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Fender Champ repair

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Re: Fender Champ repair

Postby Hugh Robjohns » Wed Apr 10, 2019 12:10 pm

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Re: Fender Champ repair

Postby Wonks » Wed Apr 10, 2019 12:31 pm

That's the one I found and mentioned as having D for diode, not CR, so it didn't tie up with the amp PCB.
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Re: Fender Champ repair

Postby Wonks » Wed Apr 10, 2019 12:35 pm

I think that's for the older Champ 15G, as it doesn't have a channel select switch.
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Re: Fender Champ repair

Postby Hugh Robjohns » Wed Apr 10, 2019 12:42 pm

There seem to be several different possible solid-state designs, some with a chip amp, some with a discrete transistor amp... but none are complicated from what I've seen and should be easy to fault-find by a competent tech.

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Re: Fender Champ repair

Postby Wonks » Wed Apr 10, 2019 1:06 pm

But value for money? These amps go for peanuts on eBay. Getting a tech involved would cost more than a replacement.
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Re: Fender Champ repair

Postby ef37a » Thu Apr 11, 2019 9:50 am

Wonks wrote:But value for money? These amps go for peanuts on eBay. Getting a tech involved would cost more than a replacement.

Quite. As far as repairing discrete transistor power amps goes, this can be very soul destroying! You fit new transistors that measured faulty, probably a couple of cooked resistors and switch on..Poof! Bloody lot fries again. Sony used to supply us with complete "kits" for their audio gear. ALL the transistors and vital resistors.

In fact, if you have an old amplifier that you love and want to keep running for certain reasons it is often better to just buy in a ready made amp "block" or assembled unit from the likes of Wellman. Just check the supply volts are in range. In a similar vein, many guitar amps used crude dropper resistors and zeners to obtain lower voltage supplies. Replace with 78/79 regulators. I used to get the all insulated type and bolt them to the chassis.

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Re: Fender Champ repair

Postby DanR » Sat Apr 13, 2019 10:17 am

ef37a wrote:We need a nameplate then.

Dave.

Serial No. VK011973-FD
Model - Champ 15G
Type - PRCPR1

The diodes are 1N4742A

The owner has removed these and will try new ones. I realize that it may not be worth
persevering too much with the amp, as they’re cheap to buy used.
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Re: Fender Champ repair

Postby ef37a » Sat Apr 13, 2019 10:29 am

DanR wrote:The diodes are 1N4742A

The owner has removed these and will try new ones. I realize that it may not be worth
persevering too much with the amp, as they’re cheap to buy used.

Those are zener diodes. We need some voltage reading IF you can do so safely.

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