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 some of the adjustments on the Marantz 2230 receiver.
|I will be performing a recap and LED conversion on a 2230 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 2230.
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. If you have questions or get stuck somewhere, just email me here email@example.com 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|
|This is ok, too|
|But this is NOT ok|
|I buy the highest quality caps from places like www.mouser.com or www.digikey.com because of the ease of buying online, and I get the 105c rated, original uF value at one standard voltage up from original. This ensures that the will last a very long time.|
|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: firstname.lastname@example.org 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. You however might like to use silver solder in your work. Nice call you HIFI tweak! ;-)|
|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.|
|Ok, let's get started. 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.|
|Cleaning pots and switches|
|Next I remove the old power supply capacitors and output caps. This model is sort of an oddball of the 2XXX line in that it has output coupling capacitors. These are easily removed by unscrewing the old hold downs and by cutting the leads. I cut the leads at the cap so that the wires stay bound together. This makes it easy to add the new caps. Note the negative goes to the white wire on the power cap, and to the coil side of the output caps.|
|Add a good amount of solder here to allow for a good, low resistance connection and solid physical strength.|
|Next I add a small bit of foam to shore up the edges of the new caps since they are so much smaller than the originals. This shows us the improvements in manufacturing and design in capacitors over the last 30 years, but we will not add additional capacitance here taking advantage of the space. This can cause disasterous results like damaged power supplies so it's best to stay with the original design specs.
Then I just add a bit of glue to hold everything in place and let it dry.
|Now it's just a matter of going from board to board replacing the bad capacitors and resoldering. You can start anywhere, but I usually start with the power supply and amps so I can power test without worry of failure. I like to make sure the previous board was correct (no backwards caps or solder bridges) before moving on to the next board. After visual inspection I will test the recevier to make certain previous work was 100%. Then move on to the next board...|
|Remove the capacitors from the power supply board and insert new caps being careful to get the orientation correct. Follow the original orientation to be 100% sure, but usually the silk screen + or - will show you which way to install the new cap. Electrolytic caps (polarized ones at least) don't take too kindly to being inserted backwards and you will likely hear a fizzle and see steam or smoke upon power up. So best to get these in the right way the first time. ;-) Solder and clip the excess leads. Reinstall the board.|
|I usually do the amplifiers next. Remove the 4 screws that hold the amp module (heat sink and board) to the chassis and lay it back by gently tugging on the wires. Remove the 4 screws that hold the board to the heat sink, and the screw that holds the diode to the heat sink, and open like a book. This will allow you access to the caps and solder on this board. Replace the caps, being extra careful of orientation, and resolder the bad connections on this board.|
|Reassemble but ONLY after doing a major visual inspection. Make sure that you got all the parts in correctly and that there are no solder bridges or other solder issues. These amps are very picky and like to turn into a pile of ashes if you don't get them just right. A few extra miutes here is always a good idea to make sure all is correct.|
|Now reasseble the diode back on the heat sink, board back on the heat sink, and then the module back on the chassis. Run a quick power check to make sure all is good and then move over to the other power amp.
Perform the same procedure on this amp but hold off before reinstalling the module. I like to keep this uninstalled to give a little extra room when doing the 2 rear left boards on this side of the chassis.
Remove each one from their posts and gently flip the board over to allow you to replace the caps on these boards. Check each board to make sure there are no errors and then move to the next one.
You will have to remove the RF shield for the FM Detector board. Be careful not to squish any wires when reinstalling this cover.
When done with these boards, reinstall everything (including the left amplifier) and check for problems.
I then do the AM and FM MPX boards to complete the recap for the top of the chassis.
|These boards can be a little stubborn to get access to the solder side, so occasionally I need to cut wires here. I usually take photos of these boards with my digital camera to be sure I get things back to the way they were. Also, clipping the wire leaving a small bit of the insulation will give you a clue when reassebling. Sometimes I even have to add a bit of wire to make things fit better. Reinstall and check out the circuits when done with these 2 boards. (Be happy when these are done, they are the hardest!)|
|Prep the tack on cap by bending the leads and clipping them. You can add heat shrink tubing to the leads if you want.
Replace the cap on the meter and the top of the receiver is now fully recapped.
|At this point flip the receiver over and work on the bottom. I like to start with the tone board and then go on to the phono board. These boards are usually easy to remove and manipulate to get the new parts installed and soldered. I then move on to the FM IF board to finish the recap for the bottom of the receiver. You will need to remove the RF shield to access the IF board. Be sure not to squish any wires when you reinstall the cover!|
|Now after a good test to make sure all the electronic work is perfect, I remove the knobs and front face to do the LED conversion.
