I have a plasma TV set that I am having some intermittent problems. Its occasionally powering off and not restarting until the TV sits for a while.
It was recapped with Panasonic FC/FM's that did not solve the problems and have a separate post that has more details:
[url]https://www.badcaps.net/forum/showthread.php?p=729382#post729382[/url]
Im now inspecting the PS board and have attached some photos below that show some of the more suspicious solder joints. None of the joints seem at all loose or not solid. Im not sure if a cold or ringed solder joint could...
kumasan
Member
Last Activity: 05-03-2017, 01:25 PM
Joined: 12-06-2014
Location: San Jose CA
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Possible Cold Solder Joints, Help to interpret photos ?
Last edited by kumasan; 03-04-2017, 10:21 PM. -
Re: Questions on ESR/RC, replacement cap selection
Here is one such example datasheet that seems to not provide ESR spec:
Seems as PeteS suggested, the higher voltage (>/= 160V) caps usually don't have their impedance specified.
I ended up getting the same series caps in 30mmx40mm (old caps size) from Mouser, looks like they had them in stock.
Thanks again for the assistance,
Kuma -
Re: Samsung 50" Plasma Recap
My soldering unit is a HAKKO 836 (36w) so it is a little underpowered. I may have a handheld unit that has more wattage. For desoldering Im using one of the velleman cheap handheld units but the tip is a little too large for some jobs.
Been meaning to pickup a better soldering iron for heavy applications and a desoldering unit. Any suggestions for decent quality/price units?
KumaLeave a comment:
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Re: Questions on ESR/RC, replacement cap selection
So if I understand correctly the cap/datasheet I pointed to earlier in the thread does not list any ESR for the cap or any way to determine with the information they provide. So basically I cannot tell which of two similar caps has a lower ESR?
If this is the case I guess these high voltage version caps are all non low-esr and so the manufacturer does not list any specs.Leave a comment:
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Re: Questions on ESR/RC, replacement cap selection
Thanks for the info and tips.
RC=ripple current.
Regarding the listing of ESR I think I did not realize that the DF (dissipation factor) could be used to derive the ESR as digikey explicitly lists ESR for some series of cap. So if I understand correctly I can calculate ESR=DF/(2*3.14*freq*C) or more importantly I can use the DF to compare the cap ESR's.
After some more research into the problem and looking at the schematic it seems the caps are the output caps for a switching cap boost converter...Leave a comment:
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Samsung 50" Plasma Recap
Have one of the Samsung 50" plasma, same model with the recalls for bad caps in power supply DYP-50W2, schematic same as in this post:
[url]https://www.badcaps.net/forum/showthread.php?t=32884[/url]
I was having intermittent problem where the TV would randomly shut off and refuse to turn back on, just an initial click, and sometimes the TV would magically turn itself back on 10 minutes later.
I recapped the main power supply, all caps except the big high voltage ones and the TV seemed to be better but shortly resumed the same or similar intermittent... -
Questions on ESR/RC, replacement cap selection
Hello veterans, thanks to help from you all I have managed to save numerous motherboards, monitors and appliances but Im still trying to improve my technique and have some questions on cap selection.
Current project is a samung 50" plasma set that I bought some replacement caps for one of the larger caps that Im starting to have second thoughts about my purchase.
I have generally used Panasonic FC/FM for my recaps of the smaller caps but with the high voltage none of the usual "good maker/series" caps from the forum are not available. I had a challenge... -
Re: Onkyo TX-DS797 Standby Transformer substitution help
Checked the mains voltages and they all looked ok.
Im not exactly sure what was happening but It now seems to be working.
While checking the mains I disconnected the power connector from the power regulator board to the mainboard that the back cards plug into while in standby mode. I made the mistake of plugging it back in while in standby mode and the main power supply relay and display were flashing/sparking away. After it got plugged in I rechecked the voltages and everything looked ok.
...Leave a comment:
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Re: Onkyo TX-DS797 Standby Transformer substitution help
Replaced the transformer and now I can turn on the unit and work the controls. Looks like the input side is working as I can select tuner or external optical in and see the digital modes change when I apply/remove a valid signal.
Problem is Im not getting any sound at all not even a click from the speakers.
Checked voltage from standby supply and it seems ok, think problem is probably not due to transformer issue.
When I power on the amp I get the first standby relay click and a...Leave a comment:
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Re: Onkyo TX-DS797 Standby Transformer substitution help
Thanks for the reply, much appreciated.
The schematic for the supply card is very simple, just the full wave rectifier and relay circuit. I tried to trace the supply output through the schematics but when it goes into the first block they abstracted the signal into a bus and it is not clear where the signal disappears.
Based on your reply and some more thought im thinking that the supply is not regulated so it must have some downstream rectification and tolerance for higher voltage.
...Leave a comment:
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Onkyo TX-DS797 Standby Transformer substitution help
I have an Onkyo TX-DS797 av amp that I am trying to repair. We had a 600v power surge thanks to local power company that took out the units standby power supply. Unit was not on so I think the main transformer and guts is ok but the standby power supply is always on to feed the microprocessor and work the relay to enable the main power supply.
Upon debugging I found the primary coil of the standby power supply blown.
Im having a challenge to find a suitable replacement transformer as the original model seems to be an unlabeled proprietary unit made by tamura:
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Re: Hans HG281D yellowed screen on top/center
Thought I should mention that the pinkish tint might be an artifact of the camera, the key issue I was seeing when viewing with the eyes is the yellowish tint at the top/right center.Leave a comment:
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Re: Hans HG281D yellowed screen on top/center
Could not find any service menu (unless there is some hidden way to access it).
I guess if it is the tubes it may be expensive to get parts unless I can find some cheap tubes online somewhere. Anybody know what size tubes are in these monitors?
I had seen some LED upgrade replacements online where you swap in a controller board and LED strips in place of inverter but the ones I had seen were expensive ~90$ Anybody have experience with these upgrades and know of a reliable source?
Im wondering if...Leave a comment:
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Hans HG281D yellowed screen on top/center
Hello, Im having some problems with an HG281D monitor related to a yellowish tint at the center of the screen more to the top (please see attached photos). Second photo has some noise picked up by camera but it is not visible to the eye (not sure if the patterns give any clues).
The monitor had previously been dead (couple seconds then blanking out) and I recapped the power and logic boards except for the 12 small caps on logic board. After replacing the 5 100uf caps on the logic board the monitor came back to life but now has a yellowish tint in the center of the screen and more... -
Re: Hanns-G HG281D, LCD Monitor no power
Per previous post, attached photo of the problem with the yellowed screen after recap.
The second photo shows some artifact from the camera (does not look this way) but the pattern seen by camera might shed some light on the problem.
Any ideas as to what to check next appreciated.
Thanks,
Kuma...Leave a comment:
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Re: New Members - please post your introductions here
Hello, Im new to the board and wanted to introduce myself. I am an electrical engineer (work on software programs to design the chips that go into PC/phones, ...).
I used to work on pc and electronics repair as a child in the 70's and have more recently fixed a couple motherboards and monitors with basic bad caps (thanks to help from this site).
I have to admit my soldering skills are green and the repairs I have made have not been completely smooth.
My latest projects, just repaired...Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Have one of these HG28 monitors that went out. Started with the power supply and replaced all caps with panasonic's. Did not fix the problem.
Next I replaced the three big caps on the logic/control board, followed by the five 100uf caps which brought the monitor back to life but not 100%. Problem now is that the colors seem off and the center of the display has a yellowish tint (left and right side and bottom seem to have less yellowing).
I have a couple questions would greatly appreciate feedback from you experts....Leave a comment:
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