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Marantz 2275 fuse popping and no left channel

Dr. Humboldt

Dr. Humboldt

Active Member
Well first this 2275 had no left channel. So we recapped pretty much everything but the FM boards. Still no left channel. So we checked the B+, it was fine (35 V). Then on the main amp boards DC offset we adjusted R741 to the correct value, all is well. Then, on the idle current adjustment, I foolishly dipped my VM leads on J705 and J706 and SPARKS! and boom the main fuse is blown (250V 5A). We put in a new fuse and it blows immediately upon power-up.

Question one: what is causing the fuse to pop and how to locate/fix it? Or links to threads answering this Q?
Question two: Any speculation about the dead left channel? We've tried the interconnects on the pre out - main in jumper in the back; it didn't solve our dead left channel problem.

We've taken meticulous notes and photographs with the intention of writing up a detailed 2275 recap thread, but we want to get it fully functional before posting that info.

THANKS SO MUCH for your help!
 
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Pull the outputs and test. My guess is one or more are bad.

Have you confirmed that your signal loss is taking place on the amplifier module? You can run the pre outs to another amp or receiver or you can cross them with RCA'S to see if it moves to the right channel.

Build a dim bulb tester!!
 
Replacing capacitors rarely "fixes" a bad channel unless the problem was caused by a bad capacitor (kind of rare actually).

It was broken.
It should be fixed first.

I will assume by your question and action that you do not actually know how to fix.

Right?

Find a tech to clean up the situation.
 
Ha ha yes, blhagstrom. I do not actually know how to fix. But I am trying to learn -- thanks to all of your expertise! I will proceed to replace the transistors and, hopefully, learn how to fix! (this one at least). I have recapped a couple of tube and SS receivers, with varying degrees of success. But I am learning and it is fun!
 
Well the good news is that the amp modules are easily unplugged and can be sent out individually to a tech for easy repair.

Bob
 
Thanks Bob! The other good news is that I'm working on my friend's amp at his place in Atlanta, about two blocks from ACK Radio Supply. I just picked up two pair of MJ15024/MJ15025 transistors. So I'm about to replace the transistors; we shall see what happens!

Thanks to all of the expertise that you gurus share with novices like myself. I enjoy very much reading up on the advice and answers on these many AK threads. I try to read up before I post a question, but I was way out of my league on this one. I'll be pretty happy if I can get this old beauty running. It belonged to my friend's late mother and will be driving a pair of Frazier Mark IV's or a pair of AR4x's.

Thanks again,
Wes
 
just guessing and replacing is a little dangerous to the unit and your pocket and sanity .
please test things for at least opens and more importantly for shorts .
when one thing goes short just about every-time something else gets taken down with it .
 
Dr. Humboldt said:
Thanks Bob! The other good news is that I'm working on my friend's amp at his place in Atlanta, about two blocks from ACK Radio Supply. I just picked up two pair of MJ15024/MJ15025 transistors. So I'm about to replace the transistors; we shall see what happens!

Thanks to all of the expertise that you gurus share with novices like myself. I enjoy very much reading up on the advice and answers on these many AK threads. I try to read up before I post a question, but I was way out of my league on this one. I'll be pretty happy if I can get this old beauty running. It belonged to my friend's late mother and will be driving a pair of Frazier Mark IV's or a pair of AR4x's.

Thanks again,
Wes
Click to expand...

You really need to build a dim bulb tester and use it.
You really need to test the rest of the parts on the blown amp (the one that you shorted).
With the shorted one unhooked, do you have sound from the other one? If not, use an RCA cable to cross connect the pre-out/main-in in the back to see if you get sound.
Then we may be able to tell what pieces and parts are working and which are not.
This is to determine L/R pre-amp areas and amps.
 
Yes , listen to Blaine!

The 2275 is one of the most desirable Marantz receivers and well worth some tlc.

I'm sure that there is more than just a shorted output or two and continually powering it up after putting in a new output transistor could irrevocably mess it up further.

Bob
 
You've just heard from three of the best. Don't power up again without a DBT, and putting new outputs in without further testing is just asking for more blown parts. Get a DBT and let these guys guide you through the tests you need to do before replacing those outputs. :thumbsup:
 
Thanks for the quick replies, knowledge, and information, gentlemen. I can't thank you enough and your advice will not be wasted. I will probably be back with specific questions about testing, but only after I build a DBT and search the relevant threads. It might be awhile, but I will be back.
 
I
Dr. Humboldt said:
Ha ha yes, blhagstrom. I do not actually know how to fix. But I am trying to learn -- thanks to all of your expertise! I will proceed to replace the transistors and, hopefully, learn how to fix! (this one at least). I have recapped a couple of tube and SS receivers, with varying degrees of success. But I am learning and it is fun!
Click to expand...
I'm clearly no expert but I would also order a set of predriver transistors as well. When I did the POOF magic trick with my meter it took one or two of those out as well. Depends on where you did the poof.
 
