Marantz 2330 Monster Receiver Restoration & Repair

Monster receivers – if you follow my site you’ll know I love them, kind of. Nothing screams statement hi-fi gear louder than the classic monster receivers of the 70’s and 80’s and this Marantz 2330 is up there with the best of them.

The Marantz 2330 is a heavy receiver, actually very heavy for its moderate size – it’s dense. It’s perhaps not quite as epic as the massive Pioneer SX-1250 or Sansui G-8000 monster receivers I’ve worked on, but it’s big, and heavy.

By the way – two more epic monster receivers coming up soon – a Sansui G-9000 and a Pioneer SX-950…

People love this classic Marantz gear for many reasons – the build, the classic blue deco aesthetic and the rich, warm sound.

In terms of engineering, the Marantz 2330 is as well-made as anything Marantz did. In fact, it’s easier to work on and better put-together in my opinion than the ridiculous Marantz PM-8 I restored recently. More on that in an upcoming article.

The problem with this 2330 is that it was stored for many years in a shed in Queensland. For those who don’t know, Queensland is in northeastern Australia. It’s tropical, hot and humid, and there are lots of very large insects.

These factors combined to create perhaps the most insect-dropping filled, dust-laden, spider web draped, rust-covered piece of otherwise good hi-fi equipment I’ve seen in a long time!

For the abbreviated version of all this, check out the before and after restoration video, on my YouTube channel.  For the intimate details, read on.

As usual, you can find manuals and specs at the HiFi Engine. Specifications here are courtesy of them.

Specifications

Tuning range: FM, MW
Power output: 130 watts per channel into 8Ω (stereo)
Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.07%
Damping factor: 60
Input sensitivity: 1.8mV (MM), 180mV (line)
Signal to noise ratio: 78dB (MM), 90dB (line)
Output: 775mV (line), 1.5V (Pre out)
Semiconductors: 4 x IC, 96 x transistors, 55 x diodes, 2 x FET
Dimensions: 491 x 146 x 386mm
Weight: 22.5kg (bloody heavy…)

Dust, Webs & Dirt…

Let’s have a look first at how this elegant old girl came to me. She was running, only one channel, and only just.

Nothing too bad at first glance right..?
Lots of exterior dust that doesn’t really show in these pics, but stick with me here…

Time to lift the lid and see what awaits inside..

At this point, you really should watch the video, from the point where I lift the lid. Remember, I haven’t seen inside to this point 🙂

Yep, this is what I found. Check out the ‘patina’ and look more closely for the insect droppings and webs…
The sands of time, heat and humidity of far north Queensland with do this to a painted surface. I actually quite like it!
Umm… Yeah. Lots of trouble here on the protection board, and of course in the amplifier module just behind it.
Here’s the other amplifier module
And yeah, she’d been running for a long time with this terminal (like the pun?) filter capacitor fault.
Restoration & Repair

I always start projects like this a proper chassis wash and dry. It’s the only way to see what I’m really dealing with, plus it helps me give the owner a better idea of what’s going on.

The main issues here are damage from classic corrosive polychloroprene glue, plus age-related issues with dry joints and capacitors.

Chassis
Those of you who follow my work will know I’m a proponent of properly washing dirty equipment like this. It’s the only way to see whats really going on, everything else is a waste of time until a component like this is properly washed, and dried.
Here you can really see the difference after washing. I can now see what I’m dealing with – corrosive polychloroprene glue, corroded capacitors, heat damaged parts and dry joints.
Regulator & Protection Board
This is the regulator and protection board. Here, the damage caused by the corrosive polychloroprene glue is clearly visible. It has eaten through a leg of this capacitor that you see bent, plus the little transistor just below it. All the capacitors on this board must be replaced.

Here’s a better view of that capacitor – look Mum, one leg! Not much help if you’re a capacitor.
Check out the little 2SC945 just to the lower left of the first dead capacitor. Do those legs look right to you?
Ah, no, they’re not right are they! They’ve corroded right through.Lucky I have NOS 2SC945s in stock.
Yep, that’s where it just fell off the board. Extensive cleaning and restoration of this board is needed.
Best way to do this is remove all the necessary components, then remove all the glue, mechanically and chemically.
Looking better now
No point messing around here, I’ve got the board out, clean and all these caps have to go.
While I work on boards containing relays, I usually like to service them also. This involves desoldering them, opening them up, removing the relay armature and carefully cleaning the contacts, before re-installation.
So here’s the finished, refurbished board. These capacitors I’ve used are all laboratory-grade, this board will work better than new, and for a very long time.
Power Supply

The next step was to address was the power supply. One of the filter capacitors has burst, releasing its corrosive contents onto the buss bar and chassis below.

