Rectifiers in parallel

[ppppenguin]

As Kalee20 pointed out, you can use series resistance to balance the currents. Exactly how much resistance you need is another question which may not have a simple answer. You also have to allow for the voltage drop and wasted power.  Might be possible to do it with suitable lengths of wire.

Far better to use a single part that can handle the whole current, though if it's 100s of amps this may not be possible.

My mistake with this Philips unit was to leave the paralleled rectifiers instead of just replacing with a single bridge as a matter of good practice. Here are my notes from July 2024 when I overhauled the unit:

This has suffered a serious failure in the past. There is heavy scorching on both the PCB and some wiring. GR1702-4 (3x BY164 bridges in parallel for +5V supply) have been replaced. There is also a heavy duty bridge bolted to the back panel. The 1250uF main reservoir capacitors have been replaced with 2200uF 50V parts. C1702, the 2500uF reservoir for the +5V supply, has been replaced with 2x 2200uF in parallel. All this work was done at the BBC. Fig XIII-4 in the scanned manual (internal page 58) shows a single external bridge for the +5V supply. The PCB is renamed as MA8555, Unit 19.

Philips' own manual shows that they had second thoughts about using paralleled bridges.