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.

Closed Thread
 
Thread Tools
Old 11th Mar 2017, 7:28 pm   #61
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,428
Default Re: Dynatron SRX30D: LH quieter than RH output

You need to confirm the heat is affecting the chip not something nearby, you may be lucky and the MC483 is ok. A long shot but worth being certain.
I would not try swooping the chips over, you may end up with two faulty channels.
Frank
Nuvistor is offline  
Old 11th Mar 2017, 7:43 pm   #62
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,738
Default Re: Dynatron SRX30D: LH quieter than RH output

I wonder if it is possible to get at the insides of the chip, I have changed loads of these in the past ,never had a go at getting inside one , what have you got to loose , It all else fails link the two channels ,you get mono sound out of both speakers . Mick.
vinrads is offline  
Old 12th Mar 2017, 12:54 am   #63
indigo.girl
Retired Dormant Member
 
Join Date: Apr 2016
Location: Loughborough, Leicestershire, UK.
Posts: 754
Default Dynatron SRX30D: LH quieter than RH output

Quote:
Originally Posted by Nuvistor View Post
You need to confirm the heat is affecting the chip not something nearby, you may be lucky and the MC483 is ok.
Hi Frank
The chip is on the edge of the board so nothing obvious nearby that the heat could be effecting.

Quote:
Originally Posted by vinrads View Post
It all else fails link the two channels ,you get mono sound out of both speakers .
Good idea about linking the 2 channels.

What do you know about these MC483's I've not even been able to track down a data sheet. There must be some old ones knocking around somewhere. What else might they have been used in?
indigo.girl is offline  
Old 12th Mar 2017, 5:57 am   #64
Boater Sam
Banned
 
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
Default Re: Dynatron SRX30D: LH quieter than RH output

Try to establish which leg is the problem by heating one at a time with it running, ensure your iron is not passing a current into the circuit by the earth returns, you should be OK as the amp has an isolation transformer. ( I would not suggest working with an unearthed iron but putting the iron on your isolation transformer will be a good idea )
Then stress the leg whilst soldering by lifting it VERY slightly.
You may be lucky.
Boater Sam is offline  
Old 12th Mar 2017, 8:30 am   #65
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,428
Default Re: Dynatron SRX30D: LH quieter than RH output

I have looked for data on the chip but couldn't find anything.
It depends on how much effort you went to spend but it is probably just a dual op amp. You could check other opamps for pin compatibility or build and piggyback something like this, it's stereo but you would only need one channel. A learning experience.
http://electronics-diy.com/electroni...tic.php?id=910
Frank

Last edited by Nuvistor; 12th Mar 2017 at 8:39 am.
Nuvistor is offline  
Old 12th Mar 2017, 9:45 pm   #66
dinker11
Tetrode
 
Join Date: Sep 2015
Location: Walthamstow, London, UK.
Posts: 54
Default Re: Dynatron SRX30D: LH quieter than RH output

My thoughts too re post 65.

I'm not clever enough to design circuits but being part of the pre amp, a lot of the members on here would probably be able to help you bypass and construct something that uses modern components and the available power on the existing chips that would suffice.

It's a lovely piece of gear that really needs to see a new lease of life if possible.
dinker11 is offline  
Old 25th Mar 2017, 8:32 pm   #67
indigo.girl
Retired Dormant Member
 
Join Date: Apr 2016
Location: Loughborough, Leicestershire, UK.
Posts: 754
Default Re: Dynatron SRX30D: LH quieter than RH output

UPDATE:
With the MC chip obselete now I decided to bypass that part of the circuit so that both channels would go via the working RHS MC483. I then split the circuit again and reconnected back into the LHS before the balance control pot so that I can still vary output strength at each speaker independently. It also means that both RHS and LHS amps would used used and feed into each speaker. Since the two channels were mixed prior to MC483 the output is only ever MONO - but thats the only comprise I had to make to get an output at both speakers so I'm happy. It's all worked nicely.

What I did:
1) Connected the two audio lines at points 307 and 306.
2) Snipped out C301, R301, R307, C313 to isolate the faulty MC483 on LHS.
3) Connected the -ve leg of C329 into -ve leg of C313 (C313 gone, just legs remain).
4) Connected HT output of RHS (point 302) into the HT output of LHS (point 301).

All working nicely. My only concern is that running both channels through the one MC483 chip will put it under extra strain - but I can't see this is a problem. Shout out if any does think so!

Thanks for your help everyone - troubleshooting and solution sorted plus loads of circuit diagrams uploaded for the next person to use
Attached Thumbnails
Click image for larger version

Name:	solution1.jpg
Views:	115
Size:	46.6 KB
ID:	139839   Click image for larger version

Name:	solution2.jpg
Views:	104
Size:	56.0 KB
ID:	139840  
indigo.girl is offline  
Old 26th Mar 2017, 12:46 am   #68
Clydeuk
Hexode
 
Join Date: Mar 2012
Location: Liverpool, Merseyside, UK.
Posts: 453
Default Re: Dynatron SRX30D: LH quieter than RH output

Without any knowledge of the circuit, I expect what you've done at this stage is dealing with signals in millivolts, so I can't see any reason why it will cause any problems at all. Others may know more of course.
Clydeuk is offline  
Old 26th Mar 2017, 12:33 pm   #69
Edward Huggins
Dekatron
 
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
Default Re: Dynatron SRX30D: LH quieter than RH output

I can't quite follow Indy's diagrams enough, but it's crucial that the LH/RH stereo signal is bridged at the cartridge in case all you are doing is feeding just ONE channel through both speakers. Running both channels through one chip will not put any stress on it.
__________________
Edward.
Edward Huggins is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:53 pm.


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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.