Beocord 9000 Tape Deck- Bad wow and poor frequency response

Dear fellow Beocord lovers...

I recently took the plunge and purchased a Beocord 9000 with (reportedly) new belts. 

But even after a good clean and demagnetisation or the heads it is still sounding poor. All functions of the tape transport work well, although FWD is weaker and slips sometimes. 

There is a serious wow problem that seems to be only present when recording - payback is relatively fine. Is there something about the position of the rec/play head making a difference to the tape tension when recording?

Is is recommended to use a rubber rejuvinator on the idler wheels and capstan drive?

With recordings, when Dolby B is used the frequency response is OK, but nothing special, but with no Dolby it is totally flat and to be frank does not sound like a top flight tape deck, although, frequency response is improving with time - I wonder if the internal controls simply all need a good deoxit or if there is some error with the recording circuitry? 

It's worth noting that all functions seem to work perfectly and the deck is in very good order generally.

Thanks for any help and advice! Seasonal greetings!

Jon

Good cleaning
Fresh lubrication
New idler wheel rubber parts
New (correct) belts
Perhaps a new pressure roller

and it will run fine again, I'm sure.
If not, check the power supply and or bent capstan and/or bent or broken brake arms etc.

Sound quality issues;
Clean tapeheads and check their alignment.
Replace capacitors in the signal path.

Martin

Hi Martin,

Thanks for your helpful answer.

I will certainly have a go at cleaning (alcohol / deoxit) and lubrication (sewing machine oil?) and first try some rubber restorer on the idler rubbers (I understand it's not so easy to replace them?).

If that doesn't improve things maybe the "new belts" the former owner installed were not the correct ones and I can try changing them (an easy job I think).

My question on the transport issues is why it would play back tapes recorded on other machines with no audible wow but has very audible wow on its own recordings?

Also, any ideas also why frequency response is much better with tapes recorded with Dolby, even when played back with Dolby off?

I have thoroughly cleaned and demagnetised the tape heads already. Is checking alignment straightforward without specialist tools? Do you mean azimuth by this or is there some other alignment?

Sorry for all the questions - I bought the unit as "serviced with new belts" and am very much a technical beginner.

So, thanks again!
Jon

jonbawn:

I will certainly have a go at cleaning (alcohol / deoxit) and lubrication (sewing machine oil?) and first try some rubber restorer on the idler rubbers (I understand it's not so easy to replace them?).

Use sinter oil for all bronze bearings.
Sewing machine oil will work but evaporates rather fast and often leaves a mess behind.

Idler wheel rubber parts are easier replaced than cleaned and ground down.
You will never be able to restore to original friction and "roundness" and new parts are available for cheap (produced by me).

If that doesn't improve things maybe the "new belts" the former owner installed were not the correct ones and I can try changing them (an easy job Ithink).

Wrong belts would absolutely not be a first.
Replacing the belts is a 2-minute job once you have the mechanical section out. And you will have to take the belts out to disassemble the rest and get to the idler wheels anyways.
(I can supply correct belts)

My question on the transport issues is why it would play back tapes recorded on other machines with no audible wow but has very audible wow on its own recordings?

Difficult to say. A power supply issue perhaps. Recording takes more power than playback.

Also, any ideas also why frequency response is much better with tapes recorded with Dolby, even when played back with Dolby off?

Depending on the type of Dolby we're talking about.
Type B is more or less a treble boost/filter, boosting treble at recording and taking it down a bit at playback, so tapes recorded with Dolby B
will have more treble when playing back without Dolby than tapes recorded without Dolby B.
Dolby C is more involved, working from the dynamic content of the programme signal.
Your deck could also have a faulty HX-PRO circuit.

And - as mentioned above - capacitors in the signal path. They are 30+ years old by now. 

I have thoroughly cleaned and demagnetised the tape heads already. Is checking alignment straightforward without specialist tools? Do you mean azimuth by this or is there some other alignment?

