McIntosh MC 2505 Repair And Restoration

This McIntosh MC 2505 solid state power amplifier is in pretty good cosmetic shape except for the wood cabinet. 

The chassis of the McIntosh MC 2505 is out of the case. Time to get decades of dust and dirt cleaned out

The original wood case of this McIntosh solid state power amplifier is pretty beat up.

The image below shows a close up of the bottom right hand corner of the case. The area of the deepest scratches. 

The image below shows the same area of the case after some sanding.

After using some Howard's furniture polish the wood case for the McIntosh MC 2505 looks much better.

The knobs have been removed for cleaning.

The glass has been removed for cleaning.

Need to clean the inside of the glass also.

Some sticky debits on the diffusion panel that I removed with Q-tips and alcohol.

This McIntosh MC 2505 solid state power amplifier has a nice blue glow when you get the dirt removed from the meters.

Warm water, dish soap and a toothbrush is the difference between the cleaned knob to the left and the dirty one to the right.

Changing out the old bulbs is a good idea. Fortunately this McIntosh MC 2505 uses inexpensive bulbs that are readily available.    

The McIntosh MC 2505 solid state power amplifier is shown with it's bottom cover removed.   

With the bottom cover removed there is easier access to some controls for cleaning with deoxit. 

Four of the bulbs used in this power amplifier are easily accessed when the bottom cover is removed. 

With a steady sine wave signal input into both channels the power meters at all ranges showed a slight difference between the channels.

 There are two pots on the meter circuit board of the McIntosh 2505 amplifier that allows you to calibrate the left and right power meters.

I'll clean up the chassis of this McIntosh 2505 power amplifier during the repair and restoration process.

Loosening the output transistor heatsinks allows for better access to the chassis for cleaning.

The filter capacitors tested out fine but after 40+ years but there is no question that they have functioned far longer then they were designed to.

I will be replacing the filter capacitors as well as re-stuffing the can capacitors during this McIntosh MC 2505 repair and restoration.

Before unhooking any wires it's always a good idea to take plenty of pictures to help you get everything back together correctly.

You can't have enough pictures or take enough notes as they may help you if you have a issue during the repair or restoration.

When re-stuffing a can capacitor it's always a good idea to leave a little bit of the colored insulated wire on the capacitor can.

Knowing where the wires were hooked up originally will help make sure that after re-stuffing the capacitor you can get it hooked back up correctly.

I have cut the can capacitor open and cleaned it out during this McIntosh MC 2505 power amplifier repair and restoration.

What you will find inside the can capacitor is shown in the picture below. In this case the whole wad just pulled right on out.

I have begun to wire up the new capacitors. Keeping the original can capacitor keeps the cosmetic look of the McIntosh 2505 original.

Putting some electrical tape around the replacement capacitors made for a nice tight fit inside the can capacitor.

All of the original electrolytic capacitors will be changed out during this McIntosh 2505 power amplifier repair and restoration.

After 40+ years every electrolytic capacitor is a ticking time bomb. When will it fail? Worst of all is what will happen to the unit when it does.

Most of the components are pretty easy to get at in the McIntosh 2505 and there is enough slack in the wires to move the assemblies where needed.

The new capacitors have been installed and this McIntosh 2505 power amplifier is getting to start it's next 40 years of service.

Now I'll check the operation of the amplifier, dc offset, power output, distortion and just the general functioning of this McIntosh 2505.

Everything on the test bench checks out fine and it's about time to put everything back together.

The MC 2505 power amplifier chassis is back in the wood case and it's time to give a final listen on the test bench.

This amplifier is ready for some music. This McIntosh MC 2505 power amplifier repair and restoration is complete.