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Old 9th Sep 2019, 1:37 am   #1
Nightcruiser
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Default 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.
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Old 9th Sep 2019, 9:42 am   #2
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Default Re: Early 1958 Bush SRP31 question update

Iím 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
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Old 9th Sep 2019, 9:46 am   #3
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Default 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.
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Old 9th Sep 2019, 9:49 am   #4
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Default 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.
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Old 9th Sep 2019, 10:06 am   #5
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Default Re: Early 1958 Bush SRP31 question update

Quote:
Originally Posted by Nightcruiser View Post
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
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Old 9th Sep 2019, 10:55 am   #6
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Default 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.
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Old 9th Sep 2019, 12:22 pm   #7
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Default Re: Early 1958 Bush SRP31 question update

Be aware that there's quite a difference between the BUSH SRP31C and SRP31D.
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Old 9th Sep 2019, 1:39 pm   #8
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Default Re: Early 1958 Bush SRP31 question update

Is that relevant to the OP's query?
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Old 9th Sep 2019, 2:56 pm   #9
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Default Re: Early 1958 Bush SRP31 question update

Edward will you tell us the difference please, thank you.
Cheers
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Old 9th Sep 2019, 4:14 pm   #10
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Default Re: Early 1958 Bush SRP31 question update

Quote:
Originally Posted by John10b View Post
Edward will you tell us the difference please, thank you.
Cheers
John
/D 2x ECL86
/C 2x ECL83
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Old 9th Sep 2019, 4:55 pm   #11
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Default Re: Early 1958 Bush SRP31 question update

Thank you Frank.
Cheers
John
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Old 9th Sep 2019, 7:26 pm   #12
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Default Re: Early 1958 Bush SRP31 question update

Also they employ a different autochanger and cartridge in each version.
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Old 9th Sep 2019, 8:20 pm   #13
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Default 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.
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Old 9th Sep 2019, 8:23 pm   #14
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Default 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!
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Old 9th Sep 2019, 8:40 pm   #15
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Default Re: Early 1958 Bush SRP31 question update

This is info on the SRP31 and 31C, I donít 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 canít confirm underside, be surprised if layout was a lot different.
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Old 9th Sep 2019, 8:58 pm   #16
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Default 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!
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Old 10th Sep 2019, 12:03 am   #17
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Default 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.
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Old 11th Sep 2019, 3:34 am   #18
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Default Re: Early 1958 Bush SRP31 question update

Quote:
Originally Posted by John10b View Post
Iím 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.
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