jaymanaa
RIP 1961-2018
With all the interest that Maggie console pulls generate, I thought it might be cool to do a step by step rebuild thread. The subjects will be a well preserved (by dust) pair of 169BBs. The first thing I always do is hook them up to a source and cheap speaker to see if they actually work. If they do I proceed, but if they don't I do some troubleshooting to make sure the iron is good. The only thing I salvage from these is the iron and the chassis, period. After confirming that the iron is good, I strip the chassis of EVERYTHING. I've discovered that parts like sockets and such are just way too affordable to have headaches with 60 year old stuff, not to mention that I have never seen a truly "flowed" solder joint on the factory terminal strips (be careful when soldering new ones to the chassis as too much heat can damage the galvanizing). I find that a big iron like the Weller SP80L makes short work out of the tear down, and chassis re-soldering. Once it's all stripped out, I carefully check the TX leads for insulation cracks and apply heat shrink as needed. The leads get awfully brittle over time and it would be a shame to toast one of these great TXs over something like cracked insulation. Then the TXs can be painted and set aside to dry. There are tons of cool paint options such as Hammertones, Crinkles, Sand Textures and so on, that make the old iron look pretty spiffy. While they're drying I give the chassis a good scrubbing with an SOS pad in the kitchen sink with hot water (best done while the wife's at work).
If you look on the underside of the chassis you will see some little tabs that were made by "punching" holes in the chassis. These were ground spots, but I use a copper buss, so these can be bent back up to fill the holes they created in the chassis top (a couple coats of primer makes them disappear). Next I solder in new tag strips and a stiff 20guage bare wire buss lengthwise through the tag ground lugs. This makes a nice ground at the front of the amp for low level stuff, and keeps the large currents back down toward the TX and filter cap. The top of the chassis can be finished anyway you like, from a bare metal, to paint, to powder coat, or I guess it could even be chromed.:scratch2: If you like the look of the polished up bare metal, I would suggest a coat or two of clear or else it will tarnish in no time (and is impossible to clean with stuff mounted). More as the project progresses.
If you look on the underside of the chassis you will see some little tabs that were made by "punching" holes in the chassis. These were ground spots, but I use a copper buss, so these can be bent back up to fill the holes they created in the chassis top (a couple coats of primer makes them disappear). Next I solder in new tag strips and a stiff 20guage bare wire buss lengthwise through the tag ground lugs. This makes a nice ground at the front of the amp for low level stuff, and keeps the large currents back down toward the TX and filter cap. The top of the chassis can be finished anyway you like, from a bare metal, to paint, to powder coat, or I guess it could even be chromed.:scratch2: If you like the look of the polished up bare metal, I would suggest a coat or two of clear or else it will tarnish in no time (and is impossible to clean with stuff mounted). More as the project progresses.
ara:
Oh, and BTW, 7591s ARE still being made.
