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G3PIJpeter · 5th Nov 2019, 6:37 pm

A long shot - there's nothing on the Web although Roband is still going after 60 years.

I purchased a very grubby rack panel at the recent VMARS auction and discovered inside it a Roband M34 stabilised PSU. Hefty Partridge transformer, block paper capacitors, GZ34 rectifier, EL34 series regulator plus a couple of 12AX7s and an 85A2.

Does anyone have a circuit diagram to share or more accurate details about the outputs? The two preset pots have only a limited effect on the output voltage, varying it from around 200 to 220 volts. The unstabilised voltage at the smoothing capacitors is a whopping 540 volts, although that measurement was taken under no-load conditions.

Photos can be provided if that will help.

Peter G3PIJ

5th Nov 2019, 6:37 pm	#1
G3PIJpeter Hexode Join Date: Nov 2011 Location: Chippenham, Wiltshire, UK. Posts: 323	Roband Electronics M34 PSU A long shot - there's nothing on the Web although Roband is still going after 60 years. I purchased a very grubby rack panel at the recent VMARS auction and discovered inside it a Roband M34 stabilised PSU. Hefty Partridge transformer, block paper capacitors, GZ34 rectifier, EL34 series regulator plus a couple of 12AX7s and an 85A2. Does anyone have a circuit diagram to share or more accurate details about the outputs? The two preset pots have only a limited effect on the output voltage, varying it from around 200 to 220 volts. The unstabilised voltage at the smoothing capacitors is a whopping 540 volts, although that measurement was taken under no-load conditions. Photos can be provided if that will help. Peter G3PIJ