Reverse engineering of C-SCOPE C-220

[Detectorfreak]

Hallo Everybody

The C-SCOPE C-220 may be 40...50 years old, but I love it. It is handy and simple to use for "fast scratching". I had trouble in stability. Off course, the manufacturer does not publish the circuit diagram. I can understand this, it contains all the know how and development cost. So, I reverse engineered the detector. It looks like a very simple but clever design. The machine is still working, after it was ripped apart. I hope this post is useful for some of you. I did my best, but i´m not responsible for errors and damage.
Have a good time
Wolfgang

[aft_72005]

Hallo Everybody

The C-SCOPE C-220 may be 40...50 years old, but I love it. It is handy and simple to use for "fast scratching". I had trouble in stability. Off course, the manufacturer does not publish the circuit diagram. I can understand this, it contains all the know how and development cost. So, I reverse engineered the detector. It looks like a very simple but clever design. The machine is still working, after it was ripped apart. I hope this post is useful for some of you. I did my best, but i´m not responsible for errors and damage.
Have a good time
Wolfgang

It was interesting... if you have an oscilloscope, check the waveforms of different parts step by step... look for the cause of instability... sometimes a capacitor causes instability... also heating and heating of one It will be a factor of instability. All parts can cause instability.

[Detectorfreak]

Thanks for your replay. You must be a professional... I changed C1, 2, 3 polystyrene caps and the D1 (414 in the osc circuit. They were reacting strong on heat of my shrink gun. Even the detector is old, my kids and i love it. For deeper search i use a CS-1220XD, one of the rare "non microprocessor, non over engineered" detectors. Have fun. Wolfgang from Bavaria

[Xtrem]

grüß Gott Wolfgang, very nice work ,thank you.
Are you sure the frequency is 120 Khz ??
Savvas

[Detectorfreak]

Good evening Savvas
Indeed... you made me a little bit unsure (would not be my first error in 70 years of live). So i double-checked. The HP-5328 is synchronized via GPS standard, TEX 2236 is on 2µs/div. Coupling was made with external coil. The osc is really working on 114...120 kHz. I can sleep well again tonight...
Have a good day
Wolfgang