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I could use some expert help on a 2250B that's not getting AM or FM

mosk

mosk

New Member
I'd love a good troubleshooting strategy from a pro (I'm quite new to all of this) on how to narrow down why I'm getting zero reception, am or fm. Biggest clue I suppose is that neither light is on for "signal strength" or "tuning". Since all the other bulbs near there are working (including the dial), my hope is that it's not the bulbs but them being unlit will help narrow it down. As I await for anyone to weigh in, I'll probably explore that further.

Any help from a pro on the order you might tackle a troubleshooting job of this nature OR, better yet, things that always go wrong on Marantzs regarding this issue (i.e. an easy fix...wouldn't that be nice?).

I have a multimeter and basic knowledge...just a little new on the journey. I've attached a picture just in case anything jumps out an anyone who knows these units in and out. I realize not much can ever be diagnosed virtually but I believe in experience and I'm sure someone out there's got something for me to go on.

Peace and big thanks in advance. Having an FM option would be nice for me as my internet is dodgy in my rural area, I only have so much vinyl, and I don't always have the will to DJ in this pro-longed isolation due to Covid-19.
 
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mosk said:
things that always go wrong
Click to expand...

Welcome to AK!

I'm not a Marantz specialist, but a very common cause of the tuner sections not working in a receiver is that the power supply regulator that serves those sections has failed. In your model, the regulator involves a transistor called H804. If the regulator is working, that transistor will have 14-ish volts DC on two of its terminals (base and emitter, with the base having slightly higher voltage) and 34-ish volts on the third terminal (collector). The first thing I would check for is the presence of those voltages.

The service manual, if you don't have it, is available in the AK database. I'll paste a google-mangled URL below, but if that doesn't work you can look in the AK subforum called "Digital Docs" and find a "sticky" thread at the top that guides to the database. It's not a great scan, so you might surf around to see if anything better is out there.

http://www.google.com/url?sa=t&rct=...20Manual.pdf&usg=AOvVaw2sYaGd7MEZfbOEASG4Fw2o

HTH,

chazix
 
Oh - forgot to mention that I think the observation about the tuning meter lamps is a red herring, though the coincidence is certainly remarkable. I'm going by the service manual schematic, which shows those lamps are wired in parallel with the tuning scale lamps - all of them would be always on.
 
chazix said:
Welcome to AK!

I'm not a Marantz specialist, but a very common cause of the tuner sections not working in a receiver is that the power supply regulator that serves those sections has failed. In your model, the regulator involves a transistor called H804. If the regulator is working, that transistor will have 14-ish volts DC on two of its terminals (base and emitter, with the base having slightly higher voltage) and 34-ish volts on the third terminal (collector). The first thing I would check for is the presence of those voltages.

The service manual, if you don't have it, is available in the AK database. I'll paste a google-mangled URL below, but if that doesn't work you can look in the AK subforum called "Digital Docs" and find a "sticky" thread at the top that guides to the database. It's not a great scan, so you might surf around to see if anything better is out there.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwisgfTM8fnoAhUVHc0KHTHoA-QQFjAAegQIARAB&url=http://akdatabase.org/AKview/albums/Marantz/Marantz%202250B%20Service%20Manual.pdf&usg=AOvVaw2sYaGd7MEZfbOEASG4Fw2o

HTH,

chazix
Click to expand...

Thanks for the tip. I did replace H804. I checked those numbers and they're close so I don't think it's that one. It's odd though, that transistor had 3 prongs. The old one had the middle one snipped off and not seeing a place for that middle terminal when I was replacing it, I ALSO snipped the new middle terminal off. Now I'm questioning that although I didn't see an obvious alternative and the unit works fine for vinyl/aux bluetooth streaming. So, dunno. But thanks.
 
This may be dumb but there's only one little post on J806. How do I measure that one? Do I have to try and access the other end of it from underneath to get both poles of the probe on it?
blhagstrom said:
Check J806 on the power supply. You should have about 14V DC there.
Click to expand...
 
mosk said:
This may be dumb but there's only one little post on J806. How do I measure that one? Do I have to try and access the other end of it from underneath to get both poles of the probe on it?
Click to expand...

Yep, that's dumb.
I'm sorry that sounds rude.
It is not.
Dumb means you don't know.

There is a longer part of the post on the bottom of the board but most electronics doesn't have a post so you need to know how to properly probe electronics to be able to diagnose and repair electronics.

If you have mini grabbers, you can get to the post better on the bottom.
If you only have probes, you just touch the post location carefully while powered up.
You should have the tip of the probe insulated completely except for the very tip to avoid accidental shorts.
To insulate, you can use electrical tape, electrical heat shrink, etc..

Since it appears that you don't know that much. I assume you don't know anything about all the rest of the methods and processes needed to make electronics repair and I probably won't have time to walk you through it all. Maybe as a family gang thing, members of AK will contribute to get you there.

mosk said:
Thanks for the tip. I did replace H804. I checked those numbers and they're close so I don't think it's that one. It's odd though, that transistor had 3 prongs. The old one had the middle one snipped off and not seeing a place for that middle terminal when I was replacing it, I ALSO snipped the new middle terminal off. Now I'm questioning that although I didn't see an obvious alternative and the unit works fine for vinyl/aux bluetooth streaming. So, dunno. But thanks.
Click to expand...

This sort of shows that you are guessing.
I recommend you don't guess, ask.
 
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