The 'Lock' LED on the front panel blinks intermittently and coincident with that the signal fails. Waiting awhile, sometimes the led and signal will return, then fail again.
Any ideas on how to fix, what might be the root cause? CC Poon the proprietor is retired, but the company was formerly in South San Francisco. I happen to live nearby so could certainly deliver to any former tech available locally.
Thanks for your insights in advance. No schematic available that I am able to access.
Any ideas on how to fix, what might be the root cause? CC Poon the proprietor is retired, but the company was formerly in South San Francisco. I happen to live nearby so could certainly deliver to any former tech available locally.
Thanks for your insights in advance. No schematic available that I am able to access.
As the very first test I would try a different input cable, and a different input source, just to make sure the issue is really in the processor.
Then, since the input switch is the only mechanical part and directly in the sensitive input path, I would start with it. What happens if you repeatedly flip the switch to "wipe off" its contacts? A glitch in the input signal would cause the SPDIF receiver to loose PLL lock, which is what you experience.
Then, since the input switch is the only mechanical part and directly in the sensitive input path, I would start with it. What happens if you repeatedly flip the switch to "wipe off" its contacts? A glitch in the input signal would cause the SPDIF receiver to loose PLL lock, which is what you experience.
^another quick note: I own two of these units. The one working correctly has a green LED and said input switch on the front panel.
The unit in question w/failure has an amber LED, and instead of the input toggle switch, a spring loaded push button labeled 'reset'. Wonder how it switches between the opto input and RCA? Maybe 'reset' does that?
The unit in question w/failure has an amber LED, and instead of the input toggle switch, a spring loaded push button labeled 'reset'. Wonder how it switches between the opto input and RCA? Maybe 'reset' does that?
The two inputs could be in parallel, no switching, assuming only one input contains signal at a time. The reset button could just reset the CS8427 transceiver to let it lock to the incoming signal.
You may be absolutely right about that, good thought thank you.
TosLink cable arrived, I swapped in the intermittent DIP unit and it works again. Weirdly, in comparing the opto input cable back to RCA coax, now the RCA input is working. Some gremlin has departed the unit at least for now. Sound quality is quite comparable, maybe a slight edge to RCA coax in.
TosLink cable arrived, I swapped in the intermittent DIP unit and it works again. Weirdly, in comparing the opto input cable back to RCA coax, now the RCA input is working. Some gremlin has departed the unit at least for now. Sound quality is quite comparable, maybe a slight edge to RCA coax in.
What kind of flaw would cause the lock LED to remain illuminated without any input? Just developed while in disuse, as it previously worked fine.
Mine does not have a reset button that I see. Is there another way to reset? Checked the rear switch to select input, it is fine. A puzzler!
CS8427 outputs high on the RERR pin in case of a problem https://www.mouser.com/datasheet/2/76/CS8427_F5-30495.pdf:
Judging from the PCB picture above, IMO the RERR pin is traced on the bottom side to the LED which may be connected to some component (looks like an old transistor - but no idea why it would be THT and so large) which could work as an invertor for the LED. Maybe that component is some old-style opamp for the coax input conditioner, and the LED is connected directly between + voltage and the RERR pin. You can check the traces, whether some moisture/dirt is maybe there. No other idea, without checking the device.
IIUC the RST pin is directly connected to the reset management IC MAX707 https://www.mouser.com/datasheet/2/308/MAX707-D-75585.pdf which tracks power supply voltage. Likely a push button could be connected in parallel with that IC output, but a series resistor should be inserted into the rst IC output to protect the output stage from the short circuit to ground when the push button is pressed.