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

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Audio (record players, hi-fi etc)

Notices

Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

Reply
 
Thread Tools
Old 27th Oct 2021, 4:08 pm   #81
theredhouseinn
Pentode
 
theredhouseinn's Avatar
 
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 179
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

You are working on a home brew lashup with exposed mains wiring, if you are not very careful you will get a nasty shock which may kill you.
You have also added an earth wire to the metalwork which increases the risk whilst you have your hands in the works.
John.
theredhouseinn is offline   Reply With Quote
Old 27th Oct 2021, 4:39 pm   #82
peter_sol
Octode
 
Join Date: Aug 2003
Location: Welwyn Garden City, Herts. UK.
Posts: 1,705
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

I think that someone with more knowledge is going need to sit with you and help out. Even with the amp working it's unlikely to produce sound with the original Acos Hi G cartridge.
peter_sol is offline   Reply With Quote
Old 27th Oct 2021, 4:46 pm   #83
Edward Huggins
Dekatron
 
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 7,162
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

This is very sound advice. I normally will try to persevere over many Posts, as I did earlier, but in this case I have now withdrawn due to the risks involved.
__________________
Edward.
Edward Huggins is offline   Reply With Quote
Old 27th Oct 2021, 5:22 pm   #84
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

There looks to be 3 pins of the IC that are not soldered to the PCB. Shown in photo of solder side in post 41. good observation taking a good look at that I can see 6 pins that need attention
Bigears is offline   Reply With Quote
Old 27th Oct 2021, 5:24 pm   #85
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

I never work on it with the mains on, but I heed your concern
Bigears is offline   Reply With Quote
Old 27th Oct 2021, 5:36 pm   #86
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Yes Lawrence, on taking a good look at the PCB I see about 6 that need attention, one of the members is concerned about my wellbeing, I am taking precautions I am not working on it live, I also know that it has a 1000 uF Cap close by
Bigears is offline   Reply With Quote
Old 27th Oct 2021, 6:07 pm   #87
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

As I am trying to understand how this works, it would help me if someone view this picture and tell me the names of the four main components, I can see one is a transformer and one is a choke I know that the transformer reduces voltage and the choke filters out AC current , I think so what do the other two do, any reply would help me understand what's going on, this record player is just something I picked at a market, something to give me hands on experience

Its just like I am interest in electronics I just wish I came into it earlier

Regards Ken
Attached Thumbnails
Click image for larger version

Name:	016 (1).jpg
Views:	63
Size:	100.4 KB
ID:	244394  
Bigears is offline   Reply With Quote
Old 27th Oct 2021, 6:14 pm   #88
Cobaltblue
Moderator
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 5,325
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

This Help?

Forgive the finger trouble typing Reservoir
Attached Thumbnails
Click image for larger version

Name:	Amp Parts.jpg
Views:	72
Size:	107.2 KB
ID:	244396  
__________________
Don't care if it was a bargain why's it in my kitchen
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is offline   Reply With Quote
Old 27th Oct 2021, 6:42 pm   #89
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 4,338
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

The mains transformer is an RS filament transformer, so its original intended purpose was to power the heaters (filaments) of valves that require 6.3V, as Laurence has previously explained this transformer has 2 separate 6.3V secondary windings and it looks like they are wired in series to provide a nominal 12.6V output.

Transformers depending upon their design can increase voltage (step up), decrease voltage (step down) or keep the input and output voltages the same like a 1:1 isolation transformer. In this case it is a step down transformer.

The AC output from the Mains transformer goes to the bridge rectifier (which effectively is 4 rectifier diodes connected in bridge rectifier configuration encapsulated in the black module). This rectifies the AC voltage to produce a DC voltage, but it is not a clean DC, it has an AC component called ripple.

To remove/reduce the AC voltage ripple, the output of the Bridge Rectifier has to be filtered/smoothed by the Choke and the large grey reservoir electrolytic capacitor.

There may also be further filtering/de-coupling capacitors at the amplifier PCB to further clean up the DC supply.

