UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Success Stories

Notices

Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

Reply
 
Thread Tools
Old 9th Feb 2019, 9:22 am   #1
Chumley
Triode
 
Join Date: Feb 2019
Location: Dereham, Norfolk, UK.
Posts: 24
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.
Attached Thumbnails
Click image for larger version

Name:	2019-02-08 09.52.50.jpg
Views:	96
Size:	62.4 KB
ID:	178073   Click image for larger version

Name:	2019-02-08 13.45.39.jpg
Views:	95
Size:	78.0 KB
ID:	178074  
Chumley is offline   Reply With Quote
Old 9th Feb 2019, 2:32 pm   #2
Sideband
Dekatron
 
Sideband's Avatar
 
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 5,133
Default Re: Bush SRP31D rectifier replacement

Neat job! Well done. I think 10W for the resistor is a bit of overkill but better high than too low.
__________________
On Spike Milligan's headstone......I told you I was ill...
Sideband is offline   Reply With Quote
Old 9th Feb 2019, 2:36 pm   #3
paulsherwin
Moderator
 
paulsherwin's Avatar
 
Join Date: Jun 2003
Location: Oxford, UK
Posts: 17,722
Default Re: Bush SRP31D rectifier replacement

Yes, nice neat job. Opinions differ, but my view is that selenium rectifiers are change on sight items. The replacement cost is tiny, and even if they haven't failed already they are highly likely to do so in the future.

I bought a big bag of metal cased 10W 220 ohm resistors a while ago for very little money. They are ideal for these jobs.
paulsherwin is offline   Reply With Quote
Old 9th Feb 2019, 3:23 pm   #4
Chumley
Triode
 
Join Date: Feb 2019
Location: Dereham, Norfolk, UK.
Posts: 24
Default Re: Bush SRP31D rectifier replacement

Thanks for the encouraging comments. Having made sure the theory works I've just done changed the same components on the second SRP31D I have. Less difference this time, so that one's Selenium rectifier must have been in better condition. Working well as a stereo pair! I shamefully neglected to take a reading from the rectifier before I disconnected it, but again the diode/resistor is giving me 207VDC.
Chumley is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 6:00 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2018, Paul Stenning.