue was in fact a physical short on A5 board (lead clipping...) Currently, things look as follows:? Q9 C .65? B? 1.36 E .65 Q10? C 2.4 B 0 E 0 Q11 C 1.3 B -.65 E 0? Output Voltage -0.002 Output Impedance? ~400k? I get the sneaking suspicion that my driver is bad as the CE voltages are roughly equivalent (maybe .002 different).? ? ?The voltage I see at the base of Q9 seems close, so I'm guessing the sensor amp is working better..? ?Q10 base at 0v is a little weird.? ?
Like I say, I'll go back through things this afternoon and see if any remaining parts saw issues in the last round of testing.? ? ?This feels like progress though.? ? ?
I don't know how to fix Q4 socket long term, but I'm mulling that over.? I kind of want to insert / solder a pin in place of the spring contacts that have been causing me so much frustration.? ? ?
On Thu, Sep 5, 2024 at 10:42?AM Michael Bafaro via <m.bafaro= [email protected]> wrote: Bill, ? The big question is what resistance do you measure at the pins of the A2 board that have the white / Violet wires going to them with the wires removed.? At this point you should read >1K Ohm at the output of the regulator.? If the resistance at the output of the regulator is < 4 Ohms don¡¯t put in a new pass device.? As I remember you had one of the white / violet wires that measured < 1 Ohm.? I seem to remember that you were going to trace out that wire to see where it went and why it read so low.? ?I remember you had one of the White / violet wires that went to the A5 assembly which runs the storage functions and you were going to find the cause of that later.? Let me know what you find. ? Mike ? ? Ugh, I put it down for a few days to work on an old Zenith my wife got for my birthday.? Today, I put a fresh pass trans in, and fired it up.? I got -2.5v for a few seconds and then it looks like it took out the transistor.? Replaced and same story.? ? ? Mike - with F4 removed, I measure ~50k ohm at the terminal you mention, so that rules out C9?? ? R49 does look ok..? my DMM only measures tenths, so I get a floating .2 to .3 ohm.? I guess I typo¡¯d the decimal or mentally transcribed wrong.. ?
Dave - I ran through each part you mention.? R44 was a little suspect in that the schematic says 20k but it measured 18k, still in range but I¡¯d have expected it to go UP. ? In a fit of rage, I replaced C8, C9 , R44, R46 and still blows pass trans.? ? ?Raw voltage in??is around 22v last I checked.
At this point, I¡¯m wondering if there is something under the board fighting me. ? It didn¡¯t look like I was the first person in here, and I¡¯ve been working from the top side only.? ? Is it worth pulling the board to look at? ? ? I could go eBay a bunch of old exotic parts, I could try to shotgun some moremodern parts in.. ? ? I do feel like I¡¯m loosing the battle on this rail though. ? Anyone in North Carolina?? :-)? ? Hello All
I have a hp 141t when it is powered up there is no trace but when I turn off the power the trace briefly appears in top right corner.
Is it the blanking circuit or do I need to do an trace? alignment or something else. I need some guidance
Has anyone encountered this problem before and let me know what you did.
73's Leroy de VK5HL
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Chuck Harris
Sent: Tuesday, 3 September 2024 1:41 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed
To amplify your comment, many times older linear supplies, when they are brute force recapped, with the best, long life, low esr caps you can find, will become beacons of chaotic oscillation.
I put a low ESR ceramic capacitor in the feedback loop of a unity gain OPAMP circuit the other day, and was amazed that it went totally unstable.? It was an older LM301 variety, where the response characteristics of the opamp are a blank slate until the designer adds in the stability network.? The designer's efforts were wiped out by my ceramic capacitor replacement for his 1uf back-to-back emulation of a non-polar electrolytic.
Sometimes the modern best replacement is not suitable for use in an older instrument.
-Chuck Harris
On Mon, 2 Sep 2024 22:40:20 +0100 "Dave_G0WBX via "
<g8kbvdave=[email protected]> wrote:
> Hi.
>
> It's just a generic term (damping is another) to slow down the
> response of a loop, to prevent it going unstable.
>
> Not an uncommon issue in some linear PSU's like those -12.6V or -100V
> regulator topologies that are not "conventionally" laid out.
>
> Unless you 'scope the thing, you often don't know it's gone unstable,
> other than some passive parts sometimes cook for no obvious reason.
> (That R49 for example!? See Mike's comment in another mail.)
