Hello
I'm busy working on two B&O model 1900 turntables. The decks are seemingly identical but appear of two different series. Each has a little power supply control box which is adjustable for voltage supply between 220 and 110Vac to their motors. Both turntable pulleys are identical.
This is where some 'confusion' starts due to lack of technical knowledge. The manual just states the components I want to replace, should be a 10 ohm resistor, .5W and a 10nf capacitor, 265V.
I removed the old parts and took them along to Communica and got 2 resistors of the above spec and two different capacitors as these were of different specs between the two turntables, contrary to what the B&O manual states.
I made a note and took pics of the wiring and electronic parts inside each p/s box and freed the first deck's seized motor, replaced the old resistor and replaced the capacitor with the item from Communica which has "JEC, J102K, X1400V and Y2300V written on it. After repairs and service, everything works fine, including the 33.3 and 45rpm speeds.
I then started on the second 1900, did all the aforementioned work and found the motor speed is only about 30% of what it's supposed to be. The (asynchronous) motor also buzzes and gets quite warm.
Both resistors are the same, being 10 ohms and the problem is definitely NOT mechanical. The motor spins freely and are not impeded by the idler wheel or the eddy brake disc.
When removing the caps and resistors for matching up at Communica, the original capacitor values were 1 x 6n8, 9/0133,9 265Vac and the second capacitor was 10n, 9/0141,9 and 265Vac.
I can't remember the history of these two decks and whether they were working when I bought them 25 years ago as they have been sitting on a shelf all these years.
Anyway, the capacitors I got from Communica are: JEC, J102K, X1400V, and Y2300V and one marked JEC, JY682M, X400V, Y2300V. The J102K replacement in deck 1 works fine - things are spinning to speed and there's no overheating.
I then measured the two coils on the laminations of the troublesome motor. The impedance of the coils differ substantially between the two decks. The working deck's coils measure 335ohms each and the deck with the speed troubles' motor coils measure 525ohms.
Here, the original capacitor was a 6n8, 9/0133,9 265Vac (again, not what the book says). Communica's replacement for this capacitor is JEC, JY682M, 250V, X1 400V and Y2 300V.
The ac voltage p/supply box is adjusted for 235V and all contacts inside the box are clean.
I also measured the ac current to both the working and faulty decks while the motors were running. Both measure 122Vac.
The faulty motor showed signs that someone had worked on it as I saw some rough-looking re-riveting on the laminations in one spot and careless soldering of one coil leadout wire, causing the joint to melt through the coil former and shorting the coil on the laminations. I also repaired this problem.
For now, I'm not sure if Communica gave me an incorrect capacitor (JY682M for 6n8).
The only other solution would be to reduce the impedance of the faulty motor's coils to correspond with that of the working motor (from 525 to 335 ohms) and use another J102K capacitor as in the working 1900 deck.
What do you think of all this?
Thanks for considering this problem.
mafioso
I'm busy working on two B&O model 1900 turntables. The decks are seemingly identical but appear of two different series. Each has a little power supply control box which is adjustable for voltage supply between 220 and 110Vac to their motors. Both turntable pulleys are identical.
This is where some 'confusion' starts due to lack of technical knowledge. The manual just states the components I want to replace, should be a 10 ohm resistor, .5W and a 10nf capacitor, 265V.
I removed the old parts and took them along to Communica and got 2 resistors of the above spec and two different capacitors as these were of different specs between the two turntables, contrary to what the B&O manual states.
I made a note and took pics of the wiring and electronic parts inside each p/s box and freed the first deck's seized motor, replaced the old resistor and replaced the capacitor with the item from Communica which has "JEC, J102K, X1400V and Y2300V written on it. After repairs and service, everything works fine, including the 33.3 and 45rpm speeds.
I then started on the second 1900, did all the aforementioned work and found the motor speed is only about 30% of what it's supposed to be. The (asynchronous) motor also buzzes and gets quite warm.
Both resistors are the same, being 10 ohms and the problem is definitely NOT mechanical. The motor spins freely and are not impeded by the idler wheel or the eddy brake disc.
When removing the caps and resistors for matching up at Communica, the original capacitor values were 1 x 6n8, 9/0133,9 265Vac and the second capacitor was 10n, 9/0141,9 and 265Vac.
I can't remember the history of these two decks and whether they were working when I bought them 25 years ago as they have been sitting on a shelf all these years.
Anyway, the capacitors I got from Communica are: JEC, J102K, X1400V, and Y2300V and one marked JEC, JY682M, X400V, Y2300V. The J102K replacement in deck 1 works fine - things are spinning to speed and there's no overheating.
I then measured the two coils on the laminations of the troublesome motor. The impedance of the coils differ substantially between the two decks. The working deck's coils measure 335ohms each and the deck with the speed troubles' motor coils measure 525ohms.
Here, the original capacitor was a 6n8, 9/0133,9 265Vac (again, not what the book says). Communica's replacement for this capacitor is JEC, JY682M, 250V, X1 400V and Y2 300V.
The ac voltage p/supply box is adjusted for 235V and all contacts inside the box are clean.
I also measured the ac current to both the working and faulty decks while the motors were running. Both measure 122Vac.
The faulty motor showed signs that someone had worked on it as I saw some rough-looking re-riveting on the laminations in one spot and careless soldering of one coil leadout wire, causing the joint to melt through the coil former and shorting the coil on the laminations. I also repaired this problem.
For now, I'm not sure if Communica gave me an incorrect capacitor (JY682M for 6n8).
The only other solution would be to reduce the impedance of the faulty motor's coils to correspond with that of the working motor (from 525 to 335 ohms) and use another J102K capacitor as in the working 1900 deck.
What do you think of all this?
Thanks for considering this problem.
mafioso
