Welcome to the restoration tutorials from the "classic" irebuildmarantz.com website. These how-to guides encouraged and enabled countless newbies to rebuild their own Marantz stereos, myself included. The models 2225, 2230, 2235B, 2245, 2252, 2265B, 2270, 2285B, and 2325 are covered.
These guides were created by Robert D. Bowish, the founder of irebuildmarantz.com. Robert once told me that IRM was originally an experiment with building a website, and that it grew into a restoration and kits business fueled by the content on the site. The how-to guides quickly became popular and they hit the top of search engines frequently.
Robert played a significant part in building interest in restorations with these guides being a big part of that. Robert is no longer associated with IRM but the best parts of his work with Marantz continue on today here at the new IRM.and the considerable traffic these pages have seen over the years shows the amount of interest in vintage stereo equipment restoration.
Some of the methods shown would not be considered best practices today, but the guides are still solid after all these years. Part of doing a restoration should include Google queries to audiokarma.org for specifics on how best to work on different issues you encounter with your model Marantz.
This page will get you started on rebuilding/restoring your Marantz receiver!
The intention of this site is to show how to replace the old electrolytic capacitors in Marantz receivers that have likely dried up over the years to restore proper functionality. This site will also show the proper steps to perform bias and DC idle current adjustments on the Marantz 2265B receiver.
|I will be restoring a 2265B model in the following photos but you should be able to do virtually any Marantz receiver by generally following this guide, however the bias settings we will be performing and the parts we will be replacing are tailored to the 2265B.
Just to let you know, I am an electronic technician and engineer and have been working in the broadcast equipment manufacturing sector for over 20 years, so you can rest assured that I know what I am doing. I have restored and/or repaired hundreds of electronics devices over the years. I've worked on and personally aligned audio equipment for places like Skywalker Sound in Marin County, CA, Paul Allen's offices in Seattle, WA, Bill Gate's residence in Redmond, WA, just to name a few. You are in good hands here :-)
I will be assuming that you know how to solder and desolder on printed circuit boards, have basic understanding of electronics and electronic components and the tools shown below, and have a decent amount of common sense. I hope I haven't assumed too much. If you have questions or get stuck somewhere, just email me here firstname.lastname@example.org Use the word "marantz " somewhere in your subject line so the spam blocker doesn't eat your message, and I will do my best to help you.
PLEASE PLEASE PLEASE, if you are headed out the door right now to buy your first soldering iron and solder with the idea that you are going to learn how to solder and repair your Marantz from this website, STOP RIGHT THERE!! Do not attemp any of the repairs on any page in this website if you have not previously had extensive soldering experience. Now, you do not have to be a full fledged engineer to work on your receiver, you do have to know how to produce very solid solder connections, however, and that only comes with plenty of soldering experience. You can very easily destroy your receiver or at least make it worse than it was by simply not knowing how to solder properly, not knowing how to use soldering tools effectively, not using the correct type of solder, the correct type of iron, the correct temperature, etc. If you still think you can do this project as a first time electronics experience, email me first and let's talk about it, BUT BY NO MEANS REMOVE ANY COVER OF THE RECEIVER, OK?
A service manual PDF scan for most models (complete with schematics and parts list) are available for download for free at HiFiEngine.com. High quality paid scans are available for a modest cost from vintage-electronics.net.
|Dried up capacitor|
|But this is NOT ok|
|This is ok, too|
|As for the parts you will need: (Available here at a resonable price.)
I use hi quality 105c electrolytics by Nichicon or United Chem-con (whenever possible) and go 1 level up in voltage. I also remove and replace the tantalums and bi-polar electrolytics. Typically I use quality foil or monolithic caps as replacements for these (.22uF-4.7uF). I recommend replacement of the speaker protection relay, especially if it is original. This unit uses the Omron LY4-0-DC24 version OEM relay (LY2 series also ok).
