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Beocenter 9500, heat and hum

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jlehtinen
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jlehtinen Posted: Mon, Apr 23 2012 8:11 PM

Hi,

My journey with BC9500 continues. Now that I got mute relay fixed I have had beocenter connecter to mains for longer time and have noticed that heat sink heats up quite a bit even in standby, also transformer hums audible (50hz hum). I found posts about setting the transformer for 240v instead of 220V. I did that and it definitely made difference, less heat and hum. After reading more post I guess the real issues to too high idle current in power amp? Any pointers for setting the idle current? Maybe I should replace some caps before trying to adjust anything?

When fixing the mute relay I saw that area around TR4 looked like it had been heating up, could that have anything to do with heating or hum?

Ah, too many questions, I should upgrade to Gold and get access to service manuals etc... Embarrassed

Jyrki

tournedos
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tournedos replied on Mon, Apr 23 2012 8:41 PM

These Beocenters use hybrid power amplifiers, and they have no adjustments. The idle current setting issues don't therefore apply.

TR4 on the power supply / amplifier board is in an identical role with the muting relay transistor you fixed, except that it controls the main power supply relay. It is therefore "on" whenever the Beocenter is being used (not on standby). I would expect it to heat a bit and possibly darken the PCB over the years. The mains voltage setting wouldn't affect this as the relays are supplied from a regulated 7V supply.

Mine hums annoyingly even on 240V if it stands on a surface that amplifies it. And still stays noticeably warm on standby. Most older¹ B&O devices would have no chance of passing the current EU regulations of <1W standby power consumption... In short, I believe everything is fine with your BC.

___

¹ not old enough to have a mechanical on-off switch Big Smile

--mika

jlehtinen
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jlehtinen replied on Mon, Apr 23 2012 11:18 PM

OK, that was good news that there is no need for adjustments in amplifier. Smile

I did check the TR4 as I still had BC open, and found something fishy I think. When power is ON the voltages are: C=7,7 B=0 and E=0, but when turning unit OFF (standby) C=7,7 B=5,1 and E=5,1. So it looks like B and E are in short circuit. There seems to be no action in power supply relay when powering ON or OFF the beocenter. Maybe an other transistor / relay replacement in order!?

I agree, sometimes old mechanical switches are sooo much better.  ;-)

BTW I found about 20 years old C-cassette and tried that in tape deck, whoa deck is working, but what truck me most was the sound quality of that old tape! I was waiting for some horribly distorted sound, but no, it was loud and clear and quality was at least the same than local radio station playing rock. Now I'm wondering if I should dig out all old tapes from attic. Huh?

Jyrki

hemenex
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hemenex replied on Tue, Apr 24 2012 8:29 AM

jlehtinen:
So it looks like B and E are in short circuit.

Probably not.

E of TR4 should be at GND-Level so I suspect bad solder or broken Ground trace.

And probably a broken T4 anyway..

  Gunther

P.S. And yes, the mp3 gereration is always surprised about sound quality on (most) analogue tapes.

Nowaday's ears are so untrained.... Sad

 

tournedos
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tournedos replied on Tue, Apr 24 2012 8:50 AM

hemenex:

Probably not.

E of TR4 should be at GND-Level so I suspect bad solder or broken Ground trace.

But then the main relay coil wouldn't get power... so probably a measurement error. And a broken T4 anyway Big Smile

(We are talking about T4 on module 60, another BC337, right?)

If it has a C-E short, the relay will be energized all the time, the amps stay on and that would explain the extra heat and possibly the odd standby button behaviour you mentioned in the other thread.

The cassette deck on these is indeed a real business, although it might seem like a cheap add-on at the first glance. Definitely worth using if you have tapes to play!

PS. as the broken relay control transistors seem a trend with this particular Beomaster, there's still a third similar circuit that controls the power to the CD unit. You should hear a relay click when you switch between CD and radio, for example.

--mika

hemenex
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hemenex replied on Tue, Apr 24 2012 9:32 AM

tournedos:
(We are talking about T4 on module 60, another BC337, right?)

Yes (at least me Stick out tongue)

And talking about a B-E short circuit wouldn't engage RL1, only as you mention a C-E short.

So it's perfectly fine to have 7V on C of BC337 and the uP obvoiusly switches as the B-voltages show.

Maybe a shorting of T4 C-E manually would engage RL1 but I'm afraid it doesn't because of E not being GND level.

Shorting to GND (housing metal?) could engage it which would prove RL1 ok.

voltage measure numbers erroneous?

