Dillen
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Sorry, I didn’t keep the numbers.
It was several years ago, but it should be easy to replicate for someone with time and means.Martin
Compare the T/S parameters of a driver restored with foam to one restored with rubber (both played in to losen up the stiff new surrounds), and you will no longer
have any doubts.I did exactly that.
I was expecting a difference but… oh dear, was I surprised.Foam!
Martin
Where’s that? Can’t for the life of me find a supplier in Belgium. Only option seems the be the one seller on eBay who charges 60 euros a piece now
Not in Belgium, though.
Martin
Could be.
Or the supplied power is not clean, making the processor run unpredictable.Martin
I would check
-Power supply ripple (bad filter capacitors).
-DC on a speaker output (bad differentiel amplifier stage).
-Idle current trimmer(s) bad.In that order.
Martin
The warm amplifier section points to a bad idle current trimmer.
Replace the trimmers (there is one for DC offset as well) and adjust them as
mentioned in the service manual.
– Or grab a kit that also contains new capacitors and a slight upgrade to the signal path.
Kit here.
Other parts here.Martin
Two different tape drives were used in these autoreverse decks.
One type has a belt-driven tape motion sensor.Martin
I agree.
And for soldering in areas where vibrations are part of the
day (portables, car stereos, speakers etc.), I like to use solder with a hint of silver.Martin
Bad tweeter?
Mixed up orange wires for the midranges – or wrong polarization(s)?Martin
Don’t get me wrong, but if you cannot see your way out of removing the screws for
the bottom plate, you may want to consider if this repair job is for you.
Perhaps it would be better if you leave it to someone with experience and training etc.Martin
Keep in mind, that if you replace electrolytic capacitors with any other type,
the new capacitors ESR will be (often very!) different – typically lower, leading to
different filter characteristics (and potentially other issues).
In speaker crossovers this will in many cases require a new calculation of the
filters, as the ESRs (equivalent series resistances) will have been taken into account in the original calculations as the (frequency dependent) resistors, they are.This is often the reason why owners experience, that their speakers sound “different” after changing capacitor types. The change in sound comes, not as much from the change in
type of capacitor, but from the fact that the filter properties were changed.Removing a few ohms ESR in f.e. a series capacitor for a 4 ohms tweeter, makes a lot of difference!
– Also for the load put on the tweeter, – that may not agree that it was such a great idea.The general speaker impedance etc. will also be different (typically lower!).
Martin
Apparently a major malfunction.
Can you tell if something burned inside? – And what?
Wrong mains voltage setting?Martin
What Filip said.
And there is a convenient kit for the servo board for exactly this.
Here.Martin
It will need a rebuild. They all do by now.
New electrolytic capacitors. Replace like for like type-wise.
New trimmers incl. adjusting.Martin
The end switch should not be reached at the end of playing a record.
It should only be reached if no record is found.End of record is indeed optically sensed using the ruler.
Has the main board been rebuilt with new capacitors, trimmers etc?Martin
Does the carriage hit on something? Cables near the transformer, perhaps?
Transport safety screws losened?Martin
The broken tuning part is (was) merely a friction clutch.
Beomaster 1400 (M/K) was produced in the late 1960s, and since 1980 there were no more working clutches. They had all disintegrated due to the choice of material.
Luciky, the tuning will work fine none-the-less, – just without the flywheel effect.Martin
