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I have a lightly used HP8920B. I think the PS is same as HP8920A. It is unlike the PS in the 8924 series from what I see from on line pictures.
I am pretty convinced one of the filter caps is venting (fishy/cat urine odor when on) and has been for a while, now maybe worse. Before I tear into it, I would like feedback from anyone who has fixed an 8920 power supply in the past. It would help to know what capacitors to order because I would like to get it open and get it done. A schematic would be great if such exists, otherwise a BOM for the common capacitors. Pictures?
I cant be the first to have to fix one, so hoping.
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I had a 8920A recently on the bench with "magic smoke" issues: suspected RIFA X2 issues from the smell.
Turned out there are 3 Rifa's in the PSU circuit proper, one blown and 2 cracked in my case (C7, C63, C65).
Replaced these with Wima mkp10 47n/630V caps (15mm version MKP1J024704C)
There is one more Rifa on the PSU pcb: a 2.2nF Y2, replaced that one for good measure as well.
It is a pain getting the PSU out of the machine, and then the PCB from its case, but for the former problem there is a nice explanation in the hp manual floating around.
good luck,
Marc.
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Hi,
There is no circuit available for 89209A/B power supply. It is a 3rd Party unit (Artesyn, previously power one?). I've repaired a couple and?they are?a pain. It is basically two PSU's in? one. A 12-28V to 300V DC-DC and a AC/DC to multi output switcher (similar to their NLP series). The AC/DC one is similar to their NLP range. One oddity is that rather than the common opto isolator, it uses a small ferrite torodial transformer for feedback isolation. This has 3 windings and fault finding around the feedback circuit is a pain. There are at least two variants (same HP part No.) that I have personally seen so you will have to dig it out, see what you have and order the right capacitors for yours.
Robert G8RPI.
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Greetings all,
See attached .pdf files for 8920x A9 Artesyn PSU Circuits and Specs...
Regards,
Ron Wilkinson
Perth - Western Australia
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It's great to be proved wrong sometimes :-) Thanks very much for that Ron.
Robert G8RPI.
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Thanks Ron. A great find. I? am assuming that Artesyn and Computer Products Power Conversion are same firm?
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Show quoted text
On Mon, Sep 30, 2019 at 04:07 AM, Ron Wilkinson wrote:
Greetings all,
See attached .pdf files for 8920x A9 Artesyn PSU Circuits and Specs...
Regards,
Ron Wilkinson
Perth - Western Australia
--
EMAIL DISCLAIMER NOTICE - This message is the property of mi-Biz Systems
Pty Ltd. The information contained herein is confidential and may be
legally privileged. It is intended solely for the addressee. Access to
this email by any other party is unauthorised. If you are not the
intended recipient, any disclosure, copying, distribution or any action
taken or omitted to be taken in reliance on it, is prohibited and may
be unlawful.
If you believe that this message has been wrongly addressed or is
otherwise misdirected, please notify mi-Biz Systems immediately via
email to mi-biz@.... Thank you.
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Marc;
I find a C7 47n/630V across T1 in Ron's schematic, but no C63 or C65. Or Y2. The BOM states last part # used is C55.? Are their different versions? There are optional C1 and C3 across the power lines to ground but no values.
More importantly was the smell like cat urine or ammonia? And, did the board get scorched?
I was assuming the problem would be the bulk capacitors C5 and C6 100U/400V and 270U/400V on the rectified input line.. This Rifa problem is very new to me. This unit is stored in AC but used seldom so does not get a good baking, especially now that it smells.
Thoughts?
Joe
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On Mon, Sep 30, 2019 at 02:23 AM, marcschrdrs wrote:
I had a 8920A recently on the bench with "magic smoke" issues: suspected RIFA X2 issues from the smell.
Turned out there are 3 Rifa's in the PSU circuit proper, one blown and 2 cracked in my case (C7, C63, C65).
Replaced these with Wima mkp10 47n/630V caps (15mm version MKP1J024704C)
There is one more Rifa on the PSU pcb: a 2.2nF Y2, replaced that one for good measure as well.
It is a pain getting the PSU out of the machine, and then the PCB from its case, but for the former problem there is a nice explanation in the hp manual floating around.
good luck,
Marc.
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Ron,
I've been reading this thread with interest.? I don't know if you can help me in finding information on a power supply for an Agilent 8753es.? I understand it's a third party module and been told a schematic is unobtanium, which probably is the case.? But since you came up with this choice morsel, I though I'd ask if you had any ideas or leads.
Burt, K6OQK
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Hello Burt,
No sorry - I have never come across a schematic for this one.? The
best data I've seen so far is the PSU troubleshooting information in
the 8753ES Repair Manual..
Regards,
Ron Wilkinson
====
Burt K6OQK wrote:
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Ron,
I've been reading this thread with interest.? I don't know if you
can help me in finding information on a power supply for an
Agilent 8753es.? I understand it's a third party module and been
told a schematic is unobtanium, which probably is the case.? But
since you came up with this choice morsel, I though I'd ask if you
had any ideas or leads.
Burt, K6OQK
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Hi there - they were in some way at the time but it all keeps
changing with Artesyn.....
Regards,
Ron Wilkinson
====
RFI-EMI-GUY wrote:
toggle quoted message
Show quoted text
Thanks Ron. A great
find. I? am assuming that Artesyn and Computer Products Power
Conversion are same firm?
On Mon, Sep 30, 2019 at 04:07 AM, Ron Wilkinson wrote:
Greetings all,
See attached .pdf files for 8920x A9 Artesyn PSU Circuits and
Specs...