|Ok, before we get started a few words: First and foremost, DO NOT ATTEMPT TO REPAIR YOUR RECEIVER WHILE IT IS PLUGGED INTO THE WALL. You would be surprised at how easy it is to forget to unplug the unit and how many people get zapped these days. Next, don't fool yourself. If you don't have the tools or know-how to unsolder and resolder new parts into a printed circuit board, you are best to leave these repairs to someone who does. You could easily make scrap out of your Marantz by not knowing what you are doing. Make sure your solder is NOT acid core. Take that roll and put it with your plumbing stuff and go get some good rosin core solder (or mildly active, organic flux solder is best). Not sure? ask me: email@example.com use the subject "Marantz questions". Personally, I use a quality eutectic solder (63/37) with rosin flux (yes, it IS important!). Eutectic solder has the narrowest plastic range which yields the best connections with hand repair work. However I use silver eutectic solder in my work.|
|Once you have your tools ready, prep your receiver by first unplugging it from the wall (Have I made my point yet?). Prepare a work area by laying down some cardboard on your kitchen table, or use your shop work area that is well lighted. Remove both top and bottom covers from the receiver and set aside. I use an old film canister to hold the screws so they don't get lost. You may want to blow the unit out with compressed air at this point (or use a vacuum cleaner) to remove accumulated dust.
I will be starting with the power supply and moving through the receiver and finally ending with the power amp. Because the AM and FM circuits will require realignment which is way out of the scope of this website, I will not be attempting any changes there (I also don't use the phono preamp, so I will not be working on that circuit either). You should decide if your receiver is functioning well enough in these areas before working in these circuits. And you should refer to qualified personell with the required tools to perform the alignments (you don't have them, ok?).
This site's purpose is really to restore the primary audio path through the amplifier to provide better security against a future component failure due to failed electrolytic capacitors, and as a result move toward a receiver that is closer to the original design specs.
|Ok, let's get started. Remove the front face by removing the knobs, the 4 front face screws, the brass center nut, and the counter sink screw on the top. Remove the hardware holding the tone board and while rotating it, pull the tone board out. Take your component cleaner (make sure it is the correct cleaner for potentiometers and switches. Be aware the wrong stuff can ruin your pots! I have used Radio Shack 64-4315 safely, for instance) and soak each switch while working the switch in and out multiple times. Do each switch one at at time. When you are satisfied you have worked it enough, move to the rotary switches and soak and work them over their entire range multiple times. Then move on to each potentiomenter (bass, treble, volume) doing the same. You will likely have to use the adapter tube to get the fluid into the potentiometer. You want the cleaner to get into the canister of the pot itself to clean the inside. Don't forget the balance control. You can access it through the front of the receiver's face.|
|Cleaning pots and switches|
|Change out the electrolytics and tantalms on this board after cleaning. Replace lamps (with LED's!!) and replace hardware and front face. Replace knobs.|
|Now I am going to replace the main audio amplifier capacitors. Disconnect the header connectors to the main audio amp and unscrew and remove the amp as an assembly. Detach it from the heat sink and rotate the board to allow access to the solder side of the board. After replacing the caps on this board, I recommend resoldering every connection with quality eutectic silver solder. These amps get hot and after many years, the solder is bad. Replacing the electrolytics with quality hi-temp caps and the receiver will last for many years without trouble. Reassemble the amp but hold of on reinstalling it.|
|While the amp is out, now is a good time to rework the power supply board. Remove the hold down screws and adjust this board as necessary to get to the solder side of the board. Replace caps here with hi-temp caps at the same capacitance, one voltage range higher (16-->25, 25-->35, 35-->50, etc.) . Screw the board down after you are done.|
|Now reinstall the main audio power amp and reconnect it. You may want to spray the connector pins with contact cleaner and use a toothbrush to clean these first.|
|Now on to the main power supply capacitors. These are the big black caps that are screwed to the chassis. Unscrew these caps and remove the solder on each pin and they come out quite easily.|
|Just keep pulling the solder out of the connection until you can free up the capacitor.
Note the polarity here. Both caps' negative terminal are pointed towards the rear of the receiver.
|Notice the difference in manufacturing over the last 30 years? These caps are both the same value.
Beware, you might want to install larger caps to take advantage of the additional room. This will put undue stress on the upstream power supply and could cause serious problems. Better to stay with the original design values.
