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With a day off and waiting for schematics and parts on other fixes, I finally got around to one of my projects. I had parts to a Peavey 400BH board and power transformer 705-18715. The goal was to cut the PC board and salvage the components for the dual power supply (+50, -50, +15, -15). I will be using this for misc projects in the future (and one of those being a small Class D amp project for learning).
As you can see, I found a logical place to run a hack saw through the board. The cut point did not include CR28 and C41 (used for the 7815 Positive Regulator) and CR29 and C42 (used for the 7915 Negative Regulator). So I had to drill holes, mount those components, and run them to the proper trace. I decided to use new caps and diodes - the old ones had short leads. For those who know this board well, I removed some of the pins on the molex connectors and those will become my outputs. On the bottom side of the board, I cut some traces, added jumpers were needed - and in the end, I have the High and Low supply circuits in tact. Yes, I have +15 and -15 coming off CR20 and CR21 respectively. BTW, I also included a Ground connection between the transformer to the circuit board. Some Peavey amps have a single black wire connecting from the transformer case to the circuit board. This one did not - so I added it. Photo and Schematic attached.
So... it all works fine. I have +50, -50 and Ground (on the top set of pins). I have +14.8, -15.6, and Ground on the bottom set of pins. I will debug the difference in these two voltages. It is an interesting difference since I have +27 and -27 feeding the respective regulators.
Now that this is working, I will look for a project box or platform to mount it - including On/Off Switch and Fuse.
With a day off and waiting for schematics and parts on other fixes, I finally got around to one of my projects. I had parts to a Peavey 400BH board and power transformer 705-18715. The goal was to cut the PC board and salvage the components for the dual power supply (+50, -50, +15, -15). I will be using this for misc projects in the future (and one of those being a small Class D amp project for learning).
As you can see, I found a logical place to run a hack saw through the board. The cut point did not include CR28 and C41 (used for the 7815 Positive Regulator) and CR29 and C42 (used for the 7915 Negative Regulator). So I had to drill holes, mount those components, and run them to the proper trace. I decided to use new caps and diodes - the old ones had short leads. For those who know this board well, I removed some of the pins on the molex connectors and those will become my outputs. On the bottom side of the board, I cut some traces, added jumpers were needed - and in the end, I have the High and Low supply circuits in tact. Yes, I have +15 and -15 coming off CR20 and CR21 respectively. BTW, I also included a Ground connection between the transformer to the circuit board. Some Peavey amps have a single black wire connecting from the transformer case to the circuit board. This one did not - so I added it. Photo and Schematic attached.
So... it all works fine. I have +50, -50 and Ground (on the top set of pins). I have +14.8, -15.6, and Ground on the bottom set of pins. I will debug the difference in these two voltages. It is an interesting difference since I have +27 and -27 feeding the respective regulators.
Now that this is working, I will look for a project box or platform to mount it - including On/Off Switch and Fuse.
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