Re: HP 8643A and Capacitors
We have sent this voltage drop problem on our ATE systems where there is plenty of power and current flying about - usually with Molex connectors yellowing due to contact oxidisation and heat discolouration as a result. Especially where the system is in a less than ideal environment on a busy factory floor where all manner of factors will cause the contact issues - heat and dust being the main culprits.
Sometimes a simple fix is to remove and reseat the connectors a few times and the wiping contact restores a good low ohmic connection. Other times it has needed a replacement umbilical cable which is a real PITA on a complex system having to unroute a thick cable and feed a new one into place. Then have the connectors recrimped / replaced back at the workshop....
Just my 2p worth. Nigel
Heat and oxidised pins are our eternal enemy. by banging a nail into a piece of wood...
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Show quoted text
On 8 Mar 2025, at 03:47, mux_folder2001 via < canthony15@...> wrote:
I spent a little time with the schematics and service manual. The service manual describes test 16 for the power supplies. It says that the supplies are checked only once at power up, not continuously. It also says that the supplies are checked on the IO board
so the motherboard connector is not a suspect in your case. The test says to measure the voltages on the IO board test points and, if all are OK, replace the IO board.
The schematic of the IO board shows a "diagnostics" analog mux which has selections for the various power supplies, some of which go through resistor dividers.
Tony
Yes, I have three of these, two of which I have recapped. One of them had a bad VCO which I was fortunate to be able to fix myself. I have had them apart many times now. I keep the various screws in marked envelopes to keep things sorted. I am very familiar
with the interconnects. Those wide connectors on the supply and filter boards have a very high retention force and are a bear to unplug.
I wish you luck tracking it down. My guess is that you have already fixed it.
Tony
The self-test code said it failed because there was less than 5 volt
(wherever it is testing). I checked the voltages at the Molex connector
going to the motherboard. It was 4.9-something, I don't remember which
side of that connector for sure. I think filter board side has the
exposed pins.
I assumed it was the power supply itself. But the power supply, removed
from the instrument and with a 2A load on the 5V output, measured 5.25
volts. The power supply appears to be OK. Nonetheless, with decades-old
electrolytics I replaced all of them in both supplies and I just
reverified their voltages are OK. I will not reinstall them until I
visually check the connectors for overheating.
At the power supply the 5V output is three Molex pins in parallel, the
ground return is four Molex pins in parallel. Those seven go via short
jumper cable with Molex connectors from power supply to filter board
with no exposed place to measure. Assuming I can reach both power supply
board and filter board I could measure the drop over those two
connectors and the jumper. Then again the drop at every place in the 5V
path where I can access two exposed places.
Nothing happens until I get the supplies reinstalled and that is going
to be a bear with all the Torx screws,
Bill
W7AAZ
On 3/7/2025 5:18 PM, mux_folder2001 via wrote:
> I thought you said you checked a TP at the output of the PS filter board where you saw the drop. The molex connector going to the motherboard is downstream of that. The connector from the main supply to the filter board would be more likely. Or did you measure
it on the IO board test point? Still, the motherboard connector would be a separate path.
>
> Tony
> AD0VC
> ________________________________
> From: [email protected] < [email protected]> on behalf of Bill Carver < bill@...>
> Sent: Friday, March 7, 2025 2:26 PM
> To: [email protected] < [email protected]>
> Subject: Re: [HP-Agilent-Keysight-equipment] HP 8643A and Capacitors
>
> Oh, and yes they are tinned pins. Grrrr. When I was designing things the
> purchasing department gave me hell about it, but I insisted that all the
> 0.025" pins HAD to be gold flashed.
>
> On 3/7/2025 1:08 PM, Don Bitters via wrote:
>> Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage
drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work,
or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
>> Don Bitters
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
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Re: HP 8643A and Capacitors
I spent a little time with the schematics and service manual. The service manual describes test 16 for the power supplies. It says that the supplies are checked only once at power up, not continuously. It also says that the supplies are checked on the IO board
so the motherboard connector is not a suspect in your case. The test says to measure the voltages on the IO board test points and, if all are OK, replace the IO board.
