Xdevo1973
Active Member
Hi Everyone,
I own two Lafayette LA64 4 channel amplifiers. Over the years I've enjoyed the versatility and flexibility of them as well as their attractive design. I've replaced various capacitors as they've failed open, etc. One of them was terribly abused prior to me acquiring it. There were no plastic "feet" on the bottom and all the fuses were blown. I could only surmise that someone removed the feet so that the unit could be sandwiched into a cabinet somewhere with absolutely no clearance. The damage included 3 burned out rectifier diodes, two shorted output transistors in different channels, two shorted driver transistors and a couple open capacitors. The good news is that I was able to buy replacement semiconductors online for less than $15 total and now this second previously abused amp sounds fantastic. I was curious, however what the voltages should be on the output; I see slightly varying voltages on each of the 4 channels, but they are all within a volt or so. The bias voltage seems to be anywhere from 0.4 to 0.55 volts. The voltage on the collectors are anywhere from 20-22 volts. The amp is rated at 50 watts per channel but I don't have a schematic. Any suggestions on what the bias and collector should be adjusted to?
I own two Lafayette LA64 4 channel amplifiers. Over the years I've enjoyed the versatility and flexibility of them as well as their attractive design. I've replaced various capacitors as they've failed open, etc. One of them was terribly abused prior to me acquiring it. There were no plastic "feet" on the bottom and all the fuses were blown. I could only surmise that someone removed the feet so that the unit could be sandwiched into a cabinet somewhere with absolutely no clearance. The damage included 3 burned out rectifier diodes, two shorted output transistors in different channels, two shorted driver transistors and a couple open capacitors. The good news is that I was able to buy replacement semiconductors online for less than $15 total and now this second previously abused amp sounds fantastic. I was curious, however what the voltages should be on the output; I see slightly varying voltages on each of the 4 channels, but they are all within a volt or so. The bias voltage seems to be anywhere from 0.4 to 0.55 volts. The voltage on the collectors are anywhere from 20-22 volts. The amp is rated at 50 watts per channel but I don't have a schematic. Any suggestions on what the bias and collector should be adjusted to?
