Fender Blues Junior Repair – Urgent Repair

Fender Blues Junior Repair

This Fender Blues Junior Repair was an urgent repair job for a London based guitarist. I got the amp at 23:30 on the Saturday after a gig in Southwell near Newark and had it diagnosed by 11:15 the next morning before he returned to the ‘big smoke’.

Actually, big smoke was obviously a problem that this amp had experienced in the past as can be seen in the image. A power valve had blown and seriously damaged the PCB. Unfortunately the amp had been taken to a Nottingham music shop for repair and I’m afraid they didn’t know what they were doing!

Whoever fixed it has did something weird and wired up a valve pin that doesn’t connect to anything – it should have been going to the cathode, although they have then wired up the cathode separately. There’s no actual harm with this, it just suggests they didn’t know what they were doing!
They also not secured the valve base very well, so it rocks and lifts the pins when you remove or move a valve. This has started to pull up a PCB track on one of the power valves. This will almost certainly cause problems in the future.

I’ve performed a temporary fix on the problem pin 7 by shaving the solder mask off the copper and adding more solder to give the pin an extra connection.

I recommended rewiring the whole power stage at some point in the not too distant future because the amp is a bit of an accident waiting to happen. Unfortunately there wasn’t time to perform the full repair before the customer left for London.

However all this was a chance discovery. I was actually asked to look at a faulty spring reverb on this blues Junior repair. The problem turned out to be with the tank itself. I checked continuity and ground on the cables and observed signal getting to the tank and nothing coming out.

I’ve got a short Accutronics reverb tank kicking around from an amp I gutted so I thought I’d try it, The impedances didn’t match and it sounded terrible with the Blues Junior! But it proved that this was the only problem with the reverb.

The good news is that the customer could buy a spring reverb unit and fit it himself – you only need a screwdriver.

The customer was kind enough to leave a review on my Facebook page.

If you have a Fender blues junior repair, please get in touch.

HH amp Repair 

HH amp repair

I’ve seen and played most amps in my career in music retail and amp repair, but this HH amp Repair was a bit of a revelation. The clean channel is a thing of beauty.

It’s a full solid state oversized 1×12 combo with two independent channels. The tube emulation circuit seems to involve distorting a signal transformer. It’s OK but nothing special. The clean sounds on both channels are really great.

The amp needed repair because it was making a strange ticking noise when the reverb was turned up.

The reason for this turned out to be a lack of local decoupling on the reverb board. This is a fairly major design flaw, but the amp obviously ‘got away with it’ for the majority of its life, the problem only appearing as central filtering components aged.

Here’s a quick video of the HH amp repair, showcasing the crackling and ticking issue then the lovely clean sound when fixed.

If you have an HH amp repair job please get in touch.

Orange Amp Repair – Rockerverb 100 MKII

orange-amp-repair

This Orange amp repair is a particularly shocking example of an amp which someone has attempted to repair without really having an understanding of what they’re doing. The customer brought it to me with two issues: a broken reverb (victim of the botched repair) and an intermittently faulty gain channel.

orange-amp-repair2I started out by performing a basic valve amp service upon the amplifier. This involves testing all the valves with my valve tester. 3 preamp valves were found to be faulty: this proved to be the cause of the gain channel dropout. This Orange amp repair didn’t require checking of the bias of the amp, because the Rockerverb MK II has Orange’s proprietary ‘DIVO’ power valve management, meaning that the amp biases itself. It’s the only system that I’m aware of that doesn’t require matched valves in the output stage, so when one of the EL34s was found to have a snapped key on its base, I installed a 6L6GC in its place! I also fixed the snapped key so it could be used.spring-reverb-repair

Turning my attention to the spring reverb repair, I noted that one of the phono cables had a broken connection. The connectors had been made up without any strain relief and this had allowed damage to happen during normal use. This is an easy fix and after fixing the broken connection I resoldered the other reverb intact connector so that both had adequate strain relief.

Upon testing the faulty spring reverb I discovered that it still wasn’t fixed so I turned my attention to the unit itself. Worryingly, one of the sockets was surrounded with glue on the outside. When I opened it up I realised that some fool(!) had tried to fix the loose socket by flooding it with superglue. Worse, as you can see in the picture the glue had dripped inside the unit and fouled the springs quite badly.

I was able to remove the superglue, but they remained quite distended. The unit still works as a reverb so my customer decided not to have me replace the tank.

If you’ve got an Orange Amp repair or a spring reverb repair, please don’t bodge it, just get in touch!