First you get the console... then you get the Power!

Time to get into it a bit! Some of the stages of this console restoration have happened simultaneously. For simplicity's sake, I will try to present everything in groups.

Eurocard bay with all of the modules removed.

After pulling all of the modules out of the console, the first thing to deal with on the console was the power supplies. Under the desk, there are two doors which open up to reveal all of the power supplies, some banks of relays, some balancing amplifiers, and a power amplifier. They are in a standard Eurocard format that is also used in some of Studer's tape machines like the a800 (hint of a future project?). In my experience, it is best to tackle the power supply before anything else because you can't do much if you have unreliable power.

You can see some of the eurocard modules here as well
as the gap where some stabilizers have been removed.

Power comes into the console through a large megal box that is bolted in on the right side of the lower eurocard bay. This unit is just a massive transformer with different secondaries to provide different AC voltages to the power supply cards.

This thing is insanely heavy...

Nothing to do here other than clean it.















The power supplies were done in a pretty interesting way. The console requires DC voltages of +/-6V, +/-15V, -24V, and +48V (Phantom Power, of course!). These voltages are regulated using three different power supply cards. Interestingly, two of these use the identical PCB. The difference between the two of them is the size of the heatsink and, obviously, the amount of heat that they can dissipate (1.915.106.00 can dissipate 18W while 1.915.108.00 can dissipate 30W at the cost of being twice as wide). Both of these can have their output voltage set by external resistors which are soldered directly onto back of the the connector in the console frame. This means that you can have a single 106 stabilizer card that can act as an extra for +6V, -6V, +15V, and -15V 18W cards! Great idea Studer!

See Pg. 482 in the Studer Manual (ftp://ftp.studer.ch/Public/Products/Mixing_Analog/900/Manuals/900_Op_Serv.pdf).

In this console, there are 4 1.916.106.00 cards (+6V, -6V, +15V, and -15V), two 1.916.108.00 cards (+15V and -15V), and one 1.916.107.00 card (A dual supply which can provide -24V and +48V). All of these had their original capacitors and looked like they could use some TLC.

A stack of 1.195.106.00 stabilizers ready for a makeover.

This is the -24V/+48V 1.915.107.00 stabilizer pictured.
All of the boards had this problem.

After removing the old capacitors, look what I found! Be ready to see a lot of this. I'm not sure whether this is leakage from the capacitors (lots of the caps in the console popped off from being so old) or corrosion of the flux. Either way, it didn't do any damage but looked incredibly ugly. Nothing that some isopropyl alcohol, q-tips, and some elbow grease didn't fix.

Here is the 1.915.107.00 -24V/+48V module with the smaller capacitors removed but the larger ones still in place. The original capacitors were mostly gold Frankos like the large ones in the picture. Some were also blue Phillips capacitors (though I'm not sure if these were original or not). Either way, they were all old and needed replacing.
You will also notice that I have removed the heat-sink plate in this picture. The plate and the metal piece in the picture were cleaned well and I got my thermal grease ready!

All clean with new caps!

Cleaned the heatsink and bottom plate with isopropyl alcohol. I had to remove the crusty old thermal paste that was there before.

This picture is a tad decieving. On the left, you can see the thermal paste that I have added to the heatsink plate. What I failed to show was that I wiped most of this paste off before I put it back on the card. The idea with thermal paste is not to layer it on and then press it up against the other part. Thermal paste is designed to fill tiny gaps between two surfaces - NOT to be a full, thick layer. What you want to do is put paste on your two surfaces, then wipe it off with your thumb. This will remove most of the excess paste while leaving it in the microscopic gaps. Putting a thick layer of thermal paste can actually be detrimental to your thermal dissipation needs (Man, did that sentence every sound nerdy!).

All four 1.915.106.00's cleaned and recapped! I guess I got caught up in the excitement and forgot to take a couple more pictures of them along the way!

One completed 1.915.108.00 and one pre-restoration.

Both Done!

And that's all there was to it! It took quite a bit longer than the amount of time that it took you to read this, but it actually wasn't so bad! The part that hurt was the price of the large capacitors. With 4 per board minimum, the cost really adds up! You may notice that there are a couple of extra completed eurocard modules in this picture. We'll get to those on Monday!