Philips AG7500 combo organ / AG7600 tube amp

Today I dug out my oldest Philicorda from the corner of my studio. The AG7500 is one of Philips first organ models. Released in 1963 it's packed with tubes both in the oscillators and in the amplifier. The amp,which also holds the spring reverb, is a separate unit mounted under the organ in the wooden stand.

One of the most elegant instruments in my studio

My AG7500 has found its place in the corner since it hasn't been working properly ever since I bought it a couple of years ago. But today I gave it a try do fix at least some of the issues on it. The organ was out of tune, the reverb wasn't working, several of the keys didn't trigger any sound and others didn't return after pressing it.

I started of with opening it up to see if I could at least tune it and get a little better response in the keys. Tuning it worked out right, but the other issues were a little harder. I didn't actually understand where the keys made contact or how I could adjust the response or the springs of the keys.

The right part of the organs inner seen from above. The twelve square silver pieces are for tuning the oscillators.

The left part of the organ seen from above. Input and output conectors to the right an the voicecards with lots of small lamps/tubes. 

The left half of the keyboard with the autochord part. Over that is the voice and vibrato selectors

The right half of the keyboard with volume, balance (between chord and solo sounds), selector (for the inputs) and chord mode switch.

Power unit and production label

The AG7600 organ amplifier
The amplifier part with the spring reverb is an interesting piece in itself. It has a 5 pole DIN output and a 5 pole IEC input connector and I guess it could work quite well as amp for any kind of instrument. This means my next project with this little thing is to build a cable or modify the amp to make it possible to connect a 6,3 mm instrument output.

Production label of the amp

Input, output, reverb amount knob and speaker outs of the amp

The insides of the tube amp

Since I couldn't get it running properly I wasn't able to  make a sound demo of it, but you can find some nice clips by others on youtube.

Philips Philicorda GM 760

I bought my first Philicorda around 1995 and then traded it for a Fender Telecaster about a year later. Probably a good deal then but ever since that day I have been looking for a new one.

A couple of years ago I then finally got hold of a AG7500 via a friend at work. It didn't seem to be working. But after a little soldering on the cables I got it running. However not playable in a traditional way. This one still stands in a corner waiting to be looked over.

About a year ago I then found my second one, a GM751. This one could not be tested where I bought it but since the price was more than right I took the chance. It sounded terrible when I first connected it at home but after a few hours connected everything fell in place without even opening it. This has been running smoothly ever since and has become my favourite organ.

A couple of weeks before Christmas I went to pick up my third Philicorda organ. This time a GM760 it's a spinet model with two manuals and bass pedals. And I didn't have the opportunity to test this either at pick-up but since it was completely free it wasn't much to talk about.

When I connected it at home everything, apart from the bass pedals and the percussion (fast, slow repeat) sounds, seemed to be working. The organ has a really warm organ sound with a marvellous plate reverb that is also possible to use on for example drum machines, synths or guitars when you use the Philicorda as an amplifier for external instruments via the connectors on the back side.

5 pole DIN input and output connectors on the lower left back side

I made a short sound demo on the parts of the organ that is actually working. First it's the clean sound then with vibrato and reverb added.

The problem with the repeat function didn't bother me to much until I saw this video where the repeat function is used (around 3 minutes into the clip) and I really loved the sound of it.

Therefore today I downloaded the service manual and opened it up to see if I could find some simple solution to the problem. I can tell you right away that my skills in electronics and in Dutch are about equal and it took me quite a few hours to get an idea of how things could be working in the Philicorda. The attempt to fix the percussive section was without any success. But I took some pictures of the cards, components and wires inside.

Compared to other organs there are plenty of space and pretty easy to get an overview of the things. Philips has also made several smart solutions with hinges and such that makes it quite easy to access backsides of the circuit boards, keyboards etc.

Here's some close-ups from the GM760.

The knobs to the left of the lower keyboard. Manual, Volume, Pedal & Balance.

The knobs to the left of the upper keyboard. Selector, Repeat, Reverbeo & Vibrato.

The far left part of the panel over the keyboards.

The voice selectors for the lower manual.

The first half of the voice selectors for the upper manual.

The second half of the voice selectors for the upper manual.

One of three circuitboards each containing four notes, loceted behind the speakers in the bottom section.

The power and amplifier part and perhaps something more that I can't recognise.

What's it all about

This blogg will mainly be about what's hapening in my studio. About my new and old gear, vintage synths, drum machines and organs.

I guess I'll start of with going through my current gear which consists of some Boss drum machines, a couple of analog synths, some Casios, and way to many home organs from Philicorda to Electone.

From left to right: Casio CZ101, Farfisa Foyer, Yamaha Electone D65, Philicorda AG 7500, Yamaha CS5, Solina String Ensemble, Philicorda GM 751, GEM Rodeo 49, Roland TR626, Yamaha AN200, Casio FZ1.