Thanks. :)
First and 3rd videos are are still being edited. Learning to use video editor software for the first time. Thrid part will be next on youtube hopefully in a few days. First part which in the the actual intro will follow... experimenting with some effects.
Then will be another 20+ or so videos to follow if I can keep up.
If you lose the primary regulating dual op-amp in the power-supply, you could lose regulation of +15 and -15 and possibile output at full rail voltage. Most chips in the keyboard cannot survive more than +18. This makes the two dual op-amps in the power supply the most critical set of integrated circuit devices in the entire keyboard. That's my opinion anyways.
The 4558 (dual op amps) are extremely reliable. But manufacturing processes in the 70's semiconductor industry were far less than ideal compared to today. Many of the early chips have short lifespans of 20-30 years. New ones last hundreds into the thousands of years. Don't know what fabrication process the originall 4558 op amps used, but since new units cost well under a dollar each, it's best to replace them.
While the power supply is apart, best to replace them with new for maximum reliability. Go with a known brand name such a National Semicondutor, Texas Instruments or Toshiba etc. Solder them to the board instead of sockets. Any other IC's you replace in the keyboard (aside from power supply) should have sockets as the boards in the CS-80 are single sided and relatively intolerant to much rework/repair.
--- On Sun, 10/25/09, Quazimodo <noddyspuncture@...> wrote:
From: Quazimodo <noddyspuncture@...>
Subject: [yamahacs80] Re: Horror!! voices of Bank I just completely down
To: yamahacs80@yahoogroups.com
Date: Sunday, October 25, 2009, 1:45 PM
Great video Gavin,
I can only find Part 2 however... where are parts 1 & 3..?
I am currently starting a re-cap of the PSU in my second CS80 (already done the first) and would like to ask, how important would it be to replace those dual op-amps?
I didn't replace those on my first unit when I did. Should I go back and do that one as well?
Cheers,
TOM
--- In yamahacs80@yahoogro ups.com, "gavincurtis" <gavincurtis@ ...> wrote:
>
> First video is in on youtube: "Saving the CS-80".
>
[Non-text portions of this message have been removed]