SO the band Im in have been using this little Fender Passport PA for practice with good results until recently it stopped working.
When powered on the protect light just lights up and no sound comes out. It does this with nothing plugged in as well (speakers mics). What would be a good starting point to try and repair it?
Thanks!
When powered on the protect light just lights up and no sound comes out. It does this with nothing plugged in as well (speakers mics). What would be a good starting point to try and repair it?
Thanks!
Agree^^^
Don't throw parts at it. Hopefully, in the NINE years since this thread, they have solved their problems. But the first step is always looking at the SMPS, and then determining where the problems lie. if there is a blown output, chances are it is only one of the two channels.
And be aware ther are a number of Passport models. I have at least seven different model service manuals in my files here, there may be more.
Don't throw parts at it. Hopefully, in the NINE years since this thread, they have solved their problems. But the first step is always looking at the SMPS, and then determining where the problems lie. if there is a blown output, chances are it is only one of the two channels.
And be aware ther are a number of Passport models. I have at least seven different model service manuals in my files here, there may be more.
If you are a technician, then you know there is little we can tell you without you assess the unit first. If the protect light comes on, it means the SMPS has shut down. it could be because the SMPS has a problem itself, or it could simply be shutting down because one of the power amp channels has shorted outputs.
Hi all,
I'm having the same issue on my Fender Passport P-250 (protect mode light turns on, both speaker channels don't output any sound), and based on another thread I am fairly confident the cause of failure to be because I used an Instrument cable instead of a Speaker cable to connect the speakers to the amp.
Currently, I am away from the Passport for the next few weeks, but I hope to have all the parts ready to go when I get back. Currently it is all dissasembled and all internal wire connectors are disconnected.
Like a fool, I did not keep track of which connectors went where... Does anyone have--or know were I can find--a schematic for this amp?
Also, what are the next steps after I (presumably) find out the transistors are blown? Here's what I'm predicting, can someone tell me if it is correct?:
I'm having the same issue on my Fender Passport P-250 (protect mode light turns on, both speaker channels don't output any sound), and based on another thread I am fairly confident the cause of failure to be because I used an Instrument cable instead of a Speaker cable to connect the speakers to the amp.
Currently, I am away from the Passport for the next few weeks, but I hope to have all the parts ready to go when I get back. Currently it is all dissasembled and all internal wire connectors are disconnected.
Like a fool, I did not keep track of which connectors went where... Does anyone have--or know were I can find--a schematic for this amp?
Also, what are the next steps after I (presumably) find out the transistors are blown? Here's what I'm predicting, can someone tell me if it is correct?:
- Unscrew the transistor from the heatsink and scrape off whatever insulation/adhesive is between the two
- Desolder the transistor and solder in a replacement one
- Use some of the previous insulation/adhesive on the new transistor and screw it to the heatsink
- Check to make sure there is complete isolation between the transistor and heatsink
- Plug all the connections back where they belong and fire up the unit
Hi Justin, may I suggest starting a new thread for your repair instead of going on the end of a old thread.
If my memory serves me - and often it does not - there is a three wire connector to the middle of the power amp board from the power supply. I THINK red, blue, and black wires. unplug it and see if the power supply will now wake up and leave protect.
I sure hope you made a map of all the connections.
To check for blown outputs, you can generally check them with a ohm meter right where they sit. If any read as shorted, THEN remove them for further tests. Just replacing them is not testing, it is just replacing everything
TO change a transistor, desolder it and remove it from the board and heatsink. The white goo is NEITHER adhesive or insulation. It is heat transferring grease. It is crucial that the transistors are also electrically insulated from the heat sink. There should be a thin mica wafer between the transistor and heat sink. The white heat grease is smeared on both sides of the wafer.
get yourself some fresh heat grease. It goes by various names: silicon heat grease, silicone thermal compound, heat sink grease. Don't try to scrape the old off and reuse it.
I usually install the new one into the holes and screw it to the heatsink, and THEN solder it. That way I don;t need to worry about positioning the thing for soldering.
If your outputs are blown, I always replace the drivers as well, and always check for open resistors associated with the parts.
I would post the schematics, but this board has a small file size limit. Contact Fender adn ask for your drawings. Include the exact model name and serial number.
If my memory serves me - and often it does not - there is a three wire connector to the middle of the power amp board from the power supply. I THINK red, blue, and black wires. unplug it and see if the power supply will now wake up and leave protect.
I sure hope you made a map of all the connections.
To check for blown outputs, you can generally check them with a ohm meter right where they sit. If any read as shorted, THEN remove them for further tests. Just replacing them is not testing, it is just replacing everything
TO change a transistor, desolder it and remove it from the board and heatsink. The white goo is NEITHER adhesive or insulation. It is heat transferring grease. It is crucial that the transistors are also electrically insulated from the heat sink. There should be a thin mica wafer between the transistor and heat sink. The white heat grease is smeared on both sides of the wafer.
get yourself some fresh heat grease. It goes by various names: silicon heat grease, silicone thermal compound, heat sink grease. Don't try to scrape the old off and reuse it.
I usually install the new one into the holes and screw it to the heatsink, and THEN solder it. That way I don;t need to worry about positioning the thing for soldering.
If your outputs are blown, I always replace the drivers as well, and always check for open resistors associated with the parts.
I would post the schematics, but this board has a small file size limit. Contact Fender adn ask for your drawings. Include the exact model name and serial number.
So I have experienced a similar volume problems and a second problem. I bought my fender Passport 250 used about 8 years ago. I only use it periodically, usually for volunteer stuff. Every now and then the left output won't work so I run both speakers out of the right when that happens. Sometimes that can be solved by tightening the thin nut on the output connector on the unit (but not always and may be a coincidence). The last time I used the unit it was for a high school after prom that I got volunteered for. The unit fired up when we first set up. Then when it was getting closer to time of show I turned on the unit and started to play back ground. Something bumped the unit and it went softer and a little hum started. So I did the natural thing and bumped it with my palm. It got even quiter. I did it again and I heard nothing. One more wack on the top and it came back to normal sound. It worked the rest of the night. There were a couple of fans running for large inflatable and it is possible they may have shared the same circuit, but the circuit never blew. Someone said too much load on a circuit can cause this but I've never heard of that. Any ideas?
I picked up a used Passport 250. The prior owner thought that it had the transistor issue but i think those check out.
I did not get the 51VDC on the main PS output. I’m not real sure where to start testing.
One question...
Are there supposed to be more fuses than just the 6.3A slow blo?
I did not get the 51VDC on the main PS output. I’m not real sure where to start testing.
One question...
Are there supposed to be more fuses than just the 6.3A slow blo?
An externally hosted image should be here but it was not working when we last tested it.
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