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Post subject: Fender Blues Deluxe problems
Posted: Tue Nov 27, 2012 5:38 pm
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Hello all, my name is Aaron and I am new here. I recently was gifted a Fender Blues deluxe (non-reissue) from my grandfather. The amp meant a lot to him and I'd like to take good care of it. When I plugged it in and turned it on to try it out once I got home I found a bit of a problem. The amp had been sitting for a little (inside) its not in too bad of shape but it hasnt been exercised in a while.

The amp would randomly cut out and the volume knob wasn't responding well. I also noticed that the red indicator light (not the big one) would illuminate as if drive was on without my applying drive. Once the led (drive) came on the sound would cut and then not work after that. I took off the back cover and sprayed some contact cleaner in the pots and gave them each about 15 full turns. After that the knobs responded much better and got rid of some crackling but when I gave it another shot the drive keeps coming on without the drive button depressed and once it does the sound is once again cut. Also if I press the drive button on and off it does not take drive on and off any longer. Im wondering if there could be a short somewhere in the drive function? (the amp does sound pretty good when it is producing sound)

If any one could give me any useful information or things i should look as well as any tips for just tube amp users in general, It'd be much appreciated. As I had said this amp means a lot to me and I'd love for it to be running and running well. :mrgreen:


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Post subject: Re: Fender Blues Deluxe problems
Posted: Tue Nov 27, 2012 8:26 pm
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Location: Indiana
Hi BluesdayBends,

You almost certainly have one or more poor solder joints, or broken trace(s), in the area of the 5-watt resistors, and zener diodes, in the +/- 16 VDC supplies. The resistors are R85 and R86, (R78 and R79 in later versions), and the zeners are CR22 and CR23 (D13 and D14 in later versions). The 16 volt supplies are for the channel switching, and other functions of the amp. It is quite a job to remove the main circuit board to inspect the joints and reflow solder or repair broken trace.

Schematics:
http://support.fender.com/schematics/guitar_amplifiers/Blues_Deluxe_schematic.pdf

You can see the two white rectangular resistors in the bottom middle of the main circuit board, to the right of the blue circular bias adjust pot. You'll have the same resistors, nearly the same place, but no bias adjust pot. Edit: Be aware of the lethal voltages inside the amp, even when unplugged from electricity!
Image

Forgot that I have a picture of the BDlx non-reissue, note the same resistors in nearly the same location as the above picture. The zeners are the black, tube shaped components with a white stripe on one end, just to the right of the aforementioned resistors.
Image

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Fender Blues Deluxe problems
Posted: Tue Nov 27, 2012 11:09 pm
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Hey shimmilou thanks a lot for the info. The pictures and info you gave me was very helpful. So should I buy these resistors and put them in (or with help) to solve this problem? or is my best bet sending the amp out and having it repaired somewhere? I'd like to go the most efficient way. I have a friend who is knowledgeable on circuit boards but it sounds like a good reworking with the solder would go a long way. I've heard a lot online about the solder work wear after time.

Once again thanks!


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Post subject: Re: Fender Blues Deluxe problems
Posted: Wed Nov 28, 2012 8:24 pm
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Joined: Tue Jun 29, 2010 1:20 pm
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You probably don't need new resistors, likely just a little solder. To remove the main board, first unplug the amp from electricity and make sure that the caps are discharged. Remove the knobs, pot nuts, and jack nuts, remove the screws that hold the board in (6 screws?), then pull the board downward enough for the pot shafts to clear the chassis, pulling the top of the board outward and swing down to access the solder joints on the other side. Be careful not to grasp components, or let the components on the edge of the board push against anything that would break even more solder joints, handle the board by the edges. Also, try to bend the ribbon cables in the middle while swinging the board down so as not to stress the joints where the ribbon cables connect to the boards on either end. Examine all joints closely, you might have to use a magnifier, and especially look at the joints previously mentioned around the big white resistors and the zeners.

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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