EML-101 - KB S&H problem

dslocum · Joined: Jul 20, 2013 Posts: 19 Location: Toms River NJ

I'm restoring an EML-101. I have everything working great except the keyboard sample & hold. Maybe someone can help....

The S&H mostly works fine, except when you take your finger off a key (not gated) the voltage instantly goes down very slightly. I recall hearing this in the past, but don't recall an answer. Before I go replacing everything, has anyone seen this before or have any suggestions?

Grumble · Posted: Sun Jun 05, 2022 6:15 am Post subject:

Posting the schematics or at least a link to that schematic will give you more and more adequate answers….

dslocum · Joined: Jul 20, 2013 Posts: 19 Location: Toms River NJ

blue hell · Posted: Sun Jun 05, 2022 8:32 am Post subject:

Ah .. it is old right? may be the S&H storage cap gone bad? (the dotted unreadable contraption)

dslocum · Joined: Jul 20, 2013 Posts: 19 Location: Toms River NJ

blue hell · Posted: Sun Jun 05, 2022 3:49 pm Post subject:

Hmm yeah .. could also be that the gate signal does not go low fast enough .. maybe a scope could tell .. but then again .. switching out two caps would be a quick test too :)

Grumble · Posted: Sun Jun 05, 2022 10:11 pm Post subject:

When using a scope: NEVER try to read the voltage over the timing cap (the probe will drain this capacitor)