Musical Fidelity F22, A100R F25 remote and selector issue - IR interference? OLD IR problem?

Yay a surprise project.

I am lucky enough to have a couple of Musical Fidelity F22 pre-amps that BOTH have the same issue today. The entire selector system doesn't work. Since this affects both in the same way it's probably come up before. I'm hoping can't find anything though so if this turns out to be the "fixit" post then great.

Already I know that, even in this kingdom of geeks, this is a bit niche :D but any and all input gratefully received.

Basic issue seems to be that the IR input is messing the selector system up - I can change source if, and only if, I completely mask the IR sensor.

Some more bits of info for Sherlock
  1. I have seen this issue many years before (on one or the other), When LED lamps were first introduced, on particular type would mess it up change of bulb sorted that - literally removed all bulbs (lamps if you prefer) that I can think of to eliminate that factor.
  2. The units seem to work in my lab (AKA kitchen) not my lounge?
  3. Closed curtains to mitigate any stray IR from tree reflections or anything. It is an unusually bright day here in Manchester UK - it's not raining at least
  4. Powered unit from the kitchen via an extension to see if that was a factor - it's not
  5. last thought - problem is not related to the connected CD or amps, same issue when they are disconnected
On the unit that the problem first appeared on, I thought 'what-ho' and busted out the soldering iron. Swapping any electrolytics out on the remote board :smash:- seemed to work see #2 above :) (handily also demonstrated a non functional remote but that's for another day)

Clearly this is a problem that needs a fix and I will update here as I make progress or not. I suspect the real question is "how to slug an IR sensor" I would estimate these are both 30 years old so it might just be an old kit issue. At which point, both having the same issue at the same time is entirely plausible

Barely use the remote so there is an easy and obvious solution but not happy with that

So this may turn out to be a brief post. Magically and after some head scratching everything was fine in the morning
Its been cooler but not hugely - forecast to be hotter in the UK soon so I guess we'll see if that was a factor

for the curious, the system hinges on the Toshiba TC9150 remote interface with the push buttons being fed through the complementary TC9148P. Net result is that the TC9150 either takes data from the TC9148P in the remote or from the TC9148P in the unit