Beomaster 4400 probleem

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Raymond Posted: Sun, Apr 11 2021 3:27 PM

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Goedemiddag mede B&O liefhebbers! Ik ben Raymond, trotse eigenaar vaan een Beomaster 4400 en een Beogram 4002.

Omdat ik een probleem met de receiver heb ben ik op internet gaan zoeken en kwam zo op dit forum terecht. Ik heb de omschrijving ook op het algemene forum geplaatst, maar meld 'm specifiek ook hier nog even.

This is the problem:

1. First speakers where attached to speaker1 port. After a while the sound from one of the channels was gone. Them I tested the speakers on speaker port 2 and everything worked again. so for then, problem solved . 
2. Next I had my Ipad attached to tape 1. Everything worked fine. After a while no sound. Tested the Ipad on tape 2, worked again. Problem solved.
3. But now, again one channel of the speakers stopped working.
4. I ordered a service kit from: https://www.beoparts-shop.com/product/service-kit-beomaster-4400/.
5. Replaced most parts except for a few capacitors which already seamed replaced. All the trimmers I replaced I put visually in the same position as the old ones.
6. Tested the receiver. Still not good.Current problems:
7. ipad on tape 2: left speaker sound much much louder than right speaker. Adjusted the trimmers, left speaker as quiet as possible, right as loud as possible then they are about even. Doesn't seem ok to me.
8. With the volume slide at 3-4 I get a very low sound, normal listening volume is now at 7-8 (previously I had my volume at 3 for normal loudness).
9. Same situitation for ipad at tape 1. Same for phono.
10. There also seems to be a lot more crackle (do'n know if this is the right word ) when sliding the volume and balance slide.

Mijn enige tools als het om electronica gaat zijn schroevendraaiers, een multimeter en een soldeerbout . Dus geen verdere meetapparaten zoals ik op de blog van Beolover wel voorbij zie komen...

Heb nu als tijdelijke oplossing een moderne marantz staan, maar dat is toch niet hetzelfde hè....

Ik hoop dat het probleem bekend voor komt en iemand me verder kan helpen. 

Bedankt alvast voor de support!

Groeten,

Raymond

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Craig replied on Sun, Apr 11 2021 3:33 PM

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Firstly check you have replaced all the capacitors with the polarity the correct way around, its very easy to put one in the wrong way....I would also check all the plug and socket connectors, give them a clean....it sounds to me like you have a bad connection somewhere....then start to look closely at the PCB's and see if there are any cracks which are causing open circuits across the copper tracks.....thats a common problem with the 4400's.....oh and post some pics....it often helps

Good luck

Craig

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Raymond replied on Sun, Apr 11 2021 6:59 PM

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Hi Craig,

Thanks for your reply!

I'll double check all the caps I replaced. You're right, a mistake is easily made.

I'll also check for bad connectors, although what I find remarkable is that the volume problem occurs on all inputs, tape1, tape 2 and the phone input...

I don't know if there is a single part behind these inputs which can cause these problems?

Thanks for your suggestions. I'll keep you posted and will add some pics....

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Dillen replied on Sun, Apr 11 2021 8:08 PM

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What are those large capacitors at the rear?
Looks way wrong.
And the one under the tape(?) - 220uF/63V or?

You cannot align anything correctly by setting the new trimmers "visually like the old ones were".
It won't work.
And even if the Beomaster perhaps ends up "somewhat working" it will not be performing like a Beomaster 4400.

With all due respect and in the best of meaning, so don't get me wrong;
I have the deepest respect for owners wanting to do repairs themselves, but if you don't have the tools and instruments needed to do it right, I suggest you consider leaving the job to someone who has.

Martin

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Raymond replied on Mon, Apr 12 2021 7:12 AM

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Hi Dillen,

Thanks for your feedback. First of all I agree with you, if you don't have the knowledge or tools leave it to the persons who have. That's why I started out by consulting my brother in law who is a professional hardware (pc's) repair guy. As I showed him some pics I took from the different boards he noticed that some capacitors had already been replaced (the strange big ones, get back to that later), and that a few trimmers (the ones on the PC 4) seemed corroded.

As I tried these corroded trimmers I noticed a lot of cracking and that the music from channel stopped. so his advice was to start with replacing these parts. That's why I bought the replacement kit from Beoparts and replaced these trimmers and all the old caps on this board.

After that I tested the amp again, but the problems stayed the same.

As changing out the old caps was a really zen job to me I decided to exchange the rest of the old caps as well from the other boards. Wouldn't hurt to get some fresh caps and I made sure their polarity is correct and the uF as well (Beo parts provided a great overview with all the components that needed to be replaced and which uF they have, but I always checked with the old cap if the numbers matched).

The big ones I left as they were, because they were already exchanged at some point so probably not so old and the amp worked fine with them prior to the occuring problems. I could still replace them as I also have these in the kit I ordered. I agree with you, they look really odd compared to the size of the caps I'm using from the kit.

Last but not least, setting the trimmers by view. I agree with you that you can't set these without proper measuring with the right equipment. So I can imagine your first thought was "what the f*#ck???" . But try to see it my way:

I see it as a preliminary setting which will need to be refined with the correct measuring equipment, but I assumed a small deviation of the correct value won't cause the cracking and strange volume problems I'm experiencing. Could well be a wrong assumption...

I hope this feedback clarifies my reasons for starting to fix the problem. Again, I totally agree with you. If you don't have the knowledge, leave it to those who have. But replacing the caps was an easy job and would be great if that would have solved the problem. As it didn't (unless the problem is in the odd big caps), my last idea was checking with you guys to see if we can find out what it is. If this won't do, I'll have to send it to an expert.

Reading your comment, I assume you are someone who has extended knowledge of repairing these amps, so if you have any ideas which could point me in the right direction, that would be greatly appreciated.

Regards,

Raymond