Burns Orbit Three
Dimensions:
21"h x 25"w x 10"d
Weight approx 37Ib
Advertised output power: 60watts (peak)
There are four different versions of this unit:
881 : 'Orbit Three' 3 x 10"
882 : 'Orbit Three' 3 x 10" with reverb
885 : 'Orbit Three Double 12' 2 x 12"
886 : 'Orbit Three Double 12' 2 x 12" with reverb
Burns quoted peak power for the Orbit Three. For testing purposes, with a continuous sine wave, expect just over 30watts rms at clipping into 2ohms.
NB: The Orbit Three Double 12 is not the same thing as an Orbit Double 12
Thanks to Jon at blackguitars.com for the 1963 advert clip.
881 / 885. Orbit Three Standard
882 / 886. Orbit Three Reverb "with extra dimensional control" if you're into that sort of thing.
Burns used a number of different circuits in Orbits, so it's pot luck whether the schematics apply. Problems finding replacement parts and service information (and the rats nest wiring) have probably contributed to the number that have been abandoned or broken up for spares. That's a shame, because they're interesting things when they work.
The unit used for the details below was a 3 x 10" that had been thrown down the stairs, buggered about with and stripped. To say 'beyond economic repair' would be to say that Ming The Merciless was a bit naughty but, luckily, it still had enough of the original components to work out the circuit and layout,
Don't be put off if the drawings don't match exactly. It should be possible to pick enough information from different versions to get the job done. Expect to find melted sleeving and back to front electrolytics from the factory, as well as multiple dry joints and fifty years worth of abuse. The resistance wire in the output device emitter circuits really doesn't like solder either and is a chief suspect if one half the output signal is distorted or missing.
Layouts below are viewed with the chassis the right way up, looking into the back of the pots.
PRINTING
Wix only provides webp images at the moment. To make a hard copy of a drawing :
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Left click when the magnifying glass icon appears and wait for the picture to clear.
(On a touch screen, tap on the image) -
Right click and 'save image as' to somewhere as a webp file.
(On a touch screen, touch and hold down to view the menu) -
Open the saved file with 'Photos' (Windows 10) or whatever app works for you.
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Use the print menu to print to A4 plain paper.
1. Burns Orbit Three Schematics.
The main changes over the years are around the tone selector in Channel 1.
Below is a copy of drawing BE 009 03, dated Sept 64, taken from the internet. The 1amp fuse seems to have been added to the schematic later and is probably fine for instrument use. It's a useful mod if your poking about in the chassis; a new set of transistors is very expensive.
2. Burns Orbit Three "6303" Schematic
The next one is a bit of a mystery at the moment. Thank you to Jon Free at Black Guitars in Australia for posting photos of some back panels with factory schematic stickers. They're described as a 6303 Amplifier. We weren't sure which model they came from, but I just found the same tone circuit in the 3x10" Orbit Three below with CCL capacitors from 1965 (no serial number, unfortunately). Some of the values are unclear, but the circuit for Channel One in particular is a lot different to the BE 009 03 version.
Jon's site's got some very interesting Burns archives. Well worth a look.
BLACK GUITARS
347 BELGRAVE-GEMBROOK ROAD, EMERALD, VICTORIA 3782, AUSTRALIA
3. Burns Orbit Three. Schematic as found on a Type 882 3 x 10" built in or after 1965.
The rest of the details and layouts come from the wreckage of a real amp and you can see straight away that the wiring around the mains voltage selector switch is different (and still @#!!£* dangerous if you don't pay attention).
There's no fuse and it's ridiculously easy to flick over to 115V by mistake. Whoever built them also managed to find three core mains wire with two browns and a green. It's just pot luck which wire's the line.
NB: The layout drawings are specific to this chassis and this schematic.
4. Burns Orbit Three. Power Supply Layout As Found
5. Burns Orbit Three. Power Amplifier Layout As Found.
6. Burns Orbit Three. Channel One Layout As Found.
7. Burns Orbit Three. Channel Two Layout As Found.
8. Burns Orbit Three. Vibrato Section Layout As Found.
9. Burns Orbit Three. Reverb Section Layout As Found.
