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Date
Re: HP83712B EPROM content

 

"tom_iphi via groups.io" <iphi@...> writes:

Hi,

does anyone happen to have the data of EPROMs U7 and U24 of the HP83712B?
I seem to have lost data...
ko4bb has


Not sure whether that's the same.
HP83712B EPROM content

 

Hi,
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does anyone happen to have the data of EPROMs U7 and U24 of the HP83712B?
I seem to have lost data...
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Tom
Re: HP 85047A test set on 8753A analyzer -- switch control board jumpers to retrofit for opt 009 (mechanical switch)

 

On Tue, 1 Apr 2025 at 03:06, David Feldman via <wb0gaz=[email protected]> wrote:
Working on a 85047A test set which needs to be retrofitted with mechanical switch 33311B,



Any suggestions at this point?


I have looked at the circuit diagram of the 85046A, and noticed a capacitor value changed between the mechanical and electronic relays. Could that be the problem??


Dave
Re: E5052A Power On Test (3.3V Bus Supply)

 

Appreciate the suggestion. I reinstalled the A3 and tried cycling all the PSU connectors, including the motherboard one. I also brushed a tiny dab of Deoxit D100 on each male pin and cycled the connectors a few times.
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Unfortunately, no changes.?
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I also checked all of the power supply test points that are made accessible. All of the voltages seemed present and at a reasonable level:
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One thing I observed on the back of the A3 board are the presence of red LED. These seem to be connected to different power rails on the back of the board.
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I noticed that 1 LED was very dim and the other was not lit. These are visible with the outer cover off, through the chassis air holes where the A3 is slotted.
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The 2 LEDs in question are the bottom most ones, which are connected to the 2 TO-220 voltage regulators U18 and U19.
Not sure what the "normal" condition should be; are both normally lit when no issues are present?
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U19 is an ON semi CS5208-1. Datasheet is as follows:
Compare to U18 which is an LT1085:
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The CS5208-1 is not available anymore, but the LT1085/1084 are. As far as I can tell, these are nearly identical regulators?
The CS5208 is rated to higher currents (6V, 9A) while the LT1085/4 is tolerant of higher voltages (30V, 3/5A). However, the pinout and output divider adjustment equations are identical?
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I can get the LT1084 on Digikey. Maybe its worth swapping both U18 and U19 out with new LT1084 and seeing if anything changes?
Re: Tricks and thoughts about the 3457A battery

 

Thanks, I will order a few pieces to have them just in case.

Best regards,
Razvan

On 01/04/2025 12:01, Joel Setton via groups.io wrote:
Hi Razvan,
I used a Radiospares 185-4654 socket, which sells for one Euro or so. It
turned out to be a no-brand Chinese import, you can find the same socket
on Epay or other sellers. I could not find this type of socket from
"premium" brands, like Keystone and others.
By the way, the same type of battery is sold as "ER14250" by some
vendors, and is available from some vendors with leads and a 2-pin
female connector. You may also want to investigate this type of solution.
Cheers,
Joel
Re: HP 53310A modulation domain analyzer memory upgrade

 

After a set from Aliexpress that didn't work, I got some from an eBay vendor I've found reliable (his stocks are all old, before the dodgy cloning started).?
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I don't remember exactly what I bought but he has and I'd expect them to be good.
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Re: HP3325A Trouble, Calibration FAIL 2 & 3

 

Hi all,
I spent some more hours with my 3325A.
I made a new effort and studied the service manual from scratch. The main trouble shooting flowchart directed me to group J, so I thoroughly examined everything around U28 to U40.
At least U39 was the culprit! ?It is another analog switch. 1826-0879, hard to find. My REV C Board has many can type opamps and ics. I found a replacement a DG301 from Harris or an TL460 from TI. But the pinout is different. I had to mount the TI reverse and soldered the pins in place.
Now it is working perfect again. I have to calibrate this nice generator, but this is not a big thing. A member here has sent me a detailed calibration guide.
Ralf
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Re: E5052A Power On Test (3.3V Bus Supply)

 

The first thing I recommend that you do is to look at all the PSU cables in the PSU area including the big multiwire one that loops back to the motherboard.
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As a first attempt, try partially removing each connector from its header and walk it up and down a few times on its header pins to try and remove any oxidation. Do this for all the connectors in this area including the big multi-way connector that loops back the CPU area. I think this one has lots of brown wires. Wiggle and walk them all in their pins and retry the unit. It could be that you have excess voltage drop in the connections to the A3DSP board.
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Re: HP6209B component location layout

 

Forgot to mention, I am thinking of leaving the 50K voltage adjustment pot in place as is, even tough already ordered a 100K replacement Bourns "Helipot".
Everything seems to work fine, and I can adjust output voltage from 0-320V no issues. Well, maybe I'll take another stab when it arrives.
Re: HP6209B component location layout

 

I poked around a bit further and discovered that the +43V reference supply that was reading low at 34.2V actually had 14V of ripple on it. After removing and checking C12 a 450uF 85V cap, it was reading 135nF. Replaced with 470uF 100V cap, and voltage came up to 43.4V. Then did the whole volt and current meter calibration, and the 12mA range was no longer pegging to the left, but now rather indicating about 4mA without any load.

Put a 5K 10T pot in parallel to the existing 30K R38 resistor and was able to zero the 12mA range without affecting the 120mA. The pot was reading 2.7K, which I then replaced with a fixed resistor and now the 12mA scale was almost zeroed, only a hair above zero, so left it there for now. It seems that the circuit really wants about 2.4K in parallel to R53 (30K with the 2.7K from the pot) to properly balance the bias on the 12mA scale, but until I can get the proper resistor did for now leave both the 30K and the newly added 2.7K in place.