The schematic of the IO board shows a "diagnostics" analog mux which has selections for the various power supplies, some of which go through resistor dividers.
Tony
toggle quoted message
Show quoted text
Yes, I have three of these, two of which I have recapped. One of them had a bad VCO which I was fortunate to be able to fix myself. I have had them apart many times now. I keep the various screws in marked envelopes to keep things sorted. I am very familiar
with the interconnects. Those wide connectors on the supply and filter boards have a very high retention force and are a bear to unplug.
I wish you luck tracking it down. My guess is that you have already fixed it.
Tony
The self-test code said it failed because there was less than 5 volt
(wherever it is testing). I checked the voltages at the Molex connector
going to the motherboard. It was 4.9-something, I don't remember which
side of that connector for sure. I think filter board side has the
exposed pins.
I assumed it was the power supply itself. But the power supply, removed
from the instrument and with a 2A load on the 5V output, measured 5.25
volts. The power supply appears to be OK. Nonetheless, with decades-old
electrolytics I replaced all of them in both supplies and I just
reverified their voltages are OK. I will not reinstall them until I
visually check the connectors for overheating.
At the power supply the 5V output is three Molex pins in parallel, the
ground return is four Molex pins in parallel. Those seven go via short
jumper cable with Molex connectors from power supply to filter board
with no exposed place to measure. Assuming I can reach both power supply
board and filter board I could measure the drop over those two
connectors and the jumper. Then again the drop at every place in the 5V
path where I can access two exposed places.
Nothing happens until I get the supplies reinstalled and that is going
to be a bear with all the Torx screws,
Bill
W7AAZ
On 3/7/2025 5:18 PM, mux_folder2001 via groups.io wrote:
> I thought you said you checked a TP at the output of the PS filter board where you saw the drop. The molex connector going to the motherboard is downstream of that. The connector from the main supply to the filter board would be more likely. Or did you measure
it on the IO board test point? Still, the motherboard connector would be a separate path.
>
> Tony
> AD0VC
> ________________________________
> From: [email protected] < [email protected]> on behalf of Bill Carver <bill@...>
> Sent: Friday, March 7, 2025 2:26 PM
> To: [email protected] < [email protected]>
> Subject: Re: [HP-Agilent-Keysight-equipment] HP 8643A and Capacitors
>
> Oh, and yes they are tinned pins. Grrrr. When I was designing things the
> purchasing department gave me hell about it, but I insisted that all the
> 0.025" pins HAD to be gold flashed.
>
> On 3/7/2025 1:08 PM, Don Bitters via groups.io wrote:
>> Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage
drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work,
or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
>> Don Bitters
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
|
I replaced the bench unit with a spare which I had in a test setup that isn't being used at the moment.? Doing some quick checks revealed when switched to the front jacks resistance would vary from 5 to 2 k ohms with a shorting plug!? Oh no!? I then took the second spare out of the test setup and put that on my bench. It runs perfectly.
I opened the one with high resistance and got some De-Oxit into that switch which immediately fixed the problem.? It now reads 2 milliohms with a shorting plug (dual banana with a piece of wire).? Ok so now I am back to two working meters.
I opened the one with the DC issue and see a COTO relay.? I hope it isn't that.? Also the display has gotten rather dim from many years of being left on.? Pretty sur I have a new spare put away but I won't change it until I figure out what's wrong with the DC attenuator as I won't waste the new display if the problem is an unobtanium part.
Now I'll go find the schematic and service manual.
Peter
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On 3/5/2025 3:44 PM, Razvan Popescu via groups.io wrote: Hello Peter,
Try to run a Self Test and see if it passes it.
