FSP139-3F01 smps power supply, and it got me stumped.
fuse was blowing, found the diode bridge with one shorted diode, but even with bridge out, the circuit doesn't really act like a typical smps, where one expects to see resistance go up as mains lytic is charging up (i have analog meter on low ohms in both directions, and digital meter show around 400-500 in diode test, also in both directions).
what interests me the most is the design with 3 chips, ie what is the purpose of u601/q601 circuit?
(chips on soldering side have their markings erased)
also, what's this j108, r501-502,j109 link of mains (unrectified) power to somewhere around u501?
i plan to unhok the L602 to see if the short circuit is in that branch.
i bet it's the standard way of doing lcd supply, but surely a first for me...
pix attached (some jumpers and diodes are cut from above, that was me searching for the short circuit)
(btw. grundig was a famous german brand that is now mostly turkish/chinese labour and parts)
fuse was blowing, found the diode bridge with one shorted diode, but even with bridge out, the circuit doesn't really act like a typical smps, where one expects to see resistance go up as mains lytic is charging up (i have analog meter on low ohms in both directions, and digital meter show around 400-500 in diode test, also in both directions).
what interests me the most is the design with 3 chips, ie what is the purpose of u601/q601 circuit?
(chips on soldering side have their markings erased)
also, what's this j108, r501-502,j109 link of mains (unrectified) power to somewhere around u501?
i plan to unhok the L602 to see if the short circuit is in that branch.
i bet it's the standard way of doing lcd supply, but surely a first for me...
pix attached (some jumpers and diodes are cut from above, that was me searching for the short circuit)
(btw. grundig was a famous german brand that is now mostly turkish/chinese labour and parts)
Attached Files