Noisy Laney

[SuperSeagull]

I recently recovered an old Laney Hardcore Max 65watt combo that I had bought s/h some years ago and that was no longer needed by the church I'd bought it for. I was hoping I could leave it at the church I now play at to save lugging gear when I play. But its noisy when the master vol is turned up. Doesn't matter if anything is plugged in or not. Tried different mains leads etc but makes no difference. However if I plug into the fx return there is no noise and it sounds not at all bad although with none of the controls then work. Does that sound fixable or am I best just using the fx return as an input and sticking my sansamp in front of it for eq etc? A quick, uneducated look at the components and PCBs doesn't seem to show anything obviously wrong. 

[Bigguy2017]

What sort of noise? Hum, hiss or crackles?

 

 

[SuperSeagull]

Sorry, that would have helped! Hum. 

[Bigguy2017]

This suggests the power amp section is AOK and the problem is in the preamp.

 

First stick a jack in/out in all the input and FX send return jack sockets - give them a squirt of contact cleaner.

 

If the opamps are socketed, give them a good push into the sockets.

 

Make certain you have a good working guitar cable...  😉

 

As usual, look for any bulged or leaky electrolytic caps...

Unplug/replug all the internal connectors inc HD3 (preamp / poweramp connections)

 

Also try unplugging the Reverb at HD1 and HD2.

 

If the opamps are socketed, give them a good push into the sockets.

 

Looking at the schematic it appears the preamp supply is Zenered down to +-15 VDC from the +-28 VDC power amp supply.

I'd have a good look at the +-15 VDC rails and their smoothing caps C36 C37 C300.

Put a 'scope on the +-28 VDC and +-15 VDC rails and look for hum. Obvs, if you have a 'scope (!) you look at the FX send and  trace the signal back to the input

 

 

Take it to a repairman....  😉

 

 

laney_hcm65r_sch.pdf

[SuperSeagull]

Helpful, many thanks. That’s not quite the right schematic, I think that is the guitar version inc reverb. Couldn’t see any obvious bulges on first look but will try all else you suggest. I’m content it’s not a cable issue having been caught out on that before 😬. To be honest, if it can’t be sorted it will function perfectly well with a preamp pedal in front of it in that environment. Thanks again, appreciate your expertise. 

[sandy_r]

47 minutes ago, SuperSeagull said:

... That’s not quite the right schematic...

 

Here are the schematics for the Bass HC Max 65W

 

Sounds like schematics aren't going to help you much ...and a competent Tech will likely have their own service info 

 

 

 

 

Edited March 1, 2024 by sandy_r

[MoonBassAlpha]

Probably electrolytic capacitors on the preamp power supply not working correctly. If  they are largeish, sometimes the vibration can fracture the solder around one of the pins too.