Denon DN-980F Remote wiring

[neilalexrose]

I throw myself on the collective wisdom of the Blue Room (possibly some of those with old school broadcast equipment knowledge). For reasons I wont go into I have a Denon DN-980F that I need to remote control. That is the easy bit. GoogleFu reavealed this page, which revealed the manual here. So I have a switch wired up to activate the Play function.

The bit I need some help with is the 'Play Tally', which as I understand it, is a means to light an LED when the unit is playing (this is where I start getting a little out of my depth). Please see pages 7 & 8 in the manual for the relevant pinout charts.

I have metered out pins 22 & 14, (Tally power and Play tally respectively) ,which as I understand it should spit out 5vDC 20ma. Currently seems to be metering around 3.5v. With an LED attached, the voltage then drops to 1.5v, and doesn't light the LED. I can attach the same LED to pins 22 & 23 (Tally power and Command common) and make it light, as there is 5vDC present. Also the voltage does not change when the unit is playing or in standby, so doesn't seem to follow the play button state at all.

The LED I have is a 2v LED with a 100ohm resistor in series, so it can deal with the potential 5v.

 

So the question I have is, am I missing something? Am I correct in thinking it should work in this way, that an LED should light in line with the main unit's play button?

 

Any help or guidance will be greatly appreciated.

 

Thanks

Neil

[kgallen]

Hi Neil,

I had a look at the tally outputs on the Tascam MD801 (just what came up from Google, no other reason) and it says they are open collector. From your linked manual it's not clear, however table 1 specs at Iol of 48mA and you'd have this spec for an open collector output - it says the output can sink 48mA when low. Also as the output stage is listed as TTL, pulling things low suits that type of technology, which is also not so good at pulling things high (sourcing current). I think having open collector outputs for this sort of thing makes a lot of sense since it's easy to implement and doesn't tie you to a particular supply voltage for whatever external circuit you want to connect to it.

Pin 22 is listed as tally power supply. I'd connect the anode of your LED there and the cathode via your resistor to pin 14.

Just one comment on the play command input - it's listed as HCMOS, so it will be very susceptible to static discharge damage. Be careful what you connect to it and avoid a direct path from the human body to that input - e.g. avoid switches with metal buttons.

Hope that helps. Let us know how you get on.

Kevin

ETA If you want a ground connection then I think that is pin 1. FG is probably 'frame ground'. You should see a good 5V from pin 22 to pin 1.

 

Neil - also your resistor should probably be more like 270 to 330 ohms to limit the current to about 10mA (a 3V drop across the resistor) which should be enough to light a normal 5mm red LED ok. Sorry I didn't check your link to confirm the spec of the LED you used... :-( but 100 ohms might be a bit low if the tally supply can only source 20mA total.

[neilalexrose]

Hi Kevin, thanks for the reply. I understand bits of it, but it strikes me that I have the wrong LED for the job. The one I chose was a 2v 20ma LED (that can deal with the current. But if your saying that the current output is lower than this, then I think I need a different LED. Could you advise on a better LED (and resistor) then please?

Incidentally I did try wiring up the kit I have before I posted, LED to pins 14 & 22, and it didn't work, with and without the resistor connected. THat's what made me think I have the wrong LED for the job.

Thanks for your help

 

Neil

[kgallen]

Hi Neil,

 

The current is set by the resistor, it's just the manual says the tally supply can only provide 20mA in total. The LED you spec is ok, just, but it's the only thing you could drive on tally (maybe that is ok for your needs). Do you really need a 10mm LED (just because it's on the physically large size)? Could you try a standard 5mm red or yellow/amber LED? They will also have a forward voltage drop of 2V (or 2.1V). That means for a 5V tally supply, there is 3V across the resistor, and for 10mA through it and V=IxR, rearranged as R=V/I, R=3V/10mA=300 ohms (you would probably pick 270ohms or 330ohms from the basic resistor series).

 

LEDs are polarised. For an open collector output, LED anode to the tally supply then through the resistor to the tally output, which pulls the LED cathode low when activated to light the LED. I'd expect this to work straight away if the output really is open collector, which is my interpretation of the manual (and I could be wrong).

