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Hello all: Having replaced the PSU (ref. 2465B Power Supply Precautions) have just powered on, J119 voltages perfect, test have some issues eg TEST 05 FAIL 42, but basically working.
Had no trigger, trigger lever stuck at -435 mV, CH 3 unstable vertical,
With Iso Alchol injected in the trigger lev pot, the trigger was improved on NORM only, NO trig on AUTO/LVL and AUTO.
U500 Trigger hybrid pressing the HS makes the AUTO/LVL and AUTO work!
QUESTIONS: I have never touched a Hybrid on 2465B.
what is the safe procedure to remove the HS, clean contacts, and replace?
Use contact cleaner or just IOS alcohol? (do not have DeOxit handy)
How to prevent cracking due to wrong HS position or torque?
MANY THANKS
Jon
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On Tue, Jan 26, 2021 at 04:21 AM, Jean-Paul wrote:
what is the safe procedure to remove the HS, clean contacts, and replace?
Use contact cleaner or just IOS alcohol? (do not have DeOxit handy)
How to prevent cracking due to wrong HS position or torque?
Jon, If you look at the hybrid you will notice one corner has an angle in the heat sink mold. This has to match the base you are reinstalling it it as it has an angle also. Review this before removing hybrid. I push down on center of hybrid with two or three finger to hold it down and loosen the nuts on all four corners. Continue holding down until all nuts are loosened and removed. Then lift finger pressure and lift it straight up. At this time you can review the base and the corner angle described above. Reassemble basically same way. Set hybrid aligned as removed and easily get push down again with finger pressure back into socket and start putting nuts back on posts. Finger tighten nuts all equally and then release. The hybrid should be most of the way down in the socket base at this time. Take finger pressure off and lightly tighten nuts with nut driver. Torque is not that important just know they are snug. Craig
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Dear Craig: Super for your fast response:
I see the orientation mark and corner on the HS and PCB.
Can I clean contacts on the PCB and Hybrid with iso alcohol? Contact cleaner? Other cleaner?
Are these static sensitive?
The hybrid IC is attached to the HS and will not fall off?
Mille Mercis,
Amenities,
Jon
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Hi Jon,
Test 5, Fail 42 typically indicates that your A5 controller
card has been damaged by leaking SMD electrolyte.
What Test 5, Fail 42 is doing, is measuring the sinewave
output from the little transformer the scope uses to provide
the signal for the LINE triggering condition. It knows
that the little transformer is always going to produce an
AC sinewave with a range of P-P values, and Fail 42 means
that the positive peak of the sinewave is higher than it
expected, and the negative peak of the sinewave is lower
than it expected.
The usual fix is to:
1) carefully replace all of the SMD electrolytic capacitors on
the A5 board.
2) scrub the board with dish soap and hot water using a toothbrush.
3) rinse with soft tap water.
4) blow off the remaining water, and then bake in a convection oven
at about 140F for several hours.
5) replace any etched away traces, and the two 10K precision resistors
that provide the current to the DAC reference.
6) go through the DAC calibration routine... and ideally full
calibration, as everything is referenced to the DAC reference.
It is very rare that it indicates a bad trigger hybrid.
-Chuck Harris
Jean-Paul wrote:
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Show quoted text
Hello all: Having replaced the PSU (ref. 2465B Power Supply Precautions) have just powered on, J119 voltages perfect, test have some issues eg TEST 05 FAIL 42, but basically working.
Had no trigger, trigger lever stuck at -435 mV, CH 3 unstable vertical,
With Iso Alchol injected in the trigger lev pot, the trigger was improved on NORM only, NO trig on AUTO/LVL and AUTO.
U500 Trigger hybrid pressing the HS makes the AUTO/LVL and AUTO work!
QUESTIONS: I have never touched a Hybrid on 2465B.
what is the safe procedure to remove the HS, clean contacts, and replace?
Use contact cleaner or just IOS alcohol? (do not have DeOxit handy)
How to prevent cracking due to wrong HS position or torque?
MANY THANKS
Jon
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Dear Chuck: Yes have done all that on all of my 2465/B. well noted!
This one exhibits the SAME fail 42 on any A5 used!
Also touching the HS of U500 seems to affect the loss of AUTO trig.
So thought to clean the hybrid contacts. That was my core concern,
Best Regards,
Jon
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Hi Jon,
I clean the hybrids in the 2465 by using a drop of
DeOxit on each pad on the hybrid. Avoid a flood.
Usually, I find that hybrids that seem to need cleaning
are just bad.
When re installing the finned hybrids, plan ahead.
You need to use one finger to press the hybrid down
to the circuit board, and the other hand to install
a pair of nuts on diagonal corners, finger tight.
It is something of a juggling act, so make sure that
the nuts are available, and I find using a nut starter
is very helpful.
If you try to use the nuts to bring the hybrid in contact
with the board, you will very likely break the ceramic
substrate. It is a tight fit, and it must be done
without flexing the ceramic. They don't need to be much
tighter than finger tight.
The path for the Fail 42 error is the same as the LINE
trigger mode, as it uses the same parts.
-Chuck Harris
Jean-Paul wrote:
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Show quoted text
Dear Chuck: Yes have done all that on all of my 2465/B. well noted!
This one exhibits the SAME fail 42 on any A5 used!
Also touching the HS of U500 seems to affect the loss of AUTO trig.
So thought to clean the hybrid contacts. That was my core concern,
Best Regards,
Jon
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Chuck WOW your are as always the authority on TEK! Perfect notes,
I suspect U500 has a slightly flaky connection, as pressing the HS seems to affect the symptom.
