McIntosh C220 Preamplifier Repair

I’ve just repaired this lovely McIntosh Laboratories C220 preamplifier. This seemingly high-quality preamp fell victim to a growing problem with newer gear – modern Pb-free production processes.

The McIntosh C220 preamplifier is a hybrid tube/transistor based preamplifier, featuring a phono preamp and microprocessor control. It’s a well-made unit, though not like the McIntosh of old. The board is high-quality fibreglass and internal layout is clean and tidy, using nice parts. Everything is well-specced, except the soldering – more on that shortly.

The unit, as it came to me. It turned on, but produced no sound at all, nothing!

The Problem With Mainstream Reviews…

There are loads of positive McIntosh C220 reviews out there, something my customer pointed out to me. This raises an interesting point. The ‘industry’ of hi-fi is set up to sell more gear. McIntosh actually doesn’t want you to keep using your very reliable C22. In fact, they’d rather sell you a new $5000 C220.

It doesn’t matter that each new model is not quite as well-made as the outgoing model, or that it won’t last as long before needing repairs. Reviewers from the big magazines and online sources are very unlikely to bite the hands that feed them and point any of this out, even if they were technically savvy enough to understand it.

Liquid Audio has no affiliations with any manufacturer. When I review something, I’m only interested in how its made and how it sounds. If I upset a manufacturer with my comments, that’s just too bad!


This particular C220, owned by a customer of mine, has failed completely, twice now. It’s only around 10 years old, so this is not a great record of service and I can assure you he wasn’t happy.

Rather than use actual switches and a volume potentiometer, the C220 uses microprocessor controlled switching and relays. Kind of cool, until it all stops working, then trying to fix this stuff becomes a real problem. The first failure was of the microprocessor. It was fixed at great expense to the owner. Do you think you’ll be able to get another programmed controller when it fails again in five years time…?

Neat internal layout with a minimum of wiring is good. Generous heatsinking for the voltage regulators is also a good thing. Board mounted tube sockets are not such a good thing though.

But perhaps the biggest issue here is the use of lead-free solder in modern production processes. The move to Pb-free happened due to safety concerns over lead in the environment. It’s especially relevant for workers in factories where printed circuit boards are made.

This is where the trouble lies – in virtually every joint you can see here. I had to re-work much of this board.

However, lead-free solder doesn’t flow or wet joints nearly as well. It resists re-work with conventional leaded solder and Pb-free soldered joints just seem to degrade over time, like had happened with this McIntosh C220.

The tube socket pins were especially degraded, along with dozens of other small joints on relays, integrated circuits and transistors. The pads are really too small to cope with the thermal output of the parts they connect. Therefore, the solder joints degrade over time.

You can start to see the issues here. My apologies for not breaking out the DSLR and macro lens here, I will next time. Zoom in to this image though, and you’ll see how bad the tube socket joints were.

I made a video showing the insides and discussing the problem, check that out.

The Repair

This C-220 needed several hours of my time and extensive board re-work to bring her back to life. I’ve never seen so many dry and dedgraded solder joints in a piece of newer equipment. The tube sockets are soldered directly to the PCB, a common point of failure in modern gear and so it was here. Three out of four tubes in this C220 had no filament voltage, all down to solder joint deterioration.

Many of the pads that components are soldered to are way too small to allow any useful amount of solder to adhere during the wave soldering process. Dozens of transistors in this C220 had this problem and I re-worked all of them.

C220 with top and bottom panels removed, ready for re-work.
Close-up of a tube socket before re-work. Again, my apologies for not using the DSLR and macro lens. But you get the picture even with this shot.

But after a good three hours spent tracing regulated rails, re-working the main board, I tested her. She turned on and all the tube filament voltages returned. Plugging in a signal, she sounded fantastic, no denying it. This is the appeal of a lot of this type of equipment – its sounds great, until it breaks!

Gorgeous, there’s no denying that McIntosh make sexy looking gear. I just wish they hadn’t moved to lead-free production and microprocessor control. In a few more years, this will no longer be repairable.

Very pretty isn’t she, and I have to say, she also sounds fantastic.

2 thoughts on “McIntosh C220 Preamplifier Repair”

  1. Interesting about the lead free solder
    Bloody Greenies!
    This new stuff presents so many issues the good old fashioned ways prevented
    The best brake pads were always more efficient with asbestos (naughty product I know) and it took some time to get things back to as good a grip as asbestos base, and don’t speak about non asbestos based clutch plates … a total disaster, so we all go to automatic cars
    I digress, it is so great to have someone around who knows how to fix things properly
    Love your work Mike
    Keep using the best material, even if politically incorrect
    Those of us in the know, know better.

    1. Ha ha, hi Rodd, yes some of these changes are definitely for the worst. I’m no fan of asbestos or asbestosis, so I’m ok with that one, but I won’t be changing from using high-quality leaded solder any time soon!!

Thanks for reading, leave a comment and let me know what you think!