Hot Rod Deluxe Problem

[rsciresijr]

To Whom It May Concern,

Any help you could give me with this issue would be greatly appreciated.

My Fender Hot Rod Deluxe amp has always made a popping noise when I engage any of my pedals, or switch the pick-up selector on my guitars. I have taken my amp to two certified Fender amp repair locations, and the techs both tell me that my amp is working within it's parameters and there is no apparent problem! I guess it depends what you think a problem is!

Anyway, it is extremely frustrating, as I have replaced; tubes, input sockets, re-tensioned the tube sockets, checked for
bad solder joints, all with no progress.

Any ideas, besides selling the amp.http://music-electronics-forum.com/i...s/icon_sad.gif

[Mark Black]

Does the amp make the popping noise when changing pickup selector on the guitar with no pedals in the chain (guitar direct to amp)? And if so does it happen also with a different guitar and cord?

[rsciresijr]

Hey Mark, Thanks for taking a stab at this one!!!

Yes, the noise happens even when no pedals are connected and I am just plugged in direct. Also, the screw that holds the pick guard down makes a static
sound when I touch it. I have tried different (new chords) as well as different guitars all with the same problem so I know it is in the amp somewhere.

Any ideas?

[Jag]

Considering that the pickguard screws do not make up any part of the amp circuit, I'd say it's static buildup on the guard, and nothing to do with the amp. Try wiping the pickguard down with an anti-static sheet.

[rsciresijr]

Hey Jag,

Thanks for the help. Yes I have heard about the pickguard static build up. I tried that and yes, it seems to help with the screw, but the pick-up
selector and pedals are really the problem. I wish I could rub them down with the anti-static sheet, and get them to stop popping.

But thank you for the reply and your time! If you hear anything else I could try let me know!

[52 Bill]

This is a real long shot, but if you have an ohm meter try this.

With the amp off and unplugged, plug in a guitar cord into input 1. Take you meter set to read high ohms and read the resistance from tip to sleeve on the free end of the cord. Do you get a 1 meg ohm reading?

[rsciresijr]

Hey Bill,

With the amp off and unplugged, plug in a guitar cord into input 1, I have my meter set to 2000k ohm and I get consistent 987. I have the Red lead
to the tip, and the Black lead to the barrel. What do you think? I have a basic understanding of electronics, know and have drained capacitors, and
can solder.

Any help would be great. Thanks for the reply

[52 Bill]

987K is what I would expect the see there, so my long shot is just that.

[rsciresijr]

Okay! What do you recommend?

[52 Bill]

Try this. Turn down the volume control, turn on the amp and plug a cord into the first input. Now take your meter and check to see if there is any voltage across the tip and sleeve contacts of the free end of the cord. Check for dc and ac as well.

[Mark Black]

Try this. Turn down the volume control, turn on the amp and plug a cord into the first input. Now take your meter and check to see if there is any voltage across the tip and sleeve contacts of the free end of the cord. Check for dc and ac as well.

Exactly where my thought process was going: DC (or possibly HF-AC) on the input. Would probably also cause a "dirty pot" scratchy/whooshy sound when rotating the guitar volume control with guitar plugged in. Doesn't take much voltage at all.

To add to Bill's suggestion - see if you can conjure a way to do the measurement without touching with fingers (maybe some alligator clip leads or something) to minimize possible induced voltages or loading.

[rsciresijr]

Bill the only voltage I get is on the DCV setting at 200m - I get 00.5 - Is that enough to cause a problem.

Let me also mention at this point that I did replace the input jacks with new ones, in hopes that would
be the solution.

All other settings show no voltage.

[rsciresijr]

Hey Mark,

I have access to the, Ground, Switch and Tip terminals of the input jack and was not able to get a reading.

[Mark Black]

Hopefully you are measuring with a plug inserted into the jack? Otherwise the tip will be grounded through the switching contacts.

[rsciresijr]

Was not testing the terminals with the plug inserted into the jack. Will do that next!

Thanks Mark!