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Post subject: Re: No Sound - Fender Twin Amp
Posted: Wed Jan 07, 2015 1:14 am
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" Perhaps someone could clarify what stratele52 means by "Check value with desoldering on end. "

Check the resistance of the resistors with one leg pulled. Should be within 5% tolerance of nominal value. Also, check R204 (one leg pulled). Also, check resistance across that "crack" in the tracings. From one exposed pad area before the crack to the one after. Should be close to zero ohms.

R205 doesn't look fried, so I suspect a bad solder point(s) or bad tracings. Carefully inspect these. If both resistors are in spec and the tracings look good --- draw up the original solder and resolder with good quality tin/lead based one. I like Kester 60/40.

http://www.amazon.com/Kester-Kwik-Draw- ... er+60%2F40

Good luck!

BTW... to post a photo, copy the entire URL address listed at the right of your photo. Listed below SHARE LINKS.


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Post subject: Re: No Sound - Fender Twin Amp
Posted: Wed Jan 07, 2015 2:19 am
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tyler23 wrote:
Ok, so I took a look at R205 and found a couple of interesting things. I didn't take any measurements as I was unclear about what exactly I was supposed to measure and decided to play it safe. Perhaps someone could clarify what stratele52 means by "Check value with desoldering on end".

I mean read resistor value in ohms with a meter in ohms scale . For accurate reading you must disconnect one end of the resistor .
On photo number 1, I can see solder is missing or very weak at one end of the resistor . This could be your problem .
What I suggest is leave the resistor as it is , put your meter's probes across and read how many ohms you get. You need to discharge filter caps before ; lethal voltage .
If reading is close to 10 K resistor look good , put some new solder on both end .Amp should work now.

If reading is way up more than 10K , you may need to disconnet one end of the resistor for accurate reading . Resistor could be open ( broken ) too and you may need a new one.


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Post subject: Re: No Sound - Fender Twin Amp
Posted: Wed Jan 07, 2015 4:28 am
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BMW2002Tii wrote:
[

Look at this photo , left side of the resistor , look missing or poor solder

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Post subject: Re: No Sound - Fender Twin Amp
Posted: Wed Jan 07, 2015 6:46 pm
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Based on this photo, I personally would replace this resistor regardless of the reading. I don't like the way it looks(it looks tired), but that's just me.
I agree that it definately looks like one side is cold soldered and the other side is flat out missing solder. Stratele and Beemer offer excellent advice.
Since you already have the chasis out, it might be a good idea to go over as many solder joint as you can to see if there are any other joints that are weak or just need a touch up.
Good luck.

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Post subject: Re: No Sound - Fender Twin Amp
Posted: Wed Jan 07, 2015 7:37 pm
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I agree, that's what I'd do. Use a quality 2 or 5-watt, metal oxide type. 5% tolerance is fine.

And to protect the tracings and soldering pads on the board... cut the old resistor where the its leads meet the body of the resistor. Now, wrap and solder the leads of the new resistor to the old leads. That way you aren't pulling or pushing out-of or into the board.

Good luck!


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