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Beocenter 7700 Belt slipping on Cassette

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DerSnap
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DerSnap posted on Fri, Jul 7 2017 10:25 PM

Hello and greetings.

 

First off I have been searching all over on this subject with no luck.

Maybe this is a simple or silly question but I can't seem to get past this point with my 7700.

Changing the belts as the original ones where basically just a gooey mess. I got this unit this way second hand years ago and now am just getting back to fixing the belt issue. Problem is the main belt off the flywheel keeps slipping off. I have a few here I tried just to test but it seems like the pulley is pushing it off the flywheel.

The second belt has no issues though but it does not do the main driving of the transport.

 

I am lost now, 

and to top it off the hinge on the cassette door (hides the controls) also broke.

 

Any help would be greatly appreciated.

 

Best Regards

 

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Dillen
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Welcome to Beoworld !

First - make sure the belts are correct. (If you bought from me, they will be).
Next - check the position of the motor pulley on the motor shaft. If it sits to low or to high the belt can run off the flywheel.
Check also that the capstan (and flywheel) spindle runs freely and hasn't seized in aged lubricants.

The hinge piece can be repaired using two-comp Epoxy. I like to use the blue standard slow-setting type.
Smoothen and paint black and it will be difficult to spot the repair.

Martin

DerSnap
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It could be the belts are not correct so no question there but I think also it is likely you hit the nail on the head with the motor pulley sitting too low.

I couldn't seem to see any place to adjust this though?

 

I will try the epoxy tip also, but need to find which version that is in Germany :)

 

Thanks for the greetings Martin :)

 

 

DerSnap
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So belt is the issue and I did find out how to lower the spindle which was needed.

I have one or two other questions if they can be answered:

 

1. How to get the panel off to get into the pots for recording levels, speakers a/b, etc. I would like to give them a spray of Deoxit as at least one speaker is a bit dirty. 

2. I can't figure out how to put the hinge together that automatically opens the panel lid.

3. Seems I am picking up a ground loop, buzz but if I lift just below the chassis on the front panel below the various solenoid controls it goes away.  Loose wire or perhaps a cap?

The service manual does not give enough detail for me to see how some things fit together and I been searching all over for picture with out much success. Also need to order the correct belts.

The epoxy is not working for me unfortunately. I think it is something strange with this specific epoxy from Pattex. Just does not seem to be getting hard and it is supposed to after 1 min.

 

As always any help is appreciated.

 

DerSnap
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So belt is the issue and I did find out how to lower the spindle which was needed.

I have one or two other questions if they can be answered:

 

1. How to get the panel off to get into the pots for recording levels, speakers a/b, etc. I would like to give them a spray of Deoxit as at least one speaker is a bit dirty. 

2. I can't figure out how to put the hinge together that automatically opens the panel lid.

3. Seems I am picking up a ground loop, buzz but if I lift just below the chassis on the front panel below the various solenoid controls it goes away.  Loose wire or perhaps a cap?

The service manual does not give enough detail for me to see how some things fit together and I been searching all over for picture with out much success. Also need to order the correct belts.

The epoxy is not working for me unfortunately. I think it is something strange with this specific epoxy from Pattex. Just does not seem to be getting hard and it is supposed to after 1 min.

 

As always any help is appreciated.

 

DerSnap
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Belt was issue and new belt did not slip off.

Bigger problem  now.

At first everything seemed to be recording fine.

Went to test playback and was ok, then realized I recorded LP at wrong speed.

Started again,

Stops about 1 min in.

Won't FF but rewinds fine.

However playback on Cassette started going slower and slower.

Checked belts all ok.

Now machine won't playback or switch to any source.

Tape, Radio, Phono, all dead.

Get LED readout and can hear amplifier relays but that is it. Oddly display was working correctly.

 

About to give up and just consider this junk (really sad) but I am just about lost.

 

IF anyone can reply with more suggestions that would perhaps help.

Oh and Epoxy never worked on hinge sadly.

 

Dillen
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Dillen replied on Tue, Jul 11 2017 9:21 PM

Using too tight belts will damage the motor bearings. I' ve seen that countless times.
If you bought standard belts (off Ebay or similar), they will probably look somewhat right but won't have the correct elasticity and friction parameters.

Using fast setting epoxy glue never works. Period!
Always use the slow setting (blue) Araldite (as I mentioned above). It sets in apprx 24 hours and
can be drilled, filed, ground and painted as you please afterwards. I have done dozens.
Cleaning off the old Kilopoise grease and adding fresh will smooth the damping function. 

Check the power supply to the processor if sluggish or defunct.
Rebuild the cassettedeck using correct belts and idler wheel rubber parts. Clean and lubricate.

In general; Use correct parts and correct repair methods.
Fast and cheap solutions won't work.  

Martin

DerSnap
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DerSnap replied on Wed, Jul 12 2017 12:07 PM

I will do checking as suggested to see what is coming off the power supply.

The other belts I had where extra original ones but they where sitting in storage for a very long time as I always was going to get around to this project. Then moved, lost the belts, found again recently. Either way they where a bit too loose, and not tight that was the issue. New ones are perfect fit and not too cheap.

I am sort of guessing here but it might need a full rebuild with correct parts. Not sure I can do it with my resources at the moment, new baby, no job (school), etc.

 

We will see though what can be done.

 

 

 

DerSnap
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Seems power goes to the amplifier Module,

and controls seem to work for selecting the sources but this is where things go strange.

Turntable has zero power now. Can not even hit the turn switch to clean a record, or have the light come one. 

Is there a fuse somewhere there? I didn't notice in the schematics.

 

Not sure how else to test and solve so I might just ebay this (sadly).

Dillen
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Dillen replied on Thu, Jul 13 2017 6:34 PM

Perhaps a silly question - but do you have a record on the platter?
The turntable won't start without a record.

Martin 

DerSnap
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Not a silly question, but yes I do have a record on it.

Smile

DerSnap
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Will add that diagnostic test for Microcomputer comes back with no error.

This was based on the service manual holding the standby and record button together.

 

Also with a tape in counter reset opens the lights for the cassette deck,

Can't do anything else there and still with turntable.

Checked fuse on power supply it is also fine. The relay in/on power supply/amp module enables when I select a source but that is as far as anything goes. It is like everything goes all the way up to the section where the individual components (turntable, Radio, Cassette, etc) do not get their main power. I can't really follow where this is actually being controlled.

 

 

Dillen
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Dillen replied on Thu, Jul 13 2017 9:45 PM

Check all plugs and connectors.
It's very easy to inadvertently pull a plug half way out, particularly when handling the tapedeck mechanical section you can
easily pull cables on the controller board unnoticed and that can cause the strangest faults.

Martin 

DerSnap
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DerSnap replied on Thu, Jul 13 2017 10:09 PM

Checked and checked the connections (Cleaned also) and there is nothing I can see unplugged.

 

DerSnap
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DerSnap replied on Sat, Jul 22 2017 11:42 AM

Just got a new Multi meter and wondering any known areas I should start on the service manual to check with?

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