Azimuth yes, but lots of electronic adjustments too, some of which will require a selection of instruments but
get a copy of the servicemanual (note: there are two types of Beocord 9000 with different Dolby circuits, motor supply etc.)

Sorry for all the questions - I bought the unit as "serviced with new belts" and am very much a technical beginner.

We all learn - also from helping others.

Which tape types are you using for recording?
And does the tape type indicators light up corresponding to the type inserted? 

 

I’m not a specialist as Martin is, but I’ve done two BC9000 and they are Nakamichi eaters when restored properly. I’ve had top Naks as well, so I know.

And the auto calibration feature is absolutely brilliant, because unlike competitors it works across the whole audio band and separately for each channel.

I also like the assisted adjustments through display LED segments.

By all means do ditch those belts and get a full set of belts and tyres from Martin

The two-speed motor will be difficult to find if it gets damaged by an eBay belt that is too tight.

Thanks Jaques. I guess it's a lot to expect a non restored 35 year old deck to perform like new. I just need to figure out if I can ever find the time to find my way to getting this thing working any time soon!

Dillen:

jonbawn:

I will certainly have a go at cleaning (alcohol / deoxit) and lubrication (sewing machine oil?) and first try some rubber restorer on the idler rubbers (I understand it's not so easy to replace them?).

Use sinter oil for all bronze bearings.
Sewing machine oil will work but evaporates rather fast and often leaves a mess behind.

Idler wheel rubber parts are easier replaced than cleaned and ground down.
You will never be able to restore to original friction and "roundness" and new parts are available for cheap (produced by me).

If that doesn't improve things maybe the "new belts" the former owner installed were not the correct ones and I can try changing them (an easy job Ithink).

Wrong belts would absolutely not be a first.
Replacing the belts is a 2-minute job once you have the mechanical section out. And you will have to take the belts out to disassemble the rest and get to the idler wheels anyways.
(I can supply correct belts)

My question on the transport issues is why it would play back tapes recorded on other machines with no audible wow but has very audible wow on its own recordings?

Difficult to say. A power supply issue perhaps. Recording takes more power than playback.

Also, any ideas also why frequency response is much better with tapes recorded with Dolby, even when played back with Dolby off?

Depending on the type of Dolby we're talking about.
Type B is more or less a treble boost/filter, boosting treble at recording and taking it down a bit at playback, so tapes recorded with Dolby B
will have more treble when playing back without Dolby than tapes recorded without Dolby B.
Dolby C is more involved, working from the dynamic content of the programme signal.
Your deck could also have a faulty HX-PRO circuit.

And - as mentioned above - capacitors in the signal path. They are 30+ years old by now. 

I have thoroughly cleaned and demagnetised the tape heads already. Is checking alignment straightforward without specialist tools? Do you mean azimuth by this or is there some other alignment?

Azimuth yes, but lots of electronic adjustments too, some of which will require a selection of instruments but
get a copy of the servicemanual (note: there are two types of Beocord 9000 with different Dolby circuits, motor supply etc.)

Sorry for all the questions - I bought the unit as "serviced with new belts" and am very much a technical beginner.

We all learn - also from helping others.

Which tape types are you using for recording?
And does the tape type indicators light up corresponding to the type inserted? 

 

Hi Martin,

 

Thanks for your comprehensive and really helpful answers!

It all makes sense to me, just need to figure out how and when or if I can spend the time or money to get the machine working. I can see how it could be several different factors, or something as simple as a bad cap in the power supply. Problem is that here in Berlin the vintage hifi repairers are swamped with business and most have a waiting list of several months if not longer. Do you know anyone in Germany who services these decks? Or do you ever take on projects on a professional basis?

I have tried TDK SA and Maxel XLII, both with unsatisfactory results that are a little better with Dolby B. The whole of the top end is missing, and that helps a little. 

Thanks again, and let me know if you have any ideas or contacts who might be able to help. At the moment I have some serious personal commitments and not a lot of free time so I'd struggle to get it done myself...

All the best,

Jon