Could be anything but older 34401A have relay faults. The OMRON relays
can be found but not the COTO relay. Newer 34401A had a newer part
instead of the COTO one but from what I remember that is also unobtainable.
Regards,
Razvan
On 05/03/2025 21:35, Peter Gottlieb via groups.io wrote:
I have an Agilent 34401A which I've used at my bench for many years.
Today I went to measure a 12 volt battery and it just started clicking.
I tried it on a power supply and auto ranging works fine up to 12 volts
where it starts clicking about twice a second.? Trying manual range,
going over the 10 volt range shows exactly zero volts to any input.
I am guessing it tries autoranging higher, sees the zero, then tries to
go lower, then repeats.
This is only on DC volts.? AC volts and resistance (didn't check
current) are fine, for example I can plug the leads into an outlet and
it shows 120 VAC just fine.
Before I dig in, is anyone familiar with this fault?
Peter
|
Re: HP 8643A and Capacitors
Yes, I have three of these, two of which I have recapped. One of them had a bad VCO which I was fortunate to be able to fix myself. I have had them apart many times now. I keep the various screws in marked envelopes to keep things sorted. I am very familiar
with the interconnects. Those wide connectors on the supply and filter boards have a very high retention force and are a bear to unplug.
I wish you luck tracking it down. My guess is that you have already fixed it.
Tony
toggle quoted message
Show quoted text
The self-test code said it failed because there was less than 5 volt
(wherever it is testing). I checked the voltages at the Molex connector
going to the motherboard. It was 4.9-something, I don't remember which
side of that connector for sure. I think filter board side has the
exposed pins.
I assumed it was the power supply itself. But the power supply, removed
from the instrument and with a 2A load on the 5V output, measured 5.25
volts. The power supply appears to be OK. Nonetheless, with decades-old
electrolytics I replaced all of them in both supplies and I just
reverified their voltages are OK. I will not reinstall them until I
visually check the connectors for overheating.
At the power supply the 5V output is three Molex pins in parallel, the
ground return is four Molex pins in parallel. Those seven go via short
jumper cable with Molex connectors from power supply to filter board
with no exposed place to measure. Assuming I can reach both power supply
board and filter board I could measure the drop over those two
connectors and the jumper. Then again the drop at every place in the 5V
path where I can access two exposed places.
Nothing happens until I get the supplies reinstalled and that is going
to be a bear with all the Torx screws,
Bill
W7AAZ
On 3/7/2025 5:18 PM, mux_folder2001 via groups.io wrote:
> I thought you said you checked a TP at the output of the PS filter board where you saw the drop. The molex connector going to the motherboard is downstream of that. The connector from the main supply to the filter board would be more likely. Or did you measure
it on the IO board test point? Still, the motherboard connector would be a separate path.
>
> Tony
> AD0VC
> ________________________________
> From: [email protected] < [email protected]> on behalf of Bill Carver <bill@...>
> Sent: Friday, March 7, 2025 2:26 PM
> To: [email protected] < [email protected]>
> Subject: Re: [HP-Agilent-Keysight-equipment] HP 8643A and Capacitors
>
> Oh, and yes they are tinned pins. Grrrr. When I was designing things the
> purchasing department gave me hell about it, but I insisted that all the
> 0.025" pins HAD to be gold flashed.
>
> On 3/7/2025 1:08 PM, Don Bitters via groups.io wrote:
>> Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage
drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work,
or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
>> Don Bitters
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
|
Re: HP 8643A and Capacitors
The self-test code said it failed because there was less than 5 volt (wherever it is testing). I checked the voltages at the Molex connector going to the motherboard. It was 4.9-something, I don't remember which side of that connector for sure. I think filter board side has the exposed pins.
I assumed it was the power supply itself. But the power supply, removed from the instrument and with a 2A load on the 5V output, measured 5.25 volts. The power supply appears to be OK. Nonetheless, with decades-old electrolytics I replaced all of them in both supplies and I just reverified their voltages are OK. I will not reinstall them until I visually check the connectors for overheating.