>
> It is also not uncommon, when modern transistors are used to replace
> older failed parts (that are not available any more) and the new
> device has "a lot" more gain at HF than the originals, that regulator
> or other control loops suddenly become "unruly" under some operating
> conditions.
>
> Sometimes a low value "Base Stopper" resistor (a few Ohms, or a
> ferrite bead) in series with the new device's Base connection can
> restore sanity!
>
> Take care.
>
> Dave B.
>
>
>
|
Re: Leaking alkaline cells
Duracell, especially AA size but others too, had a serious problem. They seem to have cured that, now have a 12 year guarantee. I have recently bought Duracell and Kirkland which are the same and have had good luck with them. The cells that leaked also had two dimples on the bottom, not there on the new cells.
I suspect all dry cells leak but the Duracells had something peculiar about them.
Not so sure this was a bean counter problem.
Duracell was originally a Mallory product, the best available at that time.
toggle quoted message
Show quoted text
On 9/5/2024 9:20 AM, Cubdriver wrote: I too have seen far too many Corrodacell err, I mean 'Duracells' spew forth their toxic venom, some even while still new in package and well before their 'use by' dates. ?About fifteen years ago folks on a photography forum I was on were talking about Sanyo (now Panasonic) Eneloop NiMH batteries (anyone who's used an electronic flash unit knows they chew through AAs like howitzer shells at the Battle of the Bulge), so I bought some. ?As long as whatever you're using them in can tolerate their lower voltage of 1.2 V, I think they're fantastic - the work in low temps (use them in a temperature sender that lives outside) and none have so far leaked. ?I now use them in everything I can.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: Schottky Diode degradation / Replacement in instrument Sram Battery backup circuits ?
On Wed, Sep 4, 2024 at 08:13 PM, gren wrote:
Max40200 (2x) as possible replacement for diode
Apart from which type of diode.. or? 'ideal diode' is suitable... in all the discussion ...what is the backup battery being referring to?
What's the battery you use to replace the 'original battery?' in the 4274A?
?
The 'original' battery for the 4274A... given in the manual you linked to,
?
HP (1980) Model 4274A Service Manual (> prefix 1850J) (04274-90012)
?
The battery mentioned there is,
A9BT1 1420-0125 Lithium Battery 2.8V?
?
1420-0125? was/is replaced by (according to Keysight)...
Part Number:
1420-0342
Part Description:
NFTS; UTG Battery 3.9V 2A-HR Li BR CL Solder-Tab
Item Status:
Obsolete
Item Type:
Keysight Qualified Part
General Information:
This part is not available for direct sale but an instrument repair is orderable through our service center. Please contact Keysight to inquire about returning your instrument for repair.
Weight:
0.005 KG
?
n.b. The replacement battery is a higher voltage.
Does that make the metal-semiconductor junction Schottky diode (and all it supposed faults) ... versus the PN semiconductor junction silicon diode... somewhat moot?
?
AFAIK, lithium bromine chloride batteries are 'specialty batteries' ... available, but expensive.
?
Perhaps? a suitable battery, at about 10% ? the cost of a LiBRCL battery is,
Saft LS 14250 battery, but this battery is not the 'solder tab type.'
?
Newark has the Saft LS 14250 battery.
|
Leaking alkaline cells (was: Keysight customer support policy)
I too have seen far too many Corrodacell err, I mean 'Duracells' spew forth their toxic venom, some even while still new in package and well before their 'use by' dates. ?About fifteen years ago folks on a photography forum I was on were talking about Sanyo (now Panasonic) Eneloop NiMH batteries (anyone who's used an electronic flash unit knows they chew through AAs like howitzer shells at the Battle of the Bulge), so I bought some. ?As long as whatever you're using them in can tolerate their lower voltage of 1.2 V, I think they're fantastic - the work in low temps (use them in a temperature sender that lives outside) and none have so far leaked. ?I now use them in everything I can. ? -Pat
?
> ------ Original Message ------
> From: kc0wjn@...
> To: [email protected]
> Sent: Thursday, September 5th 2024, 10:56 AM
> Subject: Re: [HP-Agilent-Keysight-equipment] Keysight customer support policy
That's a really good question. Around 2016 or so I started to find devices in which I had Duracell batteries long-term (Garmin GPS, Kestrel weather meter, etc.) ruined by leaking batteries, something I had never experienced during decades of using Duracells. My limited research into the problem revealed that the change in management at what was Mallory was the likely root cause of the problem. So, like others, I banned Duracells from my home and started trying other brands. Supposedly Eveready batteries were "better", so I used those for awhile, until I had several leak. Lately, (and I hate to write this) I've been using Amazon-branded AAs, AAAs and 9 volt batteries and have not had a single leak-related failure over the past five or so years.
?
DaveD KC0WJN
?
Thanks for all the fish.
? ============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
?
On Sep 5, 2024, at 09:52, Radu Bogdan Dicher via groups.io <vondicher@...> wrote:
?
As long as we're on this topic, what are some battery brands that peeps here would swear by?? ? I used to stick to Duracells, but you're confirming what I've also seen - a ton load of leakages. I'm tired of ruined units and messy cleanups.? ? I've recently bought a big box of AC Delcos, and they've been good this far. But not enough time yet to really tell.? ? To be clear, I'm thinking of garden variety batteries, like alkaline?and such.? Radu.?
?
On Thu, Sep 5, 2024 at 6:01?AM Peter Gottlieb via <hpnpilot= [email protected]> wrote: ?
On 9/5/2024 8:54 AM, greenboxmaven via wrote:
> Burgess batteries
?
|
Re: Free to good home, HP 5423A system + manuals and spares
I was one of the "biters," but I don't have the need, nor the room for it. I hope Dave makes the logistics work and grabs it.
Radu
OK Dave, pls keep me posted as it progesses.
|
Re: Free to good home, HP 5423A system + manuals and spares
OK Dave, pls keep me posted as it progesses.
|
Re: Keysight customer support policy
toggle quoted message
Show quoted text
On Thu, Sep 5, 2024, 8:33 AM nigel adams via <bristol.rell6l= [email protected]> wrote: This topic appears to have morphed from HPAK discussion regarding their inability to sell to private customers to a
Battery failure discussion - shouldn't that have become a separate topic.?
Nigel
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Larry McDavid via
Sent: 05 September 2024 16:30
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Keysight customer support policy
You believe currently manufactured Duracell AA and AAA cells now no longer leak? Does anyone have any evidence to support that? What is the current experience? I'd like to believe that...
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
On 9/5/2024 7:57 AM, Robert G8RPI via wrote:
> The Alkaline cell leakage problem in premtium brands like Duracell and
> Energiser is not entirely down to cost cutting by the manufacturers.
> The root cause was the mandated (rightly) elimination of Mercury by
> governments. It turned out that the small amount of Hg alloed the
> re-absorbsion of hydrogen generated by the cell even when not suppling
> current. This lead to a period of production of cells the were prone
> to leakage. They now seem to have fixed the chemistry and more recent
> cells don't suffer this problem.
> Robert.
>
|
Re: Keysight customer support policy
This topic appears to have morphed from HPAK discussion regarding their inability to sell to private customers to a
Battery failure discussion - shouldn't that have become a separate topic.?
Nigel
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Larry McDavid via groups.io Sent: 05 September 2024 16:30 To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] Keysight customer support policy You believe currently manufactured Duracell AA and AAA cells now no longer leak? Does anyone have any evidence to support that? What is the current experience? I'd like to believe that... Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland) On 9/5/2024 7:57 AM, Robert G8RPI via groups.io wrote: The Alkaline cell leakage problem in premtium brands like Duracell and
Energiser is not entirely down to cost cutting by the manufacturers.
The root cause was the mandated (rightly) elimination of Mercury by
governments. It turned out that the small amount of Hg alloed the
re-absorbsion of hydrogen generated by the cell even when not suppling
current. This lead to a period of production of cells the were prone
to leakage. They now seem to have fixed the chemistry and more recent
cells don't suffer this problem.
Robert.
|
Re: Keysight customer support policy
You believe currently manufactured Duracell AA and AAA cells now no longer leak? Does anyone have any evidence to support that? What is the current experience? I'd like to believe that...
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
toggle quoted message
Show quoted text
On 9/5/2024 7:57 AM, Robert G8RPI via groups.io wrote: The Alkaline cell leakage problem in premtium brands like Duracell and Energiser is not entirely down to cost cutting by the manufacturers. The root cause was the mandated (rightly) elimination of Mercury by governments. It turned out that the small amount of Hg alloed the re-absorbsion of hydrogen generated by the cell even when not suppling current. This lead to a period of production of cells the were prone to leakage. They now seem to have fixed the chemistry and more recent cells don't suffer this problem.
Robert.
|
Re: Keysight customer support policy
I've stopped using alkaline AA and AAA cells altogether because of leakage. For about three years now I've been using Energizer "Ultimate" Lithium primary cells. So far, I've never had a primary Li cell leak. I have one early failure in a set of three in series, but no leaks. I have a total of 76 AA and AAA cells in use.
