Hello everyone,
I'm trying to repair a 24V PSU from a Ricoh SP 150w printer.
So far I found and replaced:
- a burnt 33Ohms 1W resistor (R820 - top side next to main cap)
- a shorted mosfet (Q801 - top side on heatsink)
- 2 shorted optocouplers (U801, U201 - top side)
- a burnt/chipped? (didn't read any resistance) SMD resistor (R828 - back side next to the PWM IC)
- the PWM controller (IC801 - back side)
There is no output voltage at all.
I do get a stable voltage at the main capacitor (320V) but I think the PFC is not working.
The PWM IC was marked 83H08P which is supposedly an OB2283 PWM controller (possibly a copy of the original?). VCC at this IC reads 6.3V which I think is not enough to get it started (needs 12-28V).
The board looks quite different than the standard schematic from the datasheet. I don't really know how it is supposed to receive that voltage.
I tested a lot of SMD components at the back (resistors, diodes, caps,...) which were ok so I don't see what else I can try from here.
Any ideas?
Thank you ,
Hervé
----
PS: As you can see I damaged the back with the hot air station (too hot) trying to remove the diode... Because of this the board may be compromized a bit, but the traces are still intact, so maybe I can still learn something from it.
PS2: Here is a link to a russian forum with much better images than I can produce. Especially the last post.
I'm trying to repair a 24V PSU from a Ricoh SP 150w printer.
So far I found and replaced:
- a burnt 33Ohms 1W resistor (R820 - top side next to main cap)
- a shorted mosfet (Q801 - top side on heatsink)
- 2 shorted optocouplers (U801, U201 - top side)
- a burnt/chipped? (didn't read any resistance) SMD resistor (R828 - back side next to the PWM IC)
- the PWM controller (IC801 - back side)
There is no output voltage at all.
I do get a stable voltage at the main capacitor (320V) but I think the PFC is not working.
The PWM IC was marked 83H08P which is supposedly an OB2283 PWM controller (possibly a copy of the original?). VCC at this IC reads 6.3V which I think is not enough to get it started (needs 12-28V).
The board looks quite different than the standard schematic from the datasheet. I don't really know how it is supposed to receive that voltage.
I tested a lot of SMD components at the back (resistors, diodes, caps,...) which were ok so I don't see what else I can try from here.
Any ideas?
Thank you ,
Hervé
----
PS: As you can see I damaged the back with the hot air station (too hot) trying to remove the diode... Because of this the board may be compromized a bit, but the traces are still intact, so maybe I can still learn something from it.
PS2: Here is a link to a russian forum with much better images than I can produce. Especially the last post.
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