Re: HP34702A Ohms converter issues
Alex,
At first I thought that "halo" you refer to was just the way the shadows appear in the photo but the fact it is rounded on the left and right puzzles me.? Could be moisture.? The scratch or crack is in the front panel plastic lens that guards the LCD and not the LDC itself.? Looks like the meter has had a rough life and will take a lot to clean it up.? The big question is if it has been sitting out in the rain or taken a bath.? ?I know the seller?? and they move large volumes or equipment thru EBAY.? I have purchased much from them in the past and they are good sellers and try to accommodate buyers.? I do not think they are trying to hide anything. The looks of the photos tells me the meter came in from a large equipment auction sale given the way the power cord in taped up to the meter and marked on top with words:ACOUSTIC".? They probably do not want to take the time to powered up with the way things are taped up because it is too much bother for them to do so and are just passing it thru the way they received it and listed it cheap.? Just a guess.? The shipping cost at $22.10 is very reasonable and low for that instrument compared to what others usually charge.? My experience with that company is they do not gouge a customer on shipping and handling.
Make them and offer of $27 and send them a short pleasant note along with the offer.? ?Even at what they have it listed at would be fair for me to purchase but I have the resources and parts to bring it back to life that others do not.? The cleanup time to refurbish would be a huge hurdle for me to get over unless I really could use it and need it.? Which I do not.? ?Getting the label stickum and glue off the clam shell case is a real pain in the ass since the plastic covers are not smooth but have texture.
Good luck? - let me k now what you decide.
George
George
?
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Re: Strange spurious in 8568B
Does it go away if you reduce the resolution bandwidth to 1kHz or less?
Vladan
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Re: Looking for silicone HV potting goop
Some years ago I potted modules using GE Silicones (now Momentive Performance Materials) RTV615, available from Newark Electronics.
I had to un-pot the modules, make repairs and then re-pot them.? These were low not high voltage but with proper spacing and layout it should work.
This is a two-component material (10:1) which cures at room temperature to a moderately soft clear rubber.? A heat lamp can speed it up.? It is removable with a pick & tweezers.? (I use old chopstix sharpened to a point or chisel to avoid scratches.) A vacuum pump is really handy to get the air bubbles from mixing out.
From MDS: 60 - 100 % polyvinylsiloxane, 10 - 30 % polyalkylalkenylsiloxane
From datasheet:?? (1.9 mm thick sample)
Dielectric Strength, kv/mm (v/mil)??? 19.7 (500)
Dielectric Constant @ 1000 Hz??? ??? 2.7
Dissipation Factor @ 1000 Hz??? ??? 0.0006
Volume Resistivity, ohm-cm??? ??? 1.8 x 10E15
Newark sells this as a one pound kit, now for about $230.? (I seem to remember paying less than half that when I bought it.)? At the time I did a lot of looking for smallest quantities and lowest prices.? The premium price is for a clear material.? The white RTV-11 costs less than half as much.
Hope this helps.
Marshall Stevens
On Thu, Feb 14, 2019 at 3:34 PM Ed Breya via Groups.Io <edbreya= [email protected]> wrote: I've been designing up some HV testing circuits, and plan to pot the parts that run up to 30 kV. I'm reusing a couple of plastic HV CRT supply boxes salvaged from old HP scopes, such as the 180. The anode multiplier section in these were potted with a beautiful clear silicone goop that was easy to remove, and in like-new condition after fifty years. I'd like to find the same kind of stuff for this new use. Does anyone know exactly what HP used for these back then?
I definitely want clear silicone, electrical/HV grade. I want it clear because I like being able to see into the guts during potting and operation, and I may have an LED buried inside to indicate current flow. I want it silicone so it can be torn out easily for design modifications - and clearness helps a lot with this.
Online searching seems to indicate RTV-11 is probably about right, if it's available in clear. Any other ideas? I see that the RTVs are pretty spendy nowadays, so I'm looking for reasonable prices on small quantity units, say around 250 ml. The volume to be filled is about 5-6 in^3.