At the power supply the 5V output is three Molex pins in parallel, the ground return is four Molex pins in parallel. Those seven go via short jumper cable with Molex connectors from power supply to filter board with no exposed place to measure. Assuming I can reach both power supply board and filter board I could measure the drop over those two connectors and the jumper. Then again the drop at every place in the 5V path where I can access two exposed places.
Nothing happens until I get the supplies reinstalled and that is going to be a bear with all the Torx screws,
Bill
W7AAZ
toggle quoted message
Show quoted text
On 3/7/2025 5:18 PM, mux_folder2001 via groups.io wrote: I thought you said you checked a TP at the output of the PS filter board where you saw the drop. The molex connector going to the motherboard is downstream of that. The connector from the main supply to the filter board would be more likely. Or did you measure it on the IO board test point? Still, the motherboard connector would be a separate path.
Tony
AD0VC
________________________________
From: [email protected] <[email protected]> on behalf of Bill Carver <bill@...>
Sent: Friday, March 7, 2025 2:26 PM
To: [email protected] <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8643A and Capacitors
Oh, and yes they are tinned pins. Grrrr. When I was designing things the
purchasing department gave me hell about it, but I insisted that all the
0.025" pins HAD to be gold flashed.
On 3/7/2025 1:08 PM, Don Bitters via groups.io wrote:
Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work, or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
Don Bitters
|
Re: I need a new/used lab computer
I agree with the pain of commissioning a new computer. I have 30 years of past work, along with all the support applications (compilers, specialized IDEs, etc.), along with all the data, documentation, and such like. Hard drives (and now SSDs) have kept pace with my work, so I keep everything on line - about 3TB worth. Anything other than Windows is not possible - too many specialized and proprietary tools.
?
So when I get a new laptop, every 5 years or so, the first thing I do is put in the largest SSD that will fit, then copy everything across (about 20 hours at present). Then I spend the next several days installing all the tools, configuring everything, setting up all my preferences and shortcuts, network shares, etc. I hate the process, which is why I don't do it very often. I keep thinking of automating parts of it, but in many cases I can't figure out a way to do so.
~~
Mark
|
Re: I need a new/used lab computer
Jim, you should also check the computer salvage/resellers for motherbrds, memory, power supplies, etc. A lot of it is fairly inexpensive.
Don Bitters
|
Re: HP 8643A and Capacitors
I thought you said you checked a TP at the output of the PS filter board where you saw the drop. The molex connector going to the motherboard is downstream of that. The connector from the main supply to the filter board would be more likely. Or did you measure
it on the IO board test point? Still, the motherboard connector would be a separate path.
Tony
AD0VC
toggle quoted message
Show quoted text
Oh, and yes they are tinned pins. Grrrr. When I was designing things the
purchasing department gave me hell about it, but I insisted that all the
0.025" pins HAD to be gold flashed.
On 3/7/2025 1:08 PM, Don Bitters via groups.io wrote:
> Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage
drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work,
or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
> Don Bitters
>
>
>
>
>
|
HP/ Agilent catalogs and some Anritsu too!
I have:
?
1975
1977
1990
1993
1994
1995
1996
1997
1998
1999
2000 2x
2001 2x
2005
?
Anritsu
1998
2000
2001
?
You may pick them up in San Mateo, CA. No shipping. All one lot for free, BUT you must take them all.
?
Cheers
John Pease
?
|
Re: I need a new/used lab computer
If you looking for the quickest way to get back running, it's going to be to change the caps in the power supply and motherboard. It shouldn't take more than a couple of hours of work to change them with a vacuum solder sucker tool, and a hot air gun. I always pre-heat the area with the hot air, then use the vacuum solder sucker to just give it the final bit of heat to melt the solder and vacuum out the holes.
