Re: Kogan KGNFHDLED40C PSU crapped out ...
Have ordered 2 replacement FETs and a driver IC for the PFC circuit.
just for giggles while I wait, I powered up the board all fully connected (FET absent ...) and checked the PFC driver (L6562D) gate drive output pin vs VDC-. Nil DCV and only ~30mV AC present. Presumably either a shutdown beat me to it or the chip is compromised. Either way a spare is en-route so the chip may get the chop.
Sit and wait time.
pedro
Senior Member
Last Activity: 07-07-2019, 05:53 PM
Joined: 12-01-2009
Location: Sunny Perth
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Re: Kogan KGNFHDLED40C PSU crapped out ...
OK latest obs:
On application of power (NOT turn-on) both +12 and +24 appear for ~2 secs then disappear. Hitting ON causes both to power up for ~10 secs then a sub-second flash of backlight and both rails drop again.
Trusting the Leke schematic (unless stated otherwise, as it sems pretty relevant) the drive to T1 is def. affected, presumably by the PFC being disabled.Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
What I have matches both CON4 and CON3 on that leke schematic. The top CON in that row on mine is not in use.
So from that it seems I do (should have) +24V on CON6. Will check that later on, if so then 12 & 24 off T1 (leke) would make sense, and so the IC driving T1 is shutting down, prob due to PFC link. Hmmmm.Last edited by pedro; 03-29-2019, 03:06 AM.Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
No have both +5 and +5SB holding up, only the +12 drops off. VDC holds at ~340/350Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
That smoke test was with everything connected up so load was there and started with the POWER ON/OFF button, only the PFC FET missing. Was looking for some aberration to give me more clues. The only thing unexpected was the +5V holding up but the +12 going off.
As for scoping the driver, it's a PITA for several reasons. The driver is on the copper side (obviously) so hard to get access while the board is fully connected. If only the GD pin required that can be done from front OK. Also my scopes don't like having their "cold...Last edited by pedro; 03-28-2019, 06:46 PM.Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
OK had a chance to get back to this for a bit. Resistance readings on the PFC driver chip (L6562D):
+ to - to ohms diode test
. 8 7 H H
. 7 8 H L
. 7 6 H L
. 6 7 H L
(Oh for a font that respected white space.)
Vcc to gate drive OK showing the junction as expected. But those GD vs ground are worrying. Yes, 6->7 should show the protective diode, but 7->6?
Anyway plugged it back in and did a smoke test (no...Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
The FET's short every combination
Just been looking at the internals of the driver (ST L6562D) but I'm battling to see how a shorted G-S(-D) FET could take out the output (unless the VDC pulled the source up that high, source resistor looks like 1.8 ohms). And I can't see a valid test I could perform with no FET present.
(My profile says ProTech but I retired from this stuff a few years back, and there's not much selection available. I'm a bit rusty, so bear with me).Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
I'm a bit ahead of you already on that same track. Having SS pcb's and jumpers at least makes separation easier than DS pcb's.
Lifted J4 and the short disappeared. Pulled Q102 and reinstated J4, no short. Testing/replacing Q102 is next step, don't have a spare 2SK3455B or equiv lying around and it's Sunday. The question in my mind is whether having the PFC disabled thusly will allow otherwise normal function of the whole PSU (for testing ...).
Q102 is shorted. Now to dig up a replacement.Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
Quite similar in a lot of areas.
Update: Had a meter across the failed input fuse (F101, see attached partial schematic) to monitor current draw, but it was playing up. As previously mentioned, indicated 300W into the PSU only @160VAC with nothing getting that warm. Turned out to have an internal shunt failure - go figure, a $A400 DMM.
Anyway, jumpered the F101 and cranked up the variac, saw J2 go luminous and vaporise within 5 secs with still less than 50V in. OK, there's a short somewhere which...Last edited by pedro; 03-23-2019, 03:23 AM.Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
Normally do that, it was really a test to verify there was something faulty on that board - hence using the variac.
Well it was only intended for [B]recognition purposes[/B], not diagnostic work ...
I'll hopefully get a bit of time later on to get back on it.