EDIT: And looking at RL1 it's a 4 times NC so it ISN'T engaged (with 7V on C it can't); that's why BC is always on...

jlehtinen
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jlehtinen replied on Tue, Apr 24 2012 9:55 AM

Now I got access to service manuals and can see what you guys are talking about.  Wink

To summarize, the power suply relay should get 7V when BC is turned OFF, and this is not the case as the TR4 does not have E connected to GND due to bad soldering or fault in PCB. Did I get it right!? Smile  I actually tried to short circuit the C and E and nothing happened in relay, and this due to missing GND E. To verify the relay I will short the C to GND.

I'll try to verify the operation of CD relay and TR as suggested by Mika.

tournedos
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tournedos replied on Tue, Apr 24 2012 10:26 AM

Yes, I'll believe Gunther regarding the relay - so it's more likely that you have a bad connection somewhere, and the transistor might be fine.

Thanks for upgrading, Jyrki - well appreciated Yes - thumbs up

--mika

jlehtinen
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jlehtinen replied on Tue, Apr 24 2012 12:23 PM

Transistor controlling the "CD relay" is TR2 on PCB60. I can't recall hearing any relay click when "activating" CD... This means that I have something to do tonight. Wink

Talking about CD, mine seems to some issue with friction/pressure of clamper that holds CD in place. When CD spins up, there is a scraping sound and it looks like CD does not gain speed as it should -> CD does not start playing. Is this common problem with BC9500?

Jyrki

tournedos
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tournedos replied on Tue, Apr 24 2012 1:03 PM

jlehtinen:
Talking about CD, mine seems to some issue with friction/pressure of clamper that holds CD in place. When CD spins up, there is a scraping sound and it looks like CD does not gain speed as it should -> CD does not start playing. Is this common problem with BC9500?

I don't think I've seen that... but it's possible that the CD module isn't quite positioned right mechanically. When the Beocenter is normally assembled and you open the CD door, the CD mech should still be "springy" at each corner.

--mika

Johan
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Johan replied on Tue, Apr 24 2012 1:35 PM

jlehtinen:

Talking about CD, mine seems to some issue with friction/pressure of clamper that holds CD in place. When CD spins up, there is a scraping sound and it looks like CD does not gain speed as it should -> CD does not start playing. Is this common problem with BC9500?

I have to admit, I actually did this on my BC9000. I wasn't careful enough when assembling the cd mech after cleaning, and the floor/bottom (or whatever) part of it was not level (not sure now exactly how I managed..). I had to open it up again and do it right. It was quite obvious what was wrong just looking at it, as I recall.

jlehtinen
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jlehtinen replied on Tue, Apr 24 2012 1:50 PM

When placing the CD to player and spin it manually with finger there is no scraping, so the DC is not touching "chassis". it feels like axel (plate that CD is placed on) is spinnig but there is not enough friction to get CD spinning as well. Is there any rubber coating or similar friction enhansing pad in axle? Axel seems to be more or less plain metal in my case. With axel here I mean the metal plate that has contact with DC.

joeyboygolf
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jlehtinen:

Talking about CD, mine seems to some issue with friction/pressure of clamper that holds CD in place. When CD spins up, there is a scraping sound and it looks like CD does not gain speed as it should -> CD does not start playing. Is this common problem with BC9500?

Jyrki

The pressure that the clamper exerts on the CD is adjustable via the three screws that secure the clamper to the side of the mechanism.

Make sure that the two outer screws are tight and release the centre screw very slightly to drop the clamper a fraction of a mm to tighten the grip on the CD.

Regards Graham

jlehtinen
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jlehtinen replied on Tue, Apr 24 2012 2:36 PM

Thanks Graham! I'll adjust the clamper for more pressure.

My To Do list for BC9500 got just one more bullet.  Wink

Amazing amount of knowledge available here in Beoworld. Thumbs up for everyone!

jlehtinen
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jlehtinen replied on Wed, Apr 25 2012 9:18 AM

Update after last nights session with BC9500:

- No more heat and hum in standby state! Problem was bad PCB (copper foil was damaged just next to TR4 E leg) and TR4 not having contact to GND via E -> BC had power ON all the time. I also replaced the TR4 just be sure. Gunther's suggestion was spot on!

- CD relay is now working as well, faulty TR2 was replaced and voilà, CD relay is clicking again.

- Tightening the CD clamper helps to keep CD in place, but still issues to read the CD (CD spins up and after awhile stops again and CD door opens), I guess problem is capacitor  C2103. Anyone managed to get hold of those caps lately?

Jyrki

joeyboygolf
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jlehtinen:

- Tightening the CD clamper helps to keep CD in place, but still issues to read the CD (CD spins up and after awhile stops again and CD door opens), I guess problem is capacitor  C2103. Anyone managed to get hold of those caps lately?

