Re: Tektronix 214 Storage Scope


ditter2
 

There is a safety issue with modifying these 200 series analog scopes with either external batteries/power supplies, or installing BNC connectors to allow use with other standard scope probes. These scopes are double insulated. So adding a BNC connector with exposed “ground” or external batteries can expose the operator to the elevated voltage the scope is floating on, with risk of electrical shock.
As Dennis replied, there have been several postings on alternatives for the single ‘A’ size NiCd cells in the original battery packs. A simple no fuss mod is to replace with nickel metal hydride cells. Some searching on the Internet will come up with vendors selling the odd single 'A' size cell Tek used in these scopes. You can substitute without changing the charging circuit, however it will take a long time to fully charge with the lower charging current the NiCd cells could handle. But on the upside, the run time is considerably longer as the Ni metal hydride cells have nearly 10x the mA/hour rating of the original NiCd cells. A bit more work is required to update the charging circuit for faster charging. A good design will incorporate a “smart” charging IC, to prevent overcharging, as well as disconnect the battery from the load when the voltage gets too low – the cause of dry cell leakage.

Steve

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