CDTV weirdness
 

I have two CDTVs one with Taiwanese made v.2.2.1 board and another one with Japanese v.2.2 board. If I remember right the v.2.2 board came with Developer Flash board for CDTV ROMs but I've used KS 1.3 ROM from the other board when testing.

My problems are:
- low right channel audio on v.2.2.1, I have followed an old post here which was inconclusive about the actual issue but replaced U5, U6, U8 (i.e. the opamps), C11, C20, C40-43 and C77 along with Paula but still the audio is low on right channel. I've also measured 12V to be 11.86V.
-- On v.2.2 audio works great, and opamps measure the same on both machines

- On v.2.2.1 board I can get KS3.1 ROM to work, on v.2.2 it will hang on orange screen with black horizontal stripe

- On v.2.2.1 board I can't get New Zealand Story to work regardless of the KS ROM. It will get stuck at the beginning of the animation when the little birds are captured. On v.2.2 board this works fine and I can play the game. Other games I've tried work fine on both machines (mostly Sierra / LucasFilm/Arts games) apart from the muted audio.

Any guidance would be appreciated.

I can't help with CDTV issue, but welcome to the forum ! :)

I see you have +12v, did you also check -12v? all the way to the opamp circuit wise
Audio opamp`s and the Serial port require this to work

EDIT: Welcome to the forum!

Yes, both the U5, U6 opamps measure -11.9x from pin 11 (if I remember correctly). Again, if I remember correctly in both machines all U5,U6 pins measure the same voltages when compared to each other. The v2.2.1 board Paula measured 5V for right channel originally but I switched with the v2.2 Paula and it has 2.56V now on both channels. I haven't tested the broken Paula on v2.2 board as I don't want to risk breaking something.

While on topic of CDTVs, I also tried 8375 Agnus but the machines wouldn't boot with that installed. Should it work?

There are lots of versions of 8375 Agnus. If you plugged it directly into the motherboard it only works with a 1mb version. Not the 2mb version. The 2mb version needs to be used as part of a megachip