Category Archives: Amp repair

Ashdown MAG300 Bass Amp Repair

By Frank | Published: February 8, 2015

I’ve had quite a few Ashdown bass amps in the workshop for repair. Here’s the inside of a MAG300 I had in a recently. The amp was not powering up, and on inspection the mains fuse has blown. On energizing the unit employing a current limiter (a 60W light bulb in series with the amp), […]

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Vintage 70’s Ampeg SVT 300W Bass Amplifier Repair

By Frank | Published: February 2, 2015

Here’s a rare example of a 70s Ampeg SVT that I had in the workshop. Introduced in 1969, the SVT has, rightly, gained the reputation as one of the greatest bass amp ever made. Indeed, even today the SVT is the industry standard bass amp for live work. However, working on these amps is not […]

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Fender Blackface Deluxe Reverb Repaired By JPF Amplification

By Frank | Published: January 8, 2015

We’ve repaired hundreds of vintage Fender amps, and it’s always a pleasure to get these classic amps back in tip-top working order. It’s a testimony to Leo Fender that so many Fender amps from the 1960’s are in use today. Here’s a picture of the inside of a vintage 1960’s Fender Blackface Deluxe Reverb we […]

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Two Marshall JCM900 Amps Repaired At JPF Amps

By Frank | Published: December 8, 2014

Here are a couple of Marshall JCM900s guitar amplifiers we’ve had in our workshop for repair in the last few weeks.     The one on the bottom simply need new output jack. Unfortunately the one on the top needed a new mains transformer and power valves, a significantly more expensive repair. These are original early 90’s amps, […]

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Orange Crush 15R & 30R Guitar Amp Repair

By Frank | Published: October 19, 2014

Here’s some photos from a pair of Orange Crush guitar amps I’ve had in for repair: a 15R and a 30R. Both had a very loud hum when the amp was at idle. In a solid state amp this is almost always due to poor power supply filtering. and further inspection showed that this was caused […]

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Peavey ValveKing 100 Guitar Amp Repair

By Frank | Published: June 30, 2014

Peavey have earned a reputation for making well-engineered amps at reasonable prices, so I was not expecting any major issues when I took in a ValveKing 100 for repair. The symptoms where that the amp was not powering up: neither the indicator light, nor the valve heaters where illuminated. This fault is usually due to […]

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Fender Hot Rod Deluxe Guitar Amp Repair: New Filter Caps.

By Frank | Published: June 3, 2014

Here’s Fender Hot Rod Deluxe that came into our workshop in need of new filter caps. Whilst you would expect the filter caps in, say, a 40 year old Fender Twin Reverb to need changing, it’s surprising that the caps in a 10 year-old Hot Rod Deluxe should have expired; however from my own experiences, […]

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Fender Blues Junior Guitar Amp Repair

By Frank | Published: August 9, 2013

I see quite a few Fender Blues Juniors in the workshop for repair; not that they are unusually unreliable, it’s just there are a lot of them out there! However you do see many of the same faults occurring, so here’s some photos highlighting these from a recent repair. Firstly, like many amps that use […]

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Aguilar AG500 Bass Amp Repair: Man vs SMD Round 1

By Frank | Published: July 31, 2013

Here’s a repair I conducted on a more modern amp, a Aguilar AG500 bass guitar amplifier, where we were dealing with the dreaded SMDs. This amp is quite an interesting design as it has a class D output stage, however unlike most class D amps it’s not ultra light. It employs a linear power supply […]

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VOX Night Train Guitar Amplifier Repair

By Frank | Published: June 17, 2013

Here’s some photo’s from a recent repair of a VOX Night Train amplifier. The amplifier was producing no sound. Curiously the HT voltage on the first pre-amp valve was only 95 VDC, way below spec. I removed the valves and the HT on the first valve stage was still only 95 VDC. On further investigation […]

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