Jyrki

I get mine here

http://uk.farnell.com/vishay-bc-components/mal203035339e3/capacitor-33uf-16v/dp/1165415

or http://uk.farnell.com/vishay-bc-components/mal203036479e3/capacitor-47uf-25v/dp/1165421

Up to now I have always fitted the 33uF but there is a school of thought on this forum that the 47uF is preferable.

Regards Graham

Johan
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Johan replied on Wed, Apr 25 2012 9:51 AM

I get mine from elfa.se

This is the Finnish version (it's a Swedish company) but I don't know if they ship from Sweden, or if they have a local storage in Finland.

https://www.elfaelektroniikka.fi/elfa3~fi_fi/elfa/init.do?init=1&shop=ELFA_FI-FI

/  Johan

jlehtinen
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jlehtinen replied on Wed, Apr 25 2012 4:59 PM

Thanks guys! I check from Elfa, as I'm nowadays living in Stockholm,  actually quite close by Elfa in Kungens Kurva.  Wink

Jyrki

jlehtinen
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jlehtinen replied on Wed, Apr 25 2012 5:35 PM

Johan - Is this the one you have used (33uF 40V): https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=67-062-53&toc=19198

I can't find 16V version from Elfa not 33uF nor 47uF.

Jyrki

Johan
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Johan replied on Wed, Apr 25 2012 9:08 PM

jlehtinen:

Johan - Is this the one you have used (33uF 40V): https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=67-062-53&toc=19198

I can't find 16V version from Elfa not 33uF nor 47uF.

Sweet! I'm from Stockholm, but nowadays in Uppsala.

The voltage doesn't matter as long as it's over the original, so 33V should be fine. What matters, apparently, is that it's Vishay (formerly Philips) axial.
I got the 63V 47uF, but admittedly I haven't yet had time to solder it in. Though, people on the forum report that it should work. I have both a BC9000 and a BG CD 7000 that need the fix, hopefully I'll get around to it soon.

/  Johan

Johan
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Johan replied on Wed, Apr 25 2012 9:09 PM

And by 33V I mean 40V. Smile

joeyboygolf
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Johan:

jlehtinen:

Johan - Is this the one you have used (33uF 40V): https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=67-062-53&toc=19198

I can't find 16V version from Elfa not 33uF nor 47uF.

Sweet! I'm from Stockholm, but nowadays in Uppsala.

The voltage doesn't matter as long as it's over the original, so 33V should be fine. What matters, apparently, is that it's Vishay (formerly Philips) axial.
I got the 63V 47uF, but admittedly I haven't yet had time to solder it in. Though, people on the forum report that it should work. I have both a BC9000 and a BG CD 7000 that need the fix, hopefully I'll get around to it soon.

/  Johan

Regards Graham

jlehtinen
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jlehtinen replied on Wed, Apr 25 2012 9:55 PM

hhhmmm, something is not correct on Elfas specifications. if you open the datasheet that they refer, it seems to be more or less same capacitor as the one Graham provided link to....   

Here is the link for data sheet that Elfa is referring: datasheet

joeyboygolf
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jlehtinen:

hhhmmm, something is not correct on Elfas specifications. if you open the datasheet that they refer, it seems to be more or less same capacitor as the one Graham provided link to....   

Here is the link for data sheet that Elfa is referring: datasheet

Correct. I just deleted a complete post because I was confused. I have had another look at the data sheet and it states that it is for range 030 and 031

The component that they are selling is neither of the above. Unfortunately, the Farnell website is down as I am writing this but I read the spec of the 2222 range this afternoon and it has 500 hrs life at 85deg and tolerance of +/- 20% . The 030 range has tolerance -10/+50% and 3000 hours life.. There may be even more important differences.

I would stick with the 2030 range because we know they work. I have used 40 and have just ordered some more.

*edit*

OK the Farnell website is working and I have compared the specs.

The Elfa offering is indeed only 500 hours life a 85deg while the 2030 range is 3000 hours and the tolerance is as I stated They have the asame quoted ESR but the Elfa offering is twice the price of the 2030 range when the 2 are compared on the Farnell site.

The spec says they should both work but the cheaper will last 6 times as long!!! There must be something that I don't know here. Anybody help out???

Regards Graham

Johan
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Johan replied on Thu, Apr 26 2012 8:58 AM

Now I'm confused. :-)

Searching for the component number gives: http://uk.farnell.com/vishay-bc-components/2222-031-38479/capacitor-47uf-63v/dp/305637
and those specs look exactly like the specs you mentioned, not 500h?

