Recently, a friend of mine asked if I would clean up “some Kenwood receivers” he found at his Dad’s house. He said none of them were working properly and he thought a good cleaning might do the trick. I agreed to try.
I was surprised when they arrived with the units to see three Kenwoods, comprising of one KR-4600 and two KR-5600s. One of the 5600s looked in pretty good shape and was fairly easy to clean, but the 4600 and the other 5600 were a real challenge.
The issue I was having was losing sound while using the phono input. I had cleaned the volume pot on each and had zero issues while listening to the radio or aux inputs. In fact, each of these units have two phono inputs, and often Phono 2 would play fine, but on each unit, Phono 1 was still giving me problems.
It’s worth noting that last year I bought a Kenwood KR-5600 of my own off Facebook Marketplace. The owner said it played great and of course I got it home and the phono input started giving me trouble, losing sound in one channel. I took the top cover off the unit and sprayed all the pots I could see, but couldn’t get it working again. I set it aside to deal with later.
While working on my friend’s units, I noticed that the sound was most impacted when I moved the Tape Monitor and Input Selector switches, both located on the right side of the unit. I also noticed you cannot spray DeOxit into the pots at the front of the unit as there are long rods extending to the back of the unit where the pots are actually located.
I looked up the manual online and found where you can unscrew the rear of the unit and slightly peel back the preamp board (I couldn’t get it fully removed, too many screws) where you will see the pots located on the bottom of the board to spray in Deoxit.
See below screen shot of manual explaining how to access the preamp.
Note, the long rods connecting the pots to the knobs on the front of the unit will separate from the pots when you peel back the preamp board. Reinsert those properly and then turn the knobs several times to work the DeOxit in and let it do its magic.
This worked for all of the Kenwoods, including the 5600 I bought last year.
I knew I’d probably never have that many Kenwoods around again so I snapped the above photo with them stacked on each other.
If you have a Kenwood giving you trouble, trying this cleaning technique before giving up on it completely!
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I bought this Sherwood S-7200 receiver while traveling to visit family over the Thanksgiving holiday. It was listed on Facebook market for just $40 because it had a weak left channel. I sent the buyer a note while we were shopping at the local mall and it turned out he lived 5 minutes away so he brought it over to me while the family finished shopping. I snapped this photo in the parking lot after purchasing.
I’ve repaired three of these Sherwood receivers now, all with weak sound output from either the left or right channel and have found a common repair among all three.
First, it’s common for weak sound from a channel in vintage receivers to be repaired by a good Deoxit cleaning on the volume or balance pots. However, in these Sherwood models such as the 7100 and the 7200, you do NOT want to spray Deoxit into the volume pot as it also acts as the power switch. This switch contains plastic which Deoxit will corrode causing the switch to break and be completely inoperable. This is a very common issue with this line of receivers. Instead, shoot a little bit of Faderlube in there to clean.
But even with a cleaning of the pots, you will most likely still have a weak channel. Here is how I repaired…
In short, there are eight 4.7uf/25v capacitors that need to be replaced on the tone board. One of the caps is an axial lead but there’s enough room to plug in a radial cap. The below photo shows the new caps in place. I’ll include another photo with all of them circled as well. The service manual has them listed as 901a, 901b, 902b, 903a, 903b, 904a, 904b with the axial cap listed as 902a.
In the most recent model I repaired, the left channel was weak. Replacing these caps brought both channels back to life. In all three repairs, simply recapping this board fixed the issue.
It’s worth mentioning the solder pads on this board are very close to each other. Be sure to note which pads should not have solder flowed between them, especially when installing the new caps. I accidentally soldered one of the capacitors negative and positive pads together which caused the right channel to then disappear. Not good. Going back over the board, I found the mistake and cleaned it up and now it plays great. So be sure to take your time and be as clean as possible when installing the new components.
One more thing, further research online shows that the old Sanyo transistors on this tone board can eventually cause a loud hiss. Since this tone board isn’t fun to get access to, I went ahead and replaced those transistors with KSC1845s. The photo below shows the new transistors circled in red.
The hardest part of this repair is accessing the tone board. I had to unscrew the bracket holding the two big filter caps to provide for enough spacing to pull the board out and access. Be careful when you’re moving the board and