PS: An interesting thing I noticed in searching, was some talk about making cheap (and sort of clear) electrical potting compound by mixing hot melt glue sticks into molten parrafin. Has anyone heard of this, or know more info? Something like this may be OK if it's fairly clear or translucent, and can be blended to be pliable enough for easy removal. Flammability isn't an issue here, since the power levels are low, and it's only for temporary testing hookups.
Ed
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To jump in....did someone found a function of 8 dip switches on the motherboard?? Milan
On Sat, 16 Feb 2019, 17:56 Tom B, < tbryan@...> wrote: I have looked at quite a few different models.? The AP and DP models are
a different animal from the A and B models.? The A models and some of
the earlier B models have the earlier motherboard.? Analog and digital
versions all have the same motherboards. ? Most? of the difference is
that later ones have provision for 2 different models of LCD display.? I
think this was done for maintenance.? If you hook up the wrong display
in the early motherboard you will blow a transistor in the regulator for
the contrast control and the display will not work.? Later motherboards
had a dip switch to set which display you are using.
I think A and B models should be able to be changed to increase the
frequency range, but I am not sure if the instructions will work on the
early and late motherboards.? I have not tried it yet.? The ESG3000A is
one of the earliest models.
Tom Bryan
On 2/16/2019 4:45 AM, Peter wrote:
> E4432B/33B ("D" Model) and E4436B/37B ("DP" Model) have different
> hardware inside, You can compare it in the service manual PDF.
> The DP have a YIG oscillator, except for the reference board, all
> boards are different.
>
> And You can not make an "A" to a "B" instrument. Just to open up the
> upper frequency limit.
>
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Strange spurious in 8568B
Hi,
just noticed my SA has a spuriuos which is independant of carrier frequency. Always at -10,7MHz and -63dB down. Tested with tree different signal generators - same result.
What makes me wonder, that it is not symmetrical to carrier frequency. Any ideas?
Regards Ernst
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I have looked at quite a few different models.? The AP and DP models are a different animal from the A and B models.? The A models and some of the earlier B models have the earlier motherboard.? Analog and digital versions all have the same motherboards. ? Most? of the difference is that later ones have provision for 2 different models of LCD display.? I think this was done for maintenance.? If you hook up the wrong display in the early motherboard you will blow a transistor in the regulator for the contrast control and the display will not work.? Later motherboards had a dip switch to set which display you are using.
I think A and B models should be able to be changed to increase the frequency range, but I am not sure if the instructions will work on the early and late motherboards.? I have not tried it yet.? The ESG3000A is one of the earliest models.
Tom Bryan
toggle quoted message
Show quoted text
On 2/16/2019 4:45 AM, Peter wrote: E4432B/33B ("D" Model) and E4436B/37B ("DP" Model) have different hardware inside, You can compare it in the service manual PDF.
The DP have a YIG oscillator, except for the reference board, all boards are different.
And You can not make an "A" to a "B" instrument. Just to open up the upper frequency limit.
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Re: HP34702A Ohms converter issues
George, thanks so much for the input and offers for spare parts. The relays on my 3478A are not really that loud, its just that I have a good hearing so even tough the clicks are very faint, I can still easily hear them in a quiet environment. My SN is 2520A19233, not sure that would qualify it as a later production unit.
I was reviewing again the LCD situation on the 3468A I have been watching and it turns out there is also a crack on the transparent plastic in front of the display. So maybe the LCD could be cracked as well and is going bad? If you could take a look at item 202465707356 on ebay, otherwise I'd be happy to post a picture of the dark halo on the LCD on my server. https://www.ebay.com/itm/202465707356
BTW I also have a HP41CX and one of the reasons of getting a 3468A with HP-IL was to maybe eventually experiment a bit with it, mostly just for the fun of it and as a practical learning experience to understand a bit more about this obviously now phased out comm protocol.
Thanks again.
Alex
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Re: HP34702A Ohms converter issues
Alex,
I would not worry about the halo growing.? Sometimes this can be due to uneven pressure on the glass. The LCDs were the weakest link on this product.? This display technology was first implemented by HP on the 3468/78 along with the HP41C calculator.? The displays were co-developed by the Corvallis group and the Loveland group for use in the instruments and calculators.? We recognized that such was essential for longer battery life on the 3468.? I have a large collection of replacement parts and could help you out if it becomes problematic.? Best to link a picture to me and I will look it over.? It might just have always been there -- sometimes the edge glue migrated in. If it ends up being a display driver, the same is used on the 3488A - next product I was assigned to after the 3468/78.
