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Kriesler 11-20
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6915
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AORSM Volume 12 , 1954 page 224 as having the schematic
I have emailed you what is in AORSM for the 11-38. The scan quality for these pages is not very good.
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5671
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Also have that scan. Its nice to have them, but the platen on some scans was not very clean. A few for my own use have been redrawn, or cleaned.
You should have better luck with this scan. Kriesler as noted had a habit, especially around war time of chopping & changing with in the same model. I note that at a radio club fix it day, we had three of the same model & three different circuits, of something like 26.
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Location: Sydney, NSW
Member since 1 October 2025
Member #: 2742
Postcount: 39
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Thanks GTC. Pretty sure this is the schematic for my radio. After tracing around the rectifier tube I can safely say that the circuit checks out pretty much 100%. There is still a nagging doubt around that big wire wound resistor. It all checks out as far as the wiring goes except I was expecting to see 1.5K ohms across the inlets to C12 (the dual electro) as the resistor is listed at 1500 ohms. I got 745ohms instead. That makes sense as the inlets to the cap are across one end of the big resistor (R11) and the center tap. I tested R11 and it was 1500 ohms end to end and half that from center tap to each end. Started to think someone has mixed up the resistor taps but there is blue die marker on the lugs that attach the caps to the resistor. That would suggest it is original so I think what has happened is my interpretation is slightly wrong. Unless advised otherwise I am going to leave the wiring as is when I replace the big elctrolytic. As for the big R11 I will leave it alone as it tests good (I think). Also it was a huge relief to finally make sense of the two inlet one outlet config of the dual electrolytic cap C12 and the inter relationship with R11.
I have already replaced all the paper caps. Just waiting on some electros from Carl so I can do the remaining caps. Most of the resistors I have checked so far are OK. I will test and replace any that are bad. I have tested the power transformer and resistance wise it checks out. If the output transformer is bad as I expect after Marcc's comments I have a spare that will work. then I will put some power on and see what happens.
Thanks again to everyone that has helped me out so far. Have to admit I was on the verge of giving up on this one. But the new schematic has re charged my enthusiasm and I will be watching the mail box like a hawk over the next few days. I will report progress when the new caps arrive.
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5671
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Beware: Some items just cannot be checked in circuit with any degree of accuracy. If there is a dirty great electrolytic in the system, It will draw current as it attempts to charge. Resistors will often form series & parallel circuits, giving all sorts of results.
Plate resistors capacitor coupled and anything not forming a DC circuit, can be ok for measuring. Resistances testing high need further attention
Whist I often insulation test the transformer, If the primary wiring is safe, you can remove all tubes & measure the transformers AC voltages.
Krieser's love killing output transformer's; Crack a 9v transistor battery across the plate & screen of 6M5 pins 7 & 1 and if you get the sound of silence, there is a problem.
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Location: Sydney, NSW
Member since 1 October 2025
Member #: 2742
Postcount: 39
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Location: Nuriootpa, SA
Member since 28 June 2025
Member #: 2734
Postcount: 61
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I have a working 11-20 in my collection, I'll have a look to see if it is one with a 'reused' chassis like yours, and if so, you are welcome to email me with any questions for cross-checking.
Oli
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5671
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When you have repaired a few dozen Kriesler's, like others you do get a feel for what has likely killed it.
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