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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Mon Apr 29, 2013 7:07 am
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Roadie
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Krankster wrote:
Beemer, did the Deoxit routine (good stuph) and new tubes. After going over every solder joint in the amp, touching up several, it pops twice instead of five times when turned of standby. Maybe I'm on the right track. Could new filter caps cause a weak cap or resistor to malfunction. Could a filter cap have an internal short and exhibit this symptom? Thanks, Gracias, Danke Shon, Doppi (my 2 year old daughter).


I am sure you did the chop stick check already by pushing on various areas of the fiber eyelet board to see if you can duplicate the "pop". I have had issues with amps that there is something going on under the board to chassis....excess solder, debris, etc.
What I have done is remove the fiber board hold down screws and slide a few tounge depressors under the board. Dont force them. After all is clear....power up the amp and see if the noise goes away. I have done thins on more than a few amps that were "noisy". Kind of like a last resort and if the prob is there it beats unsoldering and pulling the whole board up the do the work. Just a thought


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Mon Apr 29, 2013 8:20 am
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Roadie
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Joined: Sat Mar 09, 2013 12:27 pm
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That's a good idea. The preamp board has a lot of wax on it-more than any I've seen. Every component is covered. When I took out the old e caps, I had to scrape a little wax off the eyelets. Fender must have let this one soak for a while. Yes, I did the chop stick test. I'll try lifting the board.


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Mon Apr 29, 2013 8:54 am
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Roadie
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Krankster wrote:
That's a good idea. The preamp board has a lot of wax on it-more than any I've seen. Every component is covered. When I took out the old e caps, I had to scrape a little wax off the eyelets. Fender must have let this one soak for a while. Yes, I did the chop stick test. I'll try lifting the board.

I have seen boards like this before as well. Supposedly its a good idea to heat the board with a hair dryer or carefully with a heat gun to "remelt" the wax. Apparently wax can hold moisture as well as repelling it. Its another thing I had found on the net a while back.


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Mon May 06, 2013 7:00 am
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Roadie
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She's finally finished. I went through every solder joint, replaced couple wires, two resistors and the popping sound on power up is down to one faint click. I've heard lots of old amps that sound much worse. Anyway, she sounds great and is ready for some real abuse-playing loud (that's why they call me Krank) and roadies. Most amps don't really shine unless you run them at 9. :mrgreen: Thanks for everyone's help. You're a decent buch of felons, I mean fellows.


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Mon May 06, 2013 10:54 am
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Rock Star
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Good deal! Glad it worked out for you & the amp.

:D


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Mon May 06, 2013 11:00 am
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Rawk on!

8)

Arjay

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"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


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Sat May 11, 2013 8:01 pm
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Roadie
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A note to all the viewers-

Learn how to work on your old amps. You'll save a boatload of cash and get the sound you're after. If you make a mistake, go back a try again. Learning how to solder is the hardest part. After a while, the schematics will start to make sense. Digital Mutli-Meters are $10-$20-well worth the price and easy to use. Just make sure to drain the caps before you poke around inside. Amp maintanence is like stetting up a guitar-you need to learn how to do it. There's nothing like the sound of a good Fender amp.


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Thu May 16, 2013 12:20 pm
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Roadie
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Joined: Sat Mar 09, 2013 12:27 pm
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While working on the BMR, I noticed one of the 470 ohm 1 watt screen resistors was badly burnt on the ends. I don't know if it was burnt when installed or by heat over time. Since the amp is 40 years old, should I replace both screen resistors-and 1500 ohm grid stoppers while I'm in there?


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Thu May 16, 2013 3:01 pm
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Yes, by all means.

For durability and reliability, use metal-film type resistors.

Arjay

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"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


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Thu May 16, 2013 5:32 pm
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Rock Star
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Just addendum to Arjay's post --- use flameproof resistors.

Good luck!

http://www.amazon.com/470-Ohm-Flameproo ... pd_sim_e_8


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Fri May 17, 2013 9:58 am
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Roadie
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Joined: Sat Mar 09, 2013 12:27 pm
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FYI, I disconnected one end of the 2000pf caps on the tube sockets. The amp oscillated like crazy and the vibrato ticked. So I reconnected them.-too bad. I've done this successfully on other amps with no ill effects. It made the amps sparkle. Thanks for the suggestions.


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Sat May 18, 2013 7:17 pm
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Aspiring Musician
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I did the same with my BMR, luckily no oscillation or ticking so I left them out. Luck of the draw I guess. :wink:

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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Sat Jul 06, 2013 1:38 pm
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Roadie
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Here's a pic of the Bandmaster with a 2x12" cab-WGS Veteran 30's. I like the combination of Fender and Celestion speakers.

Image


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Post subject: Re: 1974 Bandmaster Reverb Filter Caps and Resistors
Posted: Wed Jul 10, 2013 10:17 am
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Roadie
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One more try with the pic.

Image


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