The reed relays on the early units were loud but very quiet on later models were you cannot hear them.? They were extensively tested and qualified for millions of cycles.? You should not worry about wearing them out. The manufacturer is CotoCoil (4 red relays under the analog shield) having two different part numbers.? The odd man out is a special low thermal relay used to connect the meter terminal inputs to the DC front end.? Again, I have plenty of replacement parts should you start to suspect unstable thermals due to contact degradation.? If you want to minimize the self test ranging put a short across the inputs at power up.?
I always keep a 10K across the inputs of my 3468/3478 meters using a feed thru banana jack with test leads connected. Most of the time I use the meter to check battery voltages and for continuity so the loading is not a problem but actually good when testing rechargeable AA batteries.? I remove the 10K for other measurements.? My meters are never turned off for the longer the voltage references burn, the more stable they become.? Three of my units have been on constantly on for 35 years now.
George Hnatiuk? ? ? ? ? ? ? ? ?Feb 16, 2018? 9:45am
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Thanks Yves. ?I have that high level service manual. ?I picked up the module a while back at a swap meet with the thought of repurposing it in part to build up a tracking generator for my SA. ?Rather than reverse engineering it piece by piece, am looking for the schematic. ?One of those ¡°on hold¡± projects I figured I¡¯d pull of the back shelf.
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E4432B/33B ("D" Model) and E4436B/37B ("DP" Model) have different hardware inside, You can compare it in the service manual PDF.
The DP have a YIG oscillator, except for the reference board, all boards are different.
And You can not make an "A" to a "B" instrument. Just to open up the upper frequency limit.
Peter
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Looking for clip of manual N9320A spectrum analyzer
any ideas where to find ?
helge
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Re: HP34702A Ohms converter issues
Hi George,
Small world, nice getting the chance to having access to "the source" on the 3478A DMM. I currently do have one (surplus purchase on ebay a couple of years ago) 3478A on my bench, and first order was of course to replace the still original Lithium cell to retain the cal constants. I also have 3x HP974A and one HP973A handhelds, which I think are terrific DMMs as well, even tough some might not consider them as "real" HP units because they where manufactured in Japan by Jokogawa.
Oh and BTW my very first DMM when I was still in high school was a brand new out of the box HP3476A given to me as a gift, which of course back then was a huge improvement over the average 20kohm/volt cheapo analog multimeter. I probably went through at least 3-4 of those in my first years of hobby electronics, mostly burning up various ohms ranges while trying to measure the AC line. Ooops... oh well just buy the next one.
Anyway, you are probably the perfect person to ask a question regarding the 3478A which seems to use (Reed?) relays to switch input ranges. I can always hear them clicking away when the instrument is initially turned on and usually autoranging up/down between the two lower DC volts ranges with open input test leads. I always try to switch to manual range to stop the relays from clicking, as I can clearly hear them and it bothers me that they might wear out much sooner. So my questions is in regards to the life expectancy of these relays, and any possible effect on them by leaving the instrument on autorange while idle and the relays clicking like that.
Also might be adding soon a 3468A to the stable, and was very close to buy one dirty sad looking one but otherwise fully operational unit (except for a broken handle) for $30 but then I noticed on the item pictures a very distinct dark halo around the edges of the LCD screen specially towards the left/right sides (the seller confirmed it), so not sure if that would be cause for concern as all digits seem still to be fully readable. But it might be a problem if this halo would advance further towards the actual readout area. Any thoughts on that?
Thanks in advance.
Alex
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Re: HP34702A Ohms converter issues
?
Don:
?
Reading this email lead me to ask you if you know if any of the
Doumentation on Service/Repair was saved on the 3810A Total Station??? I
have one and would like to find info in case mine "goes west"!!? I read the
June, 1980 HP Journal on the unit and got a kick out how they tested it in the
Shop,? having you confirm it makes even sweeter!!!
?
