Re: HP 141T Power Supply Help Needed
Good news on -100V fix. As I mentioned in message ?#146460 swapped C&E explains the fault so it was the root cause of bad -100V: >> Are C-E terminals of Q8 correct? if C & E are swapped leakage to base could give a similar reading.?
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Ozan
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On Thu, Aug 29, 2024 at 07:52 AM, Bill Berzinskas wrote:
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 transistor tester, i found the pinout to be CBE when looking at it from the flat side.??
The center leg was bent towards the rear of the part, while the original part was bent toward the front.??
I reversed both transistors, and got -106 which i was able to adjust appropriately!? ? ??
Strange, but makes sense.? ?I have a few more of these buggers in the supply, so it sounds like I'll be sorting through that today.? ?
Will report back in a bit.??
Thanks for the help ya'll!?
On Thu, Aug 29, 2024 at 10:45?AM Frank Mashockie via <fmashockie= [email protected]> wrote:
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 the 141T. ?
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Re: OT MathCad 7 Professional
On Wed, Aug 28, 2024 at 06:29 AM, Ke-Fong Lin wrote:
A home use license for Matlab is 119 euros (should be much less than $150
Well, it turns out, according to the Mathworks Website... it's at least 150.00 USD here. (There's taxes too.)
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I don't think Mathworks is trying to 'make' money off their "Home' or "Student' editions.
And they include a lot of 'add ons'
Its the 'for commercial, or for profit' Matlab licenses which are expensive... and the licensing which is a pain.
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So I would say... if 'fiddling' with numerical methods, linear algebra, and matrix computations, are your thing... I mean you wake up in the morning... and can't wait to get those complex eigenvalues, computed from that very large set, of very large matrices... a few seconds earlier... 150.00 + tax, might be worth it to you... and it might also be worth it to put up with the Mathworks licensing irritations too. Matlab might be faster, and more numerically stable.
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Otherwise... I reckon... Octave is free, with no licensing restrictions.? And 'free' seems even to be less than 119 euros.
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I would expect Mathworks to be aggressive in their response to people using the Home, or Student, Matlab products in 'for profit' ventures.
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Re: Question about cables and probes for hp 16715a.
I said:
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...The 90-pin probing system used on more recent cards is NOT lossy with Z approx. 93 ohms.
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To be clear, what I mean is the tiny ribbon coax used in the 90-pin system has a characteristic impedance of 93 ohms.? I did not mean to imply that's the impedance at the probe tip.? The input impedance at the probe tip is much higher and is given as a model depending on the pod being used.
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-mark
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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 clips - for typically $50 and you need 4 per card. If you find a good way to it please document it as they will only get harder to find.
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I'm not familiar with the 16715A card (mine are older 16555 and similar) but as far as I understand from your message they also use the 40 pin format and not the later 90 pin format.?
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If you're in the US, this ebay lot seems quite a good buy : - elsewhere it's rather expensive. For the UK you have to add $77 and possibly VAT and duty costs too. This was after I'd discussed lower postage costs (USPS) with the seller - it was initially listed with $190 postage (expedited fedex).
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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 reduce reflections to preserve signal integrity. ?(Note that this applies for the 40-pin probing system for the 16715A cards and family. ?The 90-pin probing system used on more recent cards is NOT lossy with Z approx. 93 ohms.)
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The +5V run in the ribbon cable is used to power accessories, such as the E2433-66502 training card (aka "Credit Card Board"). ?The probe pods themselves are passive do not need power.
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n addition to providing an isolation network, the flying lead pods also have a spark gap in them for static protection.
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I'd really recommend just buying the cables and pods you need. ?By the time you're done with specialized parts and your time, I don't think it would be a win or have equivalent performance. ?If you're patient, ribbon cables can be had for US$25 and flying lead sets for around US$20 (need two per cable).? Good deals can be found when buying them in sets instead of individually.
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-mark
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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 to compensate the divider, and HP did sell parallel RC networks for building into a project and using direct connection to the analyzer.
You have 2 commonly available connections, the 20 pin pod (which I build into PC boards), and the squid (which I use only for debugging of other parts of the circuit).? The less common method would be a direct connection to the 40 pin connector with you supplying the RC networks.
Harvey
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On 8/29/2024 9:56 AM, Adrian Godwin wrote: 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 as documented in the probing manual, with SMD capacitors and a thick film resistor on the substrate. However, I didn't measure the cable resistance.
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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.? ? ?I reckon I could go after either of them given the dependencies.? ? Will grab some measurements in between or after work today.? ?
On Thu, Aug 29, 2024 at 10:52?AM Bill Berzinskas via <bberzinskas= [email protected]> wrote: 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 transistor tester, i found the pinout to be CBE when looking at it from the flat side.??