Regards,
Ron Wilkinson
Perth - Western Australia
--
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Joe,
probably some different designs out there - I can only speak for the one I saw (Robert earlier mentioned he knows of 2 designs).
As for symptoms: rifa's crack and absorb moisture. At some point they start belching black smoke.
The PCB was fine (device was switched off promptly).
So you may very well have a different issue.
Marc.
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The two I've seen were different around the feedback circuit. The faulty one had smoked several?components in the feedback circuit?the point of being un-identifiable. The other unit I tried to use as a reference had different layout and values in that area. IIRC some of the electrolytics were different too. I ended up reading the resistor colour codes on a photo from an old ebay listing!?To top it off one of the feedback transformer windings had gone open circuit, but it's just a little toroid so I was able to repair it.
Robert G8RPI.
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Thanks, but I have since fixed the issue, the driver transistor was open. I replaced it with a high voltage darlington. I get very close to the -100v, out? enough for now.. I had to physically look at the traces to determine which components were associated with the -100v supply. I checked newer manuals, and they have the same discrepancy. I guess it was never caught.
Jim
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I have read the manual and it implies that the input module must be removed first, yet the A9 and input module occupy different spaces. Did you have to rmove the input module?
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Show quoted text
On Mon, Sep 30, 2019 at 02:23 AM, marcschrdrs wrote:
I had a 8920A recently on the bench with "magic smoke" issues: suspected RIFA X2 issues from the smell.
Turned out there are 3 Rifa's in the PSU circuit proper, one blown and 2 cracked in my case (C7, C63, C65).
Replaced these with Wima mkp10 47n/630V caps (15mm version MKP1J024704C)
There is one more Rifa on the PSU pcb: a 2.2nF Y2, replaced that one for good measure as well.
It is a pain getting the PSU out of the machine, and then the PCB from its case, but for the former problem there is a nice explanation in the hp manual floating around.
good luck,
Marc.
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Joe,
At first I tried getting the supply out without the manual, and got stuck.
Consulting the manual it turned out I did have to remove all those parts mentioned.
So the manual is correct, and I guess the input module needs to get out because the mains switch
is in the PSU and gets actuated from the front by a rod running between all those modules.
Marc.
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Thanks. Looks like I need to bench it, get it open and see what is making that smell. It has always put out a bit of odor when first switched on which I thought was a bit of out-gassing of plasticizers. When I first got it, I opened it up and it was very clean and free of any dust .? It had been in a factory test rack at an Ericsson phone factory and well kept. Now the odor seems worse. I have a bunch of projects on hold while I fix this.
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Hi. I have fixed severalnif my 8920 machines power supplies. Just be careful to use an insulated screwdriver when prising off the actuator rod off the switch in the psu. I had a friend that didn't and residual rectified mains volts off the reservoir caps shorted on the screwdriver with many blown parts as a result. A commin fault barvthe RIFA? caps is a 470 k resistor near the chopper transistor goes open. It doesn't look crook though.
And yes the silver input module has to come out.
Cheers, Simon.?
Sent from my Samsung Galaxy smartphone.
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Simon; thanks for the tips. Are you finding any electrolyte leakage or wearout of the reservoir capacitors?
.
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Hi,
I have not had any real issues with electrolytics per se or any leakage. Haven't noticed anything untoward but if you do have an issue and ESR meter is a good thing to have. Just make sure the caps haven't got any volts left in them...
I did have a real doozy on one of my machines in that while using the spectrum analyser on the 8920, sweeping across the DTT TV band (I was doing a site survey at my Mum's place to see if I could get enough signal to get terrestrial TV instead of satellite). The thing had grass on the low side of my sweep and no grass on the right side. If I remember correctly it was around 580 MHz? where the cutoff was.
Looking at the circuit I had narrowed it down to the input module. Interestingly enough I found that a SMD tantalum was pulling down the 15 volt supply. The unit switches oscillator components in to sweep different parts of the band. The Tant was on the outer edge of the board. You may see discoloring but mine was hard to notice.
Re the smell. All mine, I have 3 of them, all emit a smell on startup but seems to dissipate after a while or my nose is getting used to it. Never tried tracing it down what it is but if someone does, would be interested to find out!
Cheers,
Simon
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FWIW, my 8920B also emits the Bad Smell on power-on, but it dissipates and as far as I can tell the unit is working fine.
Hi,
I have not had any real issues with electrolytics per se or any leakage. Haven't noticed anything untoward but if you do have an issue and ESR meter is a good thing to have. Just make sure the caps haven't got any volts left in them...
I did have a real doozy on one of my machines in that while using the spectrum analyser on the 8920, sweeping across the DTT TV band (I was doing a site survey at my Mum's place to see if I could get enough signal to get terrestrial TV instead of satellite). The thing had grass on the low side of my sweep and no grass on the right side. If I remember correctly it was around 580 MHz? where the cutoff was.
Looking at the circuit I had narrowed it down to the input module. Interestingly enough I found that a SMD tantalum was pulling down the 15 volt supply. The unit switches oscillator components in to sweep different parts of the band. The Tant was on the outer edge of the board. You may see discoloring but mine was hard to notice.
Re the smell. All mine, I have 3 of them, all emit a smell on startup but seems to dissipate after a while or my nose is getting used to it. Never tried tracing it down what it is but if someone does, would be interested to find out!
Cheers,
Simon
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RFI-EMI-GUY
Burt K6OQK