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Re: HP 8662a 5.2V current draw

 

You can first try a lighter weight variable 5 V PS, say a 5-10 A bench type to juice it up part way. It won't run the full load, but you can see if anything bad happens as you bring it up, and trace shorts, etc. If you use only a high current fixed on/off one, it may be too much for anything shorted. Also, a fixed high current SMPS may deliver over 20 % beyond spec current, and may limit in various ways, from constant current, to foldback, to trip/restart and others. If you do use one, you should make sure of its limiting style.

Ed
Re: meaning of "DSA failure" in hp 3585A service manual

 

Hello Alberto,
DSA means Digital Signature Analysis. A signature analyzer (like the 5004 or 5005 series) is incredible helpful if there is a problem with the logic...
Repaired two of these recently, these are beasts and very difficult to repair. I recommend to try to perform a full calibration. The troubleshooting trees are very helpful for individual problems,? but as soon as an instrument has multiple problems, they sometimes might be misleading.
Chris


On Sun, May 30, 2021 at 01:26 PM, Alberto, IZ2EWV wrote:
Hello friends,
I'm repairing a 3585A spectrum analyzer that has problems with its local oscillator ("LOCAL OSC. UNLOCKED" on the screen).
First, I found a bad 2N3055 in the A34 LO control board, which didn't give +5V to its own circuits and to the A33 N-fractional divider.
But, even if, after this repair, something more begun to become alive in that area, I'm still going on with the LO Control (A34) Troubleshooting Tree (page 11-212 of the service manual) and I'm asking the meaning of this checkpoint: "Is the problem related to a DSA failure on another board?".
Thanks in advance to every guy who can give me the explanation of DSA, which allows me to take the appropriate answer and take the right branch of the tree!
Alberto

?Hello
Re: HP 8662a 5.2V current draw

 

Thank you everyone for sharing your insights. In the process of connecting up a pile of switchers and wires to temporarily replace the transistor eating inverter.
The smallest large 5V supply I have is 25A so should be good for a true smoke test in an hour or two.
The goal is to simply see if the rest of the unit is alive. There are no obvious shorts on any of the power busses.
Thanks again.
Paul?
WB8TSL
meaning of "DSA failure" in hp 3585A service manual

 

Hello friends,
I'm repairing a 3585A spectrum analyzer that has problems with its local oscillator ("LOCAL OSC. UNLOCKED" on the screen).
First, I found a bad 2N3055 in the A34 LO control board, which didn't give +5V to its own circuits and to the A33 N-fractional divider.
But, even if, after this repair, something more begun to become alive in that area, I'm still going on with the LO Control (A34) Troubleshooting Tree (page 11-212 of the service manual) and I'm asking the meaning of this checkpoint: "Is the problem related to a DSA failure on another board?".
Thanks in advance to every guy who can give me the explanation of DSA, which allows me to take the appropriate answer and take the right branch of the tree!
Alberto
Re: HP 8753C CAUTION: NO IF FOUND: CHECK R INPUT LEVEL

 

Hi

We have now measured the voltages both when the YTO 5086-7473 is connected and not: /g/HP-Agilent-Keysight-equipment/message/71364 and at 10 MHz:

Pin/Unconnected/Connected
1: -14,8 V; 14,6 V
2: NC
3: Ground
4: 5 V; 5 V
5: 21,2 V; see scope pictures
6: 0 V; 0 V
7: NC
8: 14, 9 V; 14,9 V
9: varies; 0 V
10: 0 V; 0 V

We also tried to run the YTO outside the NA through an extended ribbon cable, ~20 cm, but the the NA said that the R input was overloaded despite nothing was connected to it.

Is it fair to conclude that the YTO needs to be repaired or are there more tests to carry out before concluding?

Bo

HP_5086_7473_Pin5_a.jpg
HP_5086_7473_Pin5_b.jpg

Re: HP 8662a 5.2V current draw

 

P.D.:
Also, the oven draw 600 mA peak with 30-31 volt suply and the cooling fan is 140 mA (mine is 230 VAC)
Re: HP 8662a 5.2V current draw

 

Hello!

In my 8663A the peak current draws are:?~12 amps in the 5.2 rail, 0.4 A in the -40 volt rail, 2.2 A in the -10V rail and 1.83 A in the +20V.
The last three measured with a calibrated programmable linear power supply, and the 5.2 estimated and now working perfectly with a brand new meanwell brick RS-75-5, which is designed to deliver 12 amps max.

Hope this helps,?

