Dim button stopped working properly

[sintech]

Success! I replaced t19, and it works great.

Thank you!

Brilliant! T19 should've been the same part as T4 on the 4k card.

 

[Jermbob]

The dim button went out again, and I replaced t19, thinking it would fix the problem, but it didn't.

Any thoughts?

[sintech]

Looking at the drawings, this what is going on:

A switch (dim button) and a diode feed a voltage to T19 and T25.

T19 feeds a control voltage into two independent circuits:

R104 (left circuit) and R106 (right circuit) these two resistors operate the Jfets that punch the Dim pot into circuit. (dimming the sound)

T25 drives the dim lamp and penthouse "Dim" LED's (this is coupled to T19 in two places)


I'd change T25 (4093) just to rule that out, then it's extender time…