I have re-built that battery pack and am looking for the Lens to reduce the
return level at short ranges, but no luck yet.? I did pick up the correct
Triple Prism set for it!!
?
Nice to hear from someone who has worked/designed the Eqipment we all Love
and Charish!!
?
Chuck McClurg
Carson City
Nevada
?
----- Original Message -----
Sent: Friday, February 15, 2019 5:59
PM
Subject: Re:
[HP-Agilent-Keysight-equipment] HP34702A Ohms converter issues
Sorry,
I just assumed that since the 3468/78A/B's came out in the 80's,? I was a
young guy at that time and the design folk I encountered were older than I
was.? Hence the assumption was you were also retired? I had very
little contact with the HP Loveland folk, except for the DMI division - I
serviced the 3800, 3805, 3810, and 3820 for 2-3 yrs. before I shifted over to
the SA division products from Santa Rosa.? I really enjoyed hearing the
info discussed on the 34702A - I have 1 or 2 still.? I also serviced
3455's for about 9 yrs.? Don't have this one, but do have a 3456A, and
34401A's.? I will save up some cash and want to get a 3458A - the
ultimate DMM ever made.? The Datron's were good, but finicky and some
times tricky to use.? Their calibrators are pretty phenominal, but the
Flukes are easier to use and program.
I
think all of the HP, Agilent design engineers were truly at the top of their
game.? 98% of or products during the heydays were unique, durable, well
documented, and supportable.?
The
Yokohama products and German products often left you scratching your head,
until you got into the designer's head.? They also liked to create
unique, undocumented IC's and assemblies that are irreplaceable.- ie, 8112A's,
and 8116A,s each have 3? LSICs that can now only be gotten from
cannaballized units - they are prime failures in these units.?
My
best regards,
Don
Bitters -
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Re: HP34702A Ohms converter issues
Don,]
It was a shame the civil engineering division got canned.? The development lab for the distance meters was just over the cubical wall from my office and it was enjoyable to see the gal every day sitting up near the ceiling rafters calibrating the "Bear" with the movable optics on tracks shooting the lasers across the length of the building our labs were situated in.? That division got the ax around 1982 soon after John Young took over as CEO from Bill and Dave.
George
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Re: HP34702A Ohms converter issues
Don,
I joined the new product development lab in Loveland, Colorado Oct. 1978 after graduating university and assigned to the 3468/78 project just as it was being staffed. The project was fully staffed by the following summer.? Four of us on the design team of 7 was fresh out of university.? The 3468A/78A was released to production in summer of 1981.? In a normal career, I would be retired but my career has been and is anything but normal? :)
George
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Hi, you may download the service manual if you don¡¯t have it( 89430-90001) but unfortunately without schematics? I have a 89430A, I can do some tests on mine if it can help you. ? Yves ? ? De?: [email protected] <[email protected]> De la part de jeffpinsky@... via Groups.Io
·¡²Ô±¹´Ç²â¨¦?: 15 f¨¦vrier 2019 13:50
??: [email protected]
Objet?: [HP-Agilent-Keysight-equipment] HP-89430A schematics ? Does anyone have the schematics or CLIP for the A10 receiver module of the 89430A analyzer? ?Haven¡¯t been able to find that level of detail. ?Thanks
Jeff
WA2SCL
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Re: HP34702A Ohms converter issues
Sorry, I just assumed that since the 3468/78A/B's came out in the 80's,? I was a young guy at that time and the design folk I encountered were older than I was.? Hence the assumption was you were also retired? I had very little contact with the HP Loveland folk, except for the DMI division - I serviced the 3800, 3805, 3810, and 3820 for 2-3 yrs. before I shifted over to the SA division products from Santa Rosa.? I really enjoyed hearing the info discussed on the 34702A - I have 1 or 2 still.? I also serviced 3455's for about 9 yrs.? Don't have this one, but do have a 3456A, and 34401A's.? I will save up some cash and want to get a 3458A - the ultimate DMM ever made.? The Datron's were good, but finicky and some times tricky to use.? Their calibrators are pretty phenominal, but the Flukes are easier to use and program. I think all of the HP, Agilent design engineers were truly at the top of their game.? 98% of or products during the heydays were unique, durable, well documented, and supportable.?
