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Great progress! I would measure the woofers as the doped cones will likely change the parameters causing a crossover modification.
I agree. Even a few grams usually make quite a difference.
– And even more so will the change to rubber surrounds.
I tried it a few times, but when I measured and compared T/S I found them
to be far out compared to the original specs, so I ripped the rubber off
again and changed it back to foam. After a few hours playing time, allowing
the new foam to losen up a bit, everything was spot on, back where it belongs.
I never used rubber again, where foam was used originally.But of course it can be done if you really MUST have rubber.
A compensation for the lack of cabinet volume
needed to satisfy the T/S with rubber (I seem to remember them requiring
8-10 liters) could perhaps be made by introducing a filler driver of some sort, though
driving it right phase-wise could be quite a task and would almost
definitely require a bit of signal processing – not least because it would
almost definitely need to be rear-facing due to lack of front area.
A passive radiator would require a too large area to have any effect, – far
more than what is available – as would surely a bass reflex system,
– and we must not forget that if both the midrange and woofer drivers
are changed to rubber surrounds, both will need compensating, and
not necessarily in the same way.
But why? – When you can just fit foam.I am looking forward to seeing the frequency response and new filter calculations.
Martin
If some lights come on, but nothing more happens, it could point to the
CPU not running or not being reset correctly.
Most like a capacitor problem.Check power supply voltages and look for excess ripple from dying filter capacitors.
Martin
Wrong wattage lamp for the FM1 indicator?
Yes, they are critical.Martin
The lifter arm with the small pad should work in the groove, so it can lift and lower the wheel.
Martin
Read my post in this thread:
https://forum.beoworld.org/forums/topic/beogram-1902-dust-cover/
Martin
I like to use a teflon-based oil called “Liquid bearing”, but any good long-term oil or light grease would be fine.
Parts here.
Martin
Note the note about cable and socket matching here:
Martin
You don’t replace it – it must be taken apart, cleaned and lubricated. It can all seize up
in dry lubricants.
New idler wheel, new lifting arm friction pad and a new belt.
The motor will almost surely also need new bearings in order to run correctly.
All of these parts are available.Martin
No! Not the circuit board (that’s not an easy task).
The large dial panel = the large black metal facia with the white lettering/frequencies
and channels, that the sliding dial pointer travels on, – that also holds the lamps.
One screw each corner of the panel (= two screws each end of the Beomaster).Martin
The large dial plate will have to be losened.
That’s four screws from below.Open the Beomaster and swing the bottom section away from the top section.
Push the dial pointer to a place where you can access its fastening to the string.
Mark up on the string where it is fitted to the pointer so you can fit it back in the
same place, remove one of the two small screws and losen the other so you can
swing the small clear plastic string holder away from the string which zigzags under it and between the screws.
Then take out the four screws holding the dial plate.
When done, make sure to align the dial plate correctly, so that both the dial
pointer and the sliding knobs are free to travel.(Same procedure for Beomaster 1200).
Martin
Yes, that’s correct. Both sideways and up/down. The metal “ears” mustn’t touch.
And it should be when the deck is upside up (not upside down as in your photo).The bushings are actually for transport safety, because the heavy motor would be free to
swing around pretty wildly in transport, if they weren’t there to limit its movements.Martin
The important thing is that the motor bracket is free floating, and its
metal “ears” will not touch the nylon bushings (or you will hear rumble/whirring/running noise).
If, when you have put it all together, and the deck is in its normal upside up position,
the metal brackets are close to the bushings, you could try swapping the two bushings
and see if it ends up better centered.There can be a washer under the nut as well.
Martin
The arm position is controlled by a steel rod running in a groove in a cam wheel.
It could seem to be put together wrongly.Martin
Any passive Beovox models would suit it, really.
But Beovox S45 (Type 6302 or 6312) springs to mind.Martin
Mark, welcome!
Martin
Fit a screw M3x10 or so through the hole from below, put a washer and a
nut on top and fit the
string loop and the spring to the excess upward pointing screw thread.
Adjust the setdown points.Martin
23 February 2024 at 17:19 in reply to: How accurate are B&O service schematics with regard to components? #52986Keep in mind, that if you measure across one component in a circuit, you may actually
measure others as well, because they are connected in some form.
Another thing is polarity; If you compare ohmic measurements make sure you have
the same polarity when measuring in both channels. A semiconductor may conduct current
in one direction and not the other, and that could give a difference in the readings.Resistors wouldn’t be the first components I’d suspect.
And they will usually go open circuit or high in value – not low.Martin
A flashing speed indicator indicates that the repeat function has been activated (you pressed Play more than once).
The cartridge rides high as the cantilever suspension losen from the micro cross inside
the cartridge and falls down.
Next step is that the cantilever falls off entirely.
That will happen very soon. Get it re-tipped.Martin
Are you using an original B&O Beogram datalink cable?
If not – that would be a clear reason.
You cannot use a Beocord cable as it is not double-shielded.Martin
Check the switching ICs. Power and shorts (oxidation on pins).
Martin
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