[Coco] WTB Orchestra 90 cartridge

Jayeson Lee-Steere cocolistemail at titaniumstudios.com
Tue Aug 2 03:35:14 EDT 2016

On Tue, Aug 2, 2016 at 2:12 PM, RETRO Innovations <go4retro at go4retro.com>

>> If you look at Zippster's pic of the unit, you can count 5 cans (1 power
> supply bypass and 4 audio) and 4 non ceramic caps (audio) alongside the
> ceramic decoupling caps.  So, at least Tandy felt they needed film for the
> RF suppression.
I think you are right that they are film. Looking at the schematic again,
the relative values are not all that small so perhaps they are actually
intended for low pass audio filtering.

The entire analog output of the Orch 90 circuit is odd to me - seems like
there really should be some reduction in the signal level and active
amplification. The challenge is finding a decent quality, low priced opamp
suitable for 5v operation. The 4458 that is used to feed back into the Coco
is probably fine for that usage, but is a noisy thing to use for line out.


More information about the Coco mailing list