Crawls Backward (When Alarmed)

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Altec 1589B Preamp Mixer Rebuild and Upgrade, Pt. 2

In the last post, I mentioned that I replaced all of the signal caps on the Altec 1589B with Elna Silmic II electrolytics. The power supply caps were replaced with Nichicon FG electrolytics.

I changed out the potentially noisy carbon composition collector resistors for metal films (I used Takman REY resistors).  And I changed the signal resistors for 'audio grade' Takman REX carbon-film resistors.   I went with 1/2 watt rated ones instead of the stock 1/4 watt ones in the interest of reducing contact noise.

I've documented this before, but here it is again for good measure. When I desolder components, I use solder wick. This cleans up all of the old solder and leaves a nice clean surface to solder your new component to.

You could also use a good quality solder sucker - in my experience the cheap, manual vacuum ones are almost useless. Hakko makes a nice electric one; but I have always had great results with wick. Takes just a couple of seconds to suck up the old solder.

Here are two pads on the Altec board that I've cleaned up and put a new resistor on ready to solder.

You can see what I mean about the wick - you get a nice clean pad to solder.  If you're going to trouble of doing all this work and putting in good quality components, your work should be perfect too.

The new joints are perfect.  New solder, tidy, no mess. Excess leads are trimmed. Looks just like the factory joints.  And remember to clean the flux off the board when you're all done.

Attention to detail like this will ensure reliability for years, and peace of mind. It doesn't take any longer to do a proper job.  This is not rocket surgery, it's just good practice.

Ok, off the soapbox.

One other thing I did is to heat sink any transistor near where I was soldering.  In other words, if I was soldering a component where a board trace ran to a transistor, I put an alligator clip on that transistor leg to keep heat off the transistor.

Transistors are sensitive to heat, especially older ones, and these are probably all out of production to boot. So a little caution doesn't hurt.

Here's the whole rebuilt board.  Only a handful of non-critical original resistors are still in place.

Closeup of those Takman resistors - the blue ones are metal (a pretty common color for modern metal films), while the carbon films are pink!  Maybe they will give a "soft, rosy glow" to the tone?  Ha.

 
 
 
 

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