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 11-98 transformer
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 Return to top of page · Post #: 1 · Written at 7:18:03 AM on 12 April 2024.
Ehsuz's Gravatar
 Location: Newcastle, NSW
 Member since 6 June 2020
 Member #: 2422
 Postcount: 13

Hello,
I think the transformer on my 11-98 Kriesler isn't working. I am getting power in but nothing is working.
Can anybody tell me how to test it and maybe the voltage readings for the wires.
Thank You


 
 Return to top of page · Post #: 2 · Written at 9:26:47 AM on 12 April 2024.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

Somewhat vague: Is it not making radio noises and is on Gram?

Go to Kevin Chants site and download the service sheet.

To check transformer only: Seeing its been powered.

Remove the rectifier 6V4;

If the tubes & dial lights glow fine. Those windings are OK;

If they do not, un plug it & check the cable & primaries resistance and the power switch is actually working;

If there is life in the globes & heaters. Locate 6V4's socket pins one, & seven, which will be adjacent the gap (tube data);

Measure from the centre tap (non grounded end of R25 100 Ohm) to pin one, then seven, of the socket (6V4 still removed);

Measure AC volts (probably around 250V AC). Do not measure pin one to pin seven unless the meter is capable of around 750VAC, or better.

If the transformer is actually good then there will be issues with the rectifier tube, or the circuit. Which is where you ask yourself, can I proceed, or am I in the deep end?

The object of removing the rectifier is risk management. There will be no High Voltage DC generated, so it cannot cause problems in an area likely to have many.

Marc


 
 Return to top of page · Post #: 3 · Written at 9:34:06 AM on 12 April 2024.
Gandhn's Gravatar
 Location: Cameron Park, NSW
 Member since 5 November 2010
 Member #: 770
 Postcount: 399

Applying power when the condition of the whole radio is not known can cause all sorts of additional problems and is not recommended.
Also you are dealing with mains voltages which can be deadly.
What makes you suggest the transformer is faulty? As with all repairs, a safe, methodical approach is needed.
Regards
Harold


 
 Return to top of page · Post #: 4 · Written at 1:41:47 PM on 12 April 2024.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

Clearly this one has missed the initial phase of what I call assessment. That determines if the unit is safe to plug in, or it needs work before powering. Most will fail that step and need work. Many of these things were replaced when they broke down: Why!

We normally start fixing by checking the power supply and I see no evidence of that. It also has paper caps according to the parts list. It has electrolytic caps; Left unused they will fail and often present as a short. This then, can cause a series of catastrophic failures. Making it commercially a non-viable repair.

So the exuberance in firing it up to see if it goes, can be rather dangerous for you and it and expensive to repair to the point of writing it off.

As it had been powered and we know not about the assumption of transformer failure. The safest way to confirm it with out doing more damage, is to remove the rectifier tube. It is appropriate to have a meter of a "class" fit for purpose. Many modern meters cannot handle Valve radio voltages and some RF.

By removing (as noted) the 6V4. I am depriving the set of high voltage DC. That means that you cannot fry the transformer nor destroy the rectifier by presenting it with possibly a high voltage short circuit.


 
 Return to top of page · Post #: 5 · Written at 8:38:05 AM on 13 April 2024.
Ehsuz's Gravatar
 Location: Newcastle, NSW
 Member since 6 June 2020
 Member #: 2422
 Postcount: 13

The set worked fine for years.
I replaced the paper caps as I wasn't happy with the sound.
I was confident switching it back on as there was no reason to think otherwise.

Now I've got 240v going into the set but no lights or sound from the radio.
The turntable moves though.

The power switch does work.

I will remove 6v4 and check , thanks Marcc.


 
 Return to top of page · Post #: 6 · Written at 1:26:57 PM on 13 April 2024.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2405

When you are clipping out old paper caps or other components it's too easy to clip a wire at the same time. That's why you should always change a max of 2 or 3 at a time and re-test. Makes it easier to find your mistakes.


 
 Return to top of page · Post #: 7 · Written at 8:30:25 PM on 13 April 2024.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

We all have our own ideas: But!

I have never believed in that method, especially if the set is too dangerous to power and never worked in the first place. Too much risk of damage from the fault you did not see. More often than not, the major issue in the older sets is the wire, wax caps, and bad resistors.

With me, after decades of fixing them, one does not pussy foot around with paper caps and worn out electrolytic caps.


 
 Return to top of page · Post #: 8 · Written at 2:44:20 PM on 14 April 2024.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2405

Yes Marc but you work on radios (not TVs) and you are much more experienced.

Are you saying you never soldered a component lead to the wrong lug? Or clipped a wire under an old component lead so that the wire was still hanging in place by the insulation but now O/C?

Of course you have!

How long did it take you to find your mistake?

Imagine if you did a whole TV chassis and made the inevitable error or two. How long would it take you to find the errors?

If a less experienced enthusiast is working on a set (radio or TV) that is already running, if poorly (having been safely brought up on a dim bulb), then it is far safer for them to replace the paper caps a few at a time, with the aim of replacing all of them.


 
 Return to top of page · Post #: 9 · Written at 4:15:10 PM on 14 April 2024.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6720

I learned the hard way decades ago to change one component at a time.

And these days, with good cameras in phones, it pays to take lots of photos before changing anything.


 
 Return to top of page · Post #: 10 · Written at 10:13:30 PM on 14 April 2024.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

I have worked on TV's and Transceivers, automotive electrics and recently a MIG welder. am not adverse to doing a major overhaul on an engine, plus all of the other fun things that go with farming.

One does make the odd stuff up but taking photos to show where it was before you put it where it wasn't, is always a good plan. One of the plans is not to get too far ahead when changing things out; That can cause confusion and delays when interrupted. It also pays, like the factories to inspect every joint in it and mark them so you do not miss any: To make sure what is on it belong there and it is amazing how many factory joints and others, I have found not soldered doing that (record is three lots of seven).

One major issue is that if you have little idea of what the fault is, especially if it comes in dead or found buried in dad's garage; Powering at the inappropriate time can be catastrophic. This being the equivalent of turning it on to see if it goes. Which over the decades, has seen some extensive damage, by several, that I am expected to fix. So you don't do it.

I will also power after repair with an analogue meter on "B" especially important with Silicon diodes & rectifiers like #80.

So I will stick to methods that work for me and I consider safer for me and the sets. For interest relating to your comment I have not ever destroyed a Transceiver, Receiver, or TV in the 50 years plus, I have been fixing.


 
 Return to top of page · Post #: 11 · Written at 7:33:36 PM on 16 April 2024.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2161

When you pulled the rectifier valve out what readings did you get from the secondary of the transformer. This will prove your transformer is OK or not. Did you use a isolation transformer?


 
 Return to top of page · Post #: 12 · Written at 1:28:27 PM on 17 April 2024.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

There is advantage to not using an isolation transformer if you have RCD's and its a transformer set. If the chassis is earthed, or touched and the transformer has earth leakage, you will quickly now about it.

Marc


 
 Return to top of page · Post #: 13 · Written at 10:22:53 AM on 19 April 2024.
DangerousDave's Gravatar
 Location: Toongabbie, VIC
 Member since 1 September 2020
 Member #: 2438
 Postcount: 131

RCD’s are installed in electrical installations for human safety, not for testing radio components for earth leakage!


 
 Return to top of page · Post #: 14 · Written at 1:29:30 PM on 19 April 2024.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

I do TAG & Test and see wonderous things. Either way, technically you are supposed to Tag & Test it. The RCD is a back up as is the isolation transformer.

However, if its not tested any time, and only used on the isolation transformer. Someone going to get caught out when it on protected mains.

Marc


 
 Return to top of page · Post #: 15 · Written at 3:19:14 PM on 25 April 2024.
Ehsuz's Gravatar
 Location: Newcastle, NSW
 Member since 6 June 2020
 Member #: 2422
 Postcount: 13

Well,
I measured pins 1 & 7. About 250 on each. However there was no signs of life in the circuit. No valves lit up or anything. A closer look at the valve and the top of the socket of pin 3 has come out.
So I need a new socket for 6V4. Do they have to be drilled out. Looks like its riveted in.
I will try evacto.


 
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