That's going to be heaps faster than getting a new machine, and re-installing all the software from scratch - especially windows - it takes forever to install and update and remember all the little tweaks you had to make along the way. If it was linux, that'd be a different story - usually installing takes about 5 minutes, updating to the latest packages online another 5 or 10, and you're pretty much ready to go. With windows, it's usually hours and hours, to days, depending on how you do it.
Well, yes, I probably could try to fix the old machine, but the limiting factor is time.? If you're retired, and I'm not, that may make sense.? No rabbit holes here, thank you very much!? And there are of course many that one could jump down in this situation.? I just need something quick and dirty.
Regarding OSs, I'm running Win 10 on this Dell all-in-one I'm writing this on, just got forcibly updated to Win 11 from Win 10 recently on my work laptop computer, and as I said originally, ran Win 7 installed in place of Vista on the now-defunct lab PC.? I've used Linux before, several years ago after a friend warned me about the danger of going online with a non-longer-supported OS like Win7 and turned me on to wubi.exe (dead simple Windows UBuntu Installer) so I was happily using Ubuntu Linux online and dual-booted to Win 7 for everything else, until one day Linux wouldn't boot.? Alas, I was unable to find wubi.exe online, and that was the end of my using Linux.? Someday I'll get back into it.? Yet another rabbit hole...
The quickest, easiest way to get back to a computer hosting the GPIB card and connecting to my cheapo USB microscope and Leo Bodnar GPSDO and to the Internet will win the day.
Thanks, everybody.
Jim
On Friday, March 7, 2025 at 02:25:26 PM CST, Adrian Godwin via <artgodwin= [email protected]> wrote:
I'm not a windows fan, but a while back got a tiny machine with windows 8 on it. It felt like using a phone as a computer. It updated to 10 (painfully, it didn't really have enough free space to do it properly) and is still horrible to use. I do have an alternate boot to win 7 on my linux laptop which I use occasionally for some proprietary config tool etc.?
But recently that was happening too often so I grabbed a cheap pc (second hand NUC 7i7 for ?70 ish) and it came with W11, no option.?
To be honest, I find it more usable than anything since W7. I think they might have walked back some of the worst errors of the last few years. It's still frustrating and naggy compared with debian but it's not quite so horrible.
?
Now I might be missing some as-yet unencountered part of the W11 experience which will drive me to distraction, but at this point I'm thinking it's not as bad as painted. Especially compared with 10. Is what does it do badly ? So far I've avoided registering it as I don't see any point but it is slowly putting in uncustomisable and unpleasant behaviour so apparently it's built to annoy. Does the level of intrusive adverts eventually grow to the point where it's unusable ?
?
|
Re: Looking for info on HP 10534C RF mixer component
Hi Ed, just found this old message. Do You have a HP10543C left ? I am searching for on for a repair of a HP8660c.
best regards, Olaf
|
The prohibition on wooden stuff is likely due in part to things
like the emerald ash borer which has caused immense damage to our
forests here in Michigan and likely elsewhere.? It supposedly came
in on a wooden shipping pallet which went to an automotive plant
near Detroit from a supplier in China.? A few years ago I had a
bunch of machines and large automotive tools and fixtures built in
Germany and Switzerland and shipped to South Carolina.? Like
everything else automotive time was of the essence but after the
machines etc. were complete and ready to be packed, there were
another couple of weeks of delays.? The builders had to wait for
specially treated and certified lumber to make the skids, crates
etc to allow for shipment to the US.? Even though the lumber was
from the shipping countries it was something like 10X the cost of
ordinary lumber!
Jack
On 3/6/2025 5:32 AM, Gabor Szucs via
groups.io wrote:
toggle quoted message
Show quoted text
That sounds quite bothersome! I'm under the
impression that a lot of the documentation/declaration
requirements depend on the carrier and service you're using and
generally, more established shipping companies seem to be able
to abstract the process a lot (although I can't say with
confidence that it's the same in the UK, especially
post-brexit). In general, package forwarders in the US only
require a short abbreviated "laymen's terms" description of the
contents that they don't seem to challenge in any way at all
(I've brought over instruments, LA and scope blades for the
16700 mainframe, consumer and industrial electronics like servo
drives and motors, teach pendants for robots etc., mostly
multiple packages consolidated into a single shipment).
