Looking for a bit of input on a sound problem on a Lynx II, pulled it out of a box after about 15 years and the sound was a bit distorted for a few days then just stopped, nothing from the headphones or the speaker.
So I changed all the sound capacitors as my starting point and still no sound, then I started following the schematic tracing the circuit, but discovered my board has two LM386s, meaning it is probably more similar to this schematic (after the volume control), posted in this thread, like this:
Hoping that everything before the volume control is the same as the original schematic; I put the two together and got this:
I put the speaker on C16 and got a the hear Chips Challenge, but it was very quiet. The path on my board from C16 goes: C16-> R42 -> Volume control -> R94 ->LM386. So I jumped C16 to the following and got:
- R42: Nothing
- Volume Control inputs: Nothing
- Volume Control Outputs: Nothing
- R93: Quiet output on right channel
- (R94 : Quiet output on leftchannel)
In my head that points to the signal at C16 (or C58) being very weak, as both LM386s are unlikely to be faulty. So what is my next step, my plan was to pull the RF shield to see if the hex invertor has a dry joint or if there is something going on there, but tbh I could do with some help and guidance, any ideas?
Edited by RestoLynx, Mon Feb 20, 2017 4:10 AM.