Orange amp restoration (lots of pics)

[strtdv]

Ok, so I've posted before on my old mid '70s Orange Reverb Twin, but I got a few pics together and thought I'd share some of the restoration process.

 

I bought the amp broken after doing enough testing on it to satisfy myself that the transformers were OK (I figured tranny replacement or re-forming was a bit ambitious and expensive for a first project).

 

The amp is an Orange Mk 125 Reverb Twin. It's based on a Fender twin, but with EL34's.

These were made in fairly small numbers from ~1973 until the late '70s.

Three versions exist, the original Mk 1 which lacks the top handle and I have only ever seen in a 1973 Orange catelogue, the Mk2 which mine is which was made in 1974 and 1975 I believe, which has the top handle, and the Mk 3 which was made from 1976 until they were discontinued which has a voltage selector mounted externally.

They were made in both 50 and 100 watt versions, both using the same chassis, but different speakers.

Mine is a 50 watt version using G12H-30's (30 watts each), the hundred watt version obviously used speakers with a higher power rating.

 

 

Here she is shortly after running a few tests on her:

 

 

After firing it up, the power tubes immediately redplated and very little sound came out.

The speaker on the right had both a tear in the cone and the coil had burnt out

The one on the left was working perfect.

 

 

This photo shows a crude standby switch that had been added (which was actually inside the amp when I got it). It also shows the remains of the footswitch cord.

An old peavey footswitch had been literally tied and taped to the end

 

 

Here's the old date sticker, 4th of August, 1975:

 

 

The internals had a few random modifications over the years as you can see:

 

 

However, the majority of the circuit was pretty sound. Notice the fluorescent bulb and LDR setup for the tremolo circuit.

 

 

Old bias resistors were shot:

 

 

And several of the rectifier diodes were done too, as well as most of the large electrolytic caps (rectifier diodes are the small black things in the back left edge of the circuit board, next to the green electrolytic):

 

 

What does the damage to the electrolytics isn't necessarily the age of the amp, it's long periods of disuse. The electrolytics need regular use to keep "formed", and if they don't get it they can leak, bulge, and even explode, especially if they get a sudden jolt of power.

Some guys do re-forming work on old electrolytics, but these were well gone in places, and neither I nor any local techs have the facilities for that.

 

I sent off the speaker to a guy in Yorkshire, who did a fantastic job re-coning it. He fixed it all up, but once it had a few hours play-in it kept a lot of the character of the other speaker.

 

Here's the speaker prior to re-coning:

 

 

 

Frame codes on both speakers date them to 1975 as well.

 

 

 

I got the electrolytic capacitors replaced, some of the rectifier diodes, the bias resistors, the circuit restored to its original condition, and new tubes.

 

I needed a replacement handle, and I found Matamp still make the identical handle that they made in the 70's which was an exact match and not too expensive at all.

 

The Orange badge on the speaker grille is a period correct one which the excellent guys at Orange dug out from old stock and sent me free of charge.

 

I haven't been able to source an original footswitch (most of these amps are missing them), so I got a standard 2 button footswitch, sprayed it white, and added an Orange logo (a standard Orange footswitch wouldn't work as it doesn't support the LED's in it).

[strtdv]

Pics of the finished amp (it's more orange in reality, camera phone had poor white balance):

 

 

 

 

 

Original coned speaker on the left, darker reconed speaker on the right:

 

 

New caps and valves:

 

 

 

I wanted to restore it without making it too new and losing the vintage vibe, I'm pretty happy with how it came out.

 

Anyway, thanks for looking

[Warhorse]

Very cool man!!

[ej]

Looks awesome dude

[Y0UNGBL00D]

{censored}ing jealous.

 

 

the wya you propped it up in the photo {censored}ed my whole world up for a second though

[Gary666]

That is cool, never seen one of those before, thanks for posting!

[Zeppelin Rules]

Awesome!