What we are looking at is the bottom of two big Panasonic filter capacitors. The shiny thing joining them is a very low impedance buss bar that is the reference circuit ground, and by connection, chassis ground also. The green goop around the screw is copper corrosion. The buss bar is actually tinned copper, nice touch by Marantz that you wouldn’t often see now. When copper corrodes it forms copper oxide, which is green. This would have happened as a result of the reaction between the ejected electrolyte from the capacitor, and the copper. Anyway, the top capacitor is toast and must be replaced. The bottom must also be replaced if we are to do the job properly.
These are the removed filter capacitors. They actually still measure pretty well, a tribute to the quality of these older parts.
Is it just me, or does this look like a dirty kid’s startled face..?!
Lovely new replacement IC capacitors in the foreground, all the way from the US of A, from my stock. Note that, even though the new parts are of higher quality and higher capacitance, they are only about 2/3 the size of the originals. The trick with replacing filter caps is to get the diameter the same, and the height less than or equal to the originals in most cases.
This is what that buss bar looks like after a good clean. Note the exposed copper.
The underside, this doesn’t need to look perfect, we will have super-low contact resistance between the buss bar and the capacitor.
New capacitors installed and this is how it should look. Note the neat cable dress on the positive (top), ground (center) and negative (bottom) terminals.
Beautiful!
Amplifier Modules

Time now to refurbish the amplifier modules. As will all good Marantz amplifiers, these modules are very thoughtfully designed and laid out.

Modules flip out from the side of the amplifier after removing some screws. Note the neat wiring, compact layout, properly heatsinked driver transistors, high-power emitter resistors and compact design. That is a 130 watt module you are looking at.
Opened up, they look like this. I now have access to the output devices, which I will clean and remount on silicone thermal pads. I’ve also got access to the back of the board, for re-work and to replace the six or so capacitors on each board.
All original output devices, very nice. You can’t tell, but these proper old-school TO-3 devices are so heavy, there is much more metal in them than the flimsy thin modern TO-3 devices.
You get a better appreciation of this from the side view. No kidding, that metal base is about twice the thickness of the bases of modern devices. Anyway, thermal grease removed from all these, I then test them and reinstall them on a now clean heatsink.
Before removal, cleaning and remounting…
And after, what an improvement.
Another view, just because we can!
The back of a board, after cleaning and re-work.
The front of the board, also after replacement of caps and re-work.
Second module, before re-work…
After output device service…
And after replacement of capacitors and re-work.
Front Panel & Cosmetics

In my opinion, there’s no point in doing all this hard work inside a lovely receiver like this 2330, only to have it look grubby on the outside. I am a big believer in making a real effort with the external appearance of vintage gear like this, whether its rare and collectible like this, or just a $200 budget receiver.

First step is always to remove the front panel. Yes, guys take shortcuts here to save time, but you can never properly clean behind knobs or the nooks and crannies of the front panel if you don’t remove it, plus all the controls.
Quality cleaners and chemicals are essential with the work I do. This is very gentle on the front panel itself, but tough on grime!
Stubborn dirt gets attention from the (soft) toothbrush.
The knobs always get warm, soapy water.
While that’s all happening, it’s time to look at other cosmetic elements important on a vintage receiver like this – lamps. One can never underestimate the importance of the visual impact of lamps working properly. A beautiful tuning dial and meters like on the 2330 need to be illuminated. To that end, I replace all these fuse style lamps…
And another 6 that you can see below these small round source lamps.
And this critical little lamp, that lights up the tuning pointer.
New tuning indicator lamp ready to go
You haven’t seen all the extra time spent cleaning and lubricating the tuning pointer sliding surface, dial string pulleys and tuning capacitor, plus a bunch of other stuff.
All the replaced parts
The Finished Marantz 2330

This is always the best part, adjusting everything, putting it all back together, and turning it on for a few final photographs. Hopefully the owner will be as happy as I am about this restoration, given how it looked before, I think we’ve really come up trumps here.

And WOW, what a difference it all makes!
That’s one very pretty receiver.
I’ve always had a soft spot for the blue meters on Marantz equipment, even faded as these are.

That dial is just stunning, a real work of art.

So that’s it for another big restoration folks. Can you believe I’ve already had people who’ve watched the video I made about this contact me to ask if they can buy this baby! I wish I could sell it!

Don’t forget, Liquid Audio specialises in the service, repair and restoration of all classic hi-fi stereo equipment. If you’d like me to look over your Marantz receiver, or any other piece of classic hi-fi gear for that matter, get in touch with me.  I’ll be happy to help.

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