Yes, Li primary cells are surely more expensive. But, I've never thrown anything away because of cell leakage. Duracell AA and AAA cells once were my preferred cell but they are now just garbage and leak even unused in packaging.
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
toggle quoted message
Show quoted text
On 9/5/2024 7:56 AM, Dave Daniel wrote: That's a really good question. Around 2016 or so I started to find devices in which I had Duracell batteries long-term (Garmin GPS, Kestrel weather meter, etc.) ruined by leaking batteries, something I had never experienced during decades of using Duracells. My limited research into the problem revealed that the change in management at what was Mallory was the likely root cause of the problem. So, like others, I banned Duracells from my home and started trying other brands. Supposedly Eveready batteries were "better", so I used those for awhile, until I had several leak. Lately, (and I hate to write this) I've been using Amazon-branded AAs, AAAs and 9 volt batteries and have not had a single leak-related failure over the past five or so years.
DaveD
KC0WJN
Thanks for all the fish.
==============================
All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994)
==============================
On Sep 5, 2024, at 09:52, Radu Bogdan Dicher via groups.io <vondicher@...> wrote:
?
As long as we're on this topic, what are some battery brands that peeps here would swear by?
I used to stick to Duracells, but you're confirming what I've also seen - a ton load of leakages. I'm tired of ruined units and messy cleanups.
I've recently bought a big box of AC Delcos, and they've been good this far. But not enough time yet to really tell.
To be clear, I'm thinking of garden variety batteries, like alkaline?and such.
Radu.
On Thu, Sep 5, 2024 at 6:01?AM Peter Gottlieb via groups.io <> <hpnpilot@... <mailto:[email protected]>> wrote:
<>
On 9/5/2024 8:54 AM, greenboxmaven via groups.io
<> wrote:
> Burgess batteries
|
Re: Keysight customer support policy
The Alkaline cell leakage problem in premtium brands like Duracell and Energiser is not entirely down to cost cutting by the manufacturers. The root cause was the mandated (rightly) elimination of Mercury by governments. It turned out that the small amount of Hg alloed the re-absorbsion of hydrogen generated by the cell even when not suppling current. This lead to a period of production of cells the were prone to leakage. They now seem to have fixed the chemistry and more recent cells don't suffer this problem.
?
Robert.
?
|
Re: Keysight customer support policy
That's a really good question. Around 2016 or so I started to find devices in which I had Duracell batteries long-term (Garmin GPS, Kestrel weather meter, etc.) ruined by leaking batteries, something I had never experienced during decades of using Duracells. My limited research into the problem revealed that the change in management at what was Mallory was the likely root cause of the problem. So, like others, I banned Duracells from my home and started trying other brands. Supposedly Eveready batteries were "better", so I used those for awhile, until I had several leak. Lately, (and I hate to write this) I've been using Amazon-branded AAs, AAAs and 9 volt batteries and have not had a single leak-related failure over the past five or so years. DaveD KC0WJN
Thanks for all the fish.
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
toggle quoted message
Show quoted text
On Sep 5, 2024, at 09:52, Radu Bogdan Dicher via groups.io <vondicher@...> wrote:
? As long as we're on this topic, what are some battery brands that peeps here would swear by??
I used to stick to Duracells, but you're confirming what I've also seen - a ton load of leakages. I'm tired of ruined units and messy cleanups.?
I've recently bought a big box of AC Delcos, and they've been good this far. But not enough time yet to really tell.?
To be clear, I'm thinking of garden variety batteries, like alkaline?and such.? Radu.? On Thu, Sep 5, 2024 at 6:01?AM Peter Gottlieb via <hpnpilot= [email protected]> wrote:
On 9/5/2024 8:54 AM, greenboxmaven via wrote:
> Burgess batteries
|
Re: Keysight customer support policy
For the very few standard alkaline batteries I use it is Energizer for the win; I also have learned the hard way about Duracell's but have not (yet) had any issues with the Energizers.? Unless something is very voltage intolerant, I use NiMH rechargeables in just about everything and I have had very good luck with both EBL and Eneloop brands - I've lost or given away several but have yet to have any go bad over several years of use.? Very affordable on Amazon although I prefer the EBL chargers to others - they seem to work just a bit better at bringing all of the cells to a full - and even - charge.
?
