UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio 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 Jan 2020, 1:32 pm   #21
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 8,699
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

You could get an idea of what valve without applying any power, measure the resistance between the heater connections on the valve holder.

Lawrence.
ms660 is online now   Reply With Quote
Old 27th Jan 2020, 1:42 pm   #22
Edward Huggins
Dekatron
 
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 5,298
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

Be aware that until 1956 Dansette made these circuits using a mains-isolated chassis with a 45V heater tap. From 1953 they used UL41s, then from around mid 1955 they used UL84s until eventually moving to EL84s by the end of 1956. This "Diploma" is a very early Model.
__________________
Edward.
Edward Huggins is online now   Reply With Quote
Old 27th Jan 2020, 2:25 pm   #23
TowerRadio
Pentode
 
Join Date: Mar 2008
Location: Bristol, UK.
Posts: 133
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

Well it would need a mains transformer to obtain the voltages indicated in the supposed correct circuit. An EL84 would be driven at a much higher HT surely. The 50 mfd capacitor only needs to be 25 volt DC working.Les
TowerRadio is offline   Reply With Quote
Old 27th Jan 2020, 2:36 pm   #24
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 8,699
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

A UL41 amplifier from another Dansette Diploma:

https://www.vintage-radio.net/forum/...6&d=1570799104

Lawrence.
ms660 is online now   Reply With Quote
Old 27th Jan 2020, 3:08 pm   #25
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,518
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

Quote:
Originally Posted by TowerRadio View Post
Well it would need a mains transformer to obtain the voltages indicated in the supposed correct circuit. An EL84 would be driven at a much higher HT surely. The 50 mfd capacitor only needs to be 25 volt DC working. Les
Supposedly correct or not I posted that circuit to help the OP and to help any members offering him advice.

One simple voltage or resistance check by the OP would hopefully resolve the question of the valve type for once and for all.

Let's wait for the OP to report back.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is offline   Reply With Quote
Old 27th Jan 2020, 3:49 pm   #26
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 5,813
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

The capacitor I was referring to is this one for the smoothing capacitor, but you will have to modify the chassis and fit a capacitor holder, also available from Cricklewood electronics.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 27th Jan 2020, 4:33 pm   #27
jmcilkley
Diode
 
Join Date: Jan 2020
Location: Ilkley, West Yorkshire, UK.
Posts: 2
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

Have a look on Youtube - lots of Dansette restore videos on there
jmcilkley is offline   Reply With Quote
Old 27th Jan 2020, 5:04 pm   #28
GWR1971
Triode
 
Join Date: May 2016
Location: Colchester, Essex, UK.
Posts: 21
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

Quote:
Originally Posted by Michael Maurice View Post
The capacitor I was referring to is this one for the smoothing capacitor, but you will have to modify the chassis and fit a capacitor holder, also available from Cricklewood electronics.
Yes, I'd already put that one in my basket

I was querying the 47uF you mentioned.
GWR1971 is offline   Reply With Quote
Old 29th Jan 2020, 2:09 am   #29
Techman
Nonode
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 2,717
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

I wouldn't start spending out on parts that you may not even need until you've first checked the important items such as the two transformers. If either of these are faulty it'll be expensive.

That smoothing can capacitor may well be perfectly serviceable. I've had a few old record players pass through my hands and even the worst relic that looked like it had been in a damp old shed for decades didn't need that can capacitor replacing and I've never known a faulty one in a record player like that yet. Why would you want to hack the chassis about to fit a different one when you don't need to? Test first and replace if necessary.

It's got a replacement cartridge which looks like it could be an Acos brand. Those pickup arms were never intended to have a relatively light weight tracking cartridge fitted, so you can't say that the tracking weight doesn't matter, as if it's too heavy it'll damage the suspension on that cartridge. It's years (the early 80s) since I had a player with that particular deck in, so I can't remember what, if any, tracking weight adjustments they have - Edward may know the exact details. I always quite liked that deck with what I call the 'boat shaped' pickup head.

Seeing that it has that 'flip-under' type cartridge tells me that the player has been in use more recently than you may think. Also that diode and resistor modification to the rectifier is an indication of more recent use, which could mean that the smoothing can capacitor is still in good condition - I NEVER replace them unless I know that they're faulty in some way.

So firstly you need to find out for sure what the valve type is - the fact that it's missing could be a clue to state of the rest of the player. If it was a UL41, then these are known for internal leakage which can cause transformer burn outs. Another possibility is that because they're getting expensive to buy, someone removed it to replace a faulty one in a radio, or perhaps to sell it on for a few quid - you never know!

Before applying any power, check the continuity of the primary of the output transformer. Next, disconnect that 0.05uf capacitor (it's likely to be leaky and can pull HT straight to deck through the output transformer primary and burn it out) and apply mains to the player via a 'lamp limiter' - look it up on here if you don't know what one is. You should have your DVM on the highest DC voltage range croc clipped onto the first smoothing capacitor in that can to monitor the voltage, a decent voltage here will indicate that all is well with the mains transformer and the rectifier. When you disconnect the player from the mains, the voltage should be quite slow to die away if that can capacitor is in good order. Don't leave the player connected to the mains (via the lamp limiter of course) for more than half a minute or so, just long enough to note the voltage reading. DO NOT touch anything until the voltage reading on the DVM has died away to nearly nothing, as a good capacitor off load with no valve fitted can hold a charge for several hours and give you a VERY nasty electric shock, long after the mains has been disconnected!

Edit to add a couple more points:
The DVM which you would have clipped onto the smoothing capacitor where it connects to the rectifier diode should obviously be done BEFORE applying any power and should have the negative lead connected to the chassis of the amplifier.

The second important point to keep in mind is that if that pickup cartridge turns out to be faulty, then because they need to be a 'high' output type, then unfortunately these are long obsolete and unobtainable, hence it being best that you try to get this player up and running as cheaply as possible so that things such as this can be tested before going the whole hog on replacement parts that could be expensive and a waste of time.

Last edited by Techman; 29th Jan 2020 at 2:30 am.
Techman is offline   Reply With Quote
Old 29th Jan 2020, 11:14 am   #30
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,518
Default Re: Beginner wanting to restore a 1950s Dansette Diploma - where to start?

Very good advice Techman.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 9:18 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 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.