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 Post subject: Scott 382-B FM reception issue
PostPosted: Feb Fri 02, 2018 4:26 am 
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Joined: Feb Fri 02, 2018 3:55 am
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Hello, new to receiver restoration and to your site. Have a Scott 382-B receiver picker up last weekend. Took it a part enough to clean all the pots and switch’s and clean out all the dust bunnies. Hooked up speakers and antenna to test FM and the reception was very poor. Now I am in the same spot I have worked on 4 other receivers and know which 3 stations to hit for test purposes but reception was very poor on this unit where other units are fine.

Tried AM and Aux and they both worked and sounded as they should. Unplugged the antenna and got pretty much got the same reception without the antenna than I did with the antenna.

Connections all look secure and solder looks goo on wires and connections I can see. Is there anything else I can test to try to get better From from this unit? The meter on the front has not moved since I plugged the not in but I don’t know if it’s broken or the FM signal is just not strong eough,

Thank you for your thoughts.


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 Post subject: Re: Scott 382-B FM reception issue
PostPosted: Feb Fri 02, 2018 8:09 pm 
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Ikura wrote:
Hooked up speakers and antenna to test FM and the reception was very poor.
First, welcome to the forums.

The service manual for your radio is here... http://akdatabase.org/AKview/albums/use ... Manual.pdf

Look at page 12. It is possible that Q201, N-Channel JFET, has been blown by electrostatic discharge via the external antenna terminal. You should be able to tell by doing the voltage checks.

If you touch an antenna wire to the output going to the next stage and the signal improves dramatically that would pretty well identify if Q201 is the problem.

I have no idea what transistor might be a good substitute. You want something rated for use above 200 MHz. An MPF102 might work fine.

If you look at page 9 you will discover that if you swap Q201 with Q204 and the problem moves from FM to AM this will also tell you that the FM Q201 JFET is the problem (Q201 and Q204 are the same type of device).

Best of luck.

Curtis Eickerman

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 Post subject: Re: Scott 382-B FM reception issue
PostPosted: Feb Sat 03, 2018 3:09 am 
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Joined: Feb Fri 02, 2018 3:55 am
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Hi Curtis, thank you for the reply. I have the sevrvice manual and took a look at page 12. I have to admit I have never read them before and holding the manual up against the actual receiver did not help, I can not tell if I am looking at each picture the way I should. I see the q201 in the pic and it’s AM equivalent but I am but sure how to identify that on the receiver. I see screws on top I could remove it I am not sure I need to go in that far. Not afraid to, just don’t want to if I don’t have.

Am I looking at the correct piece?

Sorry I tried uploading two pictures but they are larger than 256k...


Attachments:
File comment: I underlined in red the parts I thought the manual is referring to.
Receiver2.jpg
Receiver2.jpg [ 211.92 KiB | Viewed 385 times ]
Manual2.png
Manual2.png [ 133.89 KiB | Viewed 385 times ]


Last edited by Ikura on Feb Sun 04, 2018 5:49 pm, edited 1 time in total.
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 Post subject: Re: Scott 382-B FM reception issue
PostPosted: Feb Sat 03, 2018 4:25 pm 
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Ikura wrote:
Am I looking at the correct piece? Sorry I tried uploading two pictures but they are larger than 256k...
Sorry, I don't have any pictures of the inside for use in guiding you.

Try using the step by step procedure found here to see if that allows you to get to a picture size that you can post: viewtopic.php?f=7&t=329341

I believe if you remove the top cover the tuner is located in the right front of the receiver. I don't know if there are any additional covers that need to be removed.

Curtis Eickerman

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 Post subject: Re: Scott 382-B FM reception issue
PostPosted: Feb Sun 04, 2018 5:52 pm 
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Thanks again Curtis, that link worked like a charm. i updated the picture size and added them to the original post. I have been listening to my ipad on this unit the past few days, it sounds so nice. With any luck I can tweak the FM a little more so the unit can be put into play around the house. :-)


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 Post subject: Re: Scott 382-B FM reception issue
PostPosted: Feb Mon 05, 2018 4:32 pm 
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I reoriented your picture to match the picture on page 9 of the manual and added the Q-number identifications for each transistor. The good news is that they are in sockets. So swapping device 201 with 204 should be relatively easy as would be replacing a device. Be sure to get the right wires in the right places when you do so (G, D, S, GND). It would be good to draw a picture of how they are inserted before removing anything.
Attachment:
Transistors.jpg
Transistors.jpg [ 114.08 KiB | Viewed 368 times ]
It might even be good to just wiggle the devices in the sockets to make sure the issue isn't just oxidation on the leads before you swap anything.

Curtis Eickerman

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 Post subject: Re: Scott 382-B FM reception issue
PostPosted: Feb Wed 07, 2018 3:51 am 
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Joined: Feb Fri 02, 2018 3:55 am
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I swapped the 201 and the 204 and did see a noticeable change. I shot each port with deoxit and worked the transistors a few times to see if that helps. Will test again tomorrow after they dry. Going to prepare fo snow tomorrow. Lol

On another note just picked up a a Pioneer PL-A45D that seems to be fine except for the stylus that I ordered. Looking forward to spinning some LPs once the stylus arrives. Have a great evening!


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