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Marantz 2235B has no sound

Now check the associated emitter resistor with that transistor- it should be a low value like a .5 ohm or .3 ohm. You may be lucky and all that's wrong is that transistor.

Buy 2 of each - MJ21195 and MJ21196, these will replace both channels so they are matched- mouser.com
 
Am I measuring R752? If so, with the meter set at 2K, I get a reading of .215. I'm going up and check the offset and bias now.
 
I think you're to measure R756-759 which are all 22 ohms. Use the 200 ohm scale if you have one. R752 is in the driver transistor circuit. Your reading on that one looks like it's a good part.
 
Bias is 35V, Idle current is 8.2 mv, offset is 0. When I checked the Mouser site, those transistor numbers have been superceded wth the same numbers ending with the suffix g. Is that any problem? And which one replaces which Marantz number? Sorry about all the questions, but I don't know and don't want to screw anything up.
 
Bias is 35v? Bias and idle current is the same thing. 35v could be your power supply regulated voltage adjusted to 35v? idle current (which really should be called idle voltage, current is amps not volts, always been a gripe of mine) should be 8mv, 8.2 is fine, offset of zero is perfect.
 
BK, you're absolutely right. It was the power supply regulated voltage that I checked according to the manual. Oops. I had a hard time adjusting the idle voltage. Too high, too low, too high, too low. Pretty close, leave it alone. Now which of those Mouser numbers matches up with which Marantz number so that I get them in the proper place? And thank you again for the help. I got sound on one side and it didn't sound bad.
 
That's normal, the pot's are a high rating which makes the sweet spot hard to find. Ok- now it' time to do some answering of your own question. 1st- search for the datasheets for the originals- you will see one is NPN and the other PNP. Now seach for datasheets on the replacements , 1 will be npn, 1 will be pnp. Now post the results :).

I'll give you a hint- a757 is really 2sa757. There are 4 letters (besides N which were north american numbers)used for japanese transistors, ABC and D. Anthing that is 2sa/2sb is PNP, 2sc/2sd is NPN. As you do more and more repair work you will memorize this stuff.

Then you will learn "packages" , to-3, to-92, to-220...blah blah blah.

http://forum.allaboutcircuits.com/picture.php?albumid=198&pictureid=1844
 
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PS- once you have the replacements installed- set the idle current and recheck it after 10 mins then again after 30, it will climb as the amplifier heats up. Setting idle current cold is both useful and pointless- you need a starting point but it will climb. Once it's warm readjust it to 8mv and you should be good to go.
 
The transistors are changed, both channels have music! Thank you gentlemen. One last problem. The dial indicator reads about 1/4 inch to the left of the tuned frequency. Is this where I take it to someone to have it adjusted, or can I loosen the lockscrews on the tuner string pulley and slightly reposition the pulley?
 
Did you remember to set idle current/dc offset?

Tune to some station on the high end of the scale- adjust c106 with a platic slot (straight) screw driver until you line up the dial. It's on the tuning cap assembly, the part that the string turns to put it in easy terms. It's the FM front end board, page 7 of the manual.
 
Yes, I did get the idle current/dc offset adjusted. I checked it at about ten minutes and again after about half an hour. It's at spec now. I had a problem with the left channel dropping/fading out, but a few more cleanings of the volume control seems to have solved that. When it would fade out, I could get it back by sweeping the volume knob back and forth.

I tried to adjust the dial by adjusting c106, but it appears to me that the screw head has a dab of solder locking it in place. Or is that just locking it to a washer? Before I screw something up, I thought I should confirm whether I need to remove the solder in order to do the adjustment.

I have one dial light out. I saw bulbs with triple LEDs on the auction site, but the pics made them look quite bright. Any opinions on replacements?
 
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