Laney AOR 100W Series 2 HEAD Dropping vollume

[henter2017]

Hi Folks,

Got this head from ebay for £150 quid, apparently just needing a new set of tubes and a volume pot... I know... shoudnt trust ebay...

diagnosis:

Anyway got the amp tested and works fine but the volume is super low...
Moving the preamp pot while out of the AOR channel up and down gives some volume, same happens with the master volume.
Also when on the first channel, the AOR preamp volume seems to be on use to and affecting the volume... not sure if the originals use both the of the preamp volumes for the clean channel? seems weird to me.
when plugin out and in and out the guitar the volume fades to a minimun, and when moving the master volume all the way up and then down to the level required stays that way...

Done so far:

Full set of el34s an rebiased the amp.
Cleaned all pots and jacks.
I have checked all grounding from the pots and remade some bad soldering.
Seems that the amp has been "repaired" or modded somehow before, not even sure if the pots are original (attached some pictures)


Looking for some tips on where to start to look at or if someone can tell me a bit about what has been done to it with the mods etc...

[The Dude]

laney-aor-100-series-ii-circuit-diagram.pdf

My first thought would be switching jacks. Run a short cable from effects send to return and see if the amp works.

Edit: Also, It looks a mess in there. Either modded and/or a repair "in progress". I see on the paper in there notes on cap values for C33 & C34 (among other things), and notice that they are missing from the circuit board as if , maybe, someone was in mid repair and quit. You should have a close look at the schematic, compare to the amp in front of you, and see what's missing/changed/modded/etc. This doesn't look fun!

Edit (again): It also looks like someone cobbled in a board with C33 & C34- maybe rebuilt a supply due to circuit board damage? Or, maybe they were just too lazy to lift the board and fix it right. It's hard to tell what they did, but again,....... it looks a mess.

[henter2017]

bridging the FX loop made no difference, I managed to contact the original owner and told me that a repaired built the board to repair a PCB burned part, so you are right its replacing the missing components in the main board.
Also told me that the repairer told him that the volume issue comes from the push pull AOR channel master volume pot...

I have replaced the AOR preamp pot for a 100K and moved the channel switching to a toggle.
Also replaced the AOR master volume pot with a 100K push pull... the amps seems a bit better but still having issues.

When unpluging the guitar from the jack and plug it back in, volume drops, which can be 90% of the time fixing cranking the MV pot of the channel you are in and back it of to the volume required.
This happens on both of the channels, something tells me its something else but not the pots...

Is like the volume kicks in when enough signal has been given from the MVs... if this makes any sense whatsover.

Also when using the push/pulls from both of the MVs (bright switches) sometimes makes the volume fade again...

Im tapping with a stick everywhere I can but cant find any bad connection...

[henter2017]

UPDATE: I have replaced the 4 ecc83's but problem persists, also check the wiring for the output and input jacks agains the schematic and all seems fine...

[henter2017]

cheeky bump looking for some help on this one please... running out of ideas...

[nickb]

Try taking the send output to a different amplifier. If both amps have the problem then you know the problem is before the send jack.

What test equipment do you have? DVM? Signal generator? Scope?