Early 1958 Bush SRP31 question update - UK Vintage Radio Repair and Restoration Discussion Forum

Nightcruiser · 9th Sep 2019, 1:37 am

Could the more experienced members of the group please help answer my question regarding the original 1958 SRP Bush record player.

When it comes to replacing the rectifier, what is the biggest difference between the original SRP31 chassis and the later model SRP31C/D

Which diode and resistor is currently recommended for using in this early model?

As I have *absolutely no prior experience* of updating and replacing a rectifier.

Could anyone please provide/upload clear photographs to this thread as to precisely how this is to be done or PM me with the information.

Many thanks.

John.

John10b · 9th Sep 2019, 9:42 am

I’m not sure of the difference between the two models.
The typical replacement components are: 1N4007 diode and a 330 ohm 5 watt resistor connected in series. The ht voltage is about 215 volts dc.
Cheers
John

Nuvistor · 9th Sep 2019, 9:46 am

I think they changed the record player deck in the later version, both amplifiers seem the same.
Mount those components John refers to on a tag strip making sure you connect the diode the correct way round. Keep the resistor away from other components it will get hot.

John10b · 9th Sep 2019, 9:49 am

Further to my post, I took a look at the service manual and at the back it said that the SRP31c is identical electrically but with a slight difference in the cabinet and different record deck fitted.
Cheers
John

Station X · 9th Sep 2019, 10:06 am

Quote:

Originally Posted by Nightcruiser

Could anyone please provide/upload clear photographs to this thread as to precisely how this is to be done or PM me with the information.

Many thanks.

John.

Here you go:-

https://www.vintage-radio.net/forum/...d.php?t=153857

Michael Maurice · 9th Sep 2019, 10:55 am

Normally I remove the grey wire going from the transformer to the rectifier (usually grey) then mount the diode and resistor between the transformer tag where the grey wire was and the capacitor can’s tag nearest the edge of the chassis.

Edward Huggins · 9th Sep 2019, 12:22 pm

Be aware that there's quite a difference between the BUSH SRP31C and SRP31D.

Station X · 9th Sep 2019, 1:39 pm

Is that relevant to the OP's query?

John10b · 9th Sep 2019, 2:56 pm

Edward will you tell us the difference please, thank you.
Cheers
John

Nuvistor · 9th Sep 2019, 4:14 pm

Quote:

Originally Posted by John10b

Edward will you tell us the difference please, thank you.
Cheers
John

/D 2x ECL86
/C 2x ECL83

John10b · 9th Sep 2019, 4:55 pm

Thank you Frank.
Cheers
John

Edward Huggins · 9th Sep 2019, 7:26 pm

Also they employ a different autochanger and cartridge in each version.

Station X · 9th Sep 2019, 8:20 pm

Is the existing rectifier located in the same position as in the non-suffixed models? That's what's important to the OP who's seeking detailed instruction as to how to replace it.

See the thread linked to in post #5.

AC/HL · 9th Sep 2019, 8:23 pm

In this instance we're only concerned with the HT rectifier though, which is the same selenium unit. As said, replace it with a silicon diode and a resistor to bring the HT to approx the same. I used the same method as Michael in post 6, but the only requirement is a good constructional technique it's only two components.

Edit: crossed!

Nuvistor · 9th Sep 2019, 8:40 pm

This is info on the SRP31 and 31C, I don’t have under chassis layout information for the /D.

The differences described for the 31 and 31C are record deck and pickup cartridge.

The amplifier is identical using ELC83 valves in push pull.

The SRP31D with ECL86 valves has a similar upper chassis layout, I can’t confirm underside, be surprised if layout was a lot different.

Station X · 9th Sep 2019, 8:58 pm

I guess we need a picture from the OP showing the existing rectifier and wiring.

I thought the OP had asked a simple question which merited a simple answer. How wrong I was, 16 posts and counting!

Michael Maurice · 10th Sep 2019, 12:03 am

The circuit is more or less the same between the two versions (ECL83/86) but the pin outs on the valves are different. I think ECL86 was more reliable.

Rectifier and smoothing circuits exactly the same on both.

Nightcruiser · 11th Sep 2019, 3:34 am

Quote:

Originally Posted by John10b

I’m not sure of the difference between the two models.
The typical replacement components are: 1N4007 diode and a 330 ohm 5 watt resistor connected in series. The ht voltage is about 215 volts dc.
Cheers
John

Thank you John. That has been very helpful.