Hal
|
Re: Free to good home, HP 5423A system + manuals and spares
On 9/5/24 10:45, Precaud via groups.io wrote: 2nd call... so far a couple bites but no takers. It would be a shame to have to scrap and recycle this system. I spoke to a friend about this; he'll be driving through your part of the country soon. He expressed a willingness to pick it up. I've forwarded this to him to see if he can arrange it. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
|
Re: Free to good home, HP 5423A system + manuals and spares
2nd call... so far a couple bites but no takers. It would be a shame to have to scrap and recycle this system.
|
Re: HP 141T Power Supply Help Needed
Bill, ? The big question is what resistance do you measure at the pins of the A2 board that have the white / Violet wires going to them with the wires removed. ?At this point you should read >1K Ohm at the output of the regulator.? If the resistance at the output of the regulator is < 4 Ohms don¡¯t put in a new pass device. ?As I remember you had one of the white / violet wires that measured < 1 Ohm.? I seem to remember that you were going to trace out that wire to see where it went and why it read so low.? ?I remember you had one of the White / violet wires that went to the A5 assembly which runs the storage functions and you were going to find the cause of that later.? Let me know what you find. ? Mike ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Bill Berzinskas Sent: Wednesday, September 4, 2024 9:05 PM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ? Ugh, I put it down for a few days to work on an old Zenith my wife got for my birthday.? Today, I put a fresh pass trans in, and fired it up.? I got -2.5v for a few seconds and then it looks like it took out the transistor.? Replaced and same story.? ? ? Mike - with F4 removed, I measure ~50k ohm at the terminal you mention, so that rules out C9?? ? R49 does look ok..? my DMM only measures tenths, so I get a floating .2 to .3 ohm.? I guess I typo¡¯d the decimal or mentally transcribed wrong.. ?
Dave - I ran through each part you mention.? R44 was a little suspect in that the schematic says 20k but it measured 18k, still in range but I¡¯d have expected it to go UP. ? In a fit of rage, I replaced C8, C9 , R44, R46 and still blows pass trans.? ? ?Raw voltage in??is around 22v last I checked.
At this point, I¡¯m wondering if there is something under the board fighting me. ? It didn¡¯t look like I was the first person in here, and I¡¯ve been working from the top side only.? ? Is it worth pulling the board to look at? ? ? I could go eBay a bunch of old exotic parts, I could try to shotgun some moremodern parts in.. ? ? I do feel like I¡¯m loosing the battle on this rail though. ? Anyone in North Carolina?? :-)? ? Hello All
I have a hp 141t when it is powered up there is no trace but when I turn off the power the trace briefly appears in top right corner.
Is it the blanking circuit or do I need to do an trace? alignment or something else. I need some guidance
Has anyone encountered this problem before and let me know what you did.
73's Leroy de VK5HL
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Chuck Harris
Sent: Tuesday, 3 September 2024 1:41 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed
To amplify your comment, many times older linear supplies, when they are brute force recapped, with the best, long life, low esr caps you can find, will become beacons of chaotic oscillation.
I put a low ESR ceramic capacitor in the feedback loop of a unity gain OPAMP circuit the other day, and was amazed that it went totally unstable.? It was an older LM301 variety, where the response characteristics of the opamp are a blank slate until the designer adds in the stability network.? The designer's efforts were wiped out by my ceramic capacitor replacement for his 1uf back-to-back emulation of a non-polar electrolytic.
Sometimes the modern best replacement is not suitable for use in an older instrument.
-Chuck Harris
On Mon, 2 Sep 2024 22:40:20 +0100 "Dave_G0WBX via "
<g8kbvdave=[email protected]> wrote:
> Hi.
>
> It's just a generic term (damping is another) to slow down the
> response of a loop, to prevent it going unstable.
>
> Not an uncommon issue in some linear PSU's like those -12.6V or -100V
> regulator topologies that are not "conventionally" laid out.
>
> Unless you 'scope the thing, you often don't know it's gone unstable,
> other than some passive parts sometimes cook for no obvious reason.
> (That R49 for example!? See Mike's comment in another mail.)
>
> It is also not uncommon, when modern transistors are used to replace
> older failed parts (that are not available any more) and the new
> device has "a lot" more gain at HF than the originals, that regulator
> or other control loops suddenly become "unruly" under some operating
> conditions.
>
> Sometimes a low value "Base Stopper" resistor (a few Ohms, or a
> ferrite bead) in series with the new device's Base connection can
> restore sanity!
>
> Take care.
>
> Dave B.
>
>
>
|
Cubdriver
Precaud
Harold Foster
Dave McGuire