R.
HP 53150A CLIP or Service Manual

 

Hey guys,

Any ideas if the CLIP or the Service Manual are out for these counters?

Regards,
Razvan
Re: HP 8662a 5.2V current draw

 

Hi Paul,

I have noted just under 13A on the 5.2V supply on my HP 8663A.
The 8662 should not be much different.

Regards,
Askild


On Sat, May 29, 2021 at 8:10 PM paulswed <paulswedb@...> wrote:
Hello to the group.
Working on a HP 8662a power supply issue. Its a complex switching power supply.
Most of the power supplies use the classic sense resistor and a base emitter sense voltage of .6V so current can easily be calculated.
But the 5.2V power supply is a huge question. It uses a .005 ohm resistor. The service manual doesn't say what it can deliver. But looking at the diodes they can handle 35 amps. The wire to the diodes is 14 Gauge appear to handle less current. Though the wires are about 1" long. Traces indicate maybe 14 amps.
Measuring a 8662b that works but can't be opened. The power draw in VA is 300 VA. Subtracting the other supplies leaves 217 VA or 40 amps at 5.2V. I really do not believe that number. But can not find what else could be consuming lots of power.
Also actually providing a voltage into the overcurrent circuit shows that 3 mv is the trip point .003V/.005 ohms is .6A. So thats not correct.
The reason I need to figure this out is to insert external supplies temporarily to confirm nothing else is an issue with the 8662 and would like to set a reasonable current limit. I have 50 and 60A supplies. Kind of scary inserting something that large.
The switcher is very very good at eating transistors in about 1 second.
Appreciate any help.
Thank you
Paul
WB8TSL

Re: Three-volume Book about Hewlett Packard South Queensferry history to be available soon

 

FYI:

Acknowledgement

"We expect to dispatch from Scotland, UK, via AIRMAIL
on the 16 July 2021 and will email you again then
with dispatch details including your Invoice."

Larry
AC9OX
Re: HP 8662a 5.2V current draw

 

On Sat, May 29, 2021 at 11:10 AM, paulswed wrote:
Hello to the group.
Working on a HP 8662a power supply issue. Its a complex switching power supply.
Most of the power supplies use the classic sense resistor and a base emitter sense voltage of .6V so current can easily be calculated.
But the 5.2V power supply is a huge question. It uses a .005 ohm resistor. The service manual doesn't say what it can deliver. But looking at the diodes they can handle 35 amps. The wire to the diodes is 14 Gauge appear to handle less current. Though the wires are about 1" long. Traces indicate maybe 14 amps.
Measuring a 8662b that works but can't be opened. The power draw in VA is 300 VA. Subtracting the other supplies leaves 217 VA or 40 amps at 5.2V. I really do not believe that number. But can not find what else could be consuming lots of power.
Also actually providing a voltage into the overcurrent circuit shows that 3 mv is the trip point .003V/.005 ohms is .6A. So thats not correct.
The reason I need to figure this out is to insert external supplies temporarily to confirm nothing else is an issue with the 8662 and would like to set a reasonable current limit. I have 50 and 60A supplies. Kind of scary inserting something that large.
The switcher is very very good at eating transistors in about 1 second.
Appreciate any help.
Thank you
Paul
WB8TSL
----
Is the schematic of "A7A2 Control" block available online? I could only find a block diagram.
Ozan
Re: HP 8662a 5.2V current draw

 

Also, comparing line power draw between instruments has to include some idea of the efficiencies. Lower output voltages are much less efficient, unless they managed to do synchronous rectification back then. I'd guess in that era, the efficiency for the higher voltages may be 80-85 %, while the 5.2 may be 60-70 % tops.

Ed
Re: HP 8662a 5.2V current draw

 

Can you find or estimate the power rating of the 5 milliohm resistor? At normal load, it should dissipate much less than its rating - say half or less, if it's sampling actual DC load. If it's within the switcher loop, measuring the switch current, then it's a different story.