The center leg was bent towards the rear of the part, while the original part was bent toward the front.??
I reversed both transistors, and got -106 which i was able to adjust appropriately!? ? ??
Strange, but makes sense.? ?I have a few more of these buggers in the supply, so it sounds like I'll be sorting through that today.? ? Will report back in a bit.??
Thanks for the help ya'll!?
On Thu, Aug 29, 2024 at 10:45?AM Frank Mashockie via <fmashockie= [email protected]> wrote: 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 the 141T. ?
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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 transistor tester, i found the pinout to be CBE when looking at it from the flat side.??
The center leg was bent towards the rear of the part, while the original part was bent toward the front.??
I reversed both transistors, and got -106 which i was able to adjust appropriately!? ? ??
Strange, but makes sense.? ?I have a few more of these buggers in the supply, so it sounds like I'll be sorting through that today.? ? Will report back in a bit.??
Thanks for the help ya'll!?
On Thu, Aug 29, 2024 at 10:45?AM Frank Mashockie via <fmashockie= [email protected]> wrote: 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 the 141T. ?
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Re: 5342A: sometimes counts, sometimes not
Hello guys
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Yesterday I realized something else.
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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. The rear indicating sticker for this option is not set and I have never tried pressing the button to test the function. I assumed he didn't have it and that's it. Now I feel a little stupid having been so worried about not exceeding +5 dbm on the input so as not to burn U1... with option 002 installed, up to +20, +24 peak can be applied :D Still, it never hurts to be cautious.
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Yesterday I was reviewing what the amplitude measurement circuit consists of and I thought that perhaps the problem that it does not count sometimes is not due to the normal signal heterodyning circuits, but rather due to a failure in attenuation or path selection. which does the U2 front end assembly or related board (A16) or wiring.
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When I am able to get the power supply working I will test the amplitude measurement. Then the signals that route the RF through the different paths. I think the fault will be there: either the schottky in U2 are fried or it is a fault in A16 command signals.
The tests I did for this failure without even knowing that I had option 002 installed drove me crazy, because everything was apparently fine. So I'm sure there must be a problem in opt 002 related circuitry. Maybe just the RF can't get through U2 and the counter can't count :D simple as that.
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Best regards,
Ruben
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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 the 141T. ?http://www.k100.biz/e-Books.html
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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 as documented in the probing manual, with SMD capacitors and a thick film resistor on the substrate. However, I didn't measure the cable resistance.
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Re: HP 141T Power Supply Help Needed
Could very well be what's going here.??
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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 576 and drove it to failure (not above its rated max power) that I found it was the issue.
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-Frank
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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 information about them. Specifically, I
need to understand the pinout of the pod connector, and how they
differ from each other.
A) What does "L clock / K clock / M clock / J clock" mean and
the pod numbering, is there any difference in them, or are they
just stickers for the symbol?
B) And, I wonder what kind of 40 pin pods existed for logic
analyzers? Were they purely passive, or was the +5V line in the
cables used to power the probes?
B) Also, do the wires themselves, going from the 40 pin
connector to the hooks?, have the same resistance as the
16715-61601 cables? (thanks Keith)
if someone measures the cable resistance with a multimeter,
it will help me a lot.
? - Photo 40 pin pod that I'm talking:
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If you have any information on this topic, please share it.
_._,_._,_
A lot of the information you are looking for may be found in the
manual "Logic Analyzer Probing Solutions" available from Keysight
On the flying lead probe you have pictured, the individual wires
from the connector to the plastic piece with the probe number on
it is a coax and may be lossy coax however even it it is, it is
only about 22cm long and would contribute little to the 90.1K I
measured compared to the the resistance of the isolation network
housed in that same little piece of plastic.? I suspect the last
3cm from the isolation network to the tip is just a straight
wire.? In the manual there is a section concerning custom probing
that includes cautions about lead length and grounding.??
When I first got an HP analyzer? I made up rough isolation
networks based on the information from the above mentioned manual
and used about 15cm long jumpers to connect to the signals I
wanted to monitor, they worked but may have been problematic if I
had tried to monitor any really fast signals. ?
Each of the 40 pin connectors has one signal line designated as a
clock the letters assigned relate to the pod number for instance
the pod 1 in your picture is clock "J", pod 2 has clock "K" and so
on, this is how the software on you logic analysis system will
refer to the clocks.? In a pinch the clock lines can usually be
used as another probe line too.
Paul.?
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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 understand the pinout of the pod connector, and how they differ from each other.
A) What does "L clock / K clock / M clock / J clock" mean and the pod numbering, is there any difference in them, or are they just stickers for the symbol?
