Mystery mod on non functional OB8 - thoughts?
2015-08-12 by brel
hi all,
long time reader but haven't really posted.Thread
Mystery mod on non functional OB8 - thoughts?
Re: [oberheim] Mystery mod on non functional OB8 - thoughts? [1 Attachment]
2015-08-12 by Martin Ator
The red wires go to a diode bridge which smooths out the AC to the capacitor that the black gnd wire is connected to to give DC? Basically a larger version of what the two black things with heat sinks on are?
On Wednesday, 12 August 2015, 9:36, "brel pushwithlegs@... [oberheim]" <oberheim@yahoogroups.com> wrote:
[Attachment(s) from brel pushwithlegs@... [oberheim] included below] hi all,
long time reader but haven't really posted.
recently inherited a non functional OB8 - good news is that it powers up and the lights change when different presets are selected however there is no audio output.
upon inspection it appears someone has replaced the battery (logical)
but also added a mysterious mod that comes a removed rectifier (i believe) and connects to another point on the circuit board as can be seen in the photograph.
does anyone know what this mod might have been for and how one might proceed in repairing?
cheers
SamRe: [oberheim] Mystery mod on non functional OB8 - thoughts? [1 Attachment]
2015-08-12 by pjwhite@...
The rectifiers (off board, and with heat sinks) were probably attempts at improvements on the notoriously underrated W02M rectifiers that are standard on most Oberheim products. When these get too hot, which is not uncommon, they can start dropping out, causing glitches in the power supply.
I'd say, first determine if there are any problems with the power supply as things are now. If the voltage measurements on all supplies are normal, I'd say leave it alone. There are plenty of other things that could be causing your problems.
I'd say, first determine if there are any problems with the power supply as things are now. If the voltage measurements on all supplies are normal, I'd say leave it alone. There are plenty of other things that could be causing your problems.
Re: [oberheim] Mystery mod on non functional OB8 - thoughts? [1 Attachment]
2015-08-12 by Nick Zampiello
looks like they were having trouble with the power supply and moved that rectifier off the board due to heat or trace damage possibly. NEW ALLIANCE EAST!!!!
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On Wednesday, August 12, 2015 4:36 AM, "brel pushwithlegs@... [oberheim]" <oberheim@yahoogroups.com> wrote:
[Attachment(s) from brel pushwithlegs@... [oberheim] included below] hi all,
long time reader but haven't really posted.
recently inherited a non functional OB8 - good news is that it powers up and the lights change when different presets are selected however there is no audio output.
upon inspection it appears someone has replaced the battery (logical)
but also added a mysterious mod that comes a removed rectifier (i believe) and connects to another point on the circuit board as can be seen in the photograph.
does anyone know what this mod might have been for and how one might proceed in repairing?
cheers
SamRe: Mystery mod on non functional OB8 - thoughts?
2015-08-12 by synthparts@...
This is a very common mod and actually recommended for OB-8s. The existing 5V rectifier was too small so a larger one is highly recommended..Here's an even more extreme example -
Re: [oberheim] Mystery mod on non functional OB8 - thoughts? [1 Attachment]
2015-08-13 by Patrick Edwards
It looks like somebody replaced the +5v rectifier (which, when stock, overheats and dies easily) with a more robust one with better current ability. I would probably leave the mod alone if the +5v is operational.
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On Tue, Aug 11, 2015 at 11:17 PM, brel pushwithlegs@... [oberheim] <oberheim@yahoogroups.com> wrote:
[Attachment(s) from brel pushwithlegs@... [oberheim] included below]Samcheersdoes anyone know what this mod might have been for and how one might proceed in repairing?but also added a mysterious mod that comes a removed rectifier (i believe) and connects to another point on the circuit board as can be seen in the photograph.upon inspection it appears someone has replaced the battery (logical)recently inherited a non functional OB8 - good news is that it powers up and the lights change when different presets are selected however there is no audio output.hi all,long time reader but haven't really posted.
Patrick