BeoWorld North America

Re: Dead Beocord 9000 motor

Piaf — Fri, 07 Nov 2008 18:35:44 GMT

Martin is being entirely too modest.

The Beogram 4000 proved to be unreliable, problematic, and repeatedly blew fuses for the previous owner. In short, the 4000 exhausted the owner’s patience and he put it up for sale on eBay. Once it “appeared” that the fuse issue was sorted out, only then did he agree to sell the 4000 to me. (An honorable seller)

The 4000 arrived in pieces, but once it was put back together and with help from Martin and Frede…. it performed extremely well for 9 months.

Then the fuse blew and the rest of the story is well known. Martin was BEYOND patient with me, offering step by step advice, but in the end, I could not manage to locate the problem and shipped the 4000 to Martin, who is undoubtedly trying to save me embarrassment, by not revealing the details.

However, my motto is we can all learn from other people’s mistakes and although this error would be highly unlikely to be repeated, this is what happened.

The former owner purchased the Beogram 4000 in Berlin and brought it with him to the United States. He had the 4000 adapted to 115v and changed the electrical plug to US standard. Had I known that this trivial detail was important I could have saved myself a world of grief and money.

If exact details are required, I can quote from Martin’s report, or he can elaborate for himself if need be. However the long and the short of it is the 250mA fuse that worked perfectly well when the 4000 was powered in Germany with 220v was inadequate once the 4000 was switched to 115v. Internal voltage is nearly double with 115v as opposed to 220v, so as long as the Beogram did not lower the tonearm, the 4000 was a happy camper. But the minute the tonearm lowered, the voltage shot past the 250mA fuse’s capacity and it blew. Repeatedly!

The only unresolved mystery is how did the 4000 operate for 9 months without blowing the 250mA fuse? I don’t think there is an answer to that. However once an appropriate higher value fuse was installed, the Beogram 4000 tested out with no electrical faults. So it went all the way back to Denmark for a fuse.

I will be SO happy to have my much appreciated Beogram 4000 back…. there are simply no words to properly express.

The Beogram 4000 problem now fixed as well as a speed issue with my Beocord 8004 resolved…. I was attempting an adjustment sans the proper tool, but once Martin provided me with a source in the UK, that issue is behind me as well.

Currently I am “attempting” to locate the problem with my Beocord 9000. With help/advice coming in from Martin, Derek, and Bill Rapp I am getting fairly close to pinpointing the problem. First I need to rule out a few issues that Derek pointed out as possible problems all mentioned in a few threads back.

Assuming that the motor issues can be put to rest as not the problem, then I will attempt to test the power supply transistors as per Martin’s direction. Unfortunately, I very much doubt I possess the technical expertise to carry out this task properly. My limited skills are better suited in dealing with mechanical problems and adjustment of these Beograms/Beocords as compared to testing for voltage values with my handy new Fluke multimeter.

Jeff

Re: Dead Beocord 9000 motor

Friedmett — Fri, 07 Nov 2008 17:47:39 GMT

My guess. They wanted money right?

Re: Dead Beocord 9000 motor

Medogsfat — Fri, 07 Nov 2008 17:45:42 GMT

Dillen:

to be honest, the greatest challenge regarding this Beogram 4000 repair turned out to be with the danish customs.
Martin

Now why doesn't THAT surprise me

Chris.

Re: Dead Beocord 9000 motor

Dillen — Fri, 07 Nov 2008 17:39:31 GMT

I've been travelling a lot lately so time for repairs has been limited.

The fault turned out to be something quite simple though not immediately obvious.
It will be heading its way back next saturday and, to be honest, the greatest challenge regarding this Beogram 4000 repair turned out to be with the danish customs.

Martin

Re: Dead Beocord 9000 motor

Friedmett — Fri, 07 Nov 2008 16:44:23 GMT

I'm sorry to ask an off topic question but still B&O related.

How is it going with the Beogram you shipped to Dillen?

Its been a while and it would be great to hear any updates.

Re: Dead Beocord 9000 motor

Piaf — Fri, 07 Nov 2008 15:51:11 GMT

Derek,

Thank you! This information really helps…. and makes sense.

However, I have managed to confirm that the original motor is good, and still the fuse blew when it was in the Beocord 9000.

Also, the replacement motor does operate, if briefly, until the fuse blows.

This weekend, I will remove the replacement motor, as you directed and see what I can find vis a vis if the fuse blows without load.

I will also test the replacement motor outside the 9000 to verify that it is good.

