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Looking for a schematic for the Laney Pro Bass amplifier.
Anyone ?
Anyone ?
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Is that the model PB400 ?
What model do you have -
Hello Mozwell, thanks for the reply...
No model number on the amp itself.
It looks like this £70 300w laney PRO BASSComment
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i dont have any info on a "pro bass" amp
maybe one of these will be similar enough
DB400, G300H, nexus nxf, R3, R5, RB1, RB7, RB9, RBH800
If not, then these are here for posterity to help others
what is the actual problem that you have with this ampComment
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The - volt rail is pulled down... After ac to dc bridge are the main caps, then two 220 ohm resistors. Going to a 7915 and a 7815. The +15 volt is fine... The -15 volt is pulled down to 0,6 volts...Comment
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Well if the -15V rail is low, there are four possibilties.
- the 21 Vac input is bad (unlikely but possible)
- the regulator is bad
- there is a shorted capacitor on the output
- the rail is being pulled down by a component down the line.
If there is an onboard connector for the Vac line, you could test the Vac there, after disconnecting it.
The next step would be to remove the regulator & measure the output pad to ground & see if it is a low resistance.
If it is not low install a new regulator.Comment
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Fixed the -15 volt line, a zenerdiode was shorted...
Found a burned resistor... Cannot read the color indicator anymore ( burned all brown)
It is a Laney PB100-10.Comment
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In which circuit is the burnt resistor?
If it is on the -15 volt supply, there should be a mate on the +15 volt supply.Comment
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Checked that, but no there is not a pair of these on the board. Iets on the amplifier board. And it is a mono amp...
I asked Laney UK for a schematic 2 days ago... Anyone experience with them for a schematic request ?Comment
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