Hi!
I just got a C340 with the same problem: all inputs active at once, only one channel working properly, the other channel playing a very low distorted sound, both channels working when passing by the pre-amp.
I would like to fix this myself, but I've got no real experience with amp-fiddling. I would be glad if somebody could give me some advice on this.
How can I determine if it is really the IC that is broken?
What steps are required to install the new IC?
I got the amp for about 20 euros, would it be worth trying to fix this or should I simply buy a working amp?
/Oscar
I just got a C340 with the same problem: all inputs active at once, only one channel working properly, the other channel playing a very low distorted sound, both channels working when passing by the pre-amp.
I would like to fix this myself, but I've got no real experience with amp-fiddling. I would be glad if somebody could give me some advice on this.
How can I determine if it is really the IC that is broken?
What steps are required to install the new IC?
I got the amp for about 20 euros, would it be worth trying to fix this or should I simply buy a working amp?
/Oscar
yamaha used to protect the inputs of the selector chip with diodes from the inputs to the analog supply rails. the analog switches here are CMOS, and they can be damaged by static electricity, and by any voltage higher than the supply rails. usually the analog supplies are either +/- 12V or +/- 15V. 1N4148 or equivalent are usually what's used. it's a simple mod, and should protect the chip from a repeat of this problem.
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Hi Oscar,
It doesn't sound like you should attempt this repair. If you aren't familiar with the basics, then you probably don't have the correct tools either. I somehow doubt you are prepared to buy those tools either.
If you do attempt this, you will probably cause a lot of damage to the circuit board. Sell or give this unit to someone who does have the skills to fix it, or have a real good audio technician look at it (which means you are paying for the repair).
You need to start by purchasing the proper tools, then building a couple kits before attempting to work on anything commercially built. Servicing units takes a lot of training. Years in fact. That's why there are technicians who get paid for this. Even then, many technicians are not very good at what they do. That means that students and "low rent" guys will most likely turn out to be the most expensive. The professional is normally the low cost option by the time the dust settles.
Before we see a bunch of people telling Oscar how easy this is, stop and think. When you started, nothing was easy. There are those too who think things are easy because they don't understand what damage they cause.
-Chris
It doesn't sound like you should attempt this repair. If you aren't familiar with the basics, then you probably don't have the correct tools either. I somehow doubt you are prepared to buy those tools either.
If you do attempt this, you will probably cause a lot of damage to the circuit board. Sell or give this unit to someone who does have the skills to fix it, or have a real good audio technician look at it (which means you are paying for the repair).
You need to start by purchasing the proper tools, then building a couple kits before attempting to work on anything commercially built. Servicing units takes a lot of training. Years in fact. That's why there are technicians who get paid for this. Even then, many technicians are not very good at what they do. That means that students and "low rent" guys will most likely turn out to be the most expensive. The professional is normally the low cost option by the time the dust settles.
Before we see a bunch of people telling Oscar how easy this is, stop and think. When you started, nothing was easy. There are those too who think things are easy because they don't understand what damage they cause.
-Chris
i agree. fine pitch soldering is something that requires the proper equipment and well developed skills. even then it can be a challenge. traces can easily get lifted, especially with lead free solder, because of it's higher melting point.
you will probably do ok taking the amp to get fixed. it's not difficult to diagnose, and the part is available. as you say oscar, you don't have much experience. if you know somebody that can do the repair, you might ask them to teach you how to do this kind of soldering. it takes a bit of practice and a steady hand (and as much magnification as you can handle). where i work, i also have access to a hot air machine (they are expensive), and even using that is a balancing act when working with lead free solder (which is in use in just about everything these days).
you will probably do ok taking the amp to get fixed. it's not difficult to diagnose, and the part is available. as you say oscar, you don't have much experience. if you know somebody that can do the repair, you might ask them to teach you how to do this kind of soldering. it takes a bit of practice and a steady hand (and as much magnification as you can handle). where i work, i also have access to a hot air machine (they are expensive), and even using that is a balancing act when working with lead free solder (which is in use in just about everything these days).
To add to this now quite old thread, I have been asked to repair a C340 in which the TC9273N-016 switching I.C. has failed. The symptoms are that ca. +6.5vDC is present on all the R.H. channel inputs(pins 18 to 27 of the I.C.) and distorted sound in the R.H. channel(All i/ps are active at the same time). When the +17.5 & -17.5v supplies are disconnected the fault disappears, thus proving that the I.C. is faulty. My question is can the TC9274N-016 be replaced with any of the other versions of this I.C.?
A 'typo' crept into my post. What i meant to ask is 'Can a TC9273N-016 be replaced with, e.g., a TC9273N-010 or other variation? So far I haven't found a source from which to buy a TC9273N-016.
The data sheet I looked at doesn't differentiate between any versions ! Just TC9273N or F depending on package.
I really don't know is the honest answer.
Although there must be some differences I suspect they will all be similar.
Charles Hyde lists a few,
Search results for TC9273N
Have you tried NAD for spares ? Sometimes (occasionally but sometimes
)manufacturers can be helpful.
I really don't know is the honest answer.
Although there must be some differences I suspect they will all be similar.
Charles Hyde lists a few,
Search results for TC9273N
Have you tried NAD for spares ? Sometimes (occasionally but sometimes
)manufacturers can be helpful.
Is the 3 digit suffix - 008, 009, 010, 016 etc. not a firmware revision? i.e. Different models use the same chip which is adapted according to user needs. (ref. earlier posts in the thread).
The datasheet refers to an (internal ?) aluminium mask that customizes the chip for specific applications.
At 28+ quid each, you might not want to make a non-refundable choice with the version, if it affected the sequence or options on your model.
The datasheet refers to an (internal ?) aluminium mask that customizes the chip for specific applications.
At 28+ quid each, you might not want to make a non-refundable choice with the version, if it affected the sequence or options on your model.
Normally yes, that is what differentiates the same uP being used in (say) a washing machine and a CD player and a VCR as I mentioned a few posts back.
I must admit I'm not 100% sure on this one, I've looked again at that data sheet closely and I can't see how it can permanently be altered. That usually requires zapping with a higher voltage and dedicated programmer.
As you have found a source for the correct type it makes sense to go for that one.
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