Hi, I have a Mark Levinson 31.5 cd transport which works well for a while and then appears on the display: SERVO RESET. the reader does not obey to stop or change the track, it has to be turned off completely. Has anyone had a similar situation that could repair it? Thank you very much.
I asked for a service manual from Mark Levinson and as such they don't have it, only a basic schematic and some options for resetting and installing upgrades such as cdm12 to pro
" translation"
IC is a long-term discontinued IC. it has
There are two buttons, there is a reset switch on the circuit board, you can try to press it and it can be used normally.
IC is a long-term discontinued IC. it has
There are two buttons, there is a reset switch on the circuit board, you can try to press it and it can be used normally.
I changed Benchmarkq ram, but servo reset still be present. Someone know what type of part is NFV-610? (position df80 in levinson 31.5 board)
Was the RAM hard to find? NFV-610 is a varistor.
If I recall correctly, the 31 was a two-board setup, with one board handling the servo's and the digital outputs and the other the CPU stuff. Levinson gear was all about low noise in those days, so they separated as much as possible digital and microprocessor stuff. They even have separate supplies, housed in the "towers" on the sides. I assume the 31.5 takes the same approach.
The RAM is on the CPU board, by my guess would be that the servo board is throwing a signal that the cpu doesn't like, causing the unit to become in an undetermined state, needing a hard reset. I would therefore start on the other side of the device, with the servo board.
You could do some simple checks, like checking for components that get overly warm, as from your description it appears the fault presents itself when the unit runs for a while. A simple thermal imaging device would do the trick.
However, you're trying to troubleshoot a unit that is over 25 years old, using digital technology from those days, running software that is hard or impossible to obtain. You'll need a logic analyzer to properly understand what's going on in the machine. If this was my machine, I'd either get in touch with an authorized repair center (and swallow the undoubtedly huge invoice) or start off by creating a simple schematic and work off that (which is time-consuming).
If I recall correctly, the 31 was a two-board setup, with one board handling the servo's and the digital outputs and the other the CPU stuff. Levinson gear was all about low noise in those days, so they separated as much as possible digital and microprocessor stuff. They even have separate supplies, housed in the "towers" on the sides. I assume the 31.5 takes the same approach.
The RAM is on the CPU board, by my guess would be that the servo board is throwing a signal that the cpu doesn't like, causing the unit to become in an undetermined state, needing a hard reset. I would therefore start on the other side of the device, with the servo board.
You could do some simple checks, like checking for components that get overly warm, as from your description it appears the fault presents itself when the unit runs for a while. A simple thermal imaging device would do the trick.
However, you're trying to troubleshoot a unit that is over 25 years old, using digital technology from those days, running software that is hard or impossible to obtain. You'll need a logic analyzer to properly understand what's going on in the machine. If this was my machine, I'd either get in touch with an authorized repair center (and swallow the undoubtedly huge invoice) or start off by creating a simple schematic and work off that (which is time-consuming).
Winchester 76:
Thanks for your comments. It wasn't hard to get the RAM, but that didn't fix the servo error. I had some support from Levinson for a while, but they don't know much about this 31.5 either. I have done several schematics and gotten something, but without much luck. I was thinking of downgrading bypassing the 31.5 control and use the Philips transport own clock (assuming of course that it won't sound as it is configured now) to see if that transport controled by the card isn't causing the problem. (That's why I asked about the NFV-610, which is eliminated when the Philips transport is upgraded and the board is taking control of the clock, including an epromm on the other board, that I also have).
I hope to be able to activate it, since while it works for a few minutes, it sounds superior and very analogous vs all the transports that I know and have had, unlike what I have heard in audio. The difference is greater than changing a DAC, of course the better the DAC, the higher the resolution and quality in sound.
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Thanks for your comments. It wasn't hard to get the RAM, but that didn't fix the servo error. I had some support from Levinson for a while, but they don't know much about this 31.5 either. I have done several schematics and gotten something, but without much luck. I was thinking of downgrading bypassing the 31.5 control and use the Philips transport own clock (assuming of course that it won't sound as it is configured now) to see if that transport controled by the card isn't causing the problem. (That's why I asked about the NFV-610, which is eliminated when the Philips transport is upgraded and the board is taking control of the clock, including an epromm on the other board, that I also have).
I hope to be able to activate it, since while it works for a few minutes, it sounds superior and very analogous vs all the transports that I know and have had, unlike what I have heard in audio. The difference is greater than changing a DAC, of course the better the DAC, the higher the resolution and quality in sound.
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I don’t believe Mark Levinson when they say they don’t have the service manual. Of course they do, so are lying. What they mean is, they won’t supply it to a non-authorized repair center. I could respect them if they simply had said that. The trade secrecy among high-end audio companies regarding the repair of failed components is infuriating. 😠
@Ken Newton I don't doubt for a second they have some service manuals for this stuff, but that is generally not where the problems are. I did receive some service documentation for the 39 several years ago after asking nicely, but that suffices to replace failed components. Any software-related issues and it is pretty much game over.
@chansiukwing you mean the switch itself is randomly engaging? That doesn't appear to be in line with the problem the OP is describing.
@chansiukwing you mean the switch itself is randomly engaging? That doesn't appear to be in line with the problem the OP is describing.
I had the same problem. Servo Reset appears on the display, and the LEDs blink quickly. If you disconnect the CD drive, nothing changes. If you disconnect the transition cable between the right and left boards, the LEDs stop blinking, but Servo Reset does not disappear. The right board, I'm sure, works; it's responsible for communication and the display. Perhaps this will give you some ideas. Has anyone had any experience with this problem?
The IC bq4011yma-100 is a static memory (SRAM) and has no software in it. Any other ideas? Very interesting to understand. Today I checked the communication between the left and right halves. There is communication, but the same thing is transmitted, which is not surprising. And also has a strange look to the output of the IC XC3030A.
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In my ML, all the capacitors have been replaced. That is clearly not the cause. I'm going to write a program to control the CDM12 maybe so I can understand what the problem is. I assume that it has nothing to do with RAM because although it is able to store data when the power is off, it behaves like normal memory when the power is on.