More Elec. Cap Failures
- Thread starter sleddriver
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Originally Posted By: kc8adu
and a lot of those are counterfeit garbage!
Originally Posted By: i_hate_autofraud
Ebay will show some results if you search "low ESR cap", etc.
Which is why it's probably worth eating the $10 shipping charge at Digi-Key or Mouser for the assurance of knowing those caps are the real deal from an authorized distributor.
Unless you live in a town that still has an real electronics supply shop.
and a lot of those are counterfeit garbage!
Originally Posted By: i_hate_autofraud
Ebay will show some results if you search "low ESR cap", etc.
Which is why it's probably worth eating the $10 shipping charge at Digi-Key or Mouser for the assurance of knowing those caps are the real deal from an authorized distributor.
Unless you live in a town that still has an real electronics supply shop.
a small order of caps can go usps 1st class for about $3 at digikey.
there is zero reason to buy caps on ebay and roll the dice!
Originally Posted By: nthach
Originally Posted By: kc8adu
and a lot of those are counterfeit garbage!
Originally Posted By: i_hate_autofraud
Ebay will show some results if you search "low ESR cap", etc.
Which is why it's probably worth eating the $10 shipping charge at Digi-Key or Mouser for the assurance of knowing those caps are the real deal from an authorized distributor.
Unless you live in a town that still has an real electronics supply shop.
there is zero reason to buy caps on ebay and roll the dice!
Originally Posted By: nthach
Originally Posted By: kc8adu
and a lot of those are counterfeit garbage!
Originally Posted By: i_hate_autofraud
Ebay will show some results if you search "low ESR cap", etc.
Which is why it's probably worth eating the $10 shipping charge at Digi-Key or Mouser for the assurance of knowing those caps are the real deal from an authorized distributor.
Unless you live in a town that still has an real electronics supply shop.
Well further investigation reveals that an 8p smd dc-dc-cnvrtr may be at fault. I've checked all surrounding programming devices. They're good. I've also disconnected the buss to remove it and isolate the IC itself. Vout is till too low. The other issue that came to mind is something preventing the IC switcher from starting. To remain in low/standby state instead of ON. Unfortunately these parts NEW are hard to come by. Used are questionable at best.
I'd love to see the schematic for the supply you are working on.
Caps marked in red were swollen. I replaced all AEC's except for one, maybe two as they were HQ Panasonics rather than the defective Elnas. The below clip may not blow up well. Not sure if I can post a pdf here or not. Please advise.
110Vac enters from top left, through filter, then diode bridge, then into xnsfr pri. Vdc there is about 140V. Below the filter section is the main hot-side switcher IC, a MR1251. I replaced it which brought most of the supply back on-line.
The first 8p IC to the right of the xnsfrmr is suspect. It's a MD5001T. No swollen AEC's were found near it. Other C's and R's that 'program' it to Vout = 5V were also ok. As was the Schottky diode tested in ckt. on the output. Vout P8 is the top right one.
Either this IC isn't being turned on or capable of being turned on, the output is Tango Uniform or the whole thing is. The wire jumper I snipped is somewhat visible. All other rail V's are OK at the board connector shown on the top right. Thanks for your interest!
110Vac enters from top left, through filter, then diode bridge, then into xnsfr pri. Vdc there is about 140V. Below the filter section is the main hot-side switcher IC, a MR1251. I replaced it which brought most of the supply back on-line.
The first 8p IC to the right of the xnsfrmr is suspect. It's a MD5001T. No swollen AEC's were found near it. Other C's and R's that 'program' it to Vout = 5V were also ok. As was the Schottky diode tested in ckt. on the output. Vout P8 is the top right one.
Either this IC isn't being turned on or capable of being turned on, the output is Tango Uniform or the whole thing is. The wire jumper I snipped is somewhat visible. All other rail V's are OK at the board connector shown on the top right. Thanks for your interest!
Originally Posted By: Papa Bear
Years ago when I was in electronics I remember the SMPS circuits would get a leaky cap in the voltage regulation feedback circuit (usually a low value cap like a 1u or a .47u) and that allowed the voltage to creep up blowing other filter caps in the power supply.
Interesting. Didn't think to check for leakage. SMPS are a steep learning curve for me. Very persnickity! Next time the iron's hot I may just replace all of the small caps to see if it makes any difference.
