ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I have a strange fault on my 1900, the volume works fine for about 10 seconds after turning on. Then slowly takes off and goes to full blast volume by itself.
I know its old and probably needs capacitors but how do I stop this. I have replaced all the bulbs recently and checked the 15v supply is spot on.
I would be happy if it just stopped on the preset volume, I could at least use it but it is taking off and blasting.
Check that you've put the Beomaster back together correctly per the instructions in the lamp kit.The bronze contacts are of particular interest here. They need to sit correctly, each grabbing theirrespective contact pin on the boards.
Martin
It is all ok in tghat direction, it even does this fault with now covers on but will go up and down if you touch the pins with your finger but only until it warms up a little then it starts going up to maximum volume on its own and stays there.
Volume control is done using a lamp inside a closed metal housing with four LDRs (two for volume, two for loudness).The voltage supplied to the lamp controls the volume, high voltage = more light = low volume and thelamps voltage is again controlled by a decade counter on the volume board.Something must be drifting in this circuit and/or the high impedance circuits around thesensi touch pads are somehow disturbed, maybe from ambient RF noise.
Check that none of the vertically mounted components on the volume board touch eachother and/or the bronze contacts.
Is there anything I can disconnect so the set will just work on its preset volume and the up and down no longer work as this would be fine with me.
That would be a shame, really. And probably harder than repairing it.
Ok what would be the first items to test and or replace on the volume board?
First thing would be to find out if the lamp voltage is drifting.That's on the main board.
If it is, you will have to find out if the counter is counting on the volume board.If it is, you will have to find out why.If not, check if the supply voltage for the whole circuit is drifting.
I did notice that it had a transistor changed in the power supply circuit. It is the one that uses the black metal shroud for the input and speakers as a heat sink. It has a tip32a in now. This may be good or bad.
I am a radio ham and have been repairing and building radio equipment for many years. This isnt really my thing but I will have a go.
I have check the voltage to the bulb and it is rising to 1.52 volts from about 1.2 volts and staying there even when I touch the post to bring it down it flickers down a little then returns. I have no idea how to check if the board is counting up.
Servicing B&O is nothing like any other stereo.Are you measuring the voltage on the panel bulb ?You should be measuring the voltage on the bulb that sits inside the LDR casing. The bulbs connections are markedat the solder side of the board.A rising voltage will result in a lower volume.
Yes measuring the ldr bulb feed voltage.
Can you give me any ideas on exactly what to measure or test. I am at a loss and this may go in the bin at any second. I can only think of maybe fixing a voltage to the ldr bulb and using like that and adjusting the input for volume. I havnt a clue why this is rising up by itself its like its possessed.
I am going to isolate pin 10 on the counter ic and see if she still rises in volume.
ok now to put an end to this pile of junk...I figured out the problem, it was a bad connection to the relay and the 12v rail was dropping under load. I soldered it back up and put her all together. Now she wont even come out of standby.
Servicing these things is nothing like any other stereo.Lack of repairers knowledge and/or experience doesn't make it junk.Get someone who knows about to take a look at it.Most faults in these Beomasters are simple and not costly to fix.Maybe just a bad rectifier.Where are you ?
Ok guys thanks for the help so far, I have fixed it. The standby wire had come off the little volume board after I found the bad connection on the -12v rail. Its all back together and I am listening to it now.
Oh yes an I am in Warrington in the UK by the way. I am a clever guy when I put my mind to it I just get frustrated with things I have never worked on before. cheers.
Good job !
Hey folks. Just recently got my parents Beomaster 1900 when I was home for Christmas.
I'm having the same issue with the volume but everything looks to be intact. The unit is currently at a local repair shop. This issue occurred about 10 years ago when my parents had the unit in service still. To fix the problem par no. 8002292 was replaced.
B&O no longer stocks this part. Any suggestions?
Welcome to Beoworld !
That part number is the whole volume control circuit board.
All components on the board are generally available (although probably not from B&O) and it would also be possibleto find a circuit board from a donor but the Beomaster 1900 was not intended for module swap repairs, instead it willneed good old diagnosing and repairing at component level.Not impossible but maybe not something offered by all (so called) repairers.Martin
Do you have any recommendations for diagnose and repair in the US?
I'm in Denmark so I haven't used them myself but I've only heard good things about Atlantic Systems.Depending on your location, it may not be impossible to find a Beoworld member capable and willing.
Also Benny Armina, http://aminaaudio.com/ has good critics from more members, and as Martin mentions, maybe there are a member near you that can help.
Collecting Vintage B&O is not a hobby, its a lifestyle.