B) And, I wonder what kind of 40 pin pods existed for logic analyzers? Were they purely passive, or was the +5V line in the cables used to power the probes?
B) Also, do the wires themselves, going from the 40 pin connector to the hooks?, have the same resistance as the 16715-61601 cables? (thanks Keith) https://www.techtravels.org/2022/11/agilent-logic-analyzer-cable-teardown-photos/
if someone measures the cable resistance with a multimeter, it will help me a lot.
? - Photo 40 pin pod that I'm talking: https://drive.google.com/file/d/1BQOlGv18P4PRovAiXgYvDBW13E3l8o9p/view?usp=drivesdk
?
?
If you have any information on this topic, please share it.
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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.
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In the end, I decided to take the regulator board out and resolder every pad/component.
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That did the trick.
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/Ulf
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Re: HP 141T Power Supply Help Needed
On Wed, Aug 28, 2024 at 09:31 PM, Bill Berzinskas wrote:
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 interesting, but I don't know if it looks like the division is off necessarily.? ?with -1.007v in, i see -.178 and -.249.? ? A little off from what?you mention, but?
it seems like my output would be closer to the expected -100v.? ?
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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.?
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R33 measures 30.5ohm (expect 30.1), so it may be a smidge out of spec? Not enormously so, but maybe enough?? ?
CR14 looks ok on dmm, a bit over .5v and OL depending on the direction.? For kicks, I swapped out Q8 since I have a few, no change.??
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R33 is for frequency compensation, its value is not that critical.
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If you measure voltage across R33 you can tell if there is excessive leakage in C7. To make an impact it at this level it needs to pass ~ 1mA, so it would drop ~ 30mV which is not hard to measure. Should be 0mV ideally. ?
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Are C-E terminals of Q8 correct? if C & E are swapped leakage to base could give a similar reading.?
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Ozan
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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 interesting, but I don't know if it looks like the division is off necessarily.? ?with -1.007v in, i see -.178 and -.249.? ? A little off from what?you mention, but? it seems like my output would be closer to the expected -100v.? ?
R33 measures 30.5ohm (expect 30.1), so it may be a smidge out of spec? Not enormously so, but maybe enough?? ?
CR14 looks ok on dmm, a bit over .5v and OL depending on the direction.? For kicks, I swapped out Q8 since I have a few, no change.??
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My Answers are inline.?
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On Wed, Aug 28, 2024 at 07:37 PM, Bill Berzinskas wrote:
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 temporary cap across.?
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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 is also possible caps are fine and ripple at the output is because regulator is not functioning and following the ripple of the input.? You can use a DVM in AC mode to measure ripple across them, schematic has expected ripple in loaded condition, should be even less unloaded. Schematic shows ripple of the cap on one side, in regulation other side of the cap is fixed so you can take it as ripple across.?
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I saw no real changes here.? ?Not sure I understand the "probably obvious" part of C4 / Ground lead, should I just clip to chassis then?? ? ? I can re-measure as needed just want to make sure I'm doing it as expected.? ?
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Both sides of C4 is live, one side is at -100V other side is at +31.8V. Ground lead of the scope probe and ground of this circuit are shorted through ground (earth) prong of the power plugs. Connecting ground lead of scope to any side of C4 is same as shorting that side to ground through scope probe. A DVM across C4 is good enough, oscilloscope at output is useful with ground connected to ground for catching high frequency oscillations.?
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I do believe the resistors around the trimpot are good.? I just measured the pot from center to one leg and do notice some odd behavior.??
On the ends, I get 0 and 1.6k but as I turn from 1.6k downward it actually peaks up to 1.9k, then comes back down.? ? No voltage change?
is seen until its past the "hump" there, at which point I can adjust from ~67-70v.? ? Getting the gang of 3 pots out looks mildly painful but certainly possible.??
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If ripple at rectifier side is ruled out trimpot mid point is the most interesting node. It is a simple voltage divider, it shouldn't be able to produce -7.7V with -80V input.
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You can pull out F3, apply -1V to -100V terminal with the unit off. You should see ~ -155mV at CW terminal and -215mV at the other side of trimpot. These voltages are low enough that they won't turn on Q8/CR14 junctions. This checks the division ratio.
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If this is good. There are only three components touching that node, Q8, CR14, and R33. Emitter of Q8 is below -7.7 so CR14 or B-E junction can't be the one pulling that node to -7.7. Since you replaced Q8, I don't think it is C-B junction. C7 is other one but if you replaced it too. Interesting puzzle.?
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Ozan
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Re: HP 141T Power Supply Help Needed
My Answers are inline.?
