Marantz 2285 (non B) Restoration

[MBuras]

Pulled the left amp and diode tested all the outputs and didn't find any defective readings.

Swapped the amps as @catrafter suggested (they do have plugs - YAY!!!) and performed tests again. Sure enough the problem stayed on the left side. The former left board (now on the right) measured fine at 107.3wpc before clipping.

So...confirmed 2 amp boards that work. New filter caps. New rectifier. Guess we're looking at connections and not components? Or a bad ground between one of these components?

 

[catrafter]

Or a test equipment problem.

Tom

 

[MBuras]

Or a test equipment problem.

Bingo!! Just spent the last hour retracing all my steps. Following wires, making sure everything was connected properly. Then it dawned on me to flip the AUX plugs I use to generate a signal tone from my laptop. Boom! The problem switched channels without touching anything else.

So I can recreate the problem on demand by flipping the plugs (red/white, white/red). I've never experienced a problem with the AUX jack on the back of the receiver but if anyone has advice on that I'll listen. Otherwise it's either the cord has gone bad or my laptop sound card has got a problem. Will have to see if the wife will let me borrow hers for test purposes.

 

[catrafter]

Did you try powering the laptop down, unplugging the power adapter and removing the battery? I have had my computer go 'wonkie' to where completely removing power is the only way to get the sound working right again.

Tom

 

[MBuras]

Thanks for the idea Tom. I just finished using my wife's laptop and completed the tests without issue. Will have to mess with my laptop another day but for now I'm proclaiming this rebuild finished and in the burn in phase. Moved it upstairs and into the rotation for a few weeks.

Here's a few pics of the finished product. It cleaned up very nicely and shows potential to replace my 2325 as my main receiver. This thing really packs a punch. Modified output tests put it at 102wpc on the left and 99.5 on the right before clipping. Very respectable.




A huge thanks to the AK community for their help during some of the more challenging portions of the rebuild. Now on to the fun part!

 

[catrafter]

Nice, you did a wonderful job!

Tom

 

[Bkphoto]

looks great, nice job

 

[MBuras]

Thanks! They don't seem to pop up that often, at least on everyone's favorite auction site, so grab one if you find it. So far I'm finding it's one of my favorite sounding restorations. Still breaking it in and then I'll see if I still think that when I hook up my 2325.

 

[catrafter]

The 2325 is a great receiver, but I think you will find that your 2285 keeps up with it.

Tom

 

[Hipocrates]

I'm proclaiming this rebuild finished and in the burn in phase

Kudos!! Great work!

 

[don philipe]

I see the only difference between the non-B and B models is they moved the ballance control from slider to knob.Any difference on the inards that anyone has noticed?

 

[MBuras]

Internally they're quite different. The 2285B uses a single amp board and heatsink for both channels mounted on the right side(still modular plugs like the 2285), the power supply board is turned upright and crammed in between the amp & wires (lots of wires), tuner board is more of a one piece unit IIRC and the phono board is that goofy combo with the selector switch. All this means it's much harder to access.

I've worked on the 2238B/2252B/2265B/2330B and they're not my favorites as far as access. They sound ok but I'll admit I'm biased towards the 1977 and earlier models.

 

[Timewave]

In conversations with techs that have experience with many different models they tell me the 2285 is preferred over the 2285B due to differences in topology. The 2285 uses less feedback and sounds more open. The 2285B was a victim of the "spec wars" of the early '80s where they were driving advertised distortion numbers lower with excessive feedback - and we all know what that does to the sound. My 2285 sounds better than new since its full restoration by Many Moons Audio. Paul Hovenga did a marvelous job on it.

Timewave
Pasadena California

 

[MBuras]

Closest I can get to that comparison is listening to both 2252B/2265B vs the 2285. I definitely felt the mid-range B receivers were a little too clinical for my taste. I'm certainly no expert but just know what I like to hear.

Cheers to the 2285!! Enjoy!

 

[rhodus]

Just got a 2285 to restore for a friend yesterday. I'm going to study this excellent thread before, during, and after my project and also start a thread of my own. Great work!!

 

[rhodus]

I wonder where you can get those? (if that's the case)[/

For sure! I'm looking into the BA312 IC's on the tone board now. Saw a few threads about those possibly going bad. Have to check the schematic and see what voltages I should be expecting on those.

I wonder where you can get those? (if that's the case)

I know this is a 2 year old thread but I just ordered some BA312 op amp upgrade kits from AnalogEsoteric from the bay. They are on the way and I will be using them in my 2285 restore.

 

[rBuckner]

 

[Hipocrates]

@rhodus, let us know how it goes.

 

[rhodus]

@rhodus, let us know how it goes.

Got the Analog Esoteric op-amps installed last night. They are very nice. Still has the "Marantz" sound but is way better. It is not a subtle difference. I will post pictures of my progress on my 2285 thread later tonight. One thing I want to note; there is a 2285 bom list going around and I am working off of it. I noticed that ce36,37 on the pe01 board are originally bi polar. The mouser numbers on the list are not. Any suggestions?

 

[Hipocrates]

Any suggestions?

I would stick with BP.