I have had a Marshall 1960A Lead 4×12 cabinet in with problems.
Only two out of the four drivers were working on mono 4Ω mode and one of the four was making bad noises. This cab relies on the switch contacts on the two jack sockets to connect the two pairs of drivers in series (16Ω) or parallel (4Ω) depending on which socket is used. The switch contacts on the original sockets are nickel silver or tin plated and can’t stand much current without burning out. This is what happened in this case. The arcing had heated the contact enough to melt the plastic body.
To fix the fault I replaced both switch jacks with gold plated Neutrik / Rean NYS2152G replacements. They fit perfectly and should last a bit longer than the originals. I also sprayed the centre Mono / Stereo switch with contact cleaner. There was also a loose spade connector on one driver which I pinched up with pliers to solve the bad noises.
LaLuna Technology is an electronic repair workshop based in Hadfield, UK. It is a one man band owned and run by myself, Dan Davenport. I specialize in musician’s amplification repairs, valve (tube) guitar amplifiers, mixing desks and PA. I am near Glossop, twelve miles from the centre of Manchester and twenty six miles over the moors from Sheffield.
32 Station Road, Hadfield, Glossop. SK13 1BQ
Ph:07761394965 or 01457 597018
Guitar amplifier repairs and valve replacement
Loss of power, valve rattle and snaps crackles and pops are all possible symptoms of tired tubes. A heavily used amp can easily wear out tubes in 6 months. Bring it in for a valve test.
Valve amp mods
Mixing Desk Servicing
I have had a lot of success with Dynacord Powermate 600, Powermate 1000 and Powermate 1600 MK1 & MK2 mixer/amps popular with pub singers and vocal groups. These are the older and heavier ones but there are still a lot of them out on the road. The common fault with these is one blown power amp which lights the protection LED. Fixing this fault on a pm1000 will cost £170 including parts (new set of power transistors on blown channel), labour and six month warranty. A pm600 would be £115. It may be something simpler which would of course cost you less.
Power amp repair
Some PA rack mount amps can be fixed economically, depends what’s gone and make/model.
Noisy control pot clean and lube or replacement
Audio cable repair
Faulty input jack replacement
Speaker testing and replacement
PAT safety testing
Get your amps (especially vintage ones) safety tested if you don’t want to risk going to rock heaven in the footsteps of Keith Relf of the Yardbirds who died of electrocution while playing through an badly earthed guitar amp. Valve amps can use HT supplies in excess of 500 Volts DC which is more than enough to stop your heart! A lot of venues ask to see proof of PAT testing before they let you play. PAT test on a guitar amp, mains cable and multiway extension inc. certificate would cost you £10.