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Re: HP 141T Power Supply Help Needed
Good news on -100V fix. As I mentioned in message #146460 ( /g/HP-Agilent-Keysight-equipment/message/146460 ) swapped C&E explains the fault so it was the root cause of bad
By Ozan · #146475 ·
Re: OT MathCad 7 Professional
Well, it turns out, according to the Mathworks Website... it's at least 150.00 USD here. (There's taxes too.) I don't think Mathworks is trying to 'make' money off their "Home' or "Student'
By Roy Thistle · #146474 ·
Re: Question about cables and probes for hp 16715a.
I said: ...The 90-pin probing system used on more recent cards is NOT lossy with Z approx. 93 ohms. To be clear, what I mean is the tiny ribbon coax used in the 90-pin system has a characteristic
By Mark Litwack · #146473 ·
Re: Question about cables and probes for hp 16715a.
I appreciate that you want to make your own pod ends, and would encourage you. They can be difficult to find in sufficient quantity or at a reasonable price. I can see single sets of these - without
By Adrian Godwin · #146472 ·
Re: Question about cables and probes for hp 16715a.
The only place lossy cable is present is in the 4.5-foot coax ribbon cable going from the chassis to the pods. ?Earlier versions of this cable are woven, but they are still lossy. ?Its purpose is to
By Mark Litwack · #146471 ·
Re: Question about cables and probes for hp 16715a.
I seem to remember that the cable is nichrome, and about 200 ohms. IIRC about a 10K input impedance at the analyzer, and a 100K at the probe tip.? From what I remember, there's about a 7pf capacitor
By Harvey White · #146470 ·
Re: HP 141T Power Supply Help Needed
Finished that up. On the -100 I can adjust up to 96v, a little low but it is adjustable so I think I should come back to that later. On 248v I'm currently seeing 290v, and -12v I'm seeing -1.5v.
By Bill Berzinskas · #146469 ·
Re: HP 141T Power Supply Help Needed
Well, this is awkward. I had replaced both Diff Amp transistors with the same part number. I just found that this package is actually reverse from what i removed! using a dorky little heathkit
By Bill Berzinskas · #146468 ·
Re: 5342A: sometimes counts, sometimes not
Hello guys Yesterday I realized something else. I forgot to tell you that despite having had this unit for three years, I realized the other day that option 002 (amplitude measurement) is installed.
By RubenRubio · #146467 ·
Re: HP 141T Power Supply Help Needed
Also, don't forget about Gianni's HP e-book.? If I remember correctly, he goes into great detail about the 141T.? Here's the link.? They can be slow to download and I forget which section includes
By Frank Mashockie · #146466 ·
Re: Question about cables and probes for hp 16715a.
I believe the cable from 40-pin connector to tip moulding is actually twisted pair rather than coax. It certainly was in the burnt one I took apart. The tip moulding contained a ceramic hybrid circuit
By Adrian Godwin · #146465 ·
Re: HP 141T Power Supply Help Needed
Could very well be what's going here. Just another note on the diodes - in the case I mentioned with 182T I worked on, checking with a DMM diode test wasn't enough.? If it wasn't until I put it on a
By Frank Mashockie · #146464 ·
Re: Question about cables and probes for hp 16715a.
On 2024-08-29 06:05, Don't Know via groups.io wrote: > Hi all. I have two 16715a cards, with cables, but without pods with wires to connect to hooks. I would like to make them myself, but I need more
By Paul Berger · #146463 ·
Question about cables and probes for hp 16715a.
Hi all. I have two 16715a cards, with cables, but without pods with wires to connect to hooks. I would like to make them myself, but I need more information about them. Specifically, I need to
By Don't Know · #146462 ·
Re: HP 141T Power Supply Help Needed
Some years ago I had a 141 with similar problems although no fuses was blown. Trying to find multiple faults by measuring did not result in any clues. In the end, I decided to take the regulator
By Ulf Kylenfall · #146461 ·
Re: HP 141T Power Supply Help Needed
=== Looks OK. If scaled to -100V it covers -17.8V to -24.9V crossing through expected -20V. This says with -80V should give at least -80*0.178/1.007=-14V but measurement is -7.7V. == R33 is
By Ozan · #146460 ·
Re: HP 141T Power Supply Help Needed
Measuring the input capacitors, they are generally very low (0.001-0.03v) and well within what is shown on the schematic. Measuring the outputs, they all show 0v AC. The -1v test is a little
By Bill Berzinskas · #146459 ·
Re: HP 141T Power Supply Help Needed
My Answers are inline. ==== Unloaded is fine, it is the easier case for the linear regulator. However, 1Vpp at output is too high. Checking ripple across ?C1, C3, C4, C6 is a good idea. However, it
By Ozan · #146458 ·
Re: HP 141T Power Supply Help Needed
I had looked at ripple on my scope a bit, but given the supply is unloaded I'm not sure it matters.? ?I'm seeing a few supply rails in the ~1v p-p range, of those supplies I had tried to jumper a
By Bill Berzinskas · #146457 ·
Re: HP 141T Power Supply Help Needed
If output is ~ -80V, ?resistive divider around trimpot (R34/R11C/R38/R39) can only divide down to -12V even in CW position or so, it can't produce -7V. One possibility is these voltages have a large
By Ozan · #146456 ·