Re: 2247A PSU Troubleshooting


chipbee40
 

All this talk of diodes may be relevant when you get the PSU to start but its dead right? The way I work on these is remove the PSU from the case, remove the IEC power inlet from the case and reconnect to the power supply so you have a safe(ish) power connection. Put the power supply on a suitable sized cardboard box with a slot cut in it to pass the output pins through and give you a stable PSU to work with. Disconnect and insulate the multiplier feed from T2204, that saves you any worry about the EHT and also removes the multiplier as a fault. Remove the fan from the case (you can get at the bolts without removing the tube). Plug the fan into the PSU as a load.
Now as I posted previously check C2210 (4.7uF 100v) either by measuring or substitution. Check Q2209 and Q2210 (TIP32C) out of circuit using your multimeter. This the usual cause of a non starting supply.
Regarding the secondary diodes, if you really think they are suspect just lift one end, its rare that they will cause the supply to trip, maybe excess ripple on a rail.
If the supply still fails to start check Q2214 (Mosfet) might be shorted.
Just be careful! Think twice before touching anything with the power on.
My 10 cents...........JC

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