Re: Replacing a choke coil
The 494 is a generic PWM controller chip. It can be used for all sorts of different applications with completely different topologies. The datasheet isn't going to tell you anything useful about the implementation on your board.
What model of motherboard is it?
I probably have one here I can take a look at and figure it out for you, though the actual value isn't likely to be super critical as long as it is high enough to filter appropriately....
drussell
Senior Member
Last Activity: 08-07-2022, 11:40 AM
Joined: 11-04-2014
Location: Calgary, AB
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Re: panasonic tcp50s30 plasma... white level adjustment, how and where?
Does holding down [B][VOL-][/B] on the TV and pressing [B][STATUS][/B] [B][STATUS][/B] [B][STATUS][/B] on the remote enter service mode on the S30 series?
The only similar one I have here is a TC-P55ST30 but it has a cracked panel, so I can't try it to check.
Re: panasonic tcp50s30 plasma... white level adjustment, how and where?
Does holding down [B][VOL-][/B] on the TV and pressing [B][STATUS][/B] [B][STATUS][/B] [B][STATUS][/B] on the remote enter service mode on the S30 series?Leave a comment:
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Re: Two SONY VCRs eating tapes
Indeed, however, the OP states that he wants to somehow magically fix these VCRs without removing any covers and opening them up.
I believe that this would prove to be exceedingly difficult.
...
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Re: Two SONY VCRs eating tapes
I really don't understand what the OP is asking. If these units are new (unlikely since Sony hasn't made a VCR for years) then return them. If they're from a thrift store or something then you have a choice. If you think there is enough potential value there vs. what you paid to attempt a repair (which will almost certainly be successful by the sounds of it) then just proceed to void your "warranty" and fix one or both of them. If you take them back to a thrift store, they're just going to give you your money back and then throw them in the...Leave a comment:
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Re: Tx-p42x50b Green/Red dots sparkles static!
Indeed, turning down the brightness setting often reduces sparklies but they really shouldn't be there at all on a 2012/13 panel unless it has very high hours on the panel or has some sort of fault, hence the reason I suggest to the OP to check that the panel voltages are correct before trying to correct the issue or minimize the symptoms, even with the user settings.
Sparklies were [I]much[/I] more common on earlier generations of panels, regardless of age than the last few generations that were manufactured....Leave a comment:
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Re: Tx-p42x50b Green/Red dots sparkles static!
Yeah, those [B]FAN6755[/B] standby PSU controller chips at U203 on the power supply board were faulty in a bunch of models. This chip has a strange, sordid history with Fairchild being sued for patent infringement and agreeing to discontinue it, so there is virtually no admission that they ever made them at all, let alone a whole bunch of faulty ones.
The sets affected includes [I]at least[/I] (according to the Panasonic service bulletin,) the following 42 and 50 inch models with the [B]N0AE6JK00005[/B] power supply...Leave a comment:
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Re: Elcap Capacitors
[B]+[/B] signs on both ends means it is bipolar.
In a speaker crossover application like this, the capacitors [B]MUST[/B] be bipolars.
There are several ways of marking an electrolytic as being bipolar, the [B]+[/B] signs at each end being the most common. In a pinch or for testing, you can also use two regular electrolytics of [I]twice the [B]uF[/B] value each[/I] in series, connected [B]-[/B] to [B]-[/B] (well, or technically [B]+[/B] to [B]+[/B], it doesn't actually matter which) to create a bipolar electrolytic....Leave a comment:
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Re: Elcap Capacitors
The sound quality from film capacitors is significantly better than electrolytics. The only drawback is the increased cost, especially for larger values where the cost of even "cheap" film capacitors becomes prohibitive in most cases.
A typical compromise is to use film capacitors for the tweeter and midrange crossovers where it is most critical and use electrolytics for woofers, subwoofers and impedance correcting zobel networks where large values are required, though if you want to spend the money or are building/repairing really high-end...Leave a comment:
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Re: Getting Windows to boot after changing SATA from RAID to AHCI
Is your 2TB external drive a traditional standard 512 byte/sector drive or is it 4096 byte/sector?Leave a comment:
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Re: Samsung PN59D550C1FXZA, X-sustain, shorted fets from bad panel?
To answer this specific question... It depends.
