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Burns Orbit Three

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  • Richardvet
    replied
    Hi. Update on the Orbit 75, just in case anyone’s interested! It has 3 boost switches, which have the following actions: #1 bass boost which alters the knee of the tone control filter, #2 treble boost which agains alters the knee of the tone control filter plus alters bias to TR7, #3 studio boost which works the same as the Orbit 3 by changing the gain of TR8.

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  • Richardvet
    replied
    Hi, new to this forum since I was looking for info on Baldwin-Burns guitar amps. I have a BB Orbit 75, which appears to be an uprated version of the Burns Orbit 3. Two 12" Fane speakers, probably about 65-70 watts??? I found the Orbit 3 schematic on this site, and have edited this with the Orbit 75 differences (basically the channel 1 tone selector is now a standard bass tone control, as per channel 2). It appears that Baldwin took the Burns Orbit 3 and just increased the first rail voltages from 33 V to 43 V, without dealing with the power stage as far as I can make out. I have derated my Orbit 75 to Orbit 3 specs to stop it over-heating (several components were heat-damaged, hence me buying it as non-working). I have attached the Orbit 75 schematic, but it still needs some work since the Orbit 75 has both treble boost and studio boost buttons and I haven't figured out how they work as yet. The schematic represents my derated version of the Orbit 75 (R64 and R72 have new values to get the correct Orbit 3 rail voltages). The patchwork quilt effect on the schematic is a result of real cutting and pasting to produce the Orbit 75 circuit from printouts of the Orbit 3! I have recapped the entire amp, plus replaced the heat-damaged resistors and tracks. The amp has gone from a scratchy crackly dull amp to a really nice sounding amp, which due to the interstage transformer has a tendency to sound a bit valvy at times (guitar on 10). I have also replaced the EI transformer with an 80 VA toroidal and fitted a plastic main power switch as per today's regulations.
    Attached Files

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  • Jazz P Bass
    replied
    I have some AC107 Germanium transistors .
    https://www.radiomuseum.org/tubes/tube_ac107.html

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  • Jazz P Bass
    replied
    OP76 data
    Attached Files

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  • Jazz P Bass
    replied
    Attached Files
    Tube OC 76 or Röhre OC76 ID33807, Transistor, Wires and Universal shown. Radio tubes are valves.

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  • Littlecarl
    replied
    I'm slowly getting somewhere with one of the Burns amps I have.. A lot of the wires of the NKT 213 transistors had bad joints to the PCB where the wires had oxidised down the solder joints.. I have renewed the wires and those transistors are much better.. One of the input transistors had been replaced with something modern but signal was very low to the other channel so in the process of swapping the CH2 input transistor the a leg had fallen off. The one fitted is an OC706 device and I'm having a hard time trying to find on or out any information about it to find an equivalent device.. Any pointers?

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  • Littlecarl
    replied
    Thank you.. That brochure on Black guitars is fantastic..

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  • Littlecarl
    replied
    Originally posted by willy barden View Post
    I've got a schematic/circuit diagram for the pc board version of the Orbit 3. The diagram was folded up and ended up in a waste bin - luckily was recovered but in poor condition - this print shows the damage. The circuit has several errors according to the amp examples I have seen and the symbols used for components are very old - other then that it's OK .....see attachment
    It seems to be the only surviving copy doesn't it?

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  • Littlecarl
    replied
    Originally posted by welsh_chris View Post

    I've still got the schematic files I downloaded from this forum 10 years ago. I've just uploaded to drop box, https://www.dropbox.com/sh/bkiee08i7...C1rt2r-Pa?dl=0
    Thanks Chris. I have those but was hoping for a layout or anything else that might help without me having to unpick everything. I also have copies of the schematic that was inside the earleir point to point cabs. I tried transposing that clearer info to the full page and found there was a lot of different values and altered circuits.

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  • vintagekiki
    replied
    https://www.diyaudio.com/forums/instruments-and-amps/255726-burns-orbit.html
    You must log in or sign up

    http://schems.com/bmampscom/burns/Burns_20_Orbit_Three.pdf

    http://blackguitars.com/burns-amplifiers.html

    https://elektrotanya.com/?q=showresult&what=burns

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  • welsh_chris
    replied
    Originally posted by Littlecarl View Post
    Hi I'm new to this forum.. I have a Burns Orbit 3 double 12 and a Double 12 too that I need to look at.. These are the later Printed Circuit Board type compared to the earlier turret and point to point.. I did a successful rewind of a voice coil on a 10" Elac.. The glue had let go of the coil and found the top layer winding found it's way under the dust cover lol..
    I have tried to view the pic files in this thread but they don't seem to work?? Any help appreciated..
    I've still got the schematic files I downloaded from this forum 10 years ago. I've just uploaded to drop box, https://www.dropbox.com/sh/bkiee08i7...C1rt2r-Pa?dl=0

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  • dmeek
    replied
    Here's the Orbit 3 schematic, just barely readable. Burns Orbit Three 3 schematic.pdf

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  • willy barden
    replied
    I've got a schematic/circuit diagram for the pc board version of the Orbit 3. The diagram was folded up and ended up in a waste bin - luckily was recovered but in poor condition - this print shows the damage. The circuit has several errors according to the amp examples I have seen and the symbols used for components are very old - other then that it's OK .....see attachment

    Leave a comment:


  • g1
    replied
    Originally posted by Littlecarl View Post
    I have tried to view the pic files in this thread but they don't seem to work?? Any help appreciated..
    Many of the old files were lost due to a server crash several years ago.

    Leave a comment:


  • Littlecarl
    replied
    Hi I'm new to this forum.. I have a Burns Orbit 3 double 12 and a Double 12 too that I need to look at.. These are the later Printed Circuit Board type compared to the earlier turret and point to point.. I did a successful rewind of a voice coil on a 10" Elac.. The glue had let go of the coil and found the top layer winding found it's way under the dust cover lol..
    I have tried to view the pic files in this thread but they don't seem to work?? Any help appreciated..

    Leave a comment:

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