The relay, RL1, in my Citation 25 has an erratic function as it doesn't always close (click) when changing programs and if I don't make sure it clicks (closes) through quick program changes before shutdown then DC leaks to the output stage which makes it "pop" " in the speakers.
It seems that the control current to the relay is not sufficient? Which component(s) could be to blame for this?
It seems that the control current to the relay is not sufficient? Which component(s) could be to blame for this?
There are to many unknowns in this.
When you say 'Shutdown' do you mean operation of a mains switch that removes all power or do mean 'Standby' which leaves the unit powered up?
The relay seems to be a normally closed type which shorts the audio to ground to mute and so it should immediately drop out on power off. Its possible any issue could be cap related in the area that detects presence of AC power.
The relay coil is switched across the -34 volt rail to power it but with current limiting by the series resistors. It is a bit of a bizarre looking circuit tbh 🙂
When you say 'Shutdown' do you mean operation of a mains switch that removes all power or do mean 'Standby' which leaves the unit powered up?
The relay seems to be a normally closed type which shorts the audio to ground to mute and so it should immediately drop out on power off. Its possible any issue could be cap related in the area that detects presence of AC power.
The relay coil is switched across the -34 volt rail to power it but with current limiting by the series resistors. It is a bit of a bizarre looking circuit tbh 🙂
"Shutdown" means "power off" by either remote ( to standby) OR main switch button.
For some unknown reason the relay don´t ground to mute unless i first make the relay click by changing program, f.e. tape to source, several times.
For some unknown reason the relay don´t ground to mute unless i first make the relay click by changing program, f.e. tape to source, several times.
I think you need to take some voltage readings beginning with the voltage across D18 which will show what the relay sees. It would need to be zero volts to close what we assume is a normally closed relay.
When you turn the power off by the mains switch that has got to remove all voltage but one question is how quickly it falls. Again see what happens with the voltage across the relay.
You have to start somewhere 🙂 and some initial tests might get a handle on what is happening.
It looks like the base of Q13 needs to be pulled 'low' to turn the relay on and unmute. To mute the base will be at 5 volts and Q13 off.
When you turn the power off by the mains switch that has got to remove all voltage but one question is how quickly it falls. Again see what happens with the voltage across the relay.
You have to start somewhere 🙂 and some initial tests might get a handle on what is happening.
It looks like the base of Q13 needs to be pulled 'low' to turn the relay on and unmute. To mute the base will be at 5 volts and Q13 off.
Oddly enough C2 is 1000uf/50v on the schematics but 470uf/50v on the parts list, guess i´ll find whats in there.
Not only 2 x 270 Ohm but also Q698 and Q699. Someone wanted desperately to have the relay connected to -34V.
Checking if a 1000 or 470 µF is used is the first to do I think. And what is the relay type and its working voltage? If it is an open type it may also be dirt/dust delaying its action.
Checking if a 1000 or 470 µF is used is the first to do I think. And what is the relay type and its working voltage? If it is an open type it may also be dirt/dust delaying its action.
The C2 cap is 470 uF and the relay is the Fujitsu 221D024-P. Both are replaced with new parts.
I have also replaced the C18, C19, and Q11.
Next i will look into the D18 and Q13 and see what i find.
I have also replaced the C18, C19, and Q11.
Next i will look into the D18 and Q13 and see what i find.
Did you use identical parts? Did all this make a difference? The Fujitsu relay seems to be more often a cause of error.
It came to my eye that R18 is a tad high in value. Haven't calculated as I have to go now.
It came to my eye that R18 is a tad high in value. Haven't calculated as I have to go now.
Yes, identical parts and problem remains. The only difference is that the new relay is louder when it "clicks".
Can we go right back to the beginning with this?
1/ With the unit off (no mains, unplugged) can you confirm that the L and R RCA line outputs read short circuit. So that is inner to outer on the sockets. Yes or no?
2/ Switch the unit on and confirm the short on L and R is gone. Yes or no?
3/ Switch off by the remote and see if the line output sockets instantly show a short to ground, Yes or no?