Depending on the arrangement, duties and VAT was either billed
and paid for when placing the shipping order _or_ I got notified
by mail with the instructions when the goods reached the
country, then after I paid the duties, it cleared customs and it
was on its way to me.
Gabor
Some observations from the UK. TL;DR: fleabay's GSP
is wonderful, much better for me than my shipping my
sales directly.
When I've bought something direct from the orient,
e.g. a BusPirate5 or Digilent Analog Discovery, the
courier won't deliver it to me until I pay them
20%VAT/import duties plus ?20 admin fee. Those often
make it better to buy from local importers.
Import/export regulations hit more than
"electronics". Somebody in the USA put one of my ~100yo
Fuller calculators in their fleabay basket, but fleabay
wouldn't let them buy it. The reason is unclear, but is
probably that I had stated it was made of wood and
metal. Apparently the US prohibits imports of wood. I'm
glad fleabay prevented that sale, because if
fleabay's GSP shippers or US import agencies had
detected wood, it would probably have been summarily
destroyed without returning it to me. Guess who would
have lost out.
As for batteries, it seems that batteries which are
an integral part of the equipment don't provoke the
shipping immune response. Caveat: I haven't looked at
shipping equipment with "modern" lithium batteries, nor
recently shipped battery powered equipment overseas, nor
"naked" spare batteries.
As with any tree-shaped classification scheme (e.g.
Dewey Decimal for books), selecting the customs code is
not only
arbitrarily complex but also ambiguous and ever
changing. ISTR some types of fast Tek scopes with MCP
CRTs were classified differently for export purposes:
2465 OK, 2467 sometimes not OK. For the UK, the
anti-insomnia "medication" is?
?
For "oscilloscope" that leads to
and if you look down several pages you find imports
require 20% VAT and in some cases 35% retaliatory
duties. Getting those ever-changing duties correct is
something that will require vast numbers of customs
agents and border checks and/or couriers that act
conservatively because they don't want to jeopardise
their standing with governments. Wonderful, just
wonderful.
No doubt other countries have similar tools.
|
Re: HP859x Power Supply Schematics
Wow Chris! That must have been a lot of work! Hat off to your efforts!
My 8595E is happy, no PSU issues, but I saved your docs regardless, "you never know".
Many thanks,
Wilko
|
Re: HP 8643A and Capacitors
On 3/7/25 16:26, Bill Carver wrote: Oh, and yes they are tinned pins. Grrrr. When I was designing things the purchasing department gave me hell about it, but I insisted that all the 0.025" pins HAD to be gold flashed. Ugh, the number of times that has happened to me. It's one of the reasons I left corporate work years ago and vowed never to return. They take a good design with carefully-chosen components and send it to "cost engineering"...Reliable gold pins turn into cheap tinned ones causing overheating connectors, nice low-ESR capacitors get turned into cheap garbage causing switching regulators to not work, etc...then my design work gets maligned as a result! Suits. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
|
Re: HP 8643A and Capacitors
Oh, and yes they are tinned pins. Grrrr. When I was designing things the purchasing department gave me hell about it, but I insisted that all the 0.025" pins HAD to be gold flashed.
toggle quoted message
Show quoted text
On 3/7/2025 1:08 PM, Don Bitters via groups.io wrote: Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work, or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
Don Bitters
|
Re: HP 8643A and Capacitors
TU Don. I don't remember seeing browning on the white connector body but I'll take a careful look. It "feels" like it has to be something bizarre like that!
toggle quoted message
Show quoted text
On 3/7/2025 1:08 PM, Don Bitters via groups.io wrote: Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work, or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
Don Bitters
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Re: I need a new/used lab computer
This thread reminds me I have two old Dell mini-cabs running Win2k I got specifically to run MAME on for arcade cabinets.? And a few old laptops I have been holding onto for a lab machine that is more or less disposable in case of high voltage, metal flakes, etc kill it...? The problem will be remembering passwords to get data off of them when I get around to cleaning them up!
