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Sunday, July 26, 2020

Beomaster 4400 Type 2419: Personal Project: Initial Power Checks

I couldn't end the day with just having the board restoration work complete.

I am always curious whether the audio components will actually work now.

First step was to reinstall the preamplifier and FM boards.

The Beomaster is ready to power on. Like I always do with this type of amplifier I connect the power cord to my variac, ammeter, voltmeter and dim bulb test device.  That device will protect against any hidden short to grounds on the power signals and it will tell me if something is drawing too much current.

In this case...I got nothing. No lights, no voltage on the power supplies.

After a bit of investigation I discovered that one of the AC cable wires was not connected internally in the Beomaster.  That explains that.

I checked the other wires around it and checked for any shorts. Other than the disconnected AC wire everything else looked fine.

Here is my repair of the broken wire.

That looks much better.

On the second round of the power checks I still don't get any lights illuminating on the Beomaster 4400 but I do have power on the supplies.

Here are the +15 VDC and +35 VDC supply checks

and here are the ±35 VDC rail voltage checks

It looks like the Beomaster 4400 is ready for a quick listening check.

I did a quick, initial setting of the idle current for the output amplifiers by adjusting the left and right channel trimmers to get 10mVDC across the respective channel emitter resistors.

Once those were adjusted I connected an iPod Nano to the Tape 2 source input and used a pair of headphones to check if I had sound.


I connected up an FM antenna to the Beomaster 4400 antenna input and tried tuning a station.
Another success.  The FM tuner section is working great. The tuning indicator and stereo lamps do come on as well.

So for certain the Beomaster 4400 power on lamp is not working and the lamp that illuminates the radicator (the FM signal strength meter) is also not working.

I am not sure about the overload lamp but I can test that when I replace the power on lamp.

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