It's only has very few larger resistors. I guess it won't hurt to resolder it. Although I do recall measuring all the resistors and not finding anything odd. There was one resistor that had a single stripe on it but no resistance so I assumed it was like a jumper. I will provide pictures tomorrow thanx for the input
It's been suggested a couple of times that you measure voltages and compare with the other side. Sounds like a good plan to me... Start with all transistors on the heat sink. Don't probe transistor legs, one slip... measure from underneath and follow the track work to find a safe place to probe. Measuring dc voltage, black probe connected to chassis/phono ground. Measure each pin, emitter/collector/base to GND. If you are unsure which is e,c,b then measure left to right and state the part number 2SCxxx or 2SA... Clearly state working or not working side, also note + or - sign, measure to 1 decimal place.
Or maybe just continue replacing parts...
Or maybe just continue replacing parts...
Post #2, "build a dim bulb tester". This is an excellent suggestion. This should allow you to take voltage measurements without blowing up the board. "Never" probe transistor legs, use minigrabbers or similiar or probe a resistor or whatever that's connected to the same point.
Sorry for being brutal but I don't think much of the hap-hazard troubleshooting method
Sorry for being brutal but I don't think much of the hap-hazard troubleshooting method
Hi
Did you manage to resolve the AVI Lab Series amp with one dead channel ?
Mine has just done the same - almost seems like a relay issue. The amp has always had a mild switch on thump through the speakers which I assume is the output protection switching in/out. Just occasionally it would go onto one channel but when switched on a few times - the second channel would kick in. I have not looked inside yet ( they are not easy to find your way in - without service manual etc) Any help would be appreciated
Did you manage to resolve the AVI Lab Series amp with one dead channel ?
Mine has just done the same - almost seems like a relay issue. The amp has always had a mild switch on thump through the speakers which I assume is the output protection switching in/out. Just occasionally it would go onto one channel but when switched on a few times - the second channel would kick in. I have not looked inside yet ( they are not easy to find your way in - without service manual etc) Any help would be appreciated
Thanks for the reply - you measured the 1V across the dead channel terminals? I haven't looked at it yet !Cant remember the easiest way into it - some time ago I dismantled it to sort out the phono stage. It was a pain to get access - very high power and super compact design !!
I just measured voltages across speaker terminals. The working channel is 22mv the dead channel is 20mv! what should they be for this amp?
Under 50mV dc offset is acceptable for a power amp. The best engineered will have sub 1mv offset.
Mine produced no sound and had a DC of 1v. I replaced all the smaller transistors also and was still the same. I did not replace any of the transistors on the heat sinks.
AVI Lab Series Amplifier - Gone on to one channel
Anyone have experience of the AVI Lab Series amp this issue? I get the impression it may have some relay arrangement which is working on one channel only. A circuit diagram would be helpful
Anyone have experience of the AVI Lab Series amp this issue? I get the impression it may have some relay arrangement which is working on one channel only. A circuit diagram would be helpful
Need to be careful how you interpret this. If there is significant dc offset then the protection relay will release the speaker connection so the spkr terminals are no longer connected to the power amp. Best to check for dc offset at either the spkr relay or between the emitter resistors for each channel. Typically the relay will have 6 pins/solder blobs, 2 for the relay coil and 4 in close proximity for audio in/out for L&R channels, measure at the audio in pins.