Category Archives: Amp Repairs

Amplifier gear in for repair

My first official Blackstar (TM) amplifier repair on a HT Stage 100 MKI

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I have recently had LaLuna Technology accepted on the official Blackstar(TM) non-warranty service centre list and this is the first repair job that came via the Blackstar(TM) website. The amp was making a nasty screeching racket at any kind of volume setting. It was due to one or more dud power tubes. Steve, the owner of the amp went for a complete set of new tubes.

Steve (formally of Electric Rebels) now plays lead for Manchester band Whisky Bullets.

Here’s a link to their Facebook page: https://www.facebook.com/profile.php?id=61551745654010

Steve Warburton of Whisky Bullet stands with his amp

Fradan Echomatic 50

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The Fradan Echomatic 50. Tape delay and 50 Watt valve amp in one box. Delivers 50 Watts RMS into 8 Ohms. The two output jacks are paralleled for 2 x 16 Ohm cabinets if desired.

Here is how you wire the footswitch on the Fradan Echomatic 50

Put the switch between pin 1 and pin 3 and an indicator bulb (6.3V AC) between pin 1 and pin 2. There is 6.3V from the valve heater supply between pin 2 and pin 3 so don’t short those pins or you will blow the internal fuse.

 

Recent Repairs: Trace Elliot Bonneville C50

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Trace Elliot Bonneville

James Horrocks is the bass player in the Lol Goodman Band a top class blues band that can be seen at blues venues and festivals around the UK. He called in with a Trace Elliot Boneville C50 1×12 lead combo. It was sounding rubbish, kept cutting out and the reverb was weak and had a hiss. It needed a new pair of EL34 output tubes and some fresh resistors in the reverb circuit. I have never encountered one of these before. It is unusual in that it has two foot switchable channels but volume level is the only parameter you can set independently. The GAIN control and PREAMP STYLE are common to both. Also, it has an FX loop switch on the front panel that cuts off the guitar signal completely when the rear FX LOOP switch is set to SERIES. I thought this was a fault at first but when I looked at the circuit, it was designed this way. The FX OFF switch works as expected when the rear switch is in PARALLEL mode. Despite it’s quirks, it sounds and looks good, especially if you’re into motorbikes. Like the green tolex too.

James said: “Amp sound great Dan …. good job well done :)”

Cheers James!

Lol Goodman Band

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Tony’s Marshall DSL50

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August:
Tony from Oldham’s ‘A Band Of Gypsies’ (ABOG Reverb Nation and on North west bands) had some work done on his Marshall DSL 50. He didn’t like the fist pair of EL34’s I put in so I changed them for a pair of pricey but highly praised Svetlana Winged C’s. They were Hot running high gain selected  tubes for that bluesy compressed late break up.

I also fixed a couple of Marshall 4×12 cabs for Tony. The jack socket switch contacts always go on them so I replace them with Neutrik gold plated jobbies that should last a bit longer.

Tony from 'A Band Of Gypsies' and his Marshall JCM2000 DSL50.

Tony from ‘A Band Of Gypsies’ and his Marshall JCM2000 DSL50.

Dynacord Powermate 1000 MK2 Repair for Tony

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Local vocalist Tony came in with his Dynacord PowerMate 1000 MK2. This turned out to be quite a tricky repair. Something had made four IC’s in the power amp go short circuit.

I put his message below so I can come back, look at it and stroke my ego when I am feeling low!

Tony Dynacord pm1000 mk2

Tony Dynacord pm1000 mk2

Putting a valuable and much loved piece of equipment into anyone else’s hands is always nerve wracking. The repair was handled really professionally I was happy with the price,  and customer service second to none.

Thanks again Dan
Tony Denison

Marshall 1960A Cab Jack Socket Fault – Fixed

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I have had a Marshall 1960A Lead 4×12 cabinet in with problems.

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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.

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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.

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1970’s VOX AC30 Top Boost

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1970’s VOX AC30 in with a loud mains buzz. Main fault was the HT smoothing capacitor (the old one is the blue thing on the top). It also needed a new quad of EL84 tubes and a small repair to one of the speaker cones. All done, it was very hum free and hiss free. It is hard to fix the date for this one. It had 1976 on the POT’s date code. It looks like a Rose Morris era AC30 Top Boost amp without the voltage selector on the front panel and with PCB strips wired to valve sockets, not tag boards. The PCB’s are the superior glass fibre bluish ones. This is one of the better models to get. The 1970 to 1973 Birch-Stolec era models are to be avoided because the resin bonded paper PCB with directly mounted tube sockets degrades with the heat and the copper tracks come loose. Tag board wired models are easiest for techs like me to work on.

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