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Bush CT187CS - Back to the fray!  

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Katie Bush
(@katie-bush)
Famed V-Ratter Moderator
Posted by: @jayceebee

Philips although one chassis did use one as a combined surge limiter and degauss. They were prone to fuse blowing, if you removed one you gave it a shake and if it rattled it was faulty.

Would that be the KT-3 by any chance? I remember them using a three legged 'mushroom' on the PSU daughter board.

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Posted : 20/11/2020 10:41 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

Pretty sure the KT-3 used a dual posistor but for degauss alone. I think it was a portable chassis, maybe the CF1 that employed it in a dual role with surge limiting. I’m sure Sideband or Red to Black can confirm if this was the case.

John.

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Posted : 21/11/2020 12:35 pm
Katie Bush
(@katie-bush)
Famed V-Ratter Moderator
Posted by: @jayceebee

Pretty sure the KT-3 used a dual posistor

Hi John,

You're right, it did, as R2B told me earlier. I just remembered the white three legged mushroom and without thinking, I just put two and two together - and came up with five! And hang it all, I have two or three KT-3s, I just haven't lifted the back off one in over fifteen years!

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Posted : 21/11/2020 12:46 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

Had a trawl through old PTV mags online just to convince myself I wasn't imagining it and found this, it seems it was the K40 and not the CF1 that used a combined degaus/surge limiter device. Not a dual posistor as the surge limiter needs to be an NTC element.

Degauss

 

John.

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Posted : 22/11/2020 9:06 pm
colourstar
(@colourstar)
Honorable V-Ratter Registered

Back to the A823 power panel and I notice on my spare panel that diode D2 has been replaced with a wire link and R8 beneath it is deleted. Any idea what purpose this mod might have had?

Steve

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Posted : 23/11/2020 3:27 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

One of a number of mods to improve regulation and try to get rid of flutter which plagued this design, with D2 removed R8 was superfluous. You’ll find D2 is now in series with R11.

John.

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Posted : 23/11/2020 3:41 pm
colourstar
(@colourstar)
Honorable V-Ratter Registered

Thanks John- your memory is excellent! Sounds like a worthwhile mod for the board I'll be using then.

Steve

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Posted : 23/11/2020 3:48 pm
crustytv
(@crustytv)
Vrat Founder Admin

PSU mods covered on page 14 here 👍 

Crusty's Collection: Read the repair blogs
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Posted : 23/11/2020 3:58 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

Thanks Steve but it wasn’t from memory, I have two A823 sets to look at and have been reacquainting myself with its design, go to end of section H of the manual in the library.

Edit: crossed with Chris 👍 

 

John.

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Posted : 23/11/2020 4:11 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

8R13 to 1K as mentioned it the PT article does indeed make a very worthwhile improvement and would be the first I myself would implement. 

John.

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Posted : 23/11/2020 4:59 pm
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