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Post subject: Hot rod deluxe problem
Posted: Mon Dec 31, 2012 9:39 pm
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its a green board printed 1996.
issue: turn it on/standby i can feel it slightly vibrating. take off standby still slight vibrating and there is a slight crakling. just put in new 6L6s havent change preamp yet. where should i look. i know how to dissipate caps. not scared to poke around a little bit. got a chopstick and poked around didnt locate problem. not sure i'm looking in right area.


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Post subject: Re: Hot rod deluxe problem
Posted: Mon Dec 31, 2012 10:42 pm
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Please clarify: is the amp making any sound at all or is it just "vibrating"? What exactly do you mean by vibrating?

Crackling noises could be bad solder joints where the tube sockets are soldered to the PCB. They should be carefully checked out.

As the amp is 16 years old, it might be time to replace the power supply caps (at the very least).

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Post subject: Re: Hot rod deluxe problem
Posted: Mon Dec 31, 2012 10:47 pm
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yes i can play through it. i know about bad solder joints as i had to resolder all the valve joints on my blues jr. its like a very low hum that i can feel. i've been reading and i took a chopsick to a few know areas and wiggled stuff to see if i could make it better or worse.
didnt help or hurt. the hum is felt even when in standby


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Post subject: Re: Hot rod deluxe problem
Posted: Mon Dec 31, 2012 11:47 pm
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Well, if you can hear/feel the hum when in standby, it is not the tubes or circuitry as the high voltage is shut off. Sounds more like the power transformer is vibrating and creating a resonance in the chassis.

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Post subject: Re: Hot rod deluxe problem
Posted: Mon Dec 31, 2012 11:53 pm
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my blues jr nor does my deville do that. so i'm assume that is bad. is there a way to check the transformer?


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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 3:58 am
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bluesky636,

IMO , no need replacing filter caps just because they are 16 year old . This is not old 16 years for electronic device like capacitor.

blu4x5 ;

Hum in standby position ! Only Power Transformer is realy working in this position for heater voltage.


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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 7:01 am
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blu4x5 wrote:
...issue: turn it on/standby i can feel it slightly vibrating.


Not really an issue, transformers have a slight vibration, and a slight hum, no way around it. You can more easily hear the slight hum when in the back of the amp. Mine does this, but I really have to strain in a dead-quiet room to hear it. Talk about straining at gnats. :lol: Forget about it and move on to the real issue, the crackling noise.

blu4x5 wrote:
... take off standby still slight vibrating and there is a slight crakling....havent change preamp yet...


Then you should do so right away. :wink:

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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 3:56 pm
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ok before i was just poking around so i decided to take a systematic approach and follow the schematics. http://support.fender.com/schematics/guitar_amplifiers/Hot_Rod_Deluxe_schematic.pdf


question #1 WTF is this http://dl.dropbox.com/u/32815923/010113161849.jpg
and how do i fix it.

question #2 is this normal http://dl.dropbox.com/u/32815923/010113164541.jpg
seems more discolored then other parts of the board almost semi charred


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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 4:17 pm
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blu4x5 wrote:
ok before i was just poking around so i decided to take a systematic approach and follow the schematics. http://support.fender.com/schematics/guitar_amplifiers/Hot_Rod_Deluxe_schematic.pdf


question #1 WTF is this http://dl.dropbox.com/u/32815923/010113161849.jpg
and how do i fix it.

question #2 is this normal http://dl.dropbox.com/u/32815923/010113164541.jpg
seems more discolored then other parts of the board almost semi charred


Did you buy the amp new or used?

If new, I would say the first photo is an "assemblyline fix". I have a similar fix (though not as ugly) in my BDRI where a component was missed and was added on in a rather haphazard manner. If you bought it used, I'd say someone was mucking around in the amp. As far as fixing it goes, you're going to have to trace out the circuit and see what things connect to and if they are connected properly.

I see nothing wrong in the second photo. To what are you referring to?

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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 5:39 pm
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i just brought the amp last week from a guy who said it had been in storage for a few years. got good price on it to.


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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 6:33 pm
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blu4x5 wrote:
i just brought the amp last week from a guy who said it had been in storage for a few years. got good price on it to.


Then I suggest you ask him what was done to the amp. According to the PCB layout that RC network is connected to one end of where a wire jumper is supposed to be. Can't see in the photo where the other end of the network is connected and wire jumpers aren't shown in the schematic. I have no idea what the purpose of that network is as it is impossible to tell where it is connected. It looks to be located around V1B, possibly replacing the bright switch circuit. Good luck.

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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 7:09 pm
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bluesky636 wrote:
...It looks to be located around V1B, possibly replacing the bright switch circuit. Good luck.


Yep, looks like the Cathode resistor and bypass cap for V1B, and the top of C4 which was the bypass cap for V1B to the bright switch circuit, is now jumpered over to the Cathode resistor (R17) of V2A. It looks more like someones mod rather than a factory job, but hard to know for sure.

The second picture, the OP might be referring to the very slight char spots by the 5 watt resistors and zeners in the +/- 16 volt supply. Not an issue, and looks great for 16 years worth.

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Post subject: Re: Hot rod deluxe problem
Posted: Tue Jan 01, 2013 8:08 pm
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shimmilou wrote:
bluesky636 wrote:
...It looks to be located around V1B, possibly replacing the bright switch circuit. Good luck.


Yep, looks like the Cathode resistor and bypass cap for V1B, and the top of C4 which was the bypass cap for V1B to the bright switch circuit, is now jumpered over to the Cathode resistor (R17) of V2A. It looks more like someones mod rather than a factory job, but hard to know for sure.

The second picture, the OP might be referring to the very slight char spots by the 5 watt resistors and zeners in the +/- 16 volt supply. Not an issue, and looks great for 16 years worth.


Agree on all counts.

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Post subject: Re: Hot rod deluxe problem
Posted: Wed Jan 02, 2013 3:40 am
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blu4x5 wrote:
i just brought the amp last week from a guy who said it had been in storage for a few years. got good price on it to.


A good socket's contact cleaning is a must after a long storage . Oxidation appened between tubes and socket's pins when tube amp was not used since many months,

This cause strange problems. Start with that , buy a good contact cleaner.


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Post subject: Re: Hot rod deluxe problem
Posted: Thu Jan 03, 2013 5:57 am
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i took it to rehearsal last nite can't hear the crackling w/ the drums and bass and its the only place i can open the amp up at since i live in an apartment. did good for about 2hrs then it went a little haywire. loud crackling and static as described by http://www.justinholton.com/hotrod/plateloads.html
turned it off for 10 min then finish rehearsal w/o a further problems. so i'm going w/ this answer for now and i have a little time 2moro to check it out. are those resistors available at radio shack?

also while i'm doing this i'm going to replace R78/79 can i replace these w/ the 5w 330 or should i go back w/ the 5w 470.


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