My money is on the transistors in the power supply, but I will first eliminate the motor as a source problem first. Especially since it is doubtful that I have the ability to properly test those transistors.

Thank you for taking the time to explain what I need to do, how, and why.

I really appreciate your help!

Jeff

Re: Dead Beocord 9000 motor

auric — Fri, 07 Nov 2008 11:37:20 GMT

Think this through...

You have a motor driver which supplies power, a fuse, a few components, a transistor and a motor.

Start from motor driver and work your way through the chain.

We first test for presence of power which you've done (fuse blows) Fuse wont' blow if there is no power.

We should test for presence of correct power, which you haven't done. Measure the output. But you need to remove the load because if there's a short, your voltage readings will be incorrect; As you have observed, you can't measure the output if the fuse blows. Remove all unknowns that can cause fuse to blow ie everything after the fuse. REMOVE MOTOR.

1) Old motors can have bad brushes, which causes shorts thus blown fuse. I had you test the motor to eliminate bad motor scenario. Of course when you have a bad motor, the circuit will short every time regardless of whether you have 250 mA or 800 mA fuse.

You still haven't tested the motor that you are using in the deck so we still can not eliminate the possibility of a bad motor. Note you can have good motor with shorted transistor thus that's another thing to examine. All you've confirmed is that the motor you thought was bad is good. But that's no longer in the system and not really relevant as its sitting on your desk on in the deck.

2) You should remove the motor and measure the voltage output at the fuse because you want to know if the fuse will blow without a load. If it blows then it means something is shorted between the motor and the motor driver. You should then look at the component path beginning from the output of the fuse through to the motor. The fuse will not blow if the circuit is open. If it does, then its not the motor and transistor, its something in between.

3) How do you measure? One probe on the the fuse and one probe to ground.

In general the procedure is get as close to the fuse as possible eliminating variables (motor, transistor etc..) until you are able to power up without the fuse blowing. Then start adding back until it shorts out again. The part that you add that leads to the short is the part that needs to be replaced.

We can't really do more until you've looked at these areas.

Re: Dead Beocord 9000 motor

Piaf — Fri, 07 Nov 2008 02:15:15 GMT

Derek:

This is the second time that you have referred me to a previous post. While I very much appreciate your expertise, I would be ever so much more inclined to follow your directions if you explained WHY I need to do this.

1) Does the fuse blow when you power up and hit play with the motor REMOVED. Why is this important? The fuse blows repeatedly with the replacement motor in place. It also blows when reverse, fast forward, or play is selected. In short, the fuse blows any time the motor is engaged. This is EXACTLY what happened with the original motor.

2) If it does not what is the voltage reading at the output of the fuse I am only an enthusiast, an ordinary person who loves B&O products…. one lacking in ANY B&O repair facility for hundreds of kilometers. (The only one in Vancouver only answers his phone when he feels like it…. and that isn’t often.) The voltage output at the fuse? How do I test this when the fuse blows in seconds?

How are you testing the motor? I replaced the 250mA fuse and pressed STOP. The motor ran briefly…. I’d say 5mm or so and the fuse blew. I put in yet another $5.50 fuse (yes things are expensive here on Vancouver Island) and tried REVERSE, which caused the replacement motor to run briefly again and the fuse blew.

Are bypassing the transistor when you are powering through the battery? I am not powering the motor through a battery. However, if you want me to bypass the transistor first tell me why, and second tell me HOW!

Did you test the Bill Rapp motor also with battery? No, however it powers up within the Beocord 9000 until the fuse blows. Does it power up? The answer is yes.

I used the 9v battery to power up the original motor (YOUR SUGGESTION), now out of the Beocord 9000 to see if it worked. It does. With the 9v battery attached the original motor runs beautifully and with none of the growling I associated with it before the Beocord 9000 stopped playing cassettes.

Derek, I don’t know what your background is, but I am just a regular guy, a middle aged retailer with a degree in history who happens to LOVE music….. and B&O products in particular.

BeoWorld has enabled me to repair my exasperating but cosmetically flawless Beogram 4002 through countless adjustments. (I think I hold the record for the number of adjustments required to play a single record.) More recently getting my Beogram 4004, my most dependable turntable to track properly and my Beogram CDX to once again play CD’s. All are now performing splendidly.

Help with my Beogram 4000 was less successful, but in the end, all that was wrong was the wrong fuse…. Yes a 250mA fuse, incorrectly used….. and all it took was a trip back to Denmark, where Martin put all things right.

I am a guy that can talk to you for hours (reasonably intelligently) about Tsar Nicholas II of Russia, Frederick the Great of Prussia, or Alexander of Macedonia…. but with electronics, I need guidance with clear directions. At the very best I am an amateur forced to deal in a most unfamiliar world.

As such, I thank you for your patience with me.

Jeff

Re: Dead Beocord 9000 motor

auric — Fri, 07 Nov 2008 00:01:28 GMT

Jeff:

Again...I refer you back to post 154952 of this thread.

Derek

Re: Dead Beocord 9000 motor

Piaf — Thu, 06 Nov 2008 20:57:13 GMT

Derek,

The advice to try a 500mA fuse came from a highly respected B&O repair facility. However, with all I know to date, I completely agree with you. Something must be wrong and to bypass the fuse protection is to risk doing even more expensive damage.

Here is the latest on the Beocord, and I believe it significantly narrows the potential problem areas.

Plug in the Beocord 9000 and two LED's light up briefly and then one extinguishes, the other remaining permanently lit while the 9000 is plugged in.

With a 250mA fuse in place, in standby, no problem. Press STOP and the motor moves the belt about 5mm and the fuse blows. I tried replacing another fuse pressing reverse and the same thing happened, the motor briefly moved the belt and then the fuse blew.

Once the fuse is blown, if fast forward or reverse is selected a pronounced CLICK can be heard and then a second CLICK. Nothing happens with the motor as the fuse is blown.

Also, with the fuse blown and I select PLAY the heads engage briefly and then retract. They will engage as often as I like with the PLAY button depressed.

Again virtually everything appears to work properly except engaging the motor blows the one 250mA fuse.

As you know I tested the original motor with a 9v battery (away from the 9000) and it works. So now I have two good motors both with their transistor boards in place, but the fuse blows attempting to use either one.

It does appear that we have narrowed the problem area. I hope that this new information helps.

Jeff

Re: Dead Beocord 9000 motor

auric — Thu, 06 Nov 2008 15:55:48 GMT

Jeff,

1) If the motor will run on a 90 mA 9V battery what makes you think changing the value to 500 mA will help?

2) Fuses are there to protect the circuitry and very smart Danish engineers select the appropriate values accordingly. If during a fault, fuses do not blow, then something else does and usually that's more catastrophic and expensive to fix.

Derek

Re: Dead Beocord 9000 motor

Piaf — Thu, 06 Nov 2008 15:14:22 GMT

Derek,

Point taken. I will try your suggestion to remove the replacement motor and see if the fuse still blows.

It has been suggested, among other things, that I try a 500mA fuse to see if that solves the problem.

Do you see any harm in trying this first?

Jeff

Re: Dead Beocord 9000 motor

auric — Thu, 06 Nov 2008 13:26:48 GMT

>So that begs the question why would the fuse keep blowing if the original motor was OK in >the first place and the replacement motor came with the transistor board attached, yet >nothing has changed? I keep blowing fuses.

I refer you back to post 154952 of this thread.

Re: Dead Beocord 9000 motor

Piaf — Wed, 05 Nov 2008 21:55:41 GMT

Derek:

I believe that there has been some error in my information regarding the 850mA fuse value.

I checked the two fuses which I removed from my Beocord 8004 as well as the Beocord 9000 and they are identical 250mA fuses with brightly colored stripes on them. I replaced the blown fuse on the Beocord 8004 and it works perfectly again. (I was attempting to adjust the motor speed sans the proper tool and blew the fuse.)

So I would imagine that the correct fuse value for the Beocord 9000, is as you said, 250mA.

So that begs the question why would the fuse keep blowing if the original motor was OK in the first place and the replacement motor came with the transistor board attached, yet nothing has changed? I keep blowing fuses.

I need to see if the replacement motor powers up when pressing stop, which will end the standby mode. I tried to check late last night with the cassette assembly in place, merely listening for the sound of the motor running. Today’s test of the original motor proved that it is absolutely silent, so I need to go a bit further.

Now that brings up yet one more question. If indeed the original motor runs silently (as it appears), what could possibly have been the source or cause of all that growling when the 9000 was in the standby mode? No tape movement, but so long as the motor was running in standby, it snarled.

I think I am becoming more befogged than before.

Jeff

Re: Dead Beocord 9000 motor

auric — Wed, 05 Nov 2008 20:31:28 GMT

Jeff:

The correct value is located in the service manual. I seem to recall 250 mA.

850 mA is awfully high for this kind of motor. The current from a 9V batter is about 90 mA.

You can prove it to yourself with your spiffy Fluke meter. Put it in current mode. The meter of course will need to be placed in series with the motor not across the batter.

Derek