Tnx for replies, appreciated.Re: Kogan KGNFHDLED40C PSU crapped out ...
Normally do that, it was really a test to verify there was something faulty on that board - hence using the variac.
Well...Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
Just powered the board up (no output connections) with a meter across the input fuse location. As the variac was wound up the current hit 2A at 160V input. 300VA into a board with no external load???
(Can't get the TV onto the space on the workbench and too hard to move the variac etc to the set.)
Didn't check for standby yet. Just to help, there are NO pinout markings at the output connectors (or at the other boards).
Link to pic: [URL="https://www.badcaps.net/forum/showthread.php?t=75...Leave a comment:
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Re: Kogan KGNFHDLED40C PSU crapped out ...
The main fuse - T5AH/250V - is immediately after the input header. The other fuse - T2AL/250V - (looks to be between the rectified DC area and the main PSU transformer driver pair) is OK.
The diode actually measures OK. It has a small crater on the base between the legs which looks v.suss but meters good. FSU10B6, presumably in PFC duty.
As an aside, cap brands present are a mix - Chang/Chong?, CapXon and xunda. The HV ones are CapXon 47/450.
Have been hoping someone may have a light-bulb moment...Leave a comment:
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Kogan KGNFHDLED40C PSU crapped out ...
Called out of retirement to look at a Kogan KGNFHDLED40C (rebadged chinese crap with Samsung panel). Died with a loud "crack" sound and smell of escaping magic smoke.
Power board shows a failed diode and a burst ceramic-body main fuse, the apparent source of the noise. Have posted in the schematics area with pic hoping someone can ID the board and maybe lead to a schematic.
Board labelled variously as "TE22 REV1.0 DX" and "39-TE22-PCA". Also one tag as ZD-95(G)F. Controller is Q0270R.
Panel FTW is Samsung LTA400HM08. -
TE22 power board
ex Kogan KGNFHDLED40C (rebadged chinese crap with Samsung panel).
Any help welcome.... -
Re: Philips 42PFL9632D/79 2-secs-to-black
You're in Perth too? Want this set to play around with? Please. It's gathering dust right now and I need the space it is taking up.Leave a comment:
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Re: Insignia NS-L37Q-10A - No power (no standby light?)
That is not consistent with the voltages you reported, unless it has died since then .......Leave a comment:
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Re: Insignia NS-L37Q-10A - No power (no standby light?)
Those two regs are not getting source voltage so they can't put out their spec, and are *probably* fine. You need to look "upstream" from them to find out where their supply is and what is wrong with it....Leave a comment:
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Re: Philips 42PFL9632D/79 2-secs-to-black
Actually I should have said "mod kit #2" but we are on the same wavelength. (The repair kit is the four FETs and the driver IC). No I don't *need* the mod kit but was intending on fitting it while the set was here *IF* the cold start issue was resolved.
Interestingly, selecting a TVS diode for this application isn't as straightforward as some might expect. The ratio of clamping voltage to standoff voltage creates an issue, as anything with a >24V standoff will NOT have a clamping voltage less than the driver's...Leave a comment:
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Re: Philips 42PFL9632D/79 2-secs-to-black
Still no response from Philips service on their "repair kit" for these inverters.
Have spent a lot of time (probably too much) searching for a schematic for these boards, using search terms LC420WU5, PNEL-T707A etc but no joy to date. Has anyone ever seen one?
Without a schematic, and with the heat-testing not being able to identify *which* component is responding, this set looks destined for the dumpster shortly. I'm not thrilled by the prospect of a $50 chinese clone board as a long-term solutio...Leave a comment:
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Re: Philips 42PFL9632D/79 2-secs-to-black
The Samwhas on the two inverter boards have been replaced with Panasonic FR's. Recall that on the ESR meter the Samwhas measured 0.02 out of circuit (the same spec as the FR's) and I wasn't expecting the FR's to make any difference. No surprise - they didn't. But at least that variable has been removed from the equation.
Decide that while I'm in here I may as well also fit the Philips/LG mod #2 kit, which has the Philips part# 996500095005. Philips are still trying to look it up ....Leave a comment:
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