The clever method of replacing electronic tubes with crystal diodes for rectification

Old electronic instruments and audio amplifiers often use electronic tubes for rectification to obtain high voltage DC, but electronic tubes are prone to aging. Commonly used rectifier tubes include 5Z3P, 5U4, 6Z4, etc. Repairers often use high back voltage diodes such as 1N5408 to replace them, but there are two problems to be solved: 1. Rectifying the output DC high voltage with transistors will significantly increase it, which will promote the aging of other electronic tubes. Once the transistor rectifier is connected to the power supply, a high DC voltage will be established, while the cathodes of other electronic tubes in the circuit have not been fully heated, which will affect their service life; The impact of the second item is greater than that of the first item, so it is necessary to modify the circuit and add a high-voltage delay circuit.

As shown: Connect 2-5 1N5408s in series according to the voltage of the AC power supply, perform full wave rectification first, and connect the original rectifier tube (5Z3P) in series later. This can solve the two problems mentioned above; Even if the electronic tube is somewhat aged, it is still very useful.diodes

I have used it well on multiple electronic instruments and 50 watt tube amplifiers diodes