I'm having problems with the input selector. I seems like all the inputs are active at the same time, so the signals get mixed and distorted.
Does anyone know if it's a common problem in these models? What should I check out first?
Does anyone have a schematic for this amplifier?
Does anyone know if it's a common problem in these models? What should I check out first?
Does anyone have a schematic for this amplifier?
Have you tried to connect only one input source? I've once solved a similar problem with someone who connected an analogue rec/play in/output the wrong way around....
No, I haven't tried that.
I Have heard of at least to more owners of these amplifiers with the same problem. They got it fixed, but had to pay 1400 SEK (about 200 USD) for it. Not really worth it...
I Have heard of at least to more owners of these amplifiers with the same problem. They got it fixed, but had to pay 1400 SEK (about 200 USD) for it. Not really worth it...
Well, with all pre/integrated amps every source goes to the rec-outputs. Just the same the rec-outputs go to every source?
At a closer look i seems like it's the Toshiba TC9273N that makes the shifting between inputs.
Is it possible that this component may have broke in such way that all the inputs are activates at the same time?
Is it possible that this component may have broke in such way that all the inputs are activates at the same time?
Hi nlinus,
Nope. Don't do it.
-Chris
Yup.
Yup. Also check all your ground traces to make sure it didn't blow open, possibly destroying the chip at the same time.
Hi vbro,
Nope. Don't do it.
-Chris
Does anyone know where I can buy the TC9273N-010?
I have googled for about two hours, but can't find anything but dealers that sells quantities like 1000items and more.
Is there a big difference between the models? I have found -007, -008, -009, -009... ...
I have googled for about two hours, but can't find anything but dealers that sells quantities like 1000items and more.
Is there a big difference between the models? I have found -007, -008, -009, -009... ...
Hi,
a solid state input selector!
Is it worth saving/resurrecting?
What about inserting a real switch selector and hard wiring the switch output into the PCB after that Tosh chip? (That is deliberately derogatory!)
Or
making up a relay switching selector PCB?
There's sufficient room in there for many projects!
a solid state input selector!
Is it worth saving/resurrecting?
What about inserting a real switch selector and hard wiring the switch output into the PCB after that Tosh chip? (That is deliberately derogatory!)
Or
making up a relay switching selector PCB?
There's sufficient room in there for many projects!
I actually thought of that and if the amplifier was mine, maybe I would do something like that.
Right now I'm just trying to find an easy (and quite cheap) way of fixing it for my friend. 🙂
Right now I'm just trying to find an easy (and quite cheap) way of fixing it for my friend. 🙂
Easy and cheap is perhaps to connect the input to one rca input socket (left+right) and get one of those external switches (I bought one for 15EUR. with gold plated connections for three sources...it's from intertechnik...)
Well, yes it is...
...but I would not feel good about doing that. You're right, it's the cheapest way of getting around the problem 🙂
I've contacted the Swedish agent for NAD and asked if they would sell me a chip. If not, I have to find another solution.
...but I would not feel good about doing that. You're right, it's the cheapest way of getting around the problem 🙂
I've contacted the Swedish agent for NAD and asked if they would sell me a chip. If not, I have to find another solution.
MCM has the TC9273N... you would have to look at the datasheet(s) to see what the 010 buys you.
http://www.mcminone.com/search.asp?...t.x=7&btnSubmit.y=6&btnSubmit=GO&searchin=off
http://www.mcminone.com/search.asp?...t.x=7&btnSubmit.y=6&btnSubmit=GO&searchin=off
i'm beginning to hate soft switching..........
had a kenwood receiver with a lightning hit. after replacing the 12v standby xfmr, found out the processor was shorted and the power relay coil was open. after replacing those, found out the input selector chips were bad.... at that point the customer said "forget it"...... his old '70's kenwood receiver that he brought in at the same time had a bad regulator transistor, and that was it.....
the version numbers may be firmware revisions.... try to get the correct one if you can, otherwise the chip might "miscommunicate" with the processor or control panel keyboard.
had a kenwood receiver with a lightning hit. after replacing the 12v standby xfmr, found out the processor was shorted and the power relay coil was open. after replacing those, found out the input selector chips were bad.... at that point the customer said "forget it"...... his old '70's kenwood receiver that he brought in at the same time had a bad regulator transistor, and that was it.....
the version numbers may be firmware revisions.... try to get the correct one if you can, otherwise the chip might "miscommunicate" with the processor or control panel keyboard.
