Bang &Olufsen Beomaster 1900
The most stylish Hi-Fi amp/tuner on the planet. From 1977 this was and remains to be an outstanding design. It epitomizes the phrase sleek and stylish. It is a masterpiece of design with its brushed aluminium, detailled illuminated front indicators and of course the mysterious touch sensitive pads. Wonderful. The picture doesn't do it justice it is far more impressive in the flesh.
For me this Beomaster 1900 shouts 1977 it reminds me so much of the TV of that time such as Morecombe and Wise, The Professionals and in the record charts were a band called The Police ( UK residents will remember these). Exciting times they were, the Beomaster 1900 was very much a part of that.
Here is pik of my Beo 1900 finished in the teak wood option.
What made the Beomaster 1900 extra special was its elegance and uniqueness of design. It looked and felt like real quality, something short in supply at the time. The British Hi-Fi market was either poor quality or at the other end of the scale, exotic stuff for experts only. The Japanese stuff all looked the same, flat brushed aluminum face with big chunky knobs. The Beo was different, exclusive, simply majestic.
I was a great user of the Beomaster at the time so got to know the system quite well. The FM tuner was actually very good, one of the best I've heard. Everything else was as good as it gets, difficult to be too objective because it was wired to a pair of B&O S30 loudspeakers which in fact don't do the system justice. The system also had a Beo 1102 record deck and Beocord 1100 cassette deck, both of which are also superb performers. That cassette deck is not to be under rated as it gave very good audio performance.
With the passing of time the wonderful Beomaster comes into my keeping. But shock horror upon first arrival I was saddened to discover it had many faults!!! How can this be?? It was only working on one channel, which was dependant upon the balance control being in a precise spot. The bass slider was intermittent, the FM4 touch pad didn't work, the mysterious moving slider indicators (horizontal red slider indicators) were heat damaged. How sad, such a wonderful item in such disrepair, I had to sort this. The Beomaster is just too wonderful an item to leave in this state.
The Restoration
The missing channel; faulty balance and bass sliders were in fact due to broken mechanics of the variable resistors themselves. I figured replacements would not be available, indeed I did a search but none found so I had to rebuild them. It took a lot of time, effort and patience. I fixed the non-functional FM4 pad - failed resistor, circuits diagrams very useful here. I made some graphic films as used on the red illuminated sliders to get them back to former glory.
I am very pleased to say the Beomaster 1900 is now fully functional in every way, looking just as fabulous today as it did when new.
The Fix part 2
Much to my horror, after using the 1900 as my house radio it started to malfunction. It refused to switch on consistently from stand by. I would touch a pad and the 1900 would click on and off and eventually stay off. It seemed to get worse with time!
So circuits in hand onto the bench it went, oscilloscope probing here there and everywhere. This B&O gear can take quite some time to fault find, remember they were ahead of their time which usually means convoluted circuitry making tracing to a fault quite confusing.
Indeed this was no exception and it took me some 10 weeks on and off to finally trace the problem, a most unusual component failure.
More piks
Here is a close up of those fab red indicators. The resolution of the photos don't show the detail of the vertical lines within the red markers or volume indicators. These add extra mystery which makes them even more attractive.
Lid up. A gentle pull on the lid reveals the inner controls, once again sleek and stylish. Only one thing to watch is the large tuning dial over on the far right. On some units it will not be exactly flush with the top face resulting in a minor deviation from perfection, not much can be done as it is mounted on the circuit board below.
The definition of sleek and elegance.
Circuit Diagrams
When the Beomaster 1900 arrived from new I stashed the circuit diagrams knowing one day I would need them. Below are links to these documents so you can get your Beomaster working again. I've scanned the circuit diagrams as two separate A4 sheets hence the a and b references.
Beomaster_1900_circuit_1a.gif - 290kb
Beomaster_1900_circuit_1b.gif - 513kb
Beomaster_1900_circuit_2a.gif - 344kb
Beomaster_1900_circuit_2b.gif - 437kb
General Outline - 99kb
Test conditions - 136kb
Test point measurements - 56kb
Semiconductor list 1 - 124kb
Semiconductor list 2 - 145kb
Owner's Manual
Here is the owner's manual. There is not much to it because the Beo 1900 is so easy to use. Alas my old scanner is showing its age so the scans are not too good but I feel once you have seen the docs you will realise they are not that important.
Operating Instruction Page 1
Operating Instruction Page 2
Bang and Olufsen were pushing manufacturing technology to the limits which means they can be quite tricky to fix. You will need to be very careful in dismantling this gear. The style prides itself on perfection so take all precautions so not to damage it, they can be very delicate and fragile.
I look at this amplifier today and still think wow. With my life in electronics design and development I now know how much time, effort and money must have gone in to this.
June 2007