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Author Topic: EA20 and Equis II Preamp  (Read 3614 times)

Offline roobarbthedog

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EA20 and Equis II Preamp
« on: February 04, 2013, 08:39:23 AM »
I posted a comment several years ago relating to my Festival EA20 and the faulty Equis preamp. I had another bash at diagnosing the problem last night and finally think I have cracked it. First of all a description of the problem:

When plugged into an amplifier there was a really loud buzz/hum which drowned out the guitar signal. This sometimes went away after the guitar had been lying down flat. Also every time the green power LED flashed (every 1-2 seconds) there was an audible "pop" sound through the amplifier.

Solution: I removed the preamp from the guitar (4 black screws) and disconnected the connection from the jack/battery and the connection from the pickup (small jack plug).  I plugged in the 4 way connector back in and plugged in a normal guitar lead in to the main jack socket and an amplifier. I got the same buzz / hum and LED popping sound, so this ruled out a problem with the pickup connector. Turned the preamp upside down and the noise went away for a while. I then had a look at the big capacitor on the circuit boar and on closer inspection found that the solder had came away on one of the legs and that the capacitor could move about, breaking the connection to the circuit board!! Being careful (capacitors can give you a nasty shock. This one was 2200uF, 10V, won't kill you) I could move the capacitor about and was able to eliminate the buzz and the LED pop. Plugging the pickup back into the preamp proved the guitar sound was coming through. So, a quick bit of handiwork with the soldering iron and the capacitor was securely soldered back in place. I fitted everything back and played through an amplifier for at least 3 hours, with no buzz and no LED pop.

I've had this guitar from new for over 15 years and this fault must have been there for most of that time. Sounds great amped up but I still prefer it as an accoustic, as that's what I'm used to! I love this guitar, particularly the high fret access due to the cutaway.

I can send some photos if anyone is interested.
« Last Edit: February 04, 2013, 08:41:46 AM by roobarbthedog »
 

Offline evenkeel

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Re: EA20 and Equis II Preamp
« Reply #1 on: February 06, 2013, 06:43:34 AM »
Well done on the fix.  Electrical problems often boil down to breaks or shorts.  Your logical approach is a good example of how to sort things out.  Just go thru the system step by step until you find the problem.

Pics are always welcome. :) :) :)