McIntosh MR78 Cleaning

[c_dk]

Looks like a tech already has replaced the tantalum caps with common electrolytics. If one failed 20 years ago the date code (if it has one) on the regulator transistor that usually fails could tell us.

I know this forum is mostly about new McIntosh equipment, however, there is a strong McIntosh tradition in keeping the old gear working at it's very best that many of us believe needs to be kept alive.

[jdandy]

Originally Posted by c_dk

Looks like a tech already has replaced the tantalum caps with common electrolytics. If one failed 20 years ago the date code (if it has one) on the regulator transistor that usually fails could tell us.

I know this forum is mostly about new McIntosh equipment, however, there is a strong McIntosh tradition in keeping the old gear working at it's very best that many of us believe needs to be kept alive.

c_dk.......There are plenty of members that share the idea of keeping vintage gear up and running. Count me as one.

[c_dk]

Excellent, that is good to hear. Gordon always taught us the best way to grow McIntosh was to increase the value of used McIntosh.

[Vintage Pete]

Originally Posted by jdandy

c_dk.......There are plenty of members that share the idea of keeping vintage gear up and running. Count me as one.

Count me in as well

[c_dk]

We always have a few Mac restorations in progress along with our regular repair work.

Today in fact, while bench testing a Sansui 5500, we are test fitting a new dome in a second generation Mac speaker, an XR6. We have been testing a number of domes to retrofit into the 1st,2nd and 3rd generation Mac speakers over the last 4 months.

[Cohibaman]

I'll be working on my brother's MR78 tuner in the next few weeks. Primarily planning on giving it a good cleaning, replacing all of the festoon lamps and replacing the station indicator lamp with an LED.

I haven't opened it up to see what else it needs yet, but I'll also take a look at a potential recapping. This thread will certainly come in handy!

I'm definitely going to keep this beauty running! This should be a fun project.

[Vintage Pete]

[Indytown]

Besides distilled water, is there a preferred cleaner or spray that would be safe to use on painted McIntosh equipment surfaces, vintage or new production, that will not discolor or streak the finish ?

Thanks

[Vintage Pete]

Originally Posted by Indytown

Besides distilled water, is there a preferred cleaner or spray that would be safe to use on painted McIntosh equipment surfaces, vintage or new production, that will not discolor or streak the finish ?

Thanks

On the older tuners, I periodically use a very light application of household oil (such as 3-in-one) on the painted surfaces (transformers, cages and top access cover). The oil serves as a good cleaner for surface dirt, retards corrosion, and leaves a nice appearance. Aside from dusting, I don't do too much on the newer components that have a more matte paint finish.

[Cohibaman]

I finally got around to opening up the MR78. I decided the first item at hand was to replace the burnt-out tuning indicator bulb with a bright white LED as an upgrade. Although this is the most difficult of the lamp upgrades to perform, it turned out to be pretty simple.

Below is a before photo; the original burnt red diffuser; a side-by-side comparison of the new LED and the original bulb; and finally an after photo showing the completed LED upgrade.

I wound up using a red drinking straw for the new diffuser and soldered in a 220 ohm current limiting resistor in series with the LED. The photo doesn't show it too well, but color and intensity isn't too bad, plus...this upgrade should last for another 30 years.

I have the rest of the LED upgrades and a roll of light-blocking foam (to replace the deteriorated foam on the front glass) on order. I'll post more photos as work progresses.