9th Sep 2019, 1:37 am	#1
Nightcruiser Pentode Join Date: May 2011 Location: Bath, Somerset, UK. Posts: 149	Early 1958 Bush SRP31 question update Could the more experienced members of the group please help answer my question regarding the original 1958 SRP Bush record player. When it comes to replacing the rectifier, what is the biggest difference between the original SRP31 chassis and the later model SRP31C/D Which diode and resistor is currently recommended for using in this early model? As I have absolutely no prior experience of updating and replacing a rectifier. Could anyone please provide/upload clear photographs to this thread as to precisely how this is to be done or PM me with the information. Many thanks. John.

9th Sep 2019, 9:42 am	#2
John10b Nonode Join Date: Nov 2016 Location: Aberaeron, Ceredigion, Wales, UK. Posts: 2,884	Re: Early 1958 Bush SRP31 question update I’m not sure of the difference between the two models. The typical replacement components are: 1N4007 diode and a 330 ohm 5 watt resistor connected in series. The ht voltage is about 215 volts dc. Cheers John

9th Sep 2019, 9:46 am	#3
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Early 1958 Bush SRP31 question update I think they changed the record player deck in the later version, both amplifiers seem the same. Mount those components John refers to on a tag strip making sure you connect the diode the correct way round. Keep the resistor away from other components it will get hot. __________________ Frank

9th Sep 2019, 9:49 am	#4
John10b Nonode Join Date: Nov 2016 Location: Aberaeron, Ceredigion, Wales, UK. Posts: 2,884	Re: Early 1958 Bush SRP31 question update Further to my post, I took a look at the service manual and at the back it said that the SRP31c is identical electrically but with a slight difference in the cabinet and different record deck fitted. Cheers John

9th Sep 2019, 10:55 am	#6
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: Early 1958 Bush SRP31 question update Normally I remove the grey wire going from the transformer to the rectifier (usually grey) then mount the diode and resistor between the transformer tag where the grey wire was and the capacitor can’s tag nearest the edge of the chassis. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

9th Sep 2019, 12:22 pm	#7
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Early 1958 Bush SRP31 question update Be aware that there's quite a difference between the BUSH SRP31C and SRP31D. __________________ Edward.

9th Sep 2019, 1:39 pm	#8
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Early 1958 Bush SRP31 question update Is that relevant to the OP's query? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

9th Sep 2019, 2:56 pm	#9
John10b Nonode Join Date: Nov 2016 Location: Aberaeron, Ceredigion, Wales, UK. Posts: 2,884	Re: Early 1958 Bush SRP31 question update Edward will you tell us the difference please, thank you. Cheers John

9th Sep 2019, 4:55 pm	#11
John10b Nonode Join Date: Nov 2016 Location: Aberaeron, Ceredigion, Wales, UK. Posts: 2,884	Re: Early 1958 Bush SRP31 question update Thank you Frank. Cheers John

9th Sep 2019, 7:26 pm	#12
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Early 1958 Bush SRP31 question update Also they employ a different autochanger and cartridge in each version. __________________ Edward.

9th Sep 2019, 8:20 pm	#13
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Early 1958 Bush SRP31 question update Is the existing rectifier located in the same position as in the non-suffixed models? That's what's important to the OP who's seeking detailed instruction as to how to replace it. See the thread linked to in post #5. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

9th Sep 2019, 8:23 pm	#14
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Early 1958 Bush SRP31 question update In this instance we're only concerned with the HT rectifier though, which is the same selenium unit. As said, replace it with a silicon diode and a resistor to bring the HT to approx the same. I used the same method as Michael in post 6, but the only requirement is a good constructional technique it's only two components. Edit: crossed!

9th Sep 2019, 8:40 pm	#15
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Early 1958 Bush SRP31 question update This is info on the SRP31 and 31C, I don’t have under chassis layout information for the /D. The differences described for the 31 and 31C are record deck and pickup cartridge. The amplifier is identical using ELC83 valves in push pull. The SRP31D with ECL86 valves has a similar upper chassis layout, I can’t confirm underside, be surprised if layout was a lot different. Attached Thumbnails __________________ Frank

9th Sep 2019, 8:58 pm	#16
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Early 1958 Bush SRP31 question update I guess we need a picture from the OP showing the existing rectifier and wiring. I thought the OP had asked a simple question which merited a simple answer. How wrong I was, 16 posts and counting! __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

10th Sep 2019, 12:03 am	#17
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: Early 1958 Bush SRP31 question update The circuit is more or less the same between the two versions (ECL83/86) but the pin outs on the valves are different. I think ECL86 was more reliable. Rectifier and smoothing circuits exactly the same on both. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/