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 Return to top of page · Post #: 16 · Written at 9:23:50 AM on 3 August 2016.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 940

"If that has a transformer, make sure it is set on 250V not the European 230V."

My understanding is that the nominal line voltage is 230V. That said, my solar system inverter has a voltage readout and I have never seen it lower than 240V over 6 years. And from time to time it exceeds 255V, at which point the inverter closes down due to excessive line voltage.

So the above quote is good advice.


 
 Return to top of page · Post #: 17 · Written at 2:50:48 PM on 3 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

Since circa 2000, our nominal supply voltage is 230V to fit with the IEC's global harmonsation scheme, but with a +10% to –6% tolerance.

So, at any time you can expect anything between 253V and 216.2V and still be within the provisions of the standard.

I have seen my mains reach 250V late at night.


 
 Return to top of page · Post #: 18 · Written at 5:43:33 PM on 3 August 2016.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 940

When I first encountered inverter cutout, looking on the net revealed a fix for the cutout at 255V is to go inside the inverter and reset the cutout voltage to 260V. Now I wasn't inclined to do this as I am not an electrician, and anyway I am not sure if my inverter can be reset to 260V cutout voltage.
But this advice might mean that the line voltage could go as high as 260V if there is someone in your area with an inverter set at 260Vcutout.

I remember some years ago an article in SC or EA about using a 240/12V downlight transformer wired as an autotransformer to reduce the line voltage in the lighting circuit by 12V. The wiring was done in such a way that the lighting circuit current was carried by the secondary winding. Perhaps something similar could be done to protect fragile old radios.


 
 Return to top of page · Post #: 19 · Written at 8:09:57 PM on 3 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

I remember some years ago an article in SC or EA about using a 240/12V downlight transformer wired as an autotransformer to reduce the line voltage in the lighting circuit by 12V.

That's the bucking transformer method, which makes use of reverse phase winding connection between primary and secondary, for example:

http://www.radiomuseum.org/forumdata/upload/bucking_transformer_hookup~~2.jpg

Mains too high is a problem American collectors often face, since their older radios were rated at 110V and the supply is now commonly 125V, if not more.


 
 Return to top of page · Post #: 20 · Written at 11:46:21 PM on 3 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

You can see in the second photo that it is set to 220 volts. and I have been running it like that for a while and it hasn't been a issue. Also its been over here for quite a while with no issues. But I am wondering if I might be able to do some adjustments to equal things out.


 
 Return to top of page · Post #: 21 · Written at 11:52:05 PM on 3 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

First order of business for a resto is a recap. Johnny's tip about hidden caps is a good one.


 
 Return to top of page · Post #: 22 · Written at 11:54:38 PM on 3 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

Yes I agree and I really think that's all it needs .But will find out . having a service manual would be awesome.


 
 Return to top of page · Post #: 23 · Written at 12:09:47 AM on 4 August 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6002

The schematic is on Radiomuseum, but you need to be a member to download it.

Some people here are Radiomuseum members.


 
 Return to top of page · Post #: 24 · Written at 8:59:10 AM on 4 August 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4333

It is actually normal for a pentagrid to drift high as it warms & stabilises. Now it is obvious that the set is "just" working. In over 50 years of fixing these I have considered it a pointless exercise to fault find any valve radio with wax paper caps and tired electrolytic caps.

When you replace these you also check the resistors. Early electrolytics lost polarity & went short, often exploding and often wiping out the rectifier & transformer. They and the better ones in the 60's, could also "dry out", this becoming a major issue in Solid state car radios as they were used for coupling. By drying out the capacity falls and so does the volume.


 
 Return to top of page · Post #: 25 · Written at 7:34:56 PM on 4 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

Yes I agree Marcc I will take my bravery pills and get stuck into this one. One of my issues is that I am colour blind and some of the colours on these old resistors are already faded but I can actually see on this one that the circuit board has the components identified on it so I am hoping it could be a easier fix.


 
 Return to top of page · Post #: 26 · Written at 8:07:44 PM on 4 August 2016.
Redxm's avatar
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 444

Has it got disc ceramic caps in it. They are another source of problems.


 
 Return to top of page · Post #: 27 · Written at 8:38:41 PM on 4 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

I am not sure if its got Disc Ceramics in it . That service manual you got for me is awesome . I am surprised that its so easy to understand ( But then again it is German design ) The service manual corresponds with the markings on the chassis/circuit board so it also goes a long way to solving my issue with being colour blind. According to the manual it has 40 plus caps in it.


 
 Return to top of page · Post #: 28 · Written at 8:50:33 PM on 4 August 2016.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 409

Don't start changing all the caps.
If you go down that road, the chances of introducing a man made fault increases drastically.
And then you have real problems!.
Have a good visual, check logical points, measure, diagnose and hopefully fix.
Then go about and do caps if necessary as preventative maintenance.
I wouldn't mind a dollar for every hour spent repairing my apprentices man made faults.
And I had about 12 in my time.
Now that you have a manual, plus the help of the forum. Should be no worries.
Have you changed the mix/osc yet.
JJ


 
 Return to top of page · Post #: 29 · Written at 9:04:44 PM on 4 August 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1573

I haven't changed anything yet . But I am going to target all Electros and high value resistors.


 
 Return to top of page · Post #: 30 · Written at 9:27:50 PM on 4 August 2016.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 409

Electros and high value resistors won't cause drifting.
JJ


 
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