Hi all,a fairly long description follows so sorry if i bore anyone.
Got a power supply in for repair from a Humax LGB32TPVR LCD TV, the PSU is made by KN-Powertek & carries the numbers PW402k-32 & KNP-3300.
When i first got the PSU in i could see that all the voltages were taking a while to steady up & knowing that this PSU is famed for having cap problems i changed those parts. Now the PSU springs nicely into life (on the bench) & the voltages are there, steady & exactly as they should be under load.
Problem i have is this, normally PSU's i repair have a Standby pin & an On/Off or simiilar marked pin (as on the Samsungs). To switch a power supply on you normally have to connect the 5VS to the On/OFF switch (as with the Samsungs for example). On this however , with NO connection between these 2 pins, the relay immediately pulls in & the voltages all come up & the only way to switch them off is to ground the On/Off pin which drops out the relay. Now, as i dont have the rest of the set, just the PSU & i cant find a circuit diagram anywhere it could be i'm chasing a non - existant fault & that this is the way it should work. Connecting the 5VS to the On/Off does nothing, relay stays pulled in & the voltage on the On/Off pin is floating around 3v which makes me think that this is the way the thing works & that the standby voltage is connected to another board which has the standby LED & causes the On/Off pin to be grounded when switch off is required.
Anyone worked on this chassis or know where i can get the PSU cirsuit diagram or the Service Manual, usual locations have drawn blank.
Thanks in advance.
Got a power supply in for repair from a Humax LGB32TPVR LCD TV, the PSU is made by KN-Powertek & carries the numbers PW402k-32 & KNP-3300.
When i first got the PSU in i could see that all the voltages were taking a while to steady up & knowing that this PSU is famed for having cap problems i changed those parts. Now the PSU springs nicely into life (on the bench) & the voltages are there, steady & exactly as they should be under load.
Problem i have is this, normally PSU's i repair have a Standby pin & an On/Off or simiilar marked pin (as on the Samsungs). To switch a power supply on you normally have to connect the 5VS to the On/OFF switch (as with the Samsungs for example). On this however , with NO connection between these 2 pins, the relay immediately pulls in & the voltages all come up & the only way to switch them off is to ground the On/Off pin which drops out the relay. Now, as i dont have the rest of the set, just the PSU & i cant find a circuit diagram anywhere it could be i'm chasing a non - existant fault & that this is the way it should work. Connecting the 5VS to the On/Off does nothing, relay stays pulled in & the voltage on the On/Off pin is floating around 3v which makes me think that this is the way the thing works & that the standby voltage is connected to another board which has the standby LED & causes the On/Off pin to be grounded when switch off is required.
Anyone worked on this chassis or know where i can get the PSU cirsuit diagram or the Service Manual, usual locations have drawn blank.
Thanks in advance.
