SE Labs Scope Repair

[Geaney]

SCM30s are not ordinary diodes like the 1N400x series - they are unidirectional transient suppression devices which have specific breakdown characteristics - replacing with a string of 1N4007s would not work and would be unsafe as they would do nothing.

You should be able to use the cheap & common 1.5KE-series TVS diodes - do you have the schematic of the HV section that we can see so that we can suggest an alternative?

This is also a 30V, NOT a 3KV, device, so the common 1.5KE30A device would be fine - 33p ex-VAT from Farnell - http://uk.farnell.com/stmicroelectronics...dp/9884963

Thanks Nick, I'll see about scanning the circuit and posting over the weekend. In the diagram they look like they're acting as regular rectifier diodes but I'm not familiar enough with them to know exactly what role they're playing. More to come.....

Cheers, John