Posted by Thermionic [ 70.173.99.212 ] on October 26, 2006 at 00:36:52:

In Reply to: Re: Tube question... posted by Jason on October 25, 2006 at 23:27:15:

Hi Jason,

Parts cost using decent quality parts should be perhaps $75 maximum before shipping costs (excluding tubes, of course). As far as labor charges, that'll all depend on the tech's hourly bench charge. A Fender rebuild like this generally takes me about two hours bench time from the time I begin removing the chassis until the time the amp is reassembled and ready to go. But, I've been doing this a very long time, and can rip through it pretty quick. Some guys may be slower, and some may be even faster. Get an estimate up front. If they estimate more than around 3 hours bench time, I'd think about looking into another tech.

In many of these old Fenders, there's a funky fungus that grows on the eyelet board over time, which makes even the strongest-stomached a bit nauseated and gives those with allergies sneezing and irritated eyes. In such cases, I place the chassis outside with a fan blowing into it for several hours......... the smell is ROUGH!

You may want to remove the tubes and pull the chassis yourself. That'll save you some bench time charges, and you can air the board out if it's sporting a funk. Remove the nuts (underneath the chassis) from the 4 screws that go through the chrome straps on top and remove them.

Have your tech inspect all the internal wiring, to make sure nothing is burned or frayed. Check for warped or binding bushings in all the front panel pots, and replace any "iffy" ones. Likewise for the front panel bright switches and rear panel power switch. Retension any tube sockets that have excessively loose contacts.

In addition to the things I mentioned replacing earlier, also be sure to replace the stock 470 ohm/1 watt screen grid resistors with wirewounds of at least a 3 watt rating. One or both is quite likely a bit toasted. The screen grid resistors in most of these amps at least have the color coding burned off from the heat, and I've even seen them literally turned to ashes.

Finally, it's a good idea to run a brass 30 caliber rifle bore brush into each input and speaker jack a few times, to scrub any dirt loose and remove tarnish. Then, use a cotton swab moistened with a SMALL amount of denatured alcohol to remove the residues.

You literally won't even recognize the amplifier after "restoration." The highs will sparkle as never before, and it'll take on a whole new tone that'll bring a smile to your face. Another alternative is "blackfacing" the amp back to the pre-1967 AB763 blackface circuit, if you'd like. The additional cost should be minimal while the tech is already into the amp.

Thermionic

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