fender passport 250 circuit diagram

[nwbec]

Dear Sir

My passport 250 is on protect mode and I have replace the BRIDGE RECTIFIERS and now it has 240 output but also without 51V and 15V. Could you provide the related circuit diagram to us for repairing, or could you give me some informations so that I can fix it. Best regards

[Jazz P Bass]

The service manual does not include the Switch Mode Power Supply.

http://diagramasde.com/diagramas/aud...rt%20P-250.pdf

[g1]

Excellent, that was the part I didn't have.
Here's the pdf of above link and another with the power supply:

[nwbec]

g-one Thanks for your support,

[Jazz P Bass]

What was the initial fault?

Did the original rectifier test bad when you removed it?

[52 Bill]

nwbec, it seems that English is not your first language, so there may be some difficulty in communicating here.

If you are not aware of the dangers of working on a switch mode power supply, please understand that they are very dangerous to work on. Please be very careful when working on this circuit.

When this amp goes into protect mode, it means that something is drawing too much current from the power supply. The power supply senses the problem and shuts itself off to protect the amp and the power supply from further damage. Usually when there is a problem in the power supply itself, it will blow the fuse.

The way to test any of the Passport analog amps that are going into protect mode, is to start by unplugging the power supply from the power amp circuit. If the amp will power up and not go into protect, then you know that there is a problem in the power amp. If it continues to go into protect mode, then there is a problem with another part of the amp or the power supply itself. My estimation is that 95% of problems are in the power amps, usually shorted output transistors.

To do this, remove the front panel and look for the power amp board which is located at the top rear of the case. Near the middle of the board there is a 4 wire connector that carries the +&-50 volt power supplies to the board. Pull off the connector and then carefully turn on the amp to see if the protect light comes on . If it doesn't come on, then you will have to troubleshoot the power amp. Fender suggests testing for +&-50 volts at the rear external voltage connector, but I usually find that once the power supply comes out of protect all of the voltages will be okay.

[nwbec]

Hi Bill,Thanks for your suggestion, at first the fuse is broken, after replaceing the fuse the protect mode is red, I disconnected both power amp and mixer.and than, disassembly the power supply , and only connect the power cable, the on/off switch and also connect with the LED pcb. I found no 50V and 15V.output now I am going to check the parts which are connected with T3 Point 1 and 3 first,

[52 Bill]

I found no 50V and 15V.output now I am going to check the parts which are connected with T3 Point 1 and 3 first,

Yes, very common problems are shorted Mosfets Q1-Q4, shorted diodes D5 and D6. Also look for bad resistors .

And check the silicon mounting pads for the transistors. If the transistor mounting screws are over tightened, the pad will compress to the point of allowing the case to short to the heatsink.

[nwbec]

Thanks !

[Thank you all of you. the PA is OK now , mainly on KA3842B Best reagrds