Both current ranges now seem accurate (as much as that analog meter will allow). Tested the 120mA with a 2.5K 10W at 250V and meter showed 100mA right on the money, verified with by DMM also in circuit. Then put a 10mA load and the meter on 12mA scale was showing also almost right on the money.

Lesson learned, check the main caps first, you dummy.
Also checked C20 (25uF 475V) at the rear output and it read 26uF with 2.0 ohms ESR. Good enough.
The C14 main supply cap seems to be good as well, kind of a pain to remove and test, so just read the DC and AC voltage across it with DMM while output voltage was set to 320V. The cap had 334.5VDC and 0.477VAC ripple across it. With the output of the power supply still at 320V and no load, there was about 1mV of AC ripple (on the DMM), and with a 100mA load about the same amount of ripple.

I think that it can now be called good to go.

BTW needed to slightly adjust the meter mechanical zero so had to remove it, and then while trying to get it back in place was wondering who came up with that plastic mounting clip scheme. What a pain in the rear to make both sides click back in place.
Re: HP 85047A test set on 8753A analyzer -- switch control board jumpers to retrofit for opt 009 (mechanical switch)

 

I believe the control module (rear panel) has one or more abnormalities - I tried setting attenuator (stimulus>power>attenuator 1) and rather than adjusting the attenuator, the test set switched ports or had other abnormal responses depending on the selected attenuator value. This misbehavior occurred regardless of W1 and W2 jumper presence/absence.

Given this, my original posting about setting option 009 is incorrect as the test set is malfunctioning in other ways and will require repair, not just reconfiguration. (I re-routed cable back to my original test set and it continues to work normally, so the issue is in the test set under consideration.)

Dave
Re: odd HP83651A error

 

There is some information on the low band module A24 in here starting page 36:
I see now that this is a microcircuit and not repairable.
I suppose, in my low band module the oscillator has drifted over time such that it locks now to the wrong 100MHz harmonic.
A pitty, one would just have to re-tune the oscillator if it was possible.
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Does anybody know where I could obtain a replacement for the broken A24 low band module of my 83651A?
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Tom DG8SAQ
Re: HP 53310A modulation domain analyzer memory upgrade

 

Thanks Ozan..!
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Will report back here on the transition from SOJ to DIP for those that may follow...
Error 7301 on HP70820a

 

Dear friends, I ask you if possible to help me solve my problem: I have SA HP70000 and a HP70820a that worked perfectly.
At a certain point without having used it improperly an error occurred (7301 ch 1 up bus, wr addr: bit).
I ask you if anyone has info or has had the same problem.
I ask for your help in trying to solve it.
Thanks
Gianni
Re: Tricks and thoughts about the 3457A battery

 

On 3/31/25 22:12, Martin via groups.io wrote:
Or the other way round? Put the instrument on an isolation transformer.
I've got nice isolation transformers for sale if anyone needs one.
MGE Ultra Isolation 2.4 kVA and smaller.
Re: PN 1855-0064

 

Matched JFETs in TO-71, 6-pin packages are pricey.? Need to get a few with characteristics in the ballpark so I pulled a couple from a good meter and measured them.? ? ? ? ? ?
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making 8620C sweeper scales

 

Hi all,

Delurking to note that I took the liberty of uploading some additional files for DIY 8620C sweeper scales to this folder, which is hopefully okay:

/g/HP-Agilent-Keysight-equipment/files/All%20HP,%20Agilent%20and%20Keysight%20instruments%20in%20folders%20by%20part%20numbers/8000%20to%208999/8620/8620%20%20%20DIY%20Scales

I recently acquired 86240B and 86290B-H08 sweeper plugins, both missing scales. This was annoying enough that I designed a replacement blank scale in OpenSCAD for 3D printing. The STL file prints fine for me with PETG, though I had some warping problems that I think I fixed by adding internal braces. It may also require a lower bed temperature, but if the scale bows, it'll be super obvious.

I used LibreCAD to divide the lines, and added the text in OmniGraffle. I've printed a batch of these on Avery UltraDuty HGS Chemical Labels for laser printers, then cut them out using a steel straightedge and utility knife. Printing on plain paper and sticking them on with 3M 77 spray adhesive works just fine, and doesn't require sanding the scale beforehand. YMMV.

I've not found photos of the actual 86290B-H08 scales anywhere, so may not have the same major/minor ticks as the originals. Corrections welcome, but hopefully this is useful to someone.

Adam
KK7ASV
Re: Repair HP3455A Multimeter

 

Hi,
yesterday i got the Jfets from digikey, i replaced Q19,Q21,Q4 ,Q22 but the result is the same, still error 10. According to the flowchart the advice is to check Q4,Q19 and components around.
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There are many components around, so could anyone look at this part of the schematics and give an advice?
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May be U3??
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And I have a curious 8.75 V at pin 14 of U5, should be -24V, but not? in focus of cal test 10.? (I replaced already U5,U4,U6)
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Ralf
Re: Tricks and thoughts about the 3457A battery

 

Hello Greg,
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I took the option of powering the 3457A in the normal way, with an earth connection as usual. At the same time I floated the soldering iron by powering it from a car battery and a DC-to-AC converter (the type which is commonly used in campers and similar vehicles). Another option is to use line power and an isolation transformer, if you have one. A portable, battery-powered or soldering iron would work just as well.
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Cheers,
Joel
Re: Tricks and thoughts about the 3457A battery

 

Hello David,
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What you are suggesting is obviously a good solution. However, it is WAAAAAY above what my "hobby budget" can afford. To make matters worse, Keysight will not do any business with private individuals, at least in Europe. You'd have to find and alternative calibration lab, which would calibrate the meter but would not probably not replace the battery since HP does not document this replacement.
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Cheers,
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Joel
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