4/ Switch off by the power switch and see if the line output sockets instantly show a short to ground, Yes or no?
5/ Try and get it to the above condition where you think the relay has not grounded correctly and then confirm that by seeing if there it has placed a short across the line outputs. Yes or no?
6/ Do you see the base of Q10 go high every time you change programmes. Yes or no.
1/ With the unit off (no mains, unplugged) can you confirm that the L and R RCA line outputs read short circuit. So that is inner to outer on the sockets. Yes or no?
2/ Switch the unit on and confirm the short on L and R is gone. Yes or no?
Lets try and see what happens.
3/ Switch off by the remote and see if the line output sockets instantly show a short to ground, Yes or no?
4/ Switch off by the power switch and see if the line output sockets instantly show a short to ground, Yes or no?
5/ Try and get it to the above condition where you think the relay has not grounded correctly and then confirm that by seeing if there it has placed a short across the line outputs. Yes or no?
6/ Do you see the base of Q10 go high every time you change programmes. Yes or no.
1/ Yes.
2/ Yes.
3/ Yes.
4/ Yes.
5/ At first when unit is switched on, remote or power switch, the relay clicks after a few seconds, sa it should, then changing program the relay clicks as it should, BUT after a listening session there is no click changing program and if i switch the unit off then it pops in the speakers.
I have to change program several times until i hear the click before i switch off to avoid the pop (DC).
It's starting to look more and more like heat-related and possibly a bad solder joint?
2/ Yes.
3/ Yes.
4/ Yes.
5/ At first when unit is switched on, remote or power switch, the relay clicks after a few seconds, sa it should, then changing program the relay clicks as it should, BUT after a listening session there is no click changing program and if i switch the unit off then it pops in the speakers.
I have to change program several times until i hear the click before i switch off to avoid the pop (DC).
It's starting to look more and more like heat-related and possibly a bad solder joint?
Thanks for those 🙂
What about number 6 and the base of the transistor?
So number '5' is worth looking at. Try and see what triggers the relay driver has and what the driver output does.
You could begin by looking at pin 6 of IC1 and confirming it behaves differently when the fault happens.
Also C15 and D12 and D891 look to provide a means of retaining power for a very short while on IC1, long enough for it to set pin 6 at 'high' (same voltage as pin 14). Lets see if all that works. C15 is critical as it works as a battery keeping the chip powered.
You have to look logically at all the 'inputs' to that relay drive circuit and see what is different when the fault occurs. It could be a passive part like a leaky diode or bad cap or it could be that the circuit is working 'correctly' but in response to a faulty input such as the mute function to Q10. You have to look for what is different when it fails to work.
Definitely check that supply to IC1 though and that the supply remains present for a little while on power off. It may only be for a couple of seconds but that is enough for the other supplies to collapse and for the relay not to be able to pull in (and pass the pops)
What about number 6 and the base of the transistor?
So number '5' is worth looking at. Try and see what triggers the relay driver has and what the driver output does.
You could begin by looking at pin 6 of IC1 and confirming it behaves differently when the fault happens.
Also C15 and D12 and D891 look to provide a means of retaining power for a very short while on IC1, long enough for it to set pin 6 at 'high' (same voltage as pin 14). Lets see if all that works. C15 is critical as it works as a battery keeping the chip powered.
You have to look logically at all the 'inputs' to that relay drive circuit and see what is different when the fault occurs. It could be a passive part like a leaky diode or bad cap or it could be that the circuit is working 'correctly' but in response to a faulty input such as the mute function to Q10. You have to look for what is different when it fails to work.
Definitely check that supply to IC1 though and that the supply remains present for a little while on power off. It may only be for a couple of seconds but that is enough for the other supplies to collapse and for the relay not to be able to pull in (and pass the pops)
I mean measured in DMM diode mode. If it is unreliable it would not let the hex inverters input voltage dropping to 0V fast enough at power off. Honestly I am guessing as the circuit is complicated with regards to error possibilities.
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