Allanson D40-BRA-E Converter

Have you tried contacting Allanson to see if they have any information available?

(Though I do agree that replacement with a modern multistage converter, maybe something like a PD 9200 series, would be well worthwhile. There would almost certainly be a noticeable improvement both in the time required to recharge the batteries when low and in the longevity of the batteries when the RV is plugged in long-term.)

If the converter is that old, I think you should look for a modern unit with the advanced 3 and 4 stage battery charger that works so much more efficiently.