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Hi there,
I got my hands on an beomaster 1900-2, which only goes in standby. After getting a capacitor and lamp replacement kit, and some other parts from dillen, i i was able to repair this fine fine piece of receiver.
Now it plays wonderfull again, the only thing which is annoying me, is the three stage poweron volume preset. Even set to "low" it is far too loud for my small room and i have to tap "volume down" to correct this. I have already the version with the 128 step volume version.
Is there any way i can change some parts in the beomaster, to correct the startup volume to a lower volume? As far as i can see from the manual, the volume preset is connected to the ic01, which has a matrix for which position of the preset enables which output volume.
Pretty much no way to change this, but is it possible to lower the input signal to this ic alltogether? I dont need this much volume and maybe someone is able to read the manual and give me a hint. I am good at soldering and have a multimeter to messure and find a failure, but i am no profi to know how to change a capacitor or a resistance to lower the input volume so that it's not that loud at startup on "low". Is someone able to help me with this?
Thanks,
Matthias
Hi,
Looking at the service manual it appears that R136 adjusts the level. The manual states "ADJUSTMENT OF LEVEL: Volume set at MEDIUM and receiver switched to TAPE. Connect tone generator to TAPE input, 200mV, 1kHz. Connect millivoltmeter to speaker output. With 2R136 adjust for 100mV at output"
I see no reason why this couldn't be adjusted to to a lower output level if this better suited your needs.
Kind Regards,
Martin
riverstyx: Looking at the service manual it appears that R136 adjusts the level. The manual states "ADJUSTMENT OF LEVEL: Volume set at MEDIUM and receiver switched to TAPE. Connect tone generator to TAPE input, 200mV, 1kHz. Connect millivoltmeter to speaker output. With 2R136 adjust for 100mV at output" I see no reason why this couldn't be adjusted to to a lower output level if this better suited your needs.
I think that will also lower the maximum volume of the unit, and this is not quite what was requested.
I believe it's the resistors next to IC3 (R16 etc) that do the presetting, and playing around with those values might do just what the OP wants. This is just from a quick look at the schematic so don't quote me on that. Someone with at bit more knowledge might be able to give more precise advice.
/ Johan
Hello
I believe you should also ask Martin, he is on these forums, on this specific topic, as he knows a lot about this marvellous Beomaster 1900. He should provide you with a detailed answer.
Alain
Johan: I think that will also lower the maximum volume of the unit, and this is not quite what was requested.
Yes, this will reduce the maximum volume output of the unit, but I intepreted the part of the OPs question "but is it possible to lower the input signal to this ic alltogether? I dont need this much volume" to indicate that this might be an acceptable solution to him, and would obviously be easier than starting to modify the unit, but apologies if I have misinterpreted the question.
Kind regards
Dear Martin,
Thank you for your quick hint with R136. Exactly this does what i wanted. I can reduce the volume level to a much lower level. And the others are also correct, as it reduces the maximum volume level i can reach. But this does not matter for me, as i want a lower volume level. My room is much too small for the maximum volume level the beomaster 1900-2 can reach.
Thank you for your answers, this forum is great!
Hi Johan,
You mean the resistors R18 / R20 and R22 next to R16? I also looked at them but i think, that they are a toggle between -12V and 0V for the input pins of ic1. Switching the presets will change which input pin, which will be pulled down to 0V and which to 12V. Its not easy to find information about this ic1 in the internet. And i think it will be even harder to find a new one, if i grilled it with any modufication. So, Martin was leading me into the right direction.
Thank you,
Ok, yes I think you may be right.
If you're happy then all is good. :-)
baerchen2: Hi Johan, You mean the resistors R18 / R20 and R22 next to R16? I also looked at them but i think, that they are a toggle between -12V and 0V for the input pins of ic1. Switching the presets will change which input pin, which will be pulled down to 0V and which to 12V. Its not easy to find information about this ic1 in the internet. And i think it will be even harder to find a new one, if i grilled it with any modufication. So, Martin was leading me into the right direction. Thank you, Matthias
search for the 4516 datasheet. It's an ordinary binary Up/Down Counter with preset made in CMOS. You should get this chip at Reichel.de or farnell or where ever you buy your spare parts.
Changing those resistors won't solve the problem, they are just pull-ups. to lower the setting of the preset for 'LOW' one should change the assignment of the preset loading into the 4516 counter chip but this makes some modifications to the printed circuit necessary.
If two taps of 'Volume Down' is enough the modification should be easybe done by cutting one small wire at the preset switch:
Right now the preset switch let the counter load the values '6', '8' and '10' for 'L', 'M', 'H' after Modification the switch loads '4','8' and '10' as preset values.
This modification lets the maximum volume untouched
Ralph-Marcus
Cool! Thanks for clearing that out.
Wow, thank you Ralph-Marcus,
This is very good information. I will try this in the next days and keep you posted, if it worked.
Well Ralph,
I found a description for the volume preset in an beomaster 1900 manual. Here it is stated, that the "low" value should be (DCBA) 1010, but when i check my beomaster 1900-2 with a multimeter, it is (DCBA) 1100 in my beo1900-2. Maybe they changed this from beo1900 to beo1900-2. So i think i will try and pull the "B" also up to "1" (grounding to 0V) and check, if this will make the startup volume even lower. The other values for "med" and "high" in my beo1900-2 are as stated in the manual.
Also i found, that the layout of the upper board with the sliders, switches and station presets if different to the one a found in an beomaster 2400 manual. Is there a difference between beo2400 and beo1900-2? Or is this there a later and/or earlier version.of this layout?
Hi Matthias,
according to the manual and to the circuit diagramm there should be the following three input codes:
DCBA
1010 for 'L'
1000 for 'M'
0110 for 'H'
If you get for the 'L' position of the switch another code there must have been some modifications done at the switch itself or its cabling. The switch is connected to the board via 4 cables maybe someone changed the cabling. You should check the cabling from the counter chip input pins to the switch and then the connections of the switch. Check whether you get a ground connection at every pin of the switch in every position of the switch where it should be grounded according to the circuit diagram
If you know the correct function of the switch you can start to modify the circuitry.
I don't know whether they changed the layout of the board of the 1900-2. The manual you have is from the BM1900-2 if im not wrong.
Hi Ralph-Marcus,
Thank you for your comments. You are correct and the manual too. I didn't check the lines to the ic correct. So i have the PIN connected to "C", which is open = -12V = 0 in the position "low" of the preset switch. Now i grounded this PIN to 0V = 1 to get lower startup volume. I added two pictures, where it is easily to see.
Which this you get a lower startup volume for the positions "low" and "med", as the PIN "C" is changing from 0 in the matrix to 1.
1110 for low
1100 for med
0110 for high
With this the startup volume in position MED is even lower than the original startup volume in LOW! The new startup volume for LOW is now realy low and very good for my needs. The only problem is the hefty volume change to the postion HIGH now. This is a big volume step now, as it is unchanged from the original one.
Thanks for your input Ralph-Marcus, it helped me very much!
My change in the layout
And here the wire on the board