(Note: Caps pictured are for example only, not actually from or for this job)
|Moving on to the selector board:
This board requires some mechanical disassembly to get access to the component side. You will need to remove the small c-clip on the inside of the front of the chassis and slide the selector shaft, knob and all, out of the way. Then unscrew the board to allow access to the solder side of the board. Remove and replace all electrolytics on this board.
Be sure to reassemble in reverse order of removal.
The Sound of Marantz
"The Sound of Marantz is the compelling warmth of a Stradivarius. It is a dancing flute, a haughty bassoon and the plaintive call of a lone French horn. The Sound of Marantz is the sound of beauty, and Marantz equipment is designed to bring you the subtle joy of its delight. Wonderful adventures in sound await you when you discover that the Sound of Marantz is the sound of music at its very best."
--From Marantz 2230 Manual
|Now, finish up the rest of the receiver removing and replacing electrolytics and tantalums...|
|Make a quick but thourough inspection of your work and rework any areas that you were not happy with. Once you are sure that all is perfect, reassemble all mechanical components as necessary but hold off on reinstalling the covers to the receiver.
At this point I like to clean up my area and put away my soldering tools. It gives me time to go over the repairs in my head. You never know, you might have missed something and remember it now. A hasty power test can be a bad thing. I understand the excitement but go ahead and take the 10 minutes it takes to clean up to make sure in your own mind that all is done and done right.
|Beware: The following tests will require the receiver to be powered up and could result in electric shock if you put your skin where it doesn't belong. Don't put your hands (or other body parts) anywhere inside the unit that doesn't require it!! Move slowly and deliberatly to the task at hand. Be aware of the over 100VDC potential that exists inside the device and where those potentials exists!
If you don't know what you are doing, YOU COULD BE KILLED! Although most of the circuits are running on 35VDC or less, you could still get a good shock and that is no fun. Just take your time and follow my instructions carefully (remember the old Operation game?) and all will go just fine!!
OK? Let's go:
Power test the unit: Without connecting anything to the receiver, power on the unit. Be very aware of strange odors, smoke, noises, dimming of the lights. If anything out of the ordinary happens, quickly kill the power and inspect. Did you put a cap in backwards somewhere? DId you squish a wire between 2 parts? These things happen.
Upon power you should hear the speaker protection relay engage the speaker circuit, the familiar "click". Did you hear it? Yes, continue on at the next Purple words. NO?, stop at "No click? STOP!!!!" below.
No Click? STOP!!!!!!! What to do? You powered it up and it is just sitting there staring at you. Well, this means that the speaker protection circuit has determined that there is sufficient DC at the output to damage your speakers and has, thus, opened the output to protect them. If this problem was not there before, it means one of 2 things. Either the bias is off enough to engage the protection circuit, or there are more serious problems like a backwards cap, solder bridge, somethinge else. Power down and reinspect your work. Email me if you need to and I will help if I can.
If all is well, we will now proceed to the bias asjustment phase of our project. (follow along in the service manual)
If you feel everything is ok but the protection relay still doesn't engage, we can go around the relay and make the first adjustments (this will likely fix the problem).
Place your red DVM lead on test point 706 (756 for other channel) black on chassis ground (or speaker black connector of your choice) and adjust R710 on the power amp board for 0VDC reading on the DVM. You will probably hear the familiar protection relay "click" at some point in the adjustment as you get things into spec. This is what you want. If all went well, you can make the remaining adjustments following the procedure starting with the green words below. If you still have problems, or can't make the adjustments within the range of the potentiometer, you will have to stop here and troubleshoot...
|Connect DVM to the Left channel output terminals (speaker outputs) black on black or ground. It is of course important to turn on the speaker outputs, so engage the Main speaker switch at the front panel, and connect the DVM to the Main speaker terminals. If you heard no click of the speaker protection relay when initally powering the unit, you will be reading an open circuit which is not what you want to do. (see "no click "above)
Connect a DVM between J717 and J718 on the power amp board.
Adjust R716, for 20mVDC.
Repeat for other channel
That's it.. We're done!!
|At this point you may want to replace burned out lamps, and do any other repairs and additional cleaning before replacing the covers.|