Need Schematic for Laney AOR 20

[CoopDaKill]

If anyone has a schematic for a Laney AOR 20, please let me know. I have a friend that asked me to look at his amp. He replaced the electrolytic capacitors, and used it for about a year, then it started acting strange. When I play a low E string, the amp makes a garble noise. Thanks

[nosaj]

If anyone has a schematic for a Laney AOR 20, please let me know. I have a friend that asked me to look at his amp. He replaced the electrolytic capacitors, and used it for about a year, then it started acting strange. When I play a low E string, the amp makes a garble noise. Thanks

Laney will give it to you if you can prove you have a viable workbench by photo.

nosaj

[CoopDaKill]

I emailed Laney, and the replied stating they had no knowledge of them ever making a 20 watt AOR. But I have a pdf file of the user manual showing the 20 watt, 50 watt, and 100 watt models.

Anyway, I fixed the amp. The owner had installed 1ohm resistors from pins 8 & 9 of the output tubes, to the chassis ground ( to Check bias, he said). I found out this was the problem by taking voltage readings. When I touched the positive meter probe to one of those 1 ohm resistors, the amp became quite. I strummed the strings and it sounded great. The resistors measured fine, out of circuit. I replaced them with solid core wire. So, with my lack of technical knowledge, I guess the design of this amp wouldn’t allow any resistance to ground from those 6V6gt output tubes (pins 8&9)?

[nosaj]

I emailed Laney, and the replied stating they had no knowledge of them ever making a 20 watt AOR. But I have a pdf file of the user manual showing the 20 watt, 50 watt, and 100 watt models.

Anyway, I fixed the amp. The owner had installed 1ohm resistors from pins 8 & 9 of the output tubes, to the chassis ground ( to Check bias, he said). I found out this was the problem by taking voltage readings. When I touched the positive meter probe to one of those 1 ohm resistors, the amp became quite. I strummed the strings and it sounded great. The resistors measured fine, out of circuit. I replaced them with solid core wire. So, with my lack of technical knowledge, I guess the design of this amp wouldn’t allow any resistance to ground from those 6V6gt output tubes (pins 8&9)?

This one? Maybe needed to specify protube?
Glad you got it working.

nosajhttps://www.creamcitymusic.com/1987-...ube-combo-amp/

[The Dude]

I emailed Laney, and the replied stating they had no knowledge of them ever making a 20 watt AOR. But I have a pdf file of the user manual showing the 20 watt, 50 watt, and 100 watt models.

Anyway, I fixed the amp. The owner had installed 1ohm resistors from pins 8 & 9 of the output tubes, to the chassis ground ( to Check bias, he said). I found out this was the problem by taking voltage readings. When I touched the positive meter probe to one of those 1 ohm resistors, the amp became quite. I strummed the strings and it sounded great. The resistors measured fine, out of circuit. I replaced them with solid core wire. So, with my lack of technical knowledge, I guess the design of this amp wouldn’t allow any resistance to ground from those 6V6gt output tubes (pins 8&9)?

The 1 ohm resistors should not have made a difference in regards to hum. I suspect some other problem related to the resistors. In fact, in the picture posted, it looks like the connection from resistor to socket is cold and not soldered very well. Maybe when you touched your probe there, it actually completed the connection?

[Enzo]

Um... where is pin 9 on a 6V6?

A 1 ohm or 10 ohm resistor from pin 8 to ground would not affect the amp. Unless the amp was cathode biased originally.

[CoopDaKill]

Yes, Pro Tube.

The Dude : That makes more sense than my rookie explanation! Thanks

Enzo: I meant from pins 1 & 8 of the 6v6gt’s. Sorry about that.

Thanks to all for chiming in. Much appreciated!