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Altec 1592B Mixer Amplifier Rebuild, Pt. 5: Reassembly

With the amplifier board and tone control board rebuilt, and the filter caps replaced, we can reassemble the Altec 1592B and test it.

First we resolder the tone control board - those 8 connections to the pins at the bottom of the board.

Recall the board is held to the front panel via the tone control pots. Reinstall the nuts and tighten them.

There's a short brass strip that connects the ground from the main/amplifier pc board to the ground buss for the inputs.

When I took the board out originally, I undid the screw that attaches to the board (green arrow). It has a lockwasher and nut under it. I realized after the fact that the way to attach or remove the strip is to undo the screw at the buss end (blue arrow). That end is just a screw, with no nut to attach from the underside.

So this time, I undid that screw on the left, and then attached the right side screw along with the strip to the board. That way you can attach the nut from underneath with the pcb out of the mixer.

I left it a bit loose, since it will have to be adjusted to line up with the buss.

I magnetized the screwdriver so it would hang on to that little screw that goes to the main buss. Not fun to drop those things inside a piece of gear.

Now we put in the four screws holding the main board to the chassis.

And reconnect those big multi-pin connectors back to the board.

I'm not sure why Altec didn't use connectors on the tone board also.

Everything's back in place.

I fired it up and used a microphone to test all of the works!

On these projects where you're removing several boards at once and replacing a number of components all at once, you don't have the luxury of replacing a few things and then testing, as you would on a point-to-point wired radio or amplifier.

However, if you're careful and methodical as you go, you'll usually have success. If the gear in question doesn't work after putting it back together, it's usually something not connected or not grounded.

I took off all of the channel input knobs so I could clean the front panel with Simple Green. I just put a small amount on a clean painter's rag and wipe it down and then dry it.

The tone control knob screws take a flat blade, while the big knobs are allen screws.

Now we put all the knobs back on.

I connected the output of a small radio tuned to a local classical music station to the inputs using jumper cables. Looks a mess but works :-)

I didn't have enough XLR plugs to hook it up through the back panel!

I left it on for a couple days to burn it in* and make sure nothing went up in smoke.

*Following that supposed 100 hour break-in for the Silmic caps.

Here's the rebuilt Altec 1592B ready to go into the rack.  I also rebuilt 5 1588B microphone input transformers and will post about that next.

Altec 1592B Rebuild Project
Part 1: Overview and Initial Dissassembly
Part 2: Power Amplifier/Main Board
Part 3: Tone Control Board
Part 4: Filter Capacitor Replacement
Part 5: Reassembly (This page)


Post a Comment 2 comments:

  • Lakeview Drive said...
    November 19, 2017 at 10:24 PM
    So, I have an Altec 1611a and a 1592a. I have a variety of the octal preamps, but I want to mod mine for a variety of uses. First, I think that I want at least 1 channel to remain original, but maybe 2 because 1 would be a DI. The other channels I would want direct outs and also include a gain pot for each, as well. What do you think of this? Any suggestions or advice?
    Your blog is great. I enjoy it a lot.
  • Yr Fthfl Blggr said...
    January 13, 2018 at 2:52 PM
    Sorry for my delayed response. Thanks for the kind words

    The schematic I have here is from a thread on a hifi forum about using the preamp modules as you mention:

    I think if you follow that you should be able to tap the output to use independent of the regular mixer output. You probably could just disconnect the lead where it goes to the mixer board and run a shielded line out.

    I'm not sure how much output level you will get, and I also wonder about the impedance, but it's worth a try.

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