Datacorder fix

I owned two ZX Spectrum +2 computers and two +2A(B) computers. Datacorder worked on only two of them.

Using a 40 year old speaker (3000 ohms), I found that the problem was in the integrated circuit mounted on the datacorder circuit board.

I cut it out and replaced it with a new LM324 chip. It took 30 minutes. Now the datacorder works fine.