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.
Success!
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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Showing posts with label FM boards. Show all posts
Showing posts with label FM boards. Show all posts
Sunday, July 26, 2020
Beomaster 4400 Type 2419: Personal Project: Initial Power Checks
Saturday, July 25, 2020
Beomaster 4400 Type 2419: Personal Project: Preamplifier board and FM boards
The remaining boards requiring some recapping restoration are the preamplifier board and the FM boards of the Beomaster 4400.
Again, the previous post here, show the before state of the boards.
On the preamplifier board I also replaced the six, single-turn trimmers for the Phono, Tape 1 and Tape 2 source inputs.
Here is the preamplifier board after the restoration work -
Here are the three FM boards (FM1: Tuner, FM2: IF Section , FM3: Stereo Decoder and Indicator).
There is one 10uF, 10V tantalum capacitor in the FM1: Tuner board. I measured it and it is right on 10uF so I left that capacitor alone for now.
...actually that photo is a little premature. The board still needs a 1uF and 0.47uF capacitors as shown added in this next photo.
Now for the big step of reinstalling the boards and setting up the first power on test of this Beomaster.
Again, the previous post here, show the before state of the boards.
On the preamplifier board I also replaced the six, single-turn trimmers for the Phono, Tape 1 and Tape 2 source inputs.
Here is the preamplifier board after the restoration work -
Here are the three FM boards (FM1: Tuner, FM2: IF Section , FM3: Stereo Decoder and Indicator).
There is one 10uF, 10V tantalum capacitor in the FM1: Tuner board. I measured it and it is right on 10uF so I left that capacitor alone for now.
...actually that photo is a little premature. The board still needs a 1uF and 0.47uF capacitors as shown added in this next photo.
Now for the big step of reinstalling the boards and setting up the first power on test of this Beomaster.
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