It is currently Mon Mar 16, 2020 2:53 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 14 posts ] 
Author Message
Post subject: Fender Pro Jr has hiss after being in storage
Posted: Tue May 23, 2017 1:15 pm
Offline
Hobbyist
Hobbyist

Joined: Tue May 23, 2017 1:05 pm
Posts: 1
I have a Pro Jr that I bought in the mid 2000s. I used it moderately only for a year or so, then went back to school and it ended up sitting in the closet for the last 10 years or so.

I recently dug it out again, and it works OK, sounds good with my guitar but has a fairly loud hiss that wasn't there in the past. I remember being impressed that it was pretty quiet, that I had to lean down to hear if it was even turned on. Now once it warms up the hiss is fairly noticeable from several feet away, with volume all the way down. There are some faint fuzzy rustling sounds too amidst the hiss, once in a while. I'm using JJ power tubes, and Mullard and RCA preamp tubes -- these are the same tubes I used back then, which also sat in the closet.

So what might have changed between then and now to add this new hiss? Can tubes deteriorate over time? I tried cleaning the tube sockets and tube pins with Deoxit but it didn't help. I've heard electrolytic caps can go bad when they're not used for a while, but could this happen in just 10 years? I know people with 50 year old amps with original caps.

Any ideas on where this hiss comes from or how to fix it, appreciated.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 1:04 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Is there a hiss with no guitar, nothing plug in ? test and report
Bad filter caps do hum, not hiss.


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 1:34 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
slowpogo wrote:
Can tubes deteriorate over time?


Yes. The vacuum seal can and usually does deteriorate over time, regardless if the tube is actually powered on and in use or not.

slowpogo wrote:
I've heard electrolytic caps can go bad when they're not used for a while, but could this happen in just 10 years? I know people with 50 year old amps with original caps.


Yes. In today's disposable economy, nothing is built to last. Couple that with the fact that amp companies uses the cheapest import components possible and it's a foregone conclusion that those parts wear out quickly. And those folks with fifty year-old amps? Remember -- the components installed in those amps were the exact same Made-In-USA stuff used by the defense, aerospace, and commercial broadcast industries. It was, by design and specification, manufactured to last for decades.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 8:23 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sun Sep 08, 2013 8:50 pm
Posts: 4602
Location: ˚ɷ˚
slowpogo wrote:
I've heard electrolytic caps can go bad when they're not used for a while

Correct, and the important part of your sentence is "when not used for a while". Turn it on every now and then, and it will last much longer.

This is common to most aluminium based capacitors. What happens is that the electrolyte eats away at the Al2O3 (aluminium oxide, aluminium rust, sapphire dust) when there's no current, and if breaking through, will eat at the pure aluminium at a fast rate. Apply voltage, and new aluminium oxide will form, creating a protective barrier.

Many older capacitors were made with a thicker Al film, and required more layers to reach the same capacitance. That meant a bigger physical size, but also meant they lasted a lot longer.

Newer electronic equipment often have a sleep/standby mode (not to be confused with the standby mode of a tube amp) where a minimal trickle charge runs through the systems. This helps prolong the life of modern thin film capacitors.
Some equipment use caps of a different type, like tantalum caps, which don't have this problem, but are more sensitive to voltage changes, and cost a lot more.


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 12:44 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Bad filter caps don't hiss on speaker, they hum.

Post is about hiss or slowpogo can't tell the difference ?


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 3:35 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
stratele52 wrote:
Bad filter caps don't hiss on speaker, they hum.


Correct. My guess is, a marginal solder joint that finally bit the dust. Maybe more than one.

RoHS-compliant solder......gotta love it!

:x

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 7:27 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Feb 17, 2016 7:53 am
Posts: 47
Retroverbial wrote:
RoHS-compliant solder......gotta love it!


When did Fender start using RoHS-compliant solder?


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Sun Jun 04, 2017 10:50 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
2006

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Mon Jun 05, 2017 9:02 am
Offline
Hobbyist
Hobbyist

Joined: Mon Jun 05, 2017 8:35 am
Posts: 5
Warning! Could be very dangerous and possibly explosive. Qick, send it to me for your own peace of.mind.
I'll be sure to get the hiss and render it harmless.


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Mon Jun 05, 2017 9:04 am
Offline
Hobbyist
Hobbyist

Joined: Mon Jun 05, 2017 8:35 am
Posts: 5
Warning! Could be very dangerous and possibly explosive. Qick, send it to me for your own peace of.mind.
I'll be sure to get the hiss and render it harmless.


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Thu Jun 08, 2017 6:27 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
You can try some contact cleaner on the tubes and sockets. Work the things in-&-out a couple of times to insure good contact. :mrgreen:

I like Caig Deoxit D5, for this kind of thing.


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Fri Jun 09, 2017 2:45 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
BMW2002Ti wrote:
You can try some contact cleaner on the tubes and sockets. Work the things in-&-out a couple of times to insure good contact. :mrgreen:

I like Caig Deoxit D5, for this kind of thing.


Aside from intermittent switch contacts, crusty input/output jacks, or scratchy-sounding pots, I have *NEVER* found a contact cleaner that remedied an amp problem that wasn't directly related to those three types of components. Fender may be using crap tube sockets and crap tubes now but they don't usually corrode unless it's a piece of gear that was dredged up from the wreck of the RMS Titanic.

:lol:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Fri Jun 09, 2017 5:40 am
Offline
Roadie
Roadie

Joined: Sat Dec 13, 2014 7:34 am
Posts: 245
I'd replace the tubes first and go from there. If that isn't the cause it's still not a waste of money. It's always a good idea to have spares.

UN


Top
Profile
Post subject: Re: Fender Pro Jr has hiss after being in storage
Posted: Fri Jun 09, 2017 9:57 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
Tube swapping would be an easy first step in the troubleshooting process. Inexpensive as well, if replacement bottles are already in hand.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: