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 Radio going off station
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 Return to top of page · Post #: 31 · Written at 10:17:12 PM on 4 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

Its not just drifting. The stations disappear and appear further down. but not far down. The components are over 50 years old so recapping is in order any way. By disappear I mean instantly disappear.


 
 Return to top of page · Post #: 32 · Written at 10:31:23 PM on 4 August 2016.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1378

I'd be looking at the caps & resistors in the local oscillator. There's not many, you may as well just change the lot.


 
 Return to top of page · Post #: 33 · Written at 10:56:35 PM on 4 August 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4333

From the last explanation we don't have drifting we have "jumping" and the most likely thing, which is rarely the valve, is a dud cap in the oscillator circuit or a bad joint. Mica ones in the older sets often cause that and its often one with high voltage on it and in a place where it can throw the oscillator off frequency. I doubt that a ceramic would behave that much differently.

I don't have apprentices, so as one knows that 99.9% of the paper caps, will leak like sieves. Leaking positive onto valve grids has a devastating effect on bias. I don't treat hobby fixes (not done often) any differently than commercial fixes. Experience tells me what has to go, so no pussy footing around, its ruthless efficiency.

I know from Aviation & as a textile dyer that I am not colour blind, Mum was affected in the red area. She was an Artist & I often ended up matching colours for repairs & when they were in bad area of the spectrum for her.

If you cannot match against a colour chart then its a case of checking with a meter. Do note that many resistor cannot be reliably checked when they are in circuit; Plate & control grids not so much, but if an in circuit resistor tests high it is likely to have gone out of spec. Printed circuit tracks, do crack as does the solder where there is heat. Eg around the valve socket, Pay particular attention to that and switch contacts.

Note the cap next to R13: That looks like it's snapped off.


 
 Return to top of page · Post #: 34 · Written at 11:27:59 PM on 4 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

I think you mean to say R133 and that pigtail does look to be disconnected (unless it's an optical illusion).


 
 Return to top of page · Post #: 35 · Written at 1:18:32 AM on 5 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

Hell I had not noticed that capacitor. It definitely looks broken. I will have a good look when I get home from work.


 
 Return to top of page · Post #: 36 · Written at 9:04:40 PM on 5 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

GTC that pigtail was a optical illusion , I just checked it and what you can see as a pigtail is actually just poked back up through another hole lol I thought I was barmy.


 
 Return to top of page · Post #: 37 · Written at 9:19:06 PM on 5 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

A picture may be worth a thousand words -- but only if it's not deceiving. Smile


 
 Return to top of page · Post #: 38 · Written at 9:19:11 PM on 5 August 2016.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 409

I take it you have cleaned band switch contacts with a suitable cleaner.(I use white spirits on an artists tiny paint brush).
Seeing good contact cleaner is hard to get these days.
And reseat the valve sockets. (pull out valves and reinsert them to sort out contact problems).
JJ


 
 Return to top of page · Post #: 39 · Written at 9:22:56 PM on 5 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

^ good advice. I've been side-tracked by such things.

I use CRC contact cleaner.


 
 Return to top of page · Post #: 40 · Written at 8:43:17 PM on 9 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

It looks very much like I will have to replace the valve socket. I cant get under it to tighten the contacts as it mounts directly onto a circuit board. Is this a easy job do you think?.


 
 Return to top of page · Post #: 41 · Written at 9:21:24 PM on 9 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

Is this a easy job do you think?

Removing the socket from the board shouldn't be difficult if you have a good solder sucker.

Once the chassis is out of the case you should be able to get to it.

Sockets can be sourced from Evatco, and eBay.


 
 Return to top of page · Post #: 42 · Written at 1:24:24 AM on 10 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

Well I have sourced 4 sockets from Evatco at a very reasonable price. And bought three 9 pin Vacuum Tube Socket saver bases from eBay. They look to be a very usefull device.


 
 Return to top of page · Post #: 43 · Written at 12:07:54 PM on 10 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

Socket savers are useful for valve testers when you are using the same socket to test a batch of valves.


 
 Return to top of page · Post #: 44 · Written at 7:28:06 PM on 14 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

Well people the Nordmende lives. All the problem was , was the valve socket being a little dodgey. I took it to my mate around the corner and he got his tools out ( one had a hook on it ) and he got in behind the sockets and tightened them up and it now runs faultlessly. I only had to replace 3 capacitors as well. The components in this radio are all original except those 3 caps such is the quality of these german radios.


 
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