Re: New developments in my amp dilemma..

Mikey! I know you odn't remember, but your the one who helped me accurately diagnose this problem a year or two ago!! (Out put transistors.. replaced them, all was well).. I never 'disconnected' anything.. i just placed a cord from preamp out to another amp to see if it would play distorted or clean.. But I mean, with my luck, it can't just be a dirty jack or pot.. So, if you knew nothing, like I Do, and NEEDED an amp next week for a new band project, which was your whole life goal, what would your next plan of action be? ;) Thanks guys!

Mike Schway wrote: 
In article <mschway-9F2786.20161930082005@xxxxxxxxxxxxxxxxxxxxxxxx>,
 I, myself, Mike Schway <mschway@xxxxxxx> wrote:


In article <a01ah1lg9h6r9ocanojeufvon043kv335g@xxxxxxx>,
RonSonic <ronsonic@xxxxxxxxxxxxxxx> wrote:


On Tue, 30 Aug 2005 18:46:22 -0400, JohnnyK <johnkrikorian@xxxxxxx> wrote:


It seems (the fender princeton 112) comes out clean on the headphones and the preamp out channel.. But if going to the amp itself, is all crackly and distorted and cuts in and out. I assume this has to help pinpointing whats wrong.. any takers? :) Thanks! 

Power amp in jack.

Just clean the connectors, do the solders and don't fuss about ordinary
preventative maintenance. Why pinpoint one bad solder joint when your amp is
probably full of them. Why sweat the use of $0.32 worth of Deox D5. Just do it.

If you're still not sure run a cord from pre out to power in. 

Ron


Or perhaps more likely, headphone jack. My prints are back at the shop, but I think the HP is post-power-in and is merely an attenuated speaker out which disables the speaks when something is plugged in. Can be bad solder, or bad jack, sure, but try the D5 first.


About 5 seconds after I posted this, I said "aw...crap!" Posted too soon!

When the headphones are engaged, the SPEAKER's DISCONNECTED! This means there's much less vibration on the PCB. Hit a big note and the whole amp shakes itself loose. It could very well be a bad solder joint anywhere, and not jack related. If cleaning the jacks don't help, try resoldering jacks, pots, big filters and especially TO-220 devices.

When you're getting a good feed from the preamp out, are you also disconnecting the power amp? Usually not, but I should ask anyway.

When there's a jack problem way late in the chain, like headphones or pre out/power in, it's usually manifested by signal cutout, not bad crackles. This is why I'm NOW thinking it's either an input stage or power supply connection partial failure mediated by vibration.

Think first, shoot later, Mike!

--Mike

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