Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: navdave on May 06, 2015, 03:36:33 pm
-
Hello all I recently scored a Laney AOR 50 series II amp head. Well I opened it up to see if anything was out of sorts and noticed one of the output transformers secondary wires was not even hooked up it's the brown one in the picture. If you look at a schematic for one of these things you see the brown wire is for 4 ohms. This output transformer has two black wires one's going to ground the other one I guess to what is the 4 ohm tap on the selector. The other three wires are brown blue and red. I'm a little confused shouldn't the two black wires both be grounded and the brown, blue, and red go to the impedance selector?
-
The other three wires are brown blue and red. I'm a little confused shouldn't the two black wires both be grounded and the brown, blue, and red go to the impedance selector?
If you hook it like you say (DON"T, might be wrong) then what are the OT primary wires that go to the power tubes and the CT to B+?
Brad :icon_biggrin:
-
Link with OT colors listed;
http://el34world.com/charts/Schematics/files/laney/laney_aor50_series2.pdf (http://el34world.com/charts/Schematics/files/laney/laney_aor50_series2.pdf)
Is this your amp?
OT has 2 black wires, 1 as primary CT, 2 as secondary ground and 2 red, 1 for the primary pull side (v7) power tube and 2 the 8 ohm secondary tap.
Use a meter to check resistance between wires to match up the primary wires and the secondary wires.
Brad :icon_biggrin:
-
Kind of it's a series 2 but has an impedance selector instead of all the seperate jack.
On the high voltage primary side I have two red wires hooked to the b+ then two thin red/white and blue/white wires going to pin 3 of each power tube also has two thin black wires tied together with heat shrink on them.
-
On the high voltage primary side I have two red wires hooked to the b+.....
.....also has two thin black wires tied together with heat shrink on them.
Somethings screwy.
I don't think that Laney would ship out an amp with a secondary(?) wire floating unattached in the chassis and have 2 wires (twice) hooked together like you posted. Somebodies been in there messing around.
Unless you can find the Exact schematic and verify that the OT is Laney's. (maybe e-mail/call Laney)
Here's what I'd try;
1. Make a drawing of ALL the OT wires and where they go.
2. Then disconnect ALL the OT wires and take a meter set to resistance to match/group up which wires are the primary and which are the secondary.
The primary will have it's CT fly lead close to 1/2 the resistance from each end of the wind, plate fly leads.
The secondary will have the resistance go up from it's ground wire (start) fly lead as you go to the 4 ohm, 8 ohm and 16 ohm(finish) fly leads.
Brad :icon_biggrin: