Bush SRP31C restoration - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

ben · 16th Aug 2019, 10:49 pm

...Or just put the Acos back!

Techman · 16th Aug 2019, 10:59 pm

It's a good idea regarding putting the Acos back in.

Those SC11 & 12 cartridges have a nice smooth sound and dare I say rather nicer than the X5M crystal, which is more 'punchy' and perhaps a little more 'boxy'.

The Pye amplifier may well have more gain than the Bush, so perhaps not the best comparison, but the difference was like night and day. Also, the Pye has four speakers, two of them fairly large round types compared with the sigle undersized elliptical thing in the Bush.

HedleyH · 17th Aug 2019, 5:52 pm

Have just stumbled upon a BSR SC12H in my parents' attic. It was attached to a mid 1970s Fidelity MC5 that was dumped ( or rather stored) up there 20 years ago. Have fitted this and it appears to be working very well. Good volume and sound quality.

HedleyH · 17th Sep 2019, 9:01 pm

The old Bush continues to surprise me with it's sound quality. Obviously not up to digital sound reproduction we all now are used to but definitely still very good.
I've replaced another capacitor, hunts 0.2uf which was way out. Not sure this really had a noticeable affect but is now back where specified. I have a slight hum at high volume noticeable with no record playing but this doesn't adversely affect playback. The smoothing cap reads OK so I may leave this alone unless others have found replacing beneficial?

Techman · 17th Sep 2019, 10:00 pm

That (probably black) Hunts capacitor can be left alone, as replacing it makes absolutely no difference whatsoever, which you've now found out for yourself, and I've also explained in previous posts on threads on this record player model in the past. The capacitor will not have been 'way out' regarding it's capacitance, but would have read incorrectly on a tester due to it being slightly electrically leaky, which doesn't matter in the position that it's situated in this player. Capacitor testers are generally useless for testing these old capacitors because of the reason I've just given.

The rule regarding mains hum is generally always the same, in that if it's there all the time regardless of the volume control setting, then it's a smoothing issue. If it's only there as the volume is turned up to full, then it's being 'picked up', probably by the wiring. Make sure all signal wiring is correctly located and not close to where mains hum is likely to be induced into it from mains wiring or the transformer etc. The smoothing capacitor can is not known for failing in this particular model, unlike the original rectifier.

HedleyH · 17th Dec 2019, 12:17 pm

I have managed to get hold of a Bush AU31 amplifying unit to accompany my SRP31C. Are there any recommendations for cable type to use with the co-axial type connectors? Would the original have been similar/the same as that used for the flying lead to the amp in the SRP unit?

PsychMan · 17th Dec 2019, 12:55 pm

I don't think its going to matter what cable type you use, so long as it is screened

As to the original Ive never seen one of the cables, I would imagine it's much the same as the lead you suggest

Station X · 17th Dec 2019, 1:01 pm

Was this player one of those requiring RCA/Phono plugs with a long centre pin?

HedleyH · 17th Dec 2019, 2:54 pm

I've ordered some grey screened 2 core audio cable which looks very similar to the original.
The plugs look identical to a TV aerial coaxial plug.
Will have to set about checking the amp over now for the usual problem areas. Luckily have enough new components left over from the service of the main SRP unit as most are in multiple packs!

Nickthedentist · 17th Dec 2019, 3:04 pm

Yes, they used Belling-Lee (TV aerial type) co-ax plugs; a bit of a hangover from the early days of hifi.

You could probably get away with using a ready-made male-to-male aerial lead with moulded-on plugs.

N.

Station X · 18th Dec 2019, 11:20 am

I hate those plugs and always make a point of soldering the inner conductor. I use ready made leads where possible.

terrykc · 19th Dec 2019, 2:43 pm

Quote:

Originally Posted by Nickthedentist

You could probably get away with using a ready-made male-to-male aerial lead with moulded-on plugs.

Yes you could but I wouldn't recommend it.

TV aerial cable has a high capacitance between centre core and screen.

As the feed between the cartridge and the amp is high impedance it will cause the treble response to roll off. Use proper audio screened cable.

HedleyH · 26th Dec 2019, 11:57 pm

Got the amp working well now thanks to this site. After replacing the rectifier (output was 50vdc) with a 330 ohm resistor and diode the amp sounded terrific apart from a very loud mains hum. This wasn't present before the rectifier change. I began thinking of smoothing caps and electrolytic caps. What had I disturbed etc. After a quick scan over old threads I discovered my error. I re- routed the grey cable from the rectifier on the opposite side of the large smoothing cap for neatness and inadvertently induced a mains hum. Quick swap back after looking on here and it's virtually silent. Very pleased and now enjoying a nice stereo set up.

16th Aug 2019, 10:49 pm	#21
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Bush SRP31C restoration ...Or just put the Acos back! __________________ Regards, Ben.

16th Aug 2019, 10:59 pm	#22
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Bush SRP31C restoration It's a good idea regarding putting the Acos back in. Those SC11 & 12 cartridges have a nice smooth sound and dare I say rather nicer than the X5M crystal, which is more 'punchy' and perhaps a little more 'boxy'. The Pye amplifier may well have more gain than the Bush, so perhaps not the best comparison, but the difference was like night and day. Also, the Pye has four speakers, two of them fairly large round types compared with the sigle undersized elliptical thing in the Bush.

17th Aug 2019, 5:52 pm	#23
HedleyH Triode Join Date: Jul 2019 Location: Barrow-In-Furness, Cumbria, UK. Posts: 16	Re: Bush SRP31C restoration Have just stumbled upon a BSR SC12H in my parents' attic. It was attached to a mid 1970s Fidelity MC5 that was dumped ( or rather stored) up there 20 years ago. Have fitted this and it appears to be working very well. Good volume and sound quality.

17th Sep 2019, 9:01 pm	#24
HedleyH Triode Join Date: Jul 2019 Location: Barrow-In-Furness, Cumbria, UK. Posts: 16	Re: Bush SRP31C restoration The old Bush continues to surprise me with it's sound quality. Obviously not up to digital sound reproduction we all now are used to but definitely still very good. I've replaced another capacitor, hunts 0.2uf which was way out. Not sure this really had a noticeable affect but is now back where specified. I have a slight hum at high volume noticeable with no record playing but this doesn't adversely affect playback. The smoothing cap reads OK so I may leave this alone unless others have found replacing beneficial?

17th Sep 2019, 10:00 pm	#25
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Bush SRP31C restoration That (probably black) Hunts capacitor can be left alone, as replacing it makes absolutely no difference whatsoever, which you've now found out for yourself, and I've also explained in previous posts on threads on this record player model in the past. The capacitor will not have been 'way out' regarding it's capacitance, but would have read incorrectly on a tester due to it being slightly electrically leaky, which doesn't matter in the position that it's situated in this player. Capacitor testers are generally useless for testing these old capacitors because of the reason I've just given. The rule regarding mains hum is generally always the same, in that if it's there all the time regardless of the volume control setting, then it's a smoothing issue. If it's only there as the volume is turned up to full, then it's being 'picked up', probably by the wiring. Make sure all signal wiring is correctly located and not close to where mains hum is likely to be induced into it from mains wiring or the transformer etc. The smoothing capacitor can is not known for failing in this particular model, unlike the original rectifier.

17th Dec 2019, 12:17 pm	#26
HedleyH Triode Join Date: Jul 2019 Location: Barrow-In-Furness, Cumbria, UK. Posts: 16	Re: Bush SRP31C restoration I have managed to get hold of a Bush AU31 amplifying unit to accompany my SRP31C. Are there any recommendations for cable type to use with the co-axial type connectors? Would the original have been similar/the same as that used for the flying lead to the amp in the SRP unit?

17th Dec 2019, 12:55 pm	#27
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Re: Bush SRP31C restoration I don't think its going to matter what cable type you use, so long as it is screened As to the original Ive never seen one of the cables, I would imagine it's much the same as the lead you suggest

17th Dec 2019, 1:01 pm	#28
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Bush SRP31C restoration Was this player one of those requiring RCA/Phono plugs with a long centre pin? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

17th Dec 2019, 2:54 pm	#29
HedleyH Triode Join Date: Jul 2019 Location: Barrow-In-Furness, Cumbria, UK. Posts: 16	Re: Bush SRP31C restoration I've ordered some grey screened 2 core audio cable which looks very similar to the original. The plugs look identical to a TV aerial coaxial plug. Will have to set about checking the amp over now for the usual problem areas. Luckily have enough new components left over from the service of the main SRP unit as most are in multiple packs!

17th Dec 2019, 3:04 pm	#30
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,846	Re: Bush SRP31C restoration Yes, they used Belling-Lee (TV aerial type) co-ax plugs; a bit of a hangover from the early days of hifi. You could probably get away with using a ready-made male-to-male aerial lead with moulded-on plugs. N.

18th Dec 2019, 11:20 am	#31
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Bush SRP31C restoration I hate those plugs and always make a point of soldering the inner conductor. I use ready made leads where possible. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

26th Dec 2019, 11:57 pm	#33
HedleyH Triode Join Date: Jul 2019 Location: Barrow-In-Furness, Cumbria, UK. Posts: 16	Re: Bush SRP31C restoration Got the amp working well now thanks to this site. After replacing the rectifier (output was 50vdc) with a 330 ohm resistor and diode the amp sounded terrific apart from a very loud mains hum. This wasn't present before the rectifier change. I began thinking of smoothing caps and electrolytic caps. What had I disturbed etc. After a quick scan over old threads I discovered my error. I re- routed the grey cable from the rectifier on the opposite side of the large smoothing cap for neatness and inadvertently induced a mains hum. Quick swap back after looking on here and it's virtually silent. Very pleased and now enjoying a nice stereo set up.