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Old 29th January 2013, 11:12 PM   #1
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Join Date: Oct 2012
Default Crate TD35 getting radio stations

Hi,
I recently found a nice little Crate TD 35 (tube driven) that I purchased broken in orde to repair it.
When I first opened it, the two 3300uf 35v bigs caps for the power supply had to be changed
so I replaced them with some higher end 6700uf 35v from Nichicon gold tune
thinking that I can use the opportunity to enhance the original sound a little.
Then the output transistors : a pair of Darlington TIP120/TIP125 where burned
so I changed them with a pair of TIP121/TIP126 which are basically the same
with a higher voltage rating. I change also a small resistor (4.7ohm) according
to the data sheet provided by the technical support which was burned and
dedicated to supply a transistor with a small amount of current since
it was in parallel with a 600v 6a diode. I change the resistor with a 5 ohm since I cannot find the exact value.
Now I have plugged everything back and clean up every connection but when I power it up, I get radio stations !
So I am calling for help since I do not know if it is the things that I have done that made it like that or something I forgot to replace.

Here is a picture of the amp :

Click the image to open in full size.

- The amp seems to have taken some humidity and the input jack have some micro water spots on the metal connectors.
- there is a plate at the by back end of the picture which seems to connect the body of the
last potentiometer with the chassis ground so maybe it is a star ground and
I cleaned up the pot with some sand paper to help the connection but still the same result and
if someone know what this plate is really used for it would be helpful !
So I am out of idea so if someone can help me with that it would be great !
Thanks

Last edited by hotsauce1080; 30th January 2013 at 01:12 PM. Reason: Mistakes
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Old 30th January 2013, 06:41 PM   #2
diyAudio Member
 
Join Date: Oct 2012
Made some improvements lately :
I desolder every jack which seemed a little rusted or have taken a lot of
humidity and plug the plug everything back and no radio !
So it seems the problem was from them, I am going to change them and
post the results !

Click the image to open in full size.
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Old 28th February 2013, 05:23 PM   #3
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Join Date: Oct 2012
No more radio !!! Great so oxydized jacks can pick up radio !
good to know for the rest!
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Old 28th February 2013, 06:29 PM   #4
Enzo is offline Enzo  United States
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Join Date: Sep 2004
Location: Lansing, Michigan
Usually radio reception means a lack of grounding in an unterminated input. A quick burnish of the shunt contact on the jack usually solves this. And of course refreshing the solder to the jacks.

May I suggest, in projects like this, FIX the amp first, and THEN do any upgrades. Changing a bunch of stuff in hopes of making it "better" "as long as I was already in there", is just begging to set up situations like:
Quote:
So I am calling for help since I do not know if it is the things that I have done that made it like that
If you find out what is wrong with an amp first, then there is no confusion about involvement of other changes made.
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