Weak backlighting on McIntosh... any thoughts?

[TEPEZ]

Hello friends! I just got my hands on a lovely little McIntosh MC 502. Never before owned a Mac, so I thought I’d start off a minimalisticly with this one. So far, I quite like the noise it is making. And I really dont need a lot of power...

Well, to the question. The backlighting is weak (compared to pics of other mc 502’s), and uneven. See pic (appears even weaker IRL). Uneven due to broken bulbs I can understand, but weak all over I cannot really comprehend...

Any thoughts? Can old bulbs lose juice? Can it have something to do with 110/120 v conversion to 220 v (used here)?

Thankful for any input!

 

[geespot]

Have you opened it up? Bulbs could have come out of the sockets, my C712 has this issue

 

[redk9258]

Bulbs out. Old bulbs can become darkened. Maybe incorrect bulbs. Have to open it up and check it out. I would have a new set of bulbs on hand though.

 

[TEPEZ]

Alright, I’ll have a go at opening it up. Would be cool to change bulbs to LED:s, but I’m pretty sure that surpasses by abilities

Thanks for the input lads!

 

[nj pheonix]

Never been inside one.
The 352 I was inside had a bunch (12 maybe?) Bi- pin incandescent lamps . I think on mine half burned out.
If you can solder. (Assuming dc is available) changing lamps would be no harder than changing lamps to LEDs.
Waiting for inside pic to make a suggestion.
Is the S/M in digital docs?

 

[Watthour]

Isn't there a layer of diffuser paper in those Mac dial faces? If so, perhaps it has yellowed.

 

[c_dk]

The bulbs interior surface will get silvered over time, this amp was first introduced in 1980 remember.

There is also a plastic light pipe or diffuser that channels the light to the lettering. Would not be the first time it got left off if someone pulled the glass front or it might have shifted.

The Mac forum has many posts about the lighting.

I have not had one of these on the bench in over 30 years but I would expect that the lamps, typical of Mac, are run off a 5.6 AC volt winding off the power transformer. How was the 120 to 240 conversion done on your amp?