With the face and knobs set aside, remove the Phillips screw at the left of the dial plastic. Then carefully run your thumbnail or other appropriate object along the top of the dial where the pointer goes to separate the plastic from the chassis. Work slowly and carefully so as not to crack or break the plastic dial piece.
|Once separated, remove the old diffuser paper and clean the edges of the chassis and dial plastic of excess glue. Set the dial plastic aside for the moment.|
|Using an appropriate object (I use a wooden skewer), pop the old lamps out of their holders and discard (I seriously doubt you will ever want these again!).|
|I use a Dremel to roughen up the contacts to allow a better solder wetting...|
|Then with 3 hands, install the LED and solder...|
|Adjust the LEDs a bit "wall-eyed" so they spread their light evenly and then install the next one.|
|Next do the same for the meter lamp: Remove the meter lamp holder, roughen up the contacts, install and solder the LEDs in, adjust the LEDs to reduce hot spots, and then reinstall the meter lamp holder.
I turn the unit on when done to make sure all the new LEDs are functioning properly and make any final adjustments.
We will now install a new diffuser paper and reassemble the front face.
|Now take your dial plastic and use it as a guide to cut the new diffuser paper. You can use ordinary printer paper, believe it or not!
Also cut a small square to replace the diffuser for the stereo indicator lamps.
Reattach the new paper using a small amount of glue being extra careful not to get any on the areas where the light will be shining through the dial.
|Add a bead of glue along the top of the dial plastic where it meets the chassis...|
...and then use a couple pieces of cardboard wedged in the front top of the chassis to hold the plastic dial in place while the glue dries.
Clean the dial plastic of any stray glue and then give a good shine. Now is also a good time to clean up the buttons and Gyro-Touch wheel. When done clean the inside and outside of the face panel window and reinstall the face and knobs.
Now we will replace the bi-pin lamps and the dial pointer lamp.
Remove the bi-pin lamp holder bar that is behind the front lamp assembly by locating and removing the 2 or 3 Phillips screws holding it to the front plastic reflector assembly.
Using your hot soldering iron, remove the old bi-pin lamps and install the new LEDs.
Be super careful not to hit the dial string with your soldering iron!!
I like to make sure these LEDs all work ok and that I have the polarity correct before I reinstall them. So, turn on the receiver quickly and check that they are all good and then reinstall the bi-pin lamp holder bar into the reflector assembly when done.
No we just have to replace these 2 stereo indicator LEDs and the front face will be complete.
Unscrew the 2 Phillips screws and remove the stereo indicator bi-pin holder. Unsolder and remove these 2 lamps
If you are planning on only using one LED here, make sure your current limiting resistor limits to no more than 50mA or so.
Install the new LEDs, solder, adjust the beams if necessary and then reinstall the holder back into the chassis.
That just leaves the dial pointer LED...
Using a knife blade (usually), cut the tape that holds the top of the dial pointer to the body. Remove the small lamp and cut the wires at the base of it. Attach the new LED (no polarity) and solder the connections. Don't forget to put a couple of small pieces of heat shrink...
Place the LED into the dial pointer body and add a drop of glue. I use silicone glue here and if you do it right, the glue will also hold the top on.
This just leaves us with some adjustments and this receiver is pretty much restored. For these steps, you will need a volt meter capable of reading millivolts. I also use a pair of aligator clips to make the adjustment easier and reduce the possibility of slipping while making the measurements.
Power supply adjustment:
First, take the volt meter and measure the 35V rail on the power supply. This is done by placing the red test lead on J808 and the black lead on chassis ground. Adjust R810 for a reading of 35.6VDC
Amplifier bias adjustment:
Once that is set, place the receiver on its side, and clip your test leads across resistor R774. Adjust R765 for a reading of 5mV. Move over to the other amplifier module and make the same adjustment.
If you have access to a signal generator, oscilloscope, and have an 8ohm dummy load, you can make the clipping balance adjustment:
Place the scope probe across the speaker terminals for the channel you are adjusting. Add 1KHz test tone to the Aux inputs and increase the signal level until clipping occurs. Adjust R708 for equal clipping on waveform. Perform adjustment on other channel-adjust R709.
Now let her run for about 30 minutes and recheck the adjustments. When done, replace the covers.
|That pretty much does it for the restoration on the 2230. You may want to take this unit in and have a tuner alignment performed on it if you are into listening to the radio, but other than that, this receiver is ready for another 30 years of listening enjoyment. So dig out some of those old recordings you haven't listened to in awhile, turn up the volume, and enjoy!|
|Some people feel very strongly about the sound of foil capacitors. You might want to consider changing some of the remaining caps to foil caps to continue with the spirit of this website. There are many other considerations (like precision resistors and such) that are beyond this sites scope but hold equal importance in the continuing persuit of the longevity and fidelity of these amplifiers.|