The capacitors themselves should show open circuit but you also need to consider what else they are connected to on the board to possibly account for the 723 ohms. (As an example, a capacitor placed directly across a coil to form a parallel resonant circuit will measure virtually 0 ohms resistance like a direct short because the coil is across it, even if the capacitor is perfectly fine.) If you suspect any of the capacitors themselves...Leave a comment:
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Re: Samsung PS42A410 Vertical green bars
Does anything change (other than losing half of the picture) if you disconnect one or the other of the X-Buffer boards from the logic board, or does the TV fault out if you try it with one side disconnected. Most will power up with only half the screen connected and if you happen to get good picture on one side but the other one messes up the whole screen then the fault is probably in that half of the X-Buffer set rather than in the center logic board.Leave a comment:
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Re: Samsung PS42A410 Vertical green bars
Indeed. I should have looked closer, was just looking at your first couple screen photos. These kinds of faults are more common on LCDs but the principle in this part of the signal chain is the same. Something is going wrong between where the picture is generated to be sent to the buffer boards along the bottom and since the problem repeats on every set of buffers, it is most likely the signal [I]getting[/I] to the buffers is mangled rather than it being the buffers itself (mangling only its outputs) like it would be if...
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Re: Samsung PN59D550C1FXZA, X-sustain, shorted fets from bad panel?
I'm not sure what you're expecting people to be able to do for you...
Since you obviously have shorts and faulty components, you're on the right track by trying to find all the shorts and defective components but you can't tell much about many individual components while they're in-circuit without looking at the circuitry in question and understanding what the component is doing, what it is connected to.
Seeing actual flashes means you have one or more severe faults and probably multiple...Last edited by drussell; 12-12-2018, 07:07 AM.Leave a comment:
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Re: Sasmung la40m81bd - Recapped
Just a quick aside... There is no such thing as a 163 volt capacitor rating. 63? Yes. 100? Sure. 150 or 200? Yup...
Even 160 and 165 are something that (while rare), do actually exist but I've never seen a [I][B]1[/B]63[/I] volt capacitor.Re: Sasmung la40m81bd - Recapped
Just a quick aside... There is no such thing as a 163 volt capacitor rating. 63? Yes. 100? Sure. 150 or 200? Yup...
Even 160 and 165 are something that (while rare), do actually exist but I've never seen a [I][B]1[/B]63[/I] volt capacitor.Leave a comment:
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Re: Samsung PS42A410 Vertical green bars
You're obviously getting corrupted data to each bank of outputs to the panel, so either a connection problem between T/CON, shorted lines either on T/CON, cable or buffer board input or distribution lines to each bank across the board, or bad components on T/CON (bad processing chip or memory or whatnot, depending on design.)
Does re-seating the cables from the T/CON to X-Buffer board change the pattern at all? If it is not physical connection related it is [I]probably[/I] T/CON but could obviously also be a problem on the...Leave a comment:
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Re: Samsung Plasma PN60E550D1F Power LED Blinks, Appears To Come On, No Display
It sounds like your project set has more than one issue, but one of them does indeed seem to be the lack of [B]-Vscan[/B] since you now seem to briefly see the correct voltage on [B]-Vscan[/B] after chilling the entire Y-Main, whereas you did not before. That means the controller [I]is[/I] starting under those (chilled) conditions, but you probably still have another fault elsewhere since the set is apparently not coming fully powered up.
That is what made it difficult to find...Leave a comment:
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Re: Samsung Plasma PN60E550D1F Power LED Blinks, Appears To Come On, No Display
That sounds normal under lockout conditions. This board could be fine.
That is abnormal.
Don't plug this one in again without further pre-testing or you might damage other still functional components in the TV.
Uhhh, no...
Put the seemingly good X-Main in (including actually installing all of the screws on all boards) and do the prescribed tests....Leave a comment:
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Re: Samsung Plasma PN60E550D1F Power LED Blinks, Appears To Come On, No Display
Heh... 1100+ posts and no oscilloscope.
Does your meter have a min/MAX function? If that chip doesn't see close to 18V on VCC and actually start, you get insta-lockout....Leave a comment:
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Re: Samsung Plasma PN60E550D1F Power LED Blinks, Appears To Come On, No Display
The lack of [B]-Vscan[/B] will cause an immediate shutdown of the HV PSU. This lockout usually occurs before the [B]Ve[/B] even really starts to come up, which is what initially misled me to the X-Main board when I was first troubleshooting this particular issue.
Did you try the most basic of the troubleshooting from the other thread? Cooling the Y-Main by putting it in the freezer for a few minutes or shooting that area with freeze spray will often allow a verification power-on test....Leave a comment:
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Re: Samsung Plasma PN60E550D1F Power LED Blinks, Appears To Come On, No Display
The capacitors will not [I][I]look[/I][/I] bad in any way. They aren't [I]physically[/I] leaking.
They will also read right about 10 uF on a standard low voltage capacitance tester and will work just fine in most circuits. You would have to do an [B][I]electrical leakage[/I][/B] test out of circuit with 20+ volts across the cap to see the issue and we are probably talking about uA magnitude leakage here. If you have an olde-timey capacitor leakage tester, (like the ones with...Leave a comment:
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