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Beomaster 4400 type 2417

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kbaelden28
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kbaelden28 posted on Sat, Jun 17 2017 12:15 PM

Hi, I'm restoring a BM 4400 and bought a cap replacement kit from Dillen. 

I  want to replace the bulb of the signal meter but I don't see how to get to it. I managed to access the meter and remove the  plastic cover. 

I think there're 2 types and this is the difficult one.

Does anyone have a clue.

 

 

EDIT by Dillen:
Title corrected to read Beomaster 

 

 

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kbaelden28
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With photo 

Dillen
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Dillen replied on Sat, Jun 17 2017 1:39 PM

Yours is actually the easy one but you haven't noticed the socket. :-)
Put the clear cover back on before something goes wrong.
Then pull the socket out of the side of the meter (pull on the solder tabs).

Martin

kbaelden28
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So easy ! Thanks Martin.

kbaelden28
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Hi Martin, I'm replacing the capacitors of PC3 Stereo decoder and indicator circuit with the service kit you provided.

Some of the new caps  have the same uF but lower voltage, 50v instead of 63v, it's C14 1uF, C16 1uF (both yellow circles on your scheme) and C29 2,2uF, C30 2,2uF (both green circles).

Just to be sure, this will not blow up the caps? 

It's currently not possible to upload a picture with my phone.

Thanks again!
Dillen
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Dillen replied on Thu, Jun 29 2017 10:40 PM

Great to see that you are aware, but you can safely trust what's in the kit.

 

There are no voltages in the tuner anywhere near 50V so it'll be fine.

 

63V was a standard when the Beomaster was produced, and you practically couldn't find

low capacitance capacitors (1uF, 2,2uF etc) with a lower voltage rating.  

I'm sure B&O would've used 25V or 40V components had they been available at the time.

 

The problem with using capacitors with a too high voltage rating is that they won't be excited and

they will die faster than if they see voltages up closer to their rating, even if only occasionally.

It's a chemical thing. 

You could say that they will "die from boredom".

 

A good handrule is to use capacitors with ratings 10-20% above the actual working voltages.

Martin

kbaelden28
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Great, I'm not very experienced, better save than sorry :) .

For the trimpots, can I just pull them out, measure the ohm value of the old one and adjust the new one accordingly as a starter? And then adjust according service manual if necessary?

 

Thanks

Kristof

Dillen
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Dillen replied on Fri, Jun 30 2017 3:21 PM

kbaelden28:

Great, I'm not very experienced, better save than sorry :) .

For the trimpots, can I just pull them out, measure the ohm value of the old one and adjust the new one accordingly as a starter? And then adjust according service manual if necessary?

 

Thanks

Kristof

You can use the apprx physical position of the old trimmers as a starting point, or you can start with the new trimmers centered.
Given that the old trimmers will be - if not already bad, then at least marginal by now - you really shouldn't use their
current ohmic values as reference.
The servicemanual will tell how to adjust.

Martin

kbaelden28
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Hi guys,

The tuner had a good reception, the signal was good but the sound quality was bad and only the left channel worked fine, the right channel was very low even when I turned the volume at max.  

So I decided to first replace  the caps and trimmers on PC3 (stero decoder and indicator circuit), PC2 (IF-section)and one tantal of 10uF of PC1 front-end.

Now I get just a very very weak signal if I set FM dail all the way to the left. Most of the time the meter is at it's highest (right  5).

I've first set the trimpost like the old ones then started  changes all trimpost but nothing really happens, sometimes the meter goes to zero or the stereo indicator lights up but no signal whatsoever.

I have checked the tuning voltage of 2R10 but I can't go up to 25,5 V , the range is between 16,2V and 20,3V.

I didn't touch any of the front-end switches  or the L1 , L2 decoder coils.

I double checked the trimpots for correct value before inserting them, but still I might be wrong there! I can't think of anything else. 

What should be the first check to get a good signal ?

Thanks

Kristof

 

kbaelden28
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I noticed that the corners of the big red/black/yellow/black resistor attached outside the metal box broke off when I opened the box. The leads of the resistor seem to be intact.

Can this cause the lack of signal ?

 

I'm not able to upload photo's, is this a common problem?

Thanks Kristof.

kbaelden28
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I noticed that the corners of the big red/black/yellow/black resistor attached outside the metal box broke off when I opened the box. The leads of the resistor seem to be intact.

Can this cause the lack of signal ?

 

I'm not able to upload photo's, is this a common problem?

Thanks Kristof.

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