Problem with Fender Princeton DSP

[beyondreason]

I just inherited my friend's amp and I brought it home and couldn't get any sound from the Input Jack. I tried everything. I don't have the pedal so I was thinking maybe I needed it to activate the jack or something. (I'm new to electric guitars and amps). I kept trying things and out of desperation I plugged into the jack marked "Power In" and that at least showed me that the amp had power and worked to some extent. I kept trying things and noticed that when I plugged into the Input Jack and touch or pushed on any of the jacks on the right side of the amp, I could get it kick in. It doesn't hold though. Seems that there is a cross connections or loose connection or something. Do you think this is something I could trouble shoot or is it something that has to go to the shop. Thanks in advance. P.S. I'm new to forums too. I posted this problem yesterday somewhere and I can't find it today. I feel stupid.
John

[Jazz P Bass]

Princeton DSP

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Sounds to me like bad, cracked solder joints at those jacks.
Try to resolder them.
The fact that you went in Pwr Amp In, and the amp worked, means the power amp is working.
So it is a preamp problem.
Those jacks are part of the preamp

[tubeswell]

Hi there John and welcome to the forum

Honestly, if you don't know anything about amps or electric guitars, then you better take it to a tech to fix. There are lethal voltages inside tube amps.

Take care

(Edit - BTW your other post is here: http://music-electronics-forum.com/t16888/ )

[beyondreason]

I fixed it, I think

Thanks for the advice to not get hurt. I'm not as bad as I might have made myself out to be though. I just didnt' want to take the amp apart and not be able to put it back together again. I tightened the rings around the jacks and everything seems to be working fine now. They weren't loose but a little turn on each and everything seems fine. I figured that when I pushed them a bit with my finger the Input Jack worked so I just tightened them and it seems to have done the trick. Any idea why? Thanks again.

[tubeswell]

I tightened the rings around the jacks and everything seems to be working fine now. They weren't loose but a little turn on each and everything seems fine. I figured that when I pushed them a bit with my finger the Input Jack worked so I just tightened them and it seems to have done the trick. Any idea why?

Well if if isn't loose solder connections behind the input jack, then it could've been intermittent lifting of the ground return path at the input jack, causing it to cut out - by the sound of it. (No pun intended ) Tightening it would have pushed the sleeve contact firmly against the chassis/ground return path. See how it goes for a while. Could still be loose solder connections inside.

[Zipslack]

Go ahead and re-flow the solder

Don't be fooled by the name...theses are solid-state units. You won't get killed or seriously hurt, unless you mess with the AC coming in from the power transformer.

Save yourself some future headaches and go ahead and re-flow the solder pads under the input jacks, and then make sure all the nuts are tight. If it was my personal amp, I would even go so far as to apply a judicious amount of hot-glue around the input connectors to strengthen their bond to the PCB. I make a nice little bit of gas money doing repairs on Chinese-manufactured Fenders (out of warranty stuff - Fender won't even repair a lot of these under warranty, just replaces them). 9 out of 10 times, Chinese-made Fenders with the plastic input jacks soldered to the PCB will have bad solder joints, either from abuse, normal wear-and-tear, or lousy manufacturing.

[Jazz P Bass]

Solder Joints

And if the input jack connectors are soldered crappy, you know the rest of the other big pad components are probably soldered crappy.
While you are in there check the solder job.
Redo as needed.

[Zipslack]

Good point

Ditto on the remarks about checking the other pads. Also, don't try to over-torque the nuts on the control pots. The threaded barrel WILL break off if you tighten them too hard. Snug and tight, but not tight like wheel lugs!

[earache]

Just Had Similar Problem

I just fixed a similar-sounding problem with a Fender Princeton 65 DSP. It took me two tries to get the input jack resoldered adequately, but now the amp works. I also noticed that the relationship between the input jack and the drilled hole in the chassis front panel where it mounts is kinda tight - the jack is barely allowed enough height to pass thru.