#1
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Kolster 6-J need transfomers- Ideas?
Any idea what type and where to find? I would like to get this baby singing soon. Everything looks pretty clean, but saw a few pics online and looks like mine is missing the transformers that sit between the tubes towards the top?
Any help would be great. I'm a newbe to this old stuff...but enjoying! |
#2
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WOW, over a year later and no replys..
Just pulled this one out from the closet and its depresing me. Is it just a loss? Should I wait for the parts to show up on ebay or is there a place that might carry NOS parts or used parts? Anyone have any ideas at all? Thx!! |
#3
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Can you put some pictures back up? Need to identify what the missing part is exactly. Is it an output transformer, power transformer, plate choke etc.?
mike |
#4
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Here's a pic from the top.
pictures i have seen of others have 2 transfomers located on both sides of the bottom middle tube- you can see the mounting holes where something should be... -looks to be the only thing missing that I can see. Thanks for your help. Last edited by Biased; 09-20-2009 at 01:50 PM. |
#5
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I guess that I would upend her and start tracing the wiring and see what is missing. As I see it there are only a few possibilities and once we know how she is wired we can figure out current production replacements.
First thing to do is find out what tubes are in each socket and get the data sheets for them so we can find the pinouts. Then we trace the circuit. The only possible things I can see are... Power transformer, output transformer, plate choke or interstage transformer. Of course if you had a schematic it would be easier but I was unable to locate any info online. Can you give us a high resolution gut shot? mike |
Audiokarma |
#6
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Ok- I have attached a pic I found- It shows the tube types and locations. Also, a gut shot from the bottom of the main board and the top side from a few other angles.
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#7
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good news- found a schematic on Nostalgiaair
attached. thx |
#8
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Comparing your pictures to the schematic, it would appear that it's all there. The coils wound with green wire are the RF transformers that are between the first three '26's and between the third '26 and the '27 detector. Also in the bottom view of the chassis, the two transformers at the lower part of the picture are the audio transformers that go between the '27 and the fourth '26 and between the fourth '26 and the '71. One of the pictures shows the power supply with its twelve terminals.
The radio is ca. 1927 per a note on the schematic but somebody kept it going into the thirties and perhaps later because the tubes are ST type rather than the globe type which would have been originals. The ST's came out in the early 1930's. This set would have used a high impedance magnetic speaker, I believe, but for testing purposes an output transformer and any PM speaker could be used. The first order of business would be to clean everything carefully and then start checking with an ohmmeter. Typically the interstage audio transformers might be open. Not familiar with Kolster, but these transformers look similar to the ones on early Radiolas, and if they are indeed open, there are small replacement "guts" that can fit inside the original shells. You can also check the tubes with your ohmmeter: there should be continuity across the two fat pins which go to the filaments. Usually if the filaments are good the tube is good. The power supply is going to be key to the whole thing; you want to pray that the power transformer is OK. Looking at the schematic, ohm all the windings out. See if any winding is shorted to the shell or to another winding. The divider resistor shows the ohms values on the schematic, should ohm those out. Some or all may be open, but they can be replaced with individual wire wound resistors. The 2 mfd. filter caps can be replaced with larger ones for better filtering as large caps were expensive back then. You could use 10mfd at 450 volt electrolytics. But as I suggested in my PM, follow up to find a Kolster expert on ARF. Then there are further tests if you get past all this. This would be a fun one to fix up. Maybe not too hard to do! Reece
__________________
Reece Perfection is hard to reach with a screwdriver. |
#9
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Reece,
Thanks so much for breaking it down. Will do as discribed- also, if all test out ok, I plan on replacing all the wiring btween the transformers and capacitor- they are visibly cracking and or exposed and are in very close contact w/ each other. Luckly it looks to be standard plastic coated wiring (prob 16 gauge strand). Not the cloth covered I would have to order that is used throughout the rest of the radio. Here goes nothing. |
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