Lifespan of a quality solid state amplifier?

A couple of things. 1) most decent amplifiers have soft/slow start circuitry which prevents the on/off cycling problems that people mention here. Therefore for a decent high end amp, the cycling on/off damage they are talking about really isn't an issue anymore. 2). Electrolytic capacitors would be a problem and must be checked. They are like any other component in cars, etc. they give you advanced warning that they may probably fail. yes, yes, there are instances where something just simply goes out, but in most parts you can see leakage before they fail. So, take a good look inside or have a qualified technician inspect the unit to see if any problems may exist. If nothing is apparant, then leave it alone until some problem or possibility of problem presents itself. 3) apart from capacitors, the thermal damage due to the loss of heat sink compound that the transistors are using when connecting to heat sinks may be the major issue. Transistors fail for a number of reasons. a) people that short the outputs when playing with speaker cables are the number one reason. b) when the heat sink compound dries out, it presents a problem for loss of thermal conductivitity and also allows for the possibility of the transistor to come in contact with the heat sink, because not only is the heat sink compound gone, but the thermal insulator between the transistor and the heat sink may be damaged. Therefore, what I typically do with older amplifiers is to check the capacitors for leakage and replace if necessary (only if necessary) these suckers are expensive, and replace all pre-driver and output driver power transistors with the newest, latest and greatest more linear transistors and readjust the bias, which makes the amp much better sounding. This also allows me to replace the thermal insulators and the heat sink compound, thereby eliminating any possibility of the amp having issues. my "modified" amps are much better sounding then the original and also are much longer lasting because I have inspected and replaced capacitors where necessary and also I have replaced all pre-driver and output power transistors and their associated thermal insulators and heat sink thermal compound.

One last thing. I typically will add a slow start/turn on relay circuit to any amp that does not have it originally and I sometimes will modify the power supply to separate power supplies with regulators.

After all that, I guess what I am saying is for really old amps, definitely change the heat sink compound and thermal insulators at a minimum and if you can change all output transistors also and check and replace if necessary the electrolytic capacitors.

enjoy

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Minor, sounds like you are a very thorough tech.

Question: you say you check the caps for leakage and replace only as needed. What about a loss of capacitance and/or increased ESR? The amp may function with these problems but well below it's potential.

Also curious what method you use to measure the leakage.

Thanks

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Hi Herman, I too have taught in technical schools and my stint in the service industry goes back to 1974. That's how I financed my way through the Minnesota Institute of Technology. The use of 'half life' is my own and simply comes out of experience - as a service tech I have repaired thousands of amps, preamps, receivers, tuners, tape machines, etc. I'm sorry that the use of the term bothers you but it works so well and is so easy to explain that I will continue to use it. I'll try not to use it around you :)

Does this conversation really need to diverge toward the negative? You’d think this was Audio Asylum or something. I frequent these boards because they’re usually (significantly) more civil. It doesn’t seem like we’re furthering much useful conversation on the original poster’s topic, just arguing about semantic minutia.

Regarding MBTF (or MTTF) of systems, caps, half life, etc, I want to clear something up. For the exponential failure rate distribution, which most electronics follow during the majority of their lifetime, MTBF is when 63.2% of the population has failed, not 50%. When the product / part begins to wear out (failures begin to occur at an increasing rate), the normal distribution is typically used, and MTBF is indeed when 50% of the population has failed.

And getting back to the original question, I agree that good SS amplifiers can last 20+ years. Electrolytics are frequently the limiting factor, followed by the semiconductors (transistors, diodes). Much of this depends on how much margin the designers used (how much the parts are derated for relevant electrical and thermal parameters). Personally, I wouldn’t worry about any maintenance unless recommended by the manufacturer. Bringing up an amplifier slowly with a Variac after it has been out of service for 6+ months isn’t a bad idea.

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No problem Ralph. I think it is a disservice to those who are trying to learn something here but If you are comfortable muddying the water with incorrect information then that is your choice. As one of the senior "experts" around here who comes from a technical background I would think you would strive for accuracy but your choice. I think from now on I'm going to refer to tubes as transistors since they transfer a signal and both words have trans in them. It's not correct but it's just as logical as your use of half life :>)

Like I said, it amazes me that nobody around here will ever admit they are wrong about something. When called on something they either don't respond, change their story, or do as you do and rationalize their incorrect responses. Actually, I find it a bit amusing.

In any case I'm done with it. Carry on.

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