Something more sturdy with lower RDSon would not hurt as it drives a coil over a longer period. Many SMD MOSFETS are capable of ultra low (tens of milliOhms area) RDSon and a few A. For instance 2N7000/BS170 work OK with tiny micro-relays with power consumption of a LED 🙂 but not with larger relays.
I think I used ZXMN2A14FTA in a few.
I think I used ZXMN2A14FTA in a few.
Last edited:
Good question. Addition of a diode (I used a Schottky for low Vf but a 4148 type seems as good) can be used to discharge the timing cap,
Two alternative positions for the diode are possible depending on the LED drive circuit. If the LED drive circuit is an open collector type then a resistor across the LED might be needed to provide a discharge path.
A short interruption to the lock is in the centre part of the trace shown expanded.
Alternate position for diode:
If an Open Collector driver.
Two alternative positions for the diode are possible depending on the LED drive circuit. If the LED drive circuit is an open collector type then a resistor across the LED might be needed to provide a discharge path.
A short interruption to the lock is in the centre part of the trace shown expanded.
Alternate position for diode:
If an Open Collector driver.
I think that won't work as the voltage of the LED_drive circuit probably is higher (and longer available) than the voltage on C1 + the forward drop of the diode. C1 is also already discharging via D2 to its supply.
For inspiration, this one works OK as power on delayed unmuting/power off instant muting. It can be adapted to "signal lock delayed unmuting". I recall a small issue below xV PSU voltage with the Zener diode lacking enough current to do its job properly.
For inspiration, this one works OK as power on delayed unmuting/power off instant muting. It can be adapted to "signal lock delayed unmuting". I recall a small issue below xV PSU voltage with the Zener diode lacking enough current to do its job properly.
Last edited:
I think I follow what you are saying there JP.
I'm assuming the supply for the relay (Supply in the sim) is 12 volts or even higher such as an unregulated supply. The gate voltage will max out at the forward volt drop of the LED which the op has measured.
I'll attach the revised sim if you want to try it.
All three variables shown:
I'm assuming the supply for the relay (Supply in the sim) is 12 volts or even higher such as an unregulated supply. The gate voltage will max out at the forward volt drop of the LED which the op has measured.
I'll attach the revised sim if you want to try it.
All three variables shown:
Probably it is 5V as usual in old stuff. Seen with a practical eye the trouble in this case is that both digital supply voltage and the "signal lock" LED are pretty far away in the device. This will will take some time and then better make it 100% straight away.
Simplest would be to just have to connect just 2 wires to the "signal lock" LED to a separate PCB near the outputs. As the Prime II also has XLR outputs OP should confirm if those should also be muted. In that case (if it was mine) I would draw a tiny SMD PCB with both power on/off muting and signal lock muting of both RCA and XLR outputs simultaneously. Most effective covering omitted features but also most effort. It requires to be small as it can practically only be positioned on a small bracket above the XLR outputs or between RCA and XLR at the back cover. The tiny boards I made are only 32 x 22 mm and cover RCA or XLR outputs. Probably fit well at the back cover between RCA and XLR in the Prime II. I can throw one in an envelope if needed.
Wiring to the LED should probably be done with shielded cable. Routed via the front right side and PSU cabling via the back left side.
Simplest would be to just have to connect just 2 wires to the "signal lock" LED to a separate PCB near the outputs. As the Prime II also has XLR outputs OP should confirm if those should also be muted. In that case (if it was mine) I would draw a tiny SMD PCB with both power on/off muting and signal lock muting of both RCA and XLR outputs simultaneously. Most effective covering omitted features but also most effort. It requires to be small as it can practically only be positioned on a small bracket above the XLR outputs or between RCA and XLR at the back cover. The tiny boards I made are only 32 x 22 mm and cover RCA or XLR outputs. Probably fit well at the back cover between RCA and XLR in the Prime II. I can throw one in an envelope if needed.
Wiring to the LED should probably be done with shielded cable. Routed via the front right side and PSU cabling via the back left side.
Attachments
Last edited:
Perhaps grounding/clamp-down transistors at the output instead of relays in the path could be used. IMO it's a standard muting method for soundcards and dacs.
There are several ways anything like this can be implemented but in the end it comes down to what the op wants and what level of complexity is acceptable,
That is certainly an option.
Indeed. Very common in lots of gear. In a way its surprising the DAC has this issue at all as it is really a design fault I suppose.
The device has unusual processors/ICs/configuration and possibly all this together leads to this either strange phenomenon when disrupting or starting a datastream.
Omitting muting is indeed a design fault, certainly when normal operation can cause garbled output signals.
Omitting muting is indeed a design fault, certainly when normal operation can cause garbled output signals.
Last edited: