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  Tele-tales. Part 1
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 Return to top of page · Post #: 1 · Written at 3:17:22 PM on 9 January 2022.
Labrat's avatar
 Location: Penrith, NSW
 Member since 7 April 2012
 Member #: 1128
 Postcount: 305

Hi Folks. I have begun the repair of a Kriesler colour television and thought that you might like to come along on the journey. The patient is a 26” Kriesler Model 660-1, fitted with the 59-01 chassis.

For me, the first place to begin is with the power supply. No sense plugging it in and pressing the “Bang” button. So I removed the power supply and put it onto the examination table. Noticed only one new solder joint, The mounting hardware for chopper transistor had cracked, and the blue insulator washer had burned and cracked, (very common), see the pictures when posted. The blue degaussing thermistor was dry-jointed, but fortunately did not rattle. The blue thermistors are difficult to get, and are different to the white thermistors fitted to later chassis types.

I changed the main filter electrolytic cap. It read alright, but, it is forty-seven years old, and the set lives far far away. Besides, it would probably not survive the one-week test period before the set is returned. The surge limiting resistor to the cap had gone open. No cause was found. So I re-soldered any joint that looked less than pristine, gave the two pots a squirt, and put the supply onto the torture rack, (variac), and tightened the screws, (wound up the voltage).

No good. Turned out the control module was not working. Fortunately, the module is of the plug in type, and I had a working television of the same type. Very useful as source of known working boards and modules.

The little module gave me much trouble. It did not work, but I could find nothing wrong! Guess something is breaking down under voltage. So I threw a small handful of transistors and a thyristor at it, but still no go.

Ding. Round two. I dusted off the oscilloscope, printed out the pages of the, circuit description with waveforms, and soldered on some pieces of solder as test points to the board. I connected the isolation transformer, the variac, and the C.R.O. and tightened the screws. Hmm. All the waveforms in the Oscillator, Modulator, and Driver section looked good, as did the voltages. Even the drive waveform across the emitter/base of the chopper transistor looked good.

Oh well. I restored the 340V connection to the chopper and again applied the mains.
This time it worked and the seventy-five watt load lamp lit as the 155volt rail came on. Lamp running hot. Chopper running cool.

Conclusion.
1. Witchcraft ?
2. Black magic ?
3. Sorcery ?
4. After much thought, I believe a dry joint under the blob of solder attaching the socket to the module. I'm guessing pin No.2

Part two coming soon.

Wayne.

Kriesler 660-1 television
Kriesler 660-1 television
Kriesler 660-1 television


 
 Return to top of page · Post #: 2 · Written at 6:50:18 PM on 9 January 2022.
Morren's Gravatar
 Location: Killarney Vale, NSW
 Member since 19 March 2012
 Member #: 1112
 Postcount: 21

Amazing skills of deduction Warren. You’re a clever man!

I’m putting down my bet for black magic haha.

Thank you again!


 
 Return to top of page · Post #: 3 · Written at 10:50:08 AM on 10 January 2022.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 296

Hi Labrat. Take a thorough look at the control module for dry joints, especially along the sockets. In fact, re-solder the sockets regardless.

I know from bitter experience that intermittent connections on the module will result in destruction of the power supply.


 
 Return to top of page · Post #: 4 · Written at 6:08:02 PM on 11 January 2022.
Labrat's avatar
 Location: Penrith, NSW
 Member since 7 April 2012
 Member #: 1128
 Postcount: 305

Photos submitted.


 
 Return to top of page · Post #: 5 · Written at 7:30:05 PM on 11 January 2022.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6663

Photos uploaded.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 6 · Written at 1:28:18 PM on 13 January 2022.
Tinkera123's Gravatar
 Location: Melbourne, VIC
 Member since 5 October 2009
 Member #: 555
 Postcount: 424

Hi Wayne,
I would like to follow your "adventure" .... but my Google searching for a schematic came up blank.
Do you have a digital copy of it, or a web site ... ??
Cheers,
Ian


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Cheers, Ian

 
 Return to top of page · Post #: 7 · Written at 7:50:45 PM on 14 January 2022.
Labrat's avatar
 Location: Penrith, NSW
 Member since 7 April 2012
 Member #: 1128
 Postcount: 305

Hi Ian.
I've just sent two manuals in separate e-mails to you. They look to have been sent O.K.

Let me know how it went..

Wayne.


 
 Return to top of page · Post #: 8 · Written at 10:28:55 AM on 15 January 2022.
Tinkera123's Gravatar
 Location: Melbourne, VIC
 Member since 5 October 2009
 Member #: 555
 Postcount: 424

Hi Wayne,
Received both .... very clear, readable etc, thank you.
Had a quick look through them this morning and there is a lot of good info there ...
Will follow along ... good luck.
Cheers,
Ian


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Cheers, Ian

 
 Return to top of page · Post #: 9 · Written at 9:43:43 AM on 18 January 2022.
Tinkera123's Gravatar
 Location: Melbourne, VIC
 Member since 5 October 2009
 Member #: 555
 Postcount: 424

Hi Wayne,

Two phrases in your first Post caught my eye .... the "Bang" button ... and "it would probably not survive the one-week test period" ....

these both brought a smile to my face ... Smile Smile


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Cheers, Ian

 
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