Transformer Variance - AllanGallop/DigiOne GitHub Wiki

Symptom

Some transformers have a different value to that quoted in construction manual, are difficult to install or pass no audio.

Cause

The LT33 transformers used are difficult to accquire, and such have been provided by many different retailers. Some of those provided have been NOS (New, Old Stock) and as such the leads have pantina.

Known issues

One batch of transformers have been found to have excessive patina on the leads along with high varience in value and are identifable by the 'Yellow' band around the transformer core. These have been removed and the retailer has been notified, these components were only used in the prototype kits.

Resolution

The ideal impedance of the transformers 300Ω:300Ω, which when measured with multimeter these should appear as a 100-200Ω resistive load. Where leads have slight pantina it is advisable to clean the leads using either glass paper or tin them with a soldering iron. The production kits using the white band transformers are not known to have this issue