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Old 9th Feb 2019, 9:22 am   #1
Chumley
Triode
 
Join Date: Feb 2019
Location: Dereham, Norfolk, UK.
Posts: 29
Default Bush SRP31D rectifier replacement

First time dipping my toes into component replacement. Amplifier and controls were all working, but with not as much range on volume and bass as a similar machine I had. Various threads suggested the Selenium rectifier might be operating below par.

Based on Radio tirana's detailed and informative post here https://www.vintage-radio.net/forum/...23&postcount=6 which gave specific advice on which components to use, I ordered ones to that spec.

The pictures show the arrangement before and after. I chose to mount them firmly so I slightly enlarged the hole on the resistor. This meant I could screw it to the chassis where I'd removed the old rectifier. The diode is fitted after the resistor with the cathode (lined) end toward the smoothing capacitor. The brown and black sleeving is just for insulation of course.

A reading between the post where the red wire (post diode) connects at the smoothing capacitor and the chassis confirms a voltage of 207VDC. I think this is close enough to the 215VDC spec for me, meaning that Radio tirana's suggestions on components (1N4007 and a 330 ohm 10W series resistor) is ideal if you're also a newbie tacking one of these.

The result is more volume, more powerful bass, and I'd suggest there's even some top end sparkle, which I attribute to the tweeter perhaps responding better too.
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