Thanks again for all of your help -- and your very quick help, Bob, Blaine, bryans12v, Steven Tate, Pete Hall, airtime, and others who read and agreed. We will try to contribute to the AK Marantz community through a detailed recap list with pics in a future post (I found some of the less recent existing lists to be very different in terms of outdated part numbers, etc.).

Which brings us to blhagstrom's signature: we're putting a limit on our stupidity. We DID build a makeshift dim-bulb tester last night, out of IKEA switches and extension cords he had handy, but we didn't have a proper incandescent bulb in the house. As the owner of the 2275 said, "I sent you three boats!" and conceded that a tech who knows how to fix is the best path forward. I will search existing threads for tech recommendations, but if any of you who've been helping us along already are or would like to recommend a decent Marantz fellow we can deliver this beauty to, please send me a PM (maybe this question belongs in another forum?). I am in Nashville and owner is in Atlanta, and we are willing to drive this baby within four hours, one way, of either location. He also drives to PA regularly and upstate NY annually. I know a great independent tech in Nashville, but he only likes to buy-fix-sell. I've been a customer of Hi-Tech Nashville before and I love Tom's work there, but he is pretty backed up.

A little bit of history of this 2275: owner's late mom purchased it new, which is why we care so about doing it right, and it is in perfect exterior condition. The faceplate could use a cleaning, but all the lettering is 100%. It has its original wood case with few scratches. We recapped all electrolytic and film caps it with the best we could find, following the advice of many recap threads here on AK. We didn't expect that to solve the dead channel, but we hoped it might. I hope this thread will help another novice sometime in the future.

Peace and thanks,
Wes
 
There's one 'wlhd1610' AKA Bob in upstate New York that I can vouch for, great technically and a good guy. I don't know of anyone in the southeast corner of the US though - sadly.
 
Dr. Humboldt said:
Thanks again for all of your help -- and your very quick help, Bob, Blaine, bryans12v, Steven Tate, Pete Hall, airtime, and others who read and agreed. We will try to contribute to the AK Marantz community through a detailed recap list with pics in a future post (I found some of the less recent existing lists to be very different in terms of outdated part numbers, etc.).

Which brings us to blhagstrom's signature: we're putting a limit on our stupidity. We DID build a makeshift dim-bulb tester last night, out of IKEA switches and extension cords he had handy, but we didn't have a proper incandescent bulb in the house. As the owner of the 2275 said, "I sent you three boats!" and conceded that a tech who knows how to fix is the best path forward. I will search existing threads for tech recommendations, but if any of you who've been helping us along already are or would like to recommend a decent Marantz fellow we can deliver this beauty to, please send me a PM (maybe this question belongs in another forum?). I am in Nashville and owner is in Atlanta, and we are willing to drive this baby within four hours, one way, of either location. He also drives to PA regularly and upstate NY annually. I know a great independent tech in Nashville, but he only likes to buy-fix-sell. I've been a customer of Hi-Tech Nashville before and I love Tom's work there, but he is pretty backed up.

A little bit of history of this 2275: owner's late mom purchased it new, which is why we care so about doing it right, and it is in perfect exterior condition. The faceplate could use a cleaning, but all the lettering is 100%. It has its original wood case with few scratches. We recapped all electrolytic and film caps it with the best we could find, following the advice of many recap threads here on AK. We didn't expect that to solve the dead channel, but we hoped it might. I hope this thread will help another novice sometime in the future.

Peace and thanks,
Wes
Click to expand...
For what you would spend on gas money, and tolls on the east coast you could just as well ship it.

PM Bob wlhd1610, he just did a complete rebuild on my Marantz 250M and did an AMAZING job!!!!! There are several others here that are all great at what they do. It's worth the shipping cost.
 
2nd Bob in NY. Have never personally met him, yet, but I've heard and read about his excellent work and endless knowledge!
 
If you decide to send it to Bob (you couldn't do any better), there is a Packing and Shipping section on AK that most people never notice. You definitely want it packed properly so there is no movement or you will get some bent pots and/or switches (ask me how I know :D). Study that whole section and you will get a good picture of how to pack these heavy units properly.
Steve

http://audiokarma.org/forums/index.php?forums/packing-shipping.87/
 
Short list of AK folks that can "do" vintage Marantz well.

Bob, Tom, Randy, Me, others that I haven't talked to in a while and not sure how busy or if they are taking work.

Sturdy box, good foam, FedEx, insurance.
There are shipping horror stories but millions of packages a year are NOT destroyed or damaged.
2 inches of foam rubber on every side is damn near perfect. Go tear a sofa apart.
 
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