Ed
HP 8662a 5.2V current draw

 

Hello to the group.
Working on a HP 8662a power supply issue. Its a complex switching power supply.
Most of the power supplies use the classic sense resistor and a base emitter sense voltage of .6V so current can easily be calculated.
But the 5.2V power supply is a huge question. It uses a .005 ohm resistor. The service manual doesn't say what it can deliver. But looking at the diodes they can handle 35 amps. The wire to the diodes is 14 Gauge appear to handle less current. Though the wires are about 1" long. Traces indicate maybe 14 amps.
Measuring a 8662b that works but can't be opened. The power draw in VA is 300 VA. Subtracting the other supplies leaves 217 VA or 40 amps at 5.2V. I really do not believe that number. But can not find what else could be consuming lots of power.
Also actually providing a voltage into the overcurrent circuit shows that 3 mv is the trip point .003V/.005 ohms is .6A. So thats not correct.
The reason I need to figure this out is to insert external supplies temporarily to confirm nothing else is an issue with the 8662 and would like to set a reasonable current limit. I have 50 and 60A supplies. Kind of scary inserting something that large.
The switcher is very very good at eating transistors in about 1 second.
Appreciate any help.
Thank you
Paul
WB8TSL
Re: HP 182T + HP9858B repair

 

Sorry it's 8558b Analyzer
HP 182T + HP9858B repair

 

Hello,

I repaired an oscilloscopre HP182T (pb alim + miscellaneous).
I did a visual check of the analyzer. A screw was found in it and I nettoyed all the conctacts.
The display is down, so the frequency is set to "blind"

It should be noted that this material seems to have been "tinkered", but the analyzer gives me some indications.

I managed to display a screen by directly injecting an AM signal with a FY6900 generator.
I¡¯m surprised to see only a side stripe.
Is it out of order or is my generator not optimum??? Don't known
It¡¯s hard to say.

Here are the test conditions:
Signal sent directly into the input connector (I don¡¯t have an adapter yet).
AM modulation, 40MHZ, 3v.
Buttons positions on the analyzer:
Time division 1Ms,Trigger free, Frequency Span/div 200Khz resolution BW between 10 and 30 mhz.
reference level -20DB, reference level fine 0, Optimun input -40DB.
Tell me if the settings seem consistent.

See the result on captures in joined pieces.
Please inform me of other possible tests (We can create a custom signal on this generator).
If there are adjustments to be made???

As you can understand, I¡¯m not used to handling this device yet

cdt



IMG_20210529_185104.jpg
IMG_20210529_185049.jpg

Re: HP 8663A Repair Help

 

"John Miles" <john@...> writes:

Hmm, I'm still not seeing the smoking gun here. What exactly leads you to
suspect the 1M resistor?
Yeah I'm starting to lose confidence that it's a problem since the
measurements of it seem to be ok. But, it was the physical damage to it
that originally alerted me to it. It may have been a bit hard to see in
the original image. I've attached a zoomed in version; hopefully that's
easier to see. Basically, there are cracks in the side.


Matt

hp_8663_ref_osc_r23_damage_zoom.JPG

Re: HP 8663A Repair Help

 

Hmm, I'm still not seeing the smoking gun here. What exactly leads you to
suspect the 1M resistor?

-- john

-----Original Message-----
From: Matt Huszagh [mailto:huszaghmatt@...]
Sent: Friday, May 28, 2021 10:23 PM
To: John Miles; [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8663A Repair Help

Matt Huszagh <huszaghmatt@...> writes:

It's worth noting that the resistors I have are 1% metal film resistors
(though, a cheap amazon purchase), so they might be ok. Think it's ok to
take the risk here, or should I play it safe and order a replacement
with a known ppm?
I performed an imprecise comparison of the temperature coefficients of
these two resistors and the damaged one is much better than the ones I
have on hand. I used a hot air gun at 200C (with a fair amount of
separation between the nozzle and resistor) and compared the effect on
each resistor. Mine dropped precipitously. HP's barely changed. Looks
like I need a better resistor than this.

Matt
Re: HP 8663A Repair Help

 

Matt Huszagh <huszaghmatt@...> writes:

It's worth noting that the resistors I have are 1% metal film resistors
(though, a cheap amazon purchase), so they might be ok. Think it's ok to
take the risk here, or should I play it safe and order a replacement
with a known ppm?
I performed an imprecise comparison of the temperature coefficients of
these two resistors and the damaged one is much better than the ones I
have on hand. I used a hot air gun at 200C (with a fair amount of
separation between the nozzle and resistor) and compared the effect on
each resistor. Mine dropped precipitously. HP's barely changed. Looks
like I need a better resistor than this.

Matt
Re: HP 8663A Repair Help

 

Matt Huszagh <huszaghmatt@...> writes:

Anything else I should pay attention to when ordering a replacement? For
instance, operating temperature? I have a bunch of 1M 1/4W resistor, but
I don't know their temperature coefficients so I'm not eager to use
those.
It's worth noting that the resistors I have are 1% metal film resistors
(though, a cheap amazon purchase), so they might be ok. Think it's ok to
take the risk here, or should I play it safe and order a replacement
with a known ppm?

Matt
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