Marantz 2235b. Help!

[H George]

Need some help/direction. I’ve run into a frustrating problem with My 2235b which I’ve had for a few years. I purchased the unit restored from a local vintage store. I’ve already had the unit in to repair this issue once before and it’s now happening again.
What I’m getting is a very loud, harsh buzz sound happening without any sort of regularity. The sound only lasts a second or two and then stops. I’m still getting good sound although this last time I smelled smoke and shut it down. Any ideas ?

 

[runningdog]

Welcome to AK!

Was the speaker switch replaced? When the buzzing happens do the lamps flicker?

 

[H George]

The lamps do not flicker when it happens. I’m unsure about the speaker switch as when I picked it up last time from repair we went over what was done and the speaker switch wasn’t mentioned. Prior to this last repair the unit eventually stop producing any sound at all

 

[runningdog]

What I’m getting is a very loud, harsh buzz sound happening without any sort of regularity.

I asked about the speaker switch because I was thinking you are hearing it from the receiver itself. Or is the noise coming from the speakers? Both speakers or just one?

If you hear it at the speakers then not using your good speakers for now is good idea as the sound you describe could destroy them. This issue begs for the receiver to be on a bench with test gear to limit possible damage to it. IMHO, of course. Where are you located?

 

[H George]

update on this problem:

I took the unit into a local repair shop- one that has a longtime reputation for quality of service. They said after running the unit for hours a day over a few weeks they could not duplicate what was happening. I took the unit home and plugged both my turntable and harmon kardon bluetooth adaptor in and started playing some music. Within a few minutes doesn't the same harsh buzzing sound start. The buzzing stops and the unit goes completely dark and stops giving off any sound.
I unplug both the turntable and the bluetooth adaptor and plug in a small light into the switched and unswitched outlets on the unit. The light illuminates which shows the unit is getting power but of course is completely dead. Any suggestions as to what you think this might be? I'm starting to think this unit is cursed.

 

[wlhd1610]

Power switch?
Fuseholder/fuse issue?

The unswitched outlet on the rear panel is wired ahead of those.


Bob

 

[H George]

Power switch?
Fuseholder/fuse issue?

The unswitched outlet on the rear panel is wired ahead of those.


Bob

thanks. I suspect the loud harsh intermittent buzzing sound is connected to this issue even though when I brought it in for servicing because of this issue they said it couldn't be duplicated. Initially I thought it had something to do with the outlet I plugged the unit into but my Sony that I plugged into the same unit doesn't give me any trouble. I've only had this unit for 2 years and it ran fine for the first year and since then has been giving me fits.

 

[wlhd1610]

I've had Marantz units where sometimes the power switch contacts would arc a little and other times completely behave.
Murphy's law says your car never screws up when you take it to the mechanic for diagnosis!

Bob

 

[H George]

I've had Marantz units where sometimes the power switch contacts would arc a little and other times completely behave.
Murphy's law says your car never screws up when you take it to the mechanic for diagnosis!

Bob

You're absolutely right. This is the only marantz i've ever owned having wanted one since I was a child. We never had money for good audio equipment and I would spend my free time in the late 70's at the local
stereo store checking out the marantz units.

 

[Chanstarco]

Hi
Have you tried not using the bluetooth adapter?
Does this happen when listening to the radio AM/FM or when you have a source connected to the inputs?
Does it happen with your Turntable playing music?
Does it happen at higher volume or not?

If smoke came out previously then the repair shop should have seen something that burned.
Cheers

 

[H George]

Hi
Have you tried not using the bluetooth adapter?
Does this happen when listening to the radio AM/FM or when you have a source connected to the inputs?
Does it happen with your Turntable playing music?
Does it happen at higher volume or not?

If smoke came out previously then the repair shop should have seen something that burned.
Cheers

 

[H George]

I took the unit in to local repair shop that specializes in vintage repair. I was told that a fuse was blown however he was concerned as to what caused it. He was going to investigate. He said maybe a bad diode or possible bad amp? I will update once I get a call back.

 

[H George]

Finally got my Marantz 2235b back from the repair shop. I was told the left channel was weak and I had a bad bridge? He also said the issue was most likely caused by a power surge of some kind? He mentioned the possibility of speaker wires accidentally being crossed as a cause of this.

Now I know the speaker terminals on these are very close but I'm very careful to make sure no wire strands go stray when i hook up speakers.

Here's the fun part. Don't I get the unit home, and start playing both vinyl albums and streaming off my harmon kardon BT adaptor and after a few hours of listening i get the same loud, harsh buzz that caused this whole mess to begin with. The buzz occurred both when I was playing records and the blue tooth (plugged into the aux).

In both cases I immediately shut off the unit and unplugged everything to get it to stop. After plugging everything back in the unit worked fine.

The repair guy said he bench tested the unit for 20 hours and didn't have a single issue. Could it be the electrical outlet the unit is plugged into? The electrical socket initially was a non grounded, ancient, 2 prong socket which was replaced with a gfi outlet
and a power surge protector plugged into it.

Any advice would be helpful. Good grief- I'm getting to point where everything I've spent on this isn't worth it and I'm going to sell it.

 

[Lkhvl]

2 prong to GFCI could be suspect. I would swap the GFCI for a new one. Or go back to a two prong. Another option could be a surge protector with AC filtering.

 

[H George]

thanks for the suggestion- I'm going to go ahead and take them. Do you have a recommendation for a good surge protector? I also double checked my receipt from the last repair that was done. it says
RT channel has very intermittant issue- replaced bridge rectifier.

 

[Lkhvl]

@H George I thought more about this and I would first just move the stereo and set of speakers to a different outlet and see what happens? If it works fine on another outlet you know its likely the GFCI receptical. Those GFCIs can definitely go bad. Assuming the issue doesn't occur on another outlet you know it isn't the 2235b. I would then replace the GFCI with a new one from a good brand like Leviton, as I mentioned GFCIs can be finicky, so pony up $30 for a good one. The other option would be go back to the two prong and use a 3 prong to 2 prong adapter and be sure to attach the ground with the switch plate screw. The AC line filter will work to eliminate RF noise created from other electrical components that are running. So this would most impact AM/FM input. We used to sell them in RadioShack back in the day. Here is one on amazon. https://www.amazon.com/Smarthome-16...gateway&sprefix=ac+line+filter,aps,173&sr=8-8 You can read reviews to get an idea of how it works. I would get a new Leviton GFCI and the AC Filter and that should keep you at $50 give or take and allow you to use 3 prong plugs when necessary.

 

[Lkhvl]

Also, you can plug any power strip or surge protector into the AC filter, but i would try a different one than what you currently have unless the problem predates that surge protector. You are really in the process of elimination here...

 

[H George]

Great advice- to try and isolate this I think I'll move the unit and my turntable to a different outlet to see what happens. I had no idea GFCI outlets went bad but I think I'll go back to a 2 prong outlet. I'll keep you updated, thank you again

 

[H George]

Update: I moved my Marantz into a different room and hooked everything back up. The same thing happened again withing 15 minutes (very loud, harsh, intermittant buzz sound). At least now i know that the problem is with the unit itself and not the electrical outlet.. to double confirm this I setup a newer sony receiver I had using the same configuration. I played music using the sony for 3 hours and no buzzing, no harsh sound.

Here are some more details.

The harsh buzzing sound is incredibly loud and isn't affected by me turning the volume down or up.

The sound isn't effected by changing the input to fm, aux, tape or phono.

After the buzzing starts any audio I'm playing whether it's a vinyl record or streaming thru BT adaptor immediately stops.

The only way to get it to stop is to to turn off the power switch. Turning the unit off and unplugging it and plugging it back in usually resets the unit and allows to go back to playing music although
this morning after I did this it took me a few tries of turning the power switch on and off and unplugging before I could get the unit to make any sound although I could hear a low humming noise.

I'm starting to wonder whether the repair place isn't being entirely truthful by saying they've bench tested it for hours without issue. How is this even possible?

Any advice on this would be helpful as I'm out of ideas. just as a last confirmation I also changed speakers on the unit and still got the same result

 

[Artie]

This has all the earmarks of a classic cold solder joint. As the circuit board heats and expands, the joint opens up a bit. The thing is, it takes a tech with diligence and a good eye, (or a magnifying glass), to find it. At least, by your symptoms, It's probably narrowed down to the amp section. I've seen examples that were far less obvious than the pic I'm posting.