Yes, I guess so; it's a few years old but in mint condition for its age, you won't be surprised to hear it's hardly been used
. The remote control is still in its bubble wrap!
Is his a generic statement for HIFI amplifiers Chris, or aimed specifically at the Denon or Cambridge amps we've spoken about here?
That is aimed at any product containing an amplifier that has an output relay.
Contacts are damaged when they switch current. Opening is worse as there is more arcing, but contact bounce on closure isn't great either. There is absolutely nothing wrong with decent relays in circuit, but they ought to be viewed as maintenance items. They are far preferable to fuses, and some breakers can generate distortion. I have a real problem with any amplifier that does not disconnect the circuits from the load when power is cycled, or if there is a fault condition. A triac to ground works too, but is destructive to the amplifier circuit in fault conditions. dv/dt can trigger them if they aren't designed well also.
A speaker relay is the very most sensible way to protect your speakers (which are worth more than an amplifier repair).
Now having said that, a Carver amplifier is an exception. They can make a little noise when power is cycled, but it is generally very low amplitude with these. More importantly they have an excellent protection circuit that kills the power supply very quickly and the supplies have limited stored energy. So a Carver is unlikely to damage a speaker in a fault condition, but they will end most speakers easily due to some of the very high power capability they can have. And that's under normal, proper operation when you can't control yourself with the volume control! lol!
-Chris
Contacts are damaged when they switch current. Opening is worse as there is more arcing, but contact bounce on closure isn't great either. There is absolutely nothing wrong with decent relays in circuit, but they ought to be viewed as maintenance items. They are far preferable to fuses, and some breakers can generate distortion. I have a real problem with any amplifier that does not disconnect the circuits from the load when power is cycled, or if there is a fault condition. A triac to ground works too, but is destructive to the amplifier circuit in fault conditions. dv/dt can trigger them if they aren't designed well also.
A speaker relay is the very most sensible way to protect your speakers (which are worth more than an amplifier repair).
Now having said that, a Carver amplifier is an exception. They can make a little noise when power is cycled, but it is generally very low amplitude with these. More importantly they have an excellent protection circuit that kills the power supply very quickly and the supplies have limited stored energy. So a Carver is unlikely to damage a speaker in a fault condition, but they will end most speakers easily due to some of the very high power capability they can have. And that's under normal, proper operation when you can't control yourself with the volume control! lol!
-Chris
Interesting read, thank you Chris .
When I first removed the lid from my A3i I found a little plastic bag wedged carefully in the back corner which contained a spare output relay, a couple of fuses and 3x green 5mm LEDs (the LEDs mentioned in the original post of this thread back in 2008), kindly left there by Richer Sounds' repair dept. I've since used one of the green LEDs; the rest just waiting their turn should it ever arise.
.When I first removed the lid from my A3i I found a little plastic bag wedged carefully in the back corner which contained a spare output relay, a couple of fuses and 3x green 5mm LEDs (the LEDs mentioned in the original post of this thread back in 2008), kindly left there by Richer Sounds' repair dept. I've since used one of the green LEDs; the rest just waiting their turn should it ever arise
.
Well, it got me thinking about wetting current. During my time spent in the automotive industry I recall considering wetting current during relay selection for power & signal distribution systems, in order to keep the contact surfaces "clean". Now, as I don't drive my A3i hard at all, maybe I should let the power out once in a while to prevent oxidisation of the output relay contacts (and annoy the neighbours in the process).
Oh no Chris, sorry I've misled, I'm not for one minute suggesting I'm going to open/close contacts during high sound levels and risk damaging the contacts, I mean increasing the level whilst the contacts are closed to push a decent "cleaning" current through them, as mine are normally only lightly tickled 😂
Hi cucu70,
I can't tell from the pictures as the markings are too messed up.
So, look at the original specifications for those transistors, then look at currently available parts that have the same or better voltage (c-e) ratings, same or better current and dissipation ratings and around the same gain or a little higher.
You have to watch the pinouts between transistors, sometimes the leads are in a different order or they may be completely reversed.
I can't tell from the pictures as the markings are too messed up.
So, look at the original specifications for those transistors, then look at currently available parts that have the same or better voltage (c-e) ratings, same or better current and dissipation ratings and around the same gain or a little higher.
You have to watch the pinouts between transistors, sometimes the leads are in a different order or they may be completely reversed.
Hi cucu70,
I'm sorry, but I am a working technician at work now. I do not have the time to look this up for you.
If you are repairing an amplifier (or anything) you really need to understand part ratings and specifications. I did tell you what ratings at the most important on the spec sheet. fT and a couple others may be important depending on application.
I am working on one, but I can't remember the part numbers off-hand right now (or I would gladly tell you). When I get back into it I'll know what I used. But I can't do that right now. So, please look at the data sheets for each part. Do not use a cross-reference guide without checking each rating yourself. There are plenty of mistakes both in printed and on-line versions. We used to call them "the book of lies" if that gives you any clue.
-Chris
I'm sorry, but I am a working technician at work now. I do not have the time to look this up for you.
If you are repairing an amplifier (or anything) you really need to understand part ratings and specifications. I did tell you what ratings at the most important on the spec sheet. fT and a couple others may be important depending on application.
I am working on one, but I can't remember the part numbers off-hand right now (or I would gladly tell you). When I get back into it I'll know what I used. But I can't do that right now. So, please look at the data sheets for each part. Do not use a cross-reference guide without checking each rating yourself. There are plenty of mistakes both in printed and on-line versions. We used to call them "the book of lies" if that gives you any clue.
-Chris
Post 433 :
Careful, the simple tester does not know everything. If a device like this is not in its parameter
list it will not be recognised. What makes you think that these are defective - in both channels ?
My tester of similar make does not know germanium transistors and the readout is similar to that
in your picture. I think I wrote about a transistor replacement years ago here.
Careful, the simple tester does not know everything. If a device like this is not in its parameter
list it will not be recognised. What makes you think that these are defective - in both channels ?
My tester of similar make does not know germanium transistors and the readout is similar to that
in your picture. I think I wrote about a transistor replacement years ago here.