I have no Deoxit, just MS-230 contact cleaner, and 99% iso alcohol.
Would either of those be OK? Deoxit, is D-5 the best? liquid or spray?
will followup as I proceed.
Many thanks again!
Jon
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IPA should be fine, use cotton swab with a little
gentle rubbing on the hybrid side, and wiping the
contact springs towards their open ends, on the
socket side.
The red DeOxit, in the small squeeze bottle with a
hypodermic style needle applicator, is what I use.
My bottles are marked D100L-25C, which is 100%, in
a 25ml bottle. The D5 is a 5%, diluted mixture.
The spray is too hard to control, and will just soak
everything whether it needs to be, or not. DeOxit is
expensive enough without wasting it.
-Chuck Harris
Jean-Paul wrote:
toggle quoted message
Show quoted text
Chuck WOW your are as always the authority on TEK! Perfect notes,
I suspect U500 has a slightly flaky connection, as pressing the HS seems to affect the symptom.
I have no Deoxit, just MS-230 contact cleaner, and 99% iso alcohol.
Would either of those be OK? Deoxit, is D-5 the best? liquid or spray?
will followup as I proceed.
Many thanks again!
Jon
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Dear Chuck: Great advise again! Will try with ISO Alcohol, and order the Deoxit liquid.
By the way, Amazon has some 99% isopropyl alcohol in gallons or as smaller bottles, ~ 25-30$/gallon.
Enjoy!
Jon
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On Tue, Jan 26, 2021 at 05:17 AM, Jean-Paul wrote:
Can I clean contacts on the PCB and Hybrid with iso alcohol? Contact cleaner?
Other cleaner?
Are these static sensitive?
The hybrid IC is attached to the HS and will not fall off?
Jon, Static precautions need to be followed when handling. I¡¯ve heard about cleaning the hybrid mating surfaces with the iso alcohol, but personally never done it to solve any issue. Why would you have corrosion in this area unless there has been moisture or in an airborne contaminated area. Hybrid is attached to the heat sink and normally won¡¯t separate with out force. Craig
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Hello Chuck: I traced line trigger signal, fine on the main board power connector, and it DOES line trigger! As the same fault Test 05 fail 42 appears on all the A5 control boards I have checked, and all were reworked for the SMD caps, PC trace damage and NVRAM, and work fine in other units, the FAIL 42 remains a puzzle.
To Craig, I have no idea the past history of the unit but it is very clean and SN B062, rather late. The flaky CH 3 VERET POS pot and odd trigger fault leads me to suspect either bad treatment physically, or just oxidized contaces due to long dormancy. I will tackle the hybrid cleaning another day, but Chuck doubts that U500 is at fault.
The mystery deepens.....
Good day and So long!
Jon
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Hey Jon,
I don't suppose the scope had any options installed that have been removed?
After I repaired my 2467 I had a persistent TEST 05 failure. In my case
this was because the options board was out and disconnected. Some of the
trigger signals run through there, so if an option is removed, you may need
to jumper the mainboard to route the signals right...
Siggi
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On Tue, Jan 26, 2021 at 3:22 PM Jean-Paul <jonpaul@...> wrote: Hello Chuck: I traced line trigger signal, fine on the main board power
connector, and it DOES line trigger! As the same fault Test 05 fail 42
appears on all the A5 control boards I have checked, and all were reworked
for the SMD caps, PC trace damage and NVRAM, and work fine in other units,
the FAIL 42 remains a puzzle.
To Craig, I have no idea the past history of the unit but it is very clean
and SN B062, rather late. The flaky CH 3 VERET POS pot and odd trigger
fault leads me to suspect either bad treatment physically, or just oxidized
contaces due to long dormancy. I will tackle the hybrid cleaning another
day, but Chuck doubts that U500 is at fault.
The mystery deepens.....
Good day and So long!
Jon
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Siggi, indeed this unit has OPT 6,9, CTT, WR and GPIB so both CTT/WR board and GPIB are installed.
As I received the score with PSU dead and removed with all cables loose, I used the Option service manual to reconnect.
Indeed every cable seems to be in place but for sure there might be one cable missed or mismated.
Unfortunately the mechanical assembly diagrams are not specifically enough to see which interconnect cable go to which connectors.
I should follow-up on your suggestions and trace out every cable, focusing on the trigger signals.
I hope other mavens can add to this.
Bon soir¨¦e
Jon
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Why would you have corrosion in this area unless there has been moisture or in an airborne contaminated area?
Craig
No CORROSION, but certainly OXIDIZATION.
Wherever you have electricity flowing through metals contacting each other, whether or not they are the same type of metal, there is going to be oxidization.
A perfectly clean lab room's air will generate less oxidization; a basement shack's air will generate copious amounts.
That's the stuff which needs to be cleaned off completely.
The correct method is IPA first, and then DeOxit for longer-term protection.
On less sensitive electric contacts as a first treatment, such as mechanical switches I use Brasso on a cotton bud.
It's more aggressive than IPA, and MUST be wiped off completely, but works just fine in certain applications.
Followed by Deoxit.
Menahem
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Dear Menachem fine to hear from you
I thought the same, and pulled out U500 trigger, yesterday.
Completely clean, AMP socket gold pins perfect.
I used static precautions and 99% isopropyl alcohol, and a q tip to wipe the IC contacts and sockets pins.
No change in the symptoms after reassembly
I suspect that there may be missing or wrong cables or connectors to the options boards.
I shall start a new topic on what I discover.
Best Regards
Jon
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Jean-Paul
Craig Cramb