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Please help me repair my Marantz 2230!

justinfranx

justinfranx

Member
Hey there, a while back I bought a recap kit from irebuildmarantz. The unit worked fine but I wanted to do the recap just to make sure it was working as best as possible.

I am a total noob but successfully did the recap following the online guide. The last steps are to do the power supply adjustment, I completed this one.

The next one is the Amplifier bias adjustment:

"place the receiver on its side, and clip your test leads across resistor R774. Adjust R765 for a reading of 5mV. Move over to the other amplifier module and make the same adjustment.

I was trying to get a reading across r774 when my meter lead touched r744 and one of the legs that a wire attaches to on the side of the board.
I blew a fuse, I put a new fuse in, the unit comes on but the right channel doesn't work (this is the same side where I touched the pieces together). And the amp gets hot on that side now. I have now clue how to diagnose or trace down what is wrong, I am only good with a scolding iron and can follow basic instructions.
 
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So theoretically I could take the working ones from the left side and put them on the right to see if that is what is bad?

Any brand of transistor better than the other??
Thank you for the help!
 
I wouldn't use 2N3055 to replace the outputs. Much info here. Be sure to buy new parts from a reputable source to avoid counterfeits.
You can remove the outputs on the bad channel one at a time and test them using the method in Echowars excellent thread.
If you find a bad output, you should test all the other semiconductors on that power amp, particularly the drivers (H755 and H756).
Build a dimbulb tester and learn how to use it before you power the receiver up again.
Read the many threads here on AK relating to 2230 power amp problems.

Tom
 
J757 and J758 are across R774. Much less likely to short something out while doing that measurement if you attach mini grabbers to those jumpers before powering up.
 
^^^^^ +1 Great reminder for all. When making test measurements always hook up grabbers prior to power on if at all possible. Avoids those uh oh moments. :yikes:
 
I didn't have any on hand but didn't think about it being an issue. I was so proud before it happened too...

I know so little it's gonna be a real pain to figure this out and fix it
 
The good news is you already have Catrafter on this thread and he's excellent at helping troubleshoot. Fingers crossed it's nothing too bad.
 
I'm not sure if I can go without listening to vinyl long enough to trouble shoot this properly, order parts, wait a week, perform repairs and start the process over.

If I was to try to order all the parts that MIGHT need to be replaced on the right side power board what would I need to order?
 
Have you tried switching the output transistors from good side to bad side to see if the channel outage follows the output transistors?
 
check the voltages on the collectors of the outputs .. this is made easy as it happens the cases are the collectors .. one should be about 66v the other about 29v ..
if these look good then i suspect you may have burned a driver or a 10 ohm resistor that supplies the drivers collectors .
 
Can you cross patch the left pre-out to the right main-in and the right pre-out to the left main in with an RCA cable..
If the problem swaps channels, your preamp is bad. If the problem remains in the bad side then the power amp is at fault.
 
I crossed the preamp ass you suggested. When the balance knob is in the center I hear only the left speaker, nothing from the right.
With the balance all the way to the left I hear a very weak, very distorted signal in my right speaker only. When balance is turned to right I hear only the left.

I also noticed the front right transistor is getting really hot, none of the others are.
 
justinfranx said:
Totally stupid question but what is a collector or what does it look like?
Click to expand...
a transistor like the one in question has 3 junctions ..emitter collector base ... the collector receives the voltage from the power supply in this case ... anyway less of the confusing bit ...
the transistors as you will have noticed have only 2 pins ..these are base and emitter .. the case is the collector .. this is the first voltage to check as without this nothing happens in the main amp section ...
being a capacitor coupled output one of the outputs runs at around half voltage of the other so the voltages can rise and fall correctly to produce the sound .
these 2 voltages are a good way of seeing what might be wrong ..
so cut to the chase ...meter on dc volts 200v setting if it has that or 100v ... dc of course ..
black probe to shiny chassis ..red to each output transistor case .. record voltages and report back ..
and yes the unit needs to be powered up ....
good luck ..
 
Awesome, thank you so much for dumbing it down for me.

The front right transistor reads 65.4 (this is the one that is getting hot.)

The right rear is reading 0
 
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