Now, I'm not saying that one shouldn't go with what is known to work, I'm just asking because I want to understand.

Concerning prices, Elfa is usually more a tad expensive than various other websites. The reason I use it, though, is that it's very reliable. The company has been around since the 1940s, and is unlikely to disappear on you. Second, shipping is blazingly fast. On several occasions I've received my order the next day. Usually, though it takes two or three days, and sometimes a week. But never more than that. Some people ordering off of other websites have not received their stuff for months. For me, since I'm not ordering huge quantities of components, paying a dollar or so more is not an issue, when I know I'll get it quickly and reliably. Also, there is no restriction on quantity, if you want one transistor, you can order one transistor.

/  Johan

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tournedos replied on Thu, Apr 26 2012 9:12 AM

As far as I know the original component series was 138 AML, and they are still available from at least Digi-Key. I'm not saying any of the posted models wouldn't work, but those are what I've been using.

--mika

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jlehtinen replied on Thu, Apr 26 2012 9:22 AM

Found this from Vishays page: Comparison between different series  So it looks like 138AML is reted for higher tempetures (longer life) than 030/031 series.

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Going back perhaps 10 years, I originally purchased the official capacitor C2103 from B&O spares. It was branded Philips and worked 100%. They became obsolete and no longer available from B&O.

I experimented with various brands of 33uF capacitor with varying degrees of success, possibly around 50%

The 138AML series were researched and  recommended by Menehem  and I have subsequently used many of them. They are relatively expensive but guaranteed to work in the C2103 application.

About 2-3 years ago it was then pointed out, by some members, that the 2030 series also worked and were very much cheaper. I have since been using these with 100% success.

I have purchased several cap kits from Martin (Dillen) , I am not sure what type  he uses in the kit but it is 33uF/16v

The 2222 021 series are unknown to me but  the spec that I have seen looks worse and they are double the price at my supplier.

*edit* The 500hrs life is a typo on the Farnell catalogue page!! On the data sheet the lifetime is much better than the 030 series!

I am not clever enough to explain the differences in the products so I stick with what I know works. We need an expert here to give considered advice.Geeked

Regards Graham

jlehtinen
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jlehtinen replied on Thu, Apr 26 2012 10:24 PM

Thanks Graham for C2103 history lesson.  Wink

Today I went to local Elfa store to see when caps they have available and came home with couple of different caps (33uF 40V and 47uF 25V). One that tried first was 33uF 40VDC version from Vishay 030 series (2222 030 37339) and CD worked straight away! I don't know if I was just lucky, but it looks like Vishay 030/031 series caps can be used to replace the C2103.

Now that I have been practicing with BC9500, that was in bad shape to start with, I can move on and do C2103 operation to my pristine BC9000 that some times have problems to read CDs.

Jyrki

tournedos
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tournedos replied on Fri, Apr 27 2012 8:01 AM

This is an enjoyable thread! Big Smile

I'll confuse us more by telling about my CD6500. When I got it more than four years ago, it wouldn't play at all. That was the first time I learned about the C2103 issue (thanks again, Die_Bogener!) but as it was about 11PM on a Saturday night, I obviously didn't have the correct capacitors available.

The closest thing in my junk box was four can't-remember-which-type 10 µF caps and I connected them in parallel. And the player worked. I intended to replace them with the correct cap later, but simply haven't bothered because to this date, it has played every disc flawlessly.

I believe the deciding factor is some odd property you can't find on the data sheets. Try many different CDs until you declare that it works (and you should check the laser current as well after replacing the cap).

Nowadays I replace the cap every time I need to open a CD player of this type, but if there's no other reason to go in there, I have this old very scratched CD-R I try... if it doesn't play, the player needs attention even though it might still work with most CDs.

(I don't think the scratches are the issue, but the combination of the brand of the CD-R blank and the burner seem to have created a "difficult" disk.)

--mika

jlehtinen
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jlehtinen replied on Sat, Apr 28 2012 8:44 PM

I have now played about 20 different CD, some of them CD-R's, and every single one has worked fine, so it looks very promising. I have not measured the laser current, as I put everything back together before reading last comment from Mika.  Stick out tongue  I'll report back if any problem arises.

Jyrki

jlehtinen
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jlehtinen replied on Mon, May 14 2012 3:51 PM

Hello,

Just quick update, I used similar capacitor to fix the CD in BC9000 and it  is working fine. So far all CD's have worked flawlessly in BC9500 that was fixed some time ago.

This is the capacitor I used: 33uF 40VDC version from Vishay 030 series (2222 030 37339)

Jyrki

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