Hello,
I've built a BPBP some time ago, it worked perfectly foir a long time. When I moved in to a new flat I decided to put it in a chassis. My friend took it to take measurements for CNC and after assembly - it doesn't work.
The problem is a distorted sound. At first I thought I've made some bad connections, so I've taken the PCB back from chassis. Still nothing. Voltages seem okay on chips. As the issue is in both channels the only part that works in both is servo amp, so I removed it. Sadly, still nothing. Next step seems to replace all the opamps, but before I do that I'd like to ask about your opinions, maybe there is something I'm forgeting about?
I've built a BPBP some time ago, it worked perfectly foir a long time. When I moved in to a new flat I decided to put it in a chassis. My friend took it to take measurements for CNC and after assembly - it doesn't work.
The problem is a distorted sound. At first I thought I've made some bad connections, so I've taken the PCB back from chassis. Still nothing. Voltages seem okay on chips. As the issue is in both channels the only part that works in both is servo amp, so I removed it. Sadly, still nothing. Next step seems to replace all the opamps, but before I do that I'd like to ask about your opinions, maybe there is something I'm forgeting about?
This one: https://www.edn.com/Home/PrintView?contentItemId=4431638 ?
Took me a while to find a readable schematic, I think this is it:
Took me a while to find a readable schematic, I think this is it:
An externally hosted image should be here but it was not working when we last tested it.
If it is the same in both channels, opamps seem extremely unlikely, especially all of them at the same time! What is common to channels is power supply.
You said 'voltages seem OK on chips'- what does that mean? Are they OK or are they not? Did you check the DC on the opamp power pins, if so, what were the values?
Jan
You said 'voltages seem OK on chips'- what does that mean? Are they OK or are they not? Did you check the DC on the opamp power pins, if so, what were the values?
Jan
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I found in my BPBPre that feeding the HXR regulators close to the minimal voltage (Eg 2x12V) gives all kinds off problems at startup, including latching opamps which distort. I switched to a 2x13V and no problems since then.
I suspect that the primary voltage (and secundary) slightly changed when moving location.
Edit: Google "LM4562 latch" and you will get all kind of results that will point you in different sources and solutions. I know that raising the secundary voltage was the solution in my case !-)
I suspect that the primary voltage (and secundary) slightly changed when moving location.
Edit: Google "LM4562 latch" and you will get all kind of results that will point you in different sources and solutions. I know that raising the secundary voltage was the solution in my case !-)
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Gerben, did you measure the voltages coming out of the regulators when they were fed with too low voltage? Did they completely turn off?
Jan
Hi,
This was a year ago....so from memory i remember checking for voltage after the regulators and that they were not turned off so didnt understand what caused the distortion. I dont know what secundary voltage the op uses but 2*12v is close to the minimal voltage that the regs need.
As I dont understand how the HxR regs exactly work (and don't if minimal requierements are not met) and the available info on the latchup behavour of the opamps i placed the problem as a mix of causes that were solved when using the 2*13secundary....i know....not very sound ...but there is sound
Also i made sure that at startup a source was connected to the selected channel at startup.
This was a year ago....so from memory i remember checking for voltage after the regulators and that they were not turned off so didnt understand what caused the distortion. I dont know what secundary voltage the op uses but 2*12v is close to the minimal voltage that the regs need.
As I dont understand how the HxR regs exactly work (and don't if minimal requierements are not met) and the available info on the latchup behavour of the opamps i placed the problem as a mix of causes that were solved when using the 2*13secundary....i know....not very sound ...but there is sound
Also i made sure that at startup a source was connected to the selected channel at startup.
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