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On Wed, Aug 28, 2024 at 07:37 PM, Bill Berzinskas wrote:
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 temporary cap across.?
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====
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 is also possible caps are fine and ripple at the output is because regulator is not functioning and following the ripple of the input. ?You can use a DVM in AC mode to measure ripple across them, schematic has expected ripple in loaded condition, should be even less unloaded. Schematic shows ripple of the cap on one side, in regulation other side of the cap is fixed so you can take it as ripple across.?
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I saw no real changes here.? ?Not sure I understand the "probably obvious" part of C4 / Ground lead, should I just clip to chassis then?? ? ? I can re-measure as needed just want to make sure I'm doing it as expected.? ?
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===
Both sides of C4 is live, one side is at -100V other side is at +31.8V. Ground lead of the scope probe and ground of this circuit are shorted through ground (earth) prong of the power plugs. Connecting ground lead of scope to any side of C4 is same as shorting that side to ground through scope probe. A DVM across C4 is good enough, oscilloscope at output is useful with ground connected to ground for catching high frequency oscillations.?
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I do believe the resistors around the trimpot are good.? I just measured the pot from center to one leg and do notice some odd behavior.??
On the ends, I get 0 and 1.6k but as I turn from 1.6k downward it actually peaks up to 1.9k, then comes back down.? ? No voltage change?
is seen until its past the "hump" there, at which point I can adjust from ~67-70v.? ? Getting the gang of 3 pots out looks mildly painful but certainly possible.??
?
===
If ripple at rectifier side is ruled out trimpot mid point is the most interesting node. It is a simple voltage divider, it shouldn't be able to produce -7.7V with -80V input.
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You can pull out F3, apply -1V to -100V terminal with the unit off. You should see ~ -155mV at CW terminal and -215mV at the other side of trimpot. These voltages are low enough that they won't turn on Q8/CR14 junctions. This checks the division ratio.
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If this is good. There are only three components touching that node, Q8, CR14, and R33. Emitter of Q8 is below -7.7 so CR14 or B-E junction can't be the one pulling that node to -7.7. Since you replaced Q8, I don't think it is C-B junction. C7 is other one but if you replaced it too. Interesting puzzle.?
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Ozan
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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 temporary cap across.? ?I saw no real changes here.? ?Not sure I understand the "probably obvious" part of C4 / Ground lead, should I just clip to chassis then?? ? ? I can re-measure as needed just want to make sure I'm doing it as expected.? ?
I do believe the resistors around the trimpot are good.? I just measured the pot from center to one leg and do notice some odd behavior.??
On the ends, I get 0 and 1.6k but as I turn from 1.6k downward it actually peaks up to 1.9k, then comes back down.? ? No voltage change?
is seen until its past the "hump" there, at which point I can adjust from ~67-70v.? ? Getting the gang of 3 pots out looks mildly painful but certainly possible.??
The above seem like good leads though, because...??
C7 in this case is a shiny little electrolytic mounted on the PCB, I did verify orientation but I've since put the original part back in.? ?
Q8 is new, I could replace it again but it'd just be a shotgun at this point.? ??
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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. ?
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One possibility is these voltages have a large AC (ripple) on them and DC values are not meaningful. Voltmeter in AC position can be used to check, scope is better. For example large ripple across C4 can confuse this stage and measurements. Probably obvious but if you use a scope you can't connect ground lead to any of C4 terminals.
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If the voltages have little of no AC component: To get -7V at DC there should be a fault around base of Q8 pulling it higher that -7V. Possibilities
1) One of the resistors around trimpot shifted or timpot has a high impedance mid point.
2) Is new C7 wired correctly, + terminal at ground?
3) C-B leakage of Q8?
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CR14 and B-E leakage would pull base even lower so they won't cause -12V rise to -7V. ?Q7 side won't impact Q8 side with the measurements you have.?
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Ozan
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On Wed, Aug 28, 2024 at 05:33 PM, Bill Berzinskas wrote:
A few further?datapoints.? ?I measured around the transistors a bit.? ?I do think the driver is working, but maybe the differential amp or the output side is not.??
Q3 regulator
* .4v into base, schem says .6v.??
* 72.2v instead of 31.8v on the collector though.? ?
Q6 Driver?
* 1.1v at base, schem says 1.2
* collector is hooked to regulator, so also 72.2 instead of 31.8
* emitter to q3 base, so also .4v.?
Q7 / Q8 Diff Amp?
* -7.7v into base of both transistors, expect -20v
* -8.3v on emitters, expect -20.5
Adjustment trimpot does nothing, resistances look ok.? ? Kind of eyeing CR13-15 I suppose???
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RubenRubio
Frank Mashockie