Pars: Thanks! Have been looking everywhere for that (obviously not...)
Unclejed613: Yes they seem to be very fragile.
I have done some troubleshooting, please tell me what you think.
I started by leaving the amplifier off, and disconnecting the preamp from the amplifier by removing the 'whatevertheyarecalledinenglish' from the rca-sockets om the back.
I connected a signal source (cd-player playing Guns n' Roses) and started to do some measuring with my oscilloscope.
1. The amplitude of the signal seems to be a bit stronger on the input where the signal source is connected, but I got a bit confused because of the relatively high amplitude on all inputs.
However, I noted that on all the other inputs, the amplitude is weaker on the negative side.
2. Still with the amplifier off.
I measure the signal on the inputs of the TC... I discover that the signal is strongest on the input corresponding to the rca input to which the signal source is connected.
3. Amplifier on...
I now get identical signals on all of the rca inputs and on all of the TC... inputs.
4. I measure on the pre out rca connectors and find out that I get the same signal no matter which input is activated (not surprising according to #3).
5. The TC... is switched by sending 18 bits serial data through the 'Data' pin. Kind of hard to measure (with my low end el cheapo oscilloscope), but at least I can see that there is some kind of activity going on every time I switch inputs.
Also, if I connect the oscilloscope to the pre out connectors there is a small interrupt in the signal each time I switch input. This must mean that the TC... at least gets a Data signal, but does not manage to do the correct switching.
Conclusions
With the amplifier off, at least there is a measurable difference between the selected input and the other inputs.
With the amplifier on, all the inputs get connected together. The TC... gets Data signals when switching inputs, but it seems like all inputs gets connected together.
It has to be the TC... that's the faulty part.
Or am I wrong?
Unclejed613: Yes they seem to be very fragile.
I have done some troubleshooting, please tell me what you think.
I started by leaving the amplifier off, and disconnecting the preamp from the amplifier by removing the 'whatevertheyarecalledinenglish' from the rca-sockets om the back.
I connected a signal source (cd-player playing Guns n' Roses) and started to do some measuring with my oscilloscope.
1. The amplitude of the signal seems to be a bit stronger on the input where the signal source is connected, but I got a bit confused because of the relatively high amplitude on all inputs.
However, I noted that on all the other inputs, the amplitude is weaker on the negative side.
2. Still with the amplifier off.
I measure the signal on the inputs of the TC... I discover that the signal is strongest on the input corresponding to the rca input to which the signal source is connected.
3. Amplifier on...
I now get identical signals on all of the rca inputs and on all of the TC... inputs.
4. I measure on the pre out rca connectors and find out that I get the same signal no matter which input is activated (not surprising according to #3).
5. The TC... is switched by sending 18 bits serial data through the 'Data' pin. Kind of hard to measure (with my low end el cheapo oscilloscope), but at least I can see that there is some kind of activity going on every time I switch inputs.
Also, if I connect the oscilloscope to the pre out connectors there is a small interrupt in the signal each time I switch input. This must mean that the TC... at least gets a Data signal, but does not manage to do the correct switching.
Conclusions
With the amplifier off, at least there is a measurable difference between the selected input and the other inputs.
With the amplifier on, all the inputs get connected together. The TC... gets Data signals when switching inputs, but it seems like all inputs gets connected together.
It has to be the TC... that's the faulty part.
Or am I wrong?
Hi nlinus,
It would appear that your analog switching IC is defective. I can't think of any chip where this was an allowed state.
-Chris
It would appear that your analog switching IC is defective. I can't think of any chip where this was an allowed state.
-Chris
I bought a C340 with the same diagnosis. I trust your analysis and googled and found the TC9273N-010 at www.impelshop.com. I ordered a single chip - it was shipped today. Now I hope it is the right fix