 

Sorry for reiterating some of my earlier post, and possibly not adding much more info to your problem. I hope the background is useful. Apologies if you already understand this stuff!

 

ETA: If you look at Figure 8 on page 7 of the PDF, the LED is wired as I say above (ok the resistor is the other side of the LED but that should make no difference). So the tally output is o/c. Also note 3(a) says you need to enable remote control, so maybe try this if the LED still does not work.

 

By "standard" LED I mean something like this:

http://cpc.farnell.com/avago-technologies/hlmp-3301-d0000/led-5mm-red/dp/SC11575

 

 

Kevin

[neilalexrose]

Hi Kevin

Thanks for the info. Haven't had any chance to go much further with this project over the last couple of days. The LED would be the only thing on the tally output, and the size is deliberate - it's for a public A/V display, so I wanted a decent indication that the track was playing. If what I understand is correct, that the led I have should be working, then I suspect there is more at play here, either the tally output doesn't work this way, or that there is a fault inside the player itself. It's an old player, with an undisclosed history, so anything is possible. Plus the 3v I'm metering across the terminals for the tally input/output leads me to think something isn't quite right.

I'll try a couple more options, but may abandon it if it takes up too much more of my time.

 

Thanks for all your help so far.

Neil

[alistermorton]

Kevin is spot on the money - but you need to understand that the tally "outputs" don't actually supply any power - they sink it. That's what open collector means - it's like a switch between the "output" pin and ground. How are you measuring 3V across the "terminal for the tally input/output" leads?

[neilalexrose]

How are you measuring 3V across the "terminal for the tally input/output" leads?

 

According to the manual pin 22 is the tally power supply - which should be supplying the +5v that goes to the Tally, which when I put a multi-meter across pins 22 & 14 (which is the other half of the tally circuit), I get a reading of 3.5v - not the 5v I was expecting, and is (as far as I understand) what I should get to be able to light an LED.

It's been a couple of days since I last looked at this project, but from what I remember I can get the 5v when metering between pins 22 & 23 - command common, and 22 & 1 - unit's ground.

Neil

[alistermorton]

You said your LED lit when connected between tally power and ground - that's as expected, and proves the tally power is present. If you now move the connection from the ground pin to the play tally pin it should light when the unit is in play mode, if Kevin and I have understood the description correctly.

[kgallen]

Measuring from pin 22 to pin 1 you should get +5V all of the time the machine is switched on.

 

I'm not sure you can meanigfully interpret a measurement from pin 14 (play tally output) to anything else (pin 22 or pin 1 in practice) since we don't actually know the detail of the output circuit that connects to pin 14 inside the machine. All we (believe we) know is that pin 14 should get pulled close to ground (close to pin 1 potential as I'm interpretting it) when play is activated. As Alister says, the output is just like a switch between pin 14 and ground, the switch being closed when play is active and open when not.

 

If you connect your multimeter from pin 22 to pin 14, then when play is activated you should get a reading of around +5V (pin 22 is +5V and pin 14 is effectively ground). If you don't then maybe the output circuit is faulty. You could try the same on all of the tally outputs - the likelyhood of them all being broken is pretty low, and you can use this to sanity check you observations for pin 14. When play is not activated any reading on your multimeter is meaningless, because effectively pin 14 is not really connected to anything (the "switch" is open).

 

In the manual you link to, Figure 8 shows exactly how the LED/resistor/external switch should connect to the pins on the D-connector and Note 3(a) referring to Page 15 of the manual shows how to enable the remote contol functionality.

 

Sorry if we're over-cooking this for you!

 

ETA: I'm not sure what we'd expect metering across pins 22 and 23, I think that could just confuse the issue. Again, we don't know the circuit behind pin 22 (and pin 4). All we know from Figure 8 is that if we connnect a switch across them, then you can activate play.

 

(It looks like pin 22 might be at a 0V potential but we just don't know. If it we're, then it would be symmetrical with the output side being open collector, but I'm not sure whether that has any relevance!)

 

Regards,

Kevin