On 2025-03-07 3:40 PM, Jim Ford via wrote:
> The quickest, easiest way to get back to a computer hosting the GPIB
> card and connecting to my cheapo USB microscope and Leo Bodnar GPSDO
> and to the Internet will win the day.
If your software can use USB/serial or Telnet to access the data, my
KISS-488 offers a whole lot of OS-agnostic and platform-agnostic ways to
access GPIB.
Steve Hendrix
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Re: I need a new/used lab computer
On 2025-03-07 3:40 PM, Jim Ford via groups.io wrote: The quickest, easiest way to get back to a computer hosting the GPIB card and connecting to my cheapo USB microscope and Leo Bodnar GPSDO and to the Internet will win the day. If your software can use USB/serial or Telnet to access the data, my KISS-488 offers a whole lot of OS-agnostic and platform-agnostic ways to access GPIB. www.hxengineering.com Steve Hendrix
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Re: HP 8643A and Capacitors
Some HP gear used molex connectors for power to the motherboard. It is not uncommon for the?higher current pins to show a brown heated condition. Easily proven by simply bypassing?the pin with a big jumper. (Easier said than done) If that clears the issue you know whats wrong. Good luck Paul WB8TSL
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Re: I need a new/used lab computer
Well, yes, I probably could try to fix the old machine, but the limiting factor is time.? If you're retired, and I'm not, that may make sense.? No rabbit holes here, thank you very much!? And there are of course many that one could jump down in this situation.? I just need something quick and dirty.
Regarding OSs, I'm running Win 10 on this Dell all-in-one I'm writing this on, just got forcibly updated to Win 11 from Win 10 recently on my work laptop computer, and as I said originally, ran Win 7 installed in place of Vista on the now-defunct lab PC.? I've used Linux before, several years ago after a friend warned me about the danger of going online with a non-longer-supported OS like Win7 and turned me on to wubi.exe (dead simple Windows UBuntu Installer) so I was happily using Ubuntu Linux online and dual-booted to Win 7 for everything else, until one day Linux wouldn't boot.? Alas, I was unable to find wubi.exe online, and that was the end of my using Linux.? Someday I'll get back into it.? Yet another rabbit hole...
The quickest, easiest way to get back to a computer hosting the GPIB card and connecting to my cheapo USB microscope and Leo Bodnar GPSDO and to the Internet will win the day.
Thanks, everybody.
Jim
On Friday, March 7, 2025 at 02:25:26 PM CST, Adrian Godwin via groups.io <artgodwin@...> wrote:
I'm not a windows fan, but a while back got a tiny machine with windows 8 on it. It felt like using a phone as a computer. It updated to 10 (painfully, it didn't really have enough free space to do it properly) and is still horrible to use. I do have an alternate boot to win 7 on my linux laptop which I use occasionally for some proprietary config tool etc.?
But recently that was happening too often so I grabbed a cheap pc (second hand NUC 7i7 for ?70 ish) and it came with W11, no option.?
To be honest, I find it more usable than anything since W7. I think they might have walked back some of the worst errors of the last few years. It's still frustrating and naggy compared with debian but it's not quite so horrible.
?
Now I might be missing some as-yet unencountered part of the W11 experience which will drive me to distraction, but at this point I'm thinking it's not as bad as painted. Especially compared with 10. Is what does it do badly ? So far I've avoided registering it as I don't see any point but it is slowly putting in uncustomisable and unpleasant behaviour so apparently it's built to annoy. Does the level of intrusive adverts eventually grow to the point where it's unusable ?
?
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Bill Carver
Dave McGuire
Nick Andrews