Thanks for the tip!
Years ago when I was in electronics I remember the SMPS circuits would get a leaky cap in the voltage regulation feedback circuit (usually a low value cap like a 1u or a .47u) and that allowed the voltage to creep up blowing other filter caps in the power supply.
Interesting. Didn't think to check for leakage. SMPS are a steep learning curve for me. Very persnickity! Next time the iron's hot I may just replace all of the small caps to see if it makes any difference.
Thanks for the tip!
There are many different ways to skin a cat (design an SMPS)
I have seen some that were so simple - so forgiving .... and some that totally blew up if you looked at them wrong.
Yours is one of the uglier ones ....
Good luck to you.
I have seen some that were so simple - so forgiving .... and some that totally blew up if you looked at them wrong.
Yours is one of the uglier ones ....
Good luck to you.
Gee and I was hoping for a grand AH-HA from the great white north! So disappointing......
Before replacing the bad caps + main switcher IC, the whole thing was Toes Up. Now it's just one rail. However, this one is definitely a "nested switcher" where each V-rail comes from a 'lower-tier' switcher IC. A bit of a bugger to learn on but there it is.
Thank GOD I fixed my old Tek o'scope a few years back when it was acting up. Wish I had the Fluke 77 issues straightened out. I think it has a leaky transistor.
Before replacing the bad caps + main switcher IC, the whole thing was Toes Up. Now it's just one rail. However, this one is definitely a "nested switcher" where each V-rail comes from a 'lower-tier' switcher IC. A bit of a bugger to learn on but there it is.
Thank GOD I fixed my old Tek o'scope a few years back when it was acting up. Wish I had the Fluke 77 issues straightened out. I think it has a leaky transistor.
It didn't go Tango Uniform from that. Further testing reveals it may have overheated from having too much current pulled out due to a faulty IC downstream. I traced all IC's fed from it and the list is very extensive.
I remember like a bad dream (nightmare) when units like yours came into the shop right after a lightning storm.
I'd even have to change the transformers to get the supply to stop blowing up.
And you had to change all the parts all at once... leave one defective part in and all the new stuff smoked.
Good luck - I feel your pain.
As Kenny Rogers said so well "You gotta know when to hold 'em .. know when to fold 'em"
I'd even have to change the transformers to get the supply to stop blowing up.
And you had to change all the parts all at once... leave one defective part in and all the new stuff smoked.
Good luck - I feel your pain.
As Kenny Rogers said so well "You gotta know when to hold 'em .. know when to fold 'em"
No lightning damage fortunately. However, diagnoses has turned into a black hole time-wise. I don't like giving up either so I press on. Odd so many reports of "all fine" after cap replacement, yet mine continues to frustrate. Rotten luck....
I've ordered a replacement dc-dc buck converter IC, confirmed there are no shorts downstream, traced some more PCB tracks and verified parts I found. I also discovered that this 3.3V rail is key to a good 'sys pfail' flag. Without it, the firmware hangs waiting for the flag to clear. I even tried adding 4V from a bench supply to make up for it, yet the unit still wouldn't complete it's 'self-check' routine. Odd that....
The IC output current is 1A max and features over-temp and protection built in. Yet it still failed. Mine's not alone. Failure results in several errors commonly seen posted.
The IC output current is 1A max and features over-temp and protection built in. Yet it still failed. Mine's not alone. Failure results in several errors commonly seen posted.
Originally Posted By: sleddriver
It didn't go Tango Uniform from that. Further testing reveals it may have overheated from having too much current pulled out due to a faulty IC downstream. I traced all IC's fed from it and the list is very extensive.
I'm quoting myself as a way to edit this earlier post. This problematic IC is a known cause of U81 errors and others. There are no signs it is internally shorted between the power pin and ground, which would usually short. So something else internally happened. I await its replacement to determine if it is the chief cause of the units current non-start state or if something else is amiss.
I originally thought it supplied MOST of the Vcc rail power as well. Turns out that duty is carried by the 1.8V rail which feeds two downstream regulators (1.2V and 1.5V) which then provide power to several IC's. The analog IC's have their own regulated power rails, separate from the digital domain.
The above diagram is the first page of the PS. Additional cktry is located on the 2nd page. I traced through what IC's were powered by which rails. D3.3V feeds about 18 IC's, making it quite critical.
