[Solved] Kikusui KSG4100 Sig Gen Circuit diagram needed

[SuomiKiwi]

This is a shot in the dark as I have been unable to turn up any schematics of this 25 year old sig gen. I purchased this off eBay and it works..mostly. I have the operations manual which is great but not so good for fault finding. The unit cannot change frequency, modulation, amplitude using the rotary dial. It all works fine with manual data entry so its just a minor annoyance..but still. Its really useful to tune the output manually. In any case I dissasembled the front panel, hoping for an easy fix but its not to be. I can still chase the logic states around the front panel with a scope but a schematic would be really useful, can anyone help? Kikusui themselves couldn't help me as they told the product was discontinued 25 years ago and is not supported...no surprise but no offer of a manual from the archives came either.

[coromonadalix]

ask directly  at Kikusui

Under an non disclosure agreement they could accept  to send you schematics


They did  for a few EEVblog members here  for psu's ...  me included

[SuomiKiwi]

Thanks, I did try that but got the following response;

KSG4100 of Signal Generators is very old model and the model was discontinued since over 25 years ago.
 
Unfortunately, we finished repair support and providing technical documents for this model.
 
Sorry for the inconvenience but thank you for understanding.

So looks like hand drawn schematic time for me....

[SuomiKiwi]

Handchasing the logic lead me to the CPU which is housed in one of the internally screened modules. A hard reset using the unlabelled switch on the CPU fixed the problem. Kikusui thoughtfully provide an access hole to the reset
switch so actually no need to even remove the screened cover. The service manual would have saved me a ton of time but we got there in the end.