Re: 2215A LVPS repair

Carsten Bormann

On Aug 17, 2018, at 18:56, garp66 <hrgerson@...> wrote:

Could someone please post the model # for a replacement of the Schaffner line filter unit for a standard 120V North American powered Tek 2215a scope ?
I don’t know what is in the Tek scopes, but if it is a FN323-1/01 as was mentioned earlier, you want a Schaffner FN9222-1-06 (and probably some isolated quick-connect connectors and a crimper so you don’t have to solder them in again).
You *don’t* want NOS, because even unused ones of the old style are likely to have exactly the same problem (moisture intake to a metal/paper capacitor the plastic shell of which has crazed).

I put these replacements into all my HP 3457a DVMs after one of the original ones exploded (the DVM had been stored and then shipped, and that probably exacerbated the moisture problem).

I strongly advise anyone who has an FN323-1/01 or similar to replace these *before* connecting line power, and, if there is absolutely no way to avoid connecting the unit to line power before the replacement, make sure there is something like a steel plate in the passageway the molten/vaporized tar will shoot out into from the back of the unit. And have a flashlight in your pocket so you can find the breaker box after the fireworks.

Oh, and replace the other metal/paper RIFA (or WIMA) capacitors from the 1980s, too, if they see high-energy voltages — in particular if you already can see the crazing. But this is not quite as critical as these are much less of a bomb setup than the capacitors tar-sealed into Schaffner line filters.

Grüße, Carsten

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