The Yokohama products and German products often left you scratching your head, until you got into the designer's head.? They also liked to create unique, undocumented IC's and assemblies that are irreplaceable.- ie, 8112A's, and 8116A,s each have 3? LSICs that can now only be gotten from cannaballized units - they are prime failures in these units.?
My best regards, Don Bitters -
|
Re: Looking for silicone HV potting goop
I have used paraffin wax on high voltage/high impedance circuits to keep moisture away. I know there is special stuff for that as well (moisture, conformal coatings). You don't have to pot, just give a coating. It makes for easy repairs but is no good at high temperatures. PeterB?
On Fri, Feb 15, 2019 at 11:12 AM Chuck Harris < cfharris@...> wrote: A lot of potting is done with the same wax material that
is used in the medical industry for theraputic things.
It melts at a cozy temperature, and is quite flexible.
Same sort of stuff used for removal of body hair in barbaric
ways.
You could also simply use beeswax, and melt and pour it off
when you needed to do rework.? If you mix in paraffin, you
can achieve a mixture where mot much shrinkage happens when
the wax cools... about 70% beeswax seems best.
I use straight hotglue for some things.? I made an outdoor
photocell for the Army, and it was potted with straight clear
hot glue.? You can't remove it from pvc boxes, though as the
boxes will melt before the glue melts.
-Chuck Harris
Ed Breya via Groups.Io wrote:
> I've been designing up some HV testing circuits, and plan to pot the parts that run up to 30 kV. I'm reusing a couple of plastic HV CRT supply boxes salvaged from old HP scopes, such as the 180. The anode multiplier section in these were potted with a beautiful clear silicone goop that was easy to remove, and in like-new condition after fifty years. I'd like to find the same kind of stuff for this new use. Does anyone know exactly what HP used for these back then?
>
> I definitely want clear silicone, electrical/HV grade. I want it clear because I like being able to see into the guts during potting and operation, and I may have an LED buried inside to indicate current flow. I want it silicone so it can be torn out easily for design modifications - and clearness helps a lot with this.
>
> Online searching seems to indicate RTV-11 is probably about right, if it's available in clear. Any other ideas? I see that the RTVs are pretty spendy nowadays, so I'm looking for reasonable prices on small quantity units, say around 250 ml. The volume to be filled is about 5-6 in^3.
>
> PS: An interesting thing I noticed in searching, was some talk about making cheap (and sort of clear) electrical potting compound by mixing hot melt glue sticks into molten parrafin. Has anyone heard of this, or know more info? Something like this may be OK if it's fairly clear or translucent, and can be blended to be pliable enough for easy removal. Flammability isn't an issue here, since the power levels are low, and it's only for temporary testing hookups.
>
> Ed
|
My objective in doing equipment repairs always has been to make a printed circuit board repair invisible, in other words you couldn¡¯t tell where the repair had been done. After removing as much of the original solder and putting in a replacement part, the important thing to do is to quickly wipe off the flux with a brush and a solvent like pure alcohol, and then clean it off possibly with a Q-tip or cloth. I¡¯ve seen some factory repairs that were much sloppier than that and probably reduced the life of the equipment.
Stuart K6YAZ
Los Angeles, California
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Re: WANTED: Analyzer Cover Latches
Looks like you already got some on the way, but I think I ordered them from (then) Agilent when I got my 8594 a long time ago. I seem to remember them being slightly expensive, but not compared to the spectrum analyzer itself. The screws were separate, and outrageously expensive - I found some that fit in a junk box somewhere.
Now, in a few weeks I could probably make them myself!
On Thu, Feb 14, 2019 at 3:42 PM Colby Burkett < burkettc@...> wrote: These? ~37x18.5mm
Send me your address and I'll get them in post tomorrow.
On Sun, Feb 10, 2019, 10:45 AM Steve J. Noll, WA6EJO < sjnoll@...> wrote: I'm looking for a pair of the Catch Latches 5021-5483 that go on either side of a 8593E case. The cover latches hook on them. I have a cover from a 8920A that I think should fit but there's nothing on the 8593E case for it to hook on to. TNX, WA6EJO.
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