David
DMcMahon is offline   Reply With Quote
Old 27th Oct 2021, 10:29 pm   #90
jamesperrett
Octode
 
Join Date: May 2007
Location: Liss, Hampshire, UK.
Posts: 1,427
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Quote:
Originally Posted by Bigears View Post
OK I did the test again 7.90 volts thats with the red lead of the millimetre going to the red lead red lead of the smoothing capacitor and the black to the black
If the two secondary windings are in series (as others have said) then that voltage is far too low. It is even a little low for the windings in parallel as I'd expect to see roughly 9V unless the transformer was heavily loaded.
jamesperrett is online now   Reply With Quote
Old 28th Oct 2021, 9:54 am   #91
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Yes, thank you that's a big help regards Ken
Bigears is offline   Reply With Quote
Old 28th Oct 2021, 10:01 am   #92
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Thanks Dave I have saved it in word, its a big help Regards Ken
Bigears is offline   Reply With Quote
Old 28th Oct 2021, 10:04 am   #93
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

thanks Lawrence
Bigears is offline   Reply With Quote
Old 28th Oct 2021, 3:12 pm   #94
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 4,338
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Quote:
Originally Posted by jamesperrett View Post
If the two secondary windings are in series (as others have said) then that voltage is far too low. It is even a little low for the windings in parallel as I'd expect to see roughly 9V unless the transformer was heavily loaded.
Important point this in terms of fault finding. Would be useful Ken if you could take a close up photo of the secondary windings side of the mains transformer to be 100% sure the 2 windings are connected in series. Also would be good to get a photo of the primary winding side of the transformer to make sure it is connected correctly, i.e. one side of the mains should connect to the 245V tap and the other side of the mains to the 0V tap.

David
DMcMahon is offline   Reply With Quote
Old 28th Oct 2021, 5:33 pm   #95
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

I tested it again today the smoothing capacitor and it showed 9.80 volts
Bigears is offline   Reply With Quote
Old 28th Oct 2021, 6:10 pm   #96
Bigears
Tetrode
 
Join Date: Nov 2017
Location: Durham, County Durham, UK.
Posts: 99
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Trace the red and black? wires from the power supply area to the amplifier. what voltage do you see on the amplifier end of the leads? Is the polarity correct? 5.42 Volts

Is the polarity correct? yes regards Ken
Bigears is offline   Reply With Quote
Old 28th Oct 2021, 6:19 pm   #97
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 18,688
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

9.80V-5.42V=4.38V which is one helluva volt drop.

Do the wires lead directly from the smoothing cap to the amplifier?

It might help if you drew out the circuit of the PSU section ie mains transformer, bridge rectifier, choke and smoothing capacitor.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 29th Oct 2021, 2:06 am   #98
Refugee
Dekatron
 
Refugee's Avatar
 
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,210
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

That valve amp smoothing choke looks like a misguided addition. It is not needed for a transistor/IC amplifier.
The measured voltages show that the primary of the mains transformer is right but the secondary are in parallel. Once the transformer is right and the choke is out of the way the amplifier can be got going. You should get about 15 to 18 volts.
The deck can be put to one side until the amp is working.
There is also a transformer of unknown heritage between the pickup and amplifier most likely added because the pickup was duff.
Refugee is offline   Reply With Quote
Old 29th Oct 2021, 5:13 am   #99
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 18,688
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Quote:
Originally Posted by Refugee View Post
There is also a transformer of unknown heritage between the pickup and amplifier most likely added because the pickup was duff.
Which transformer is that? I think you may be referring to the unnecessary output transformer which was discussed up thread.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 29th Oct 2021, 9:23 am   #100
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 11,653
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Need to establish the secondary windings configuration of the mains transformer, ie: are the two windings electrically separate, connected in parallel or connected in series.

Also need to establish the filter configuration for the output of the rectifier, ie: is it CL or LC, if it's the former then I can't see that the choke is doing anything unless there's another large capacitor hidden away somewhere to make it CLC.

Lawrence.
ms660 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 12:03 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 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.