It didn't go Tango Uniform from that. Further testing reveals it may have overheated from having too much current pulled out due to a faulty IC downstream. I traced all IC's fed from it and the list is very extensive.
I'm quoting myself as a way to edit this earlier post. This problematic IC is a known cause of U81 errors and others. There are no signs it is internally shorted between the power pin and ground, which would usually short. So something else internally happened. I await its replacement to determine if it is the chief cause of the units current non-start state or if something else is amiss.
I originally thought it supplied MOST of the Vcc rail power as well. Turns out that duty is carried by the 1.8V rail which feeds two downstream regulators (1.2V and 1.5V) which then provide power to several IC's. The analog IC's have their own regulated power rails, separate from the digital domain.
The above diagram is the first page of the PS. Additional cktry is located on the 2nd page. I traced through what IC's were powered by which rails. D3.3V feeds about 18 IC's, making it quite critical.
YES!!
Today is the day I've been looking for! The new IC arrived in the mail, I soldered it in and now have a D3.3V rail! Next reinstalled the main board, DVD & HDD, and PSB back into the chassis and plugged it in. It ran through it's start-up routine, finished, then turned off automatically (which is normal).
I turned it back on and it remembered its previous check, so it quickly went to the main page. Remote works as before. Haven't reinstalled it into the rack yet. I'll run through some service menu checks first.
Very pleased this turned out OK!
Today is the day I've been looking for! The new IC arrived in the mail, I soldered it in and now have a D3.3V rail! Next reinstalled the main board, DVD & HDD, and PSB back into the chassis and plugged it in. It ran through it's start-up routine, finished, then turned off automatically (which is normal).
I turned it back on and it remembered its previous check, so it quickly went to the main page. Remote works as before. Haven't reinstalled it into the rack yet. I'll run through some service menu checks first.
Very pleased this turned out OK!
Cool beans !
Thanks.
Here's more news: Though DVD's were played fine after reassembly, all media on the HDD was no longer in the navigator menu! IOW, no longer accessible. What I've read indicated that the HDD TOC is stored in RAM on the MB. Obviously this was erased due to having the unit off-line for such a long time during repair. I knew all the media was still present, but how to access it?
While reading over the service manual, I noticed the code to initiate a "HDD read inspection." I thought by doing this it would find the TOC on the HDD and reload it into RAM, allowing me access to the recorded material.
It took 4hrs to verify the 80G HDD and it reported no errors. It also did as I hoped and restored access via the Navigator function! Wow, am I happy! Murphy lost this one. Now I can transfer the HDD content to the confuser using DVD-RAM disks.
Time to celebrate well!
Here's more news: Though DVD's were played fine after reassembly, all media on the HDD was no longer in the navigator menu! IOW, no longer accessible. What I've read indicated that the HDD TOC is stored in RAM on the MB. Obviously this was erased due to having the unit off-line for such a long time during repair. I knew all the media was still present, but how to access it?
While reading over the service manual, I noticed the code to initiate a "HDD read inspection." I thought by doing this it would find the TOC on the HDD and reload it into RAM, allowing me access to the recorded material.
It took 4hrs to verify the 80G HDD and it reported no errors. It also did as I hoped and restored access via the Navigator function! Wow, am I happy! Murphy lost this one. Now I can transfer the HDD content to the confuser using DVD-RAM disks.
Time to celebrate well!
That sounded like what I did to a old Sony DVR - the hard drive had to be initialized and formatted. The system firmware was loaded onto an EEPROM somewhere. My dad still has it but it's worthless unless it's hooked up to a cable box or a DTV converter as the tuner is analog-only.
The hard drive is a 120GB IDE drive, and no one is making that interface anymore. That means time for a SATA-IDE adapter or install a SD/mSATA to IDE card.
The hard drive is a 120GB IDE drive, and no one is making that interface anymore. That means time for a SATA-IDE adapter or install a SD/mSATA to IDE card.
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The tuner in the Pan. is NTSC analog, so similar to your Sony. I use it with an external ATSC tuner box. The timer function still works and I use it to time-shift OTA programs. Unable to use a larger HDD as the firmware is set to use only a single size. With this all said, it's been in regular use with no issues until recently. Having the PS recapped with fresh, low-z switcher caps means it'll be operating better & cooler than previously. Too bad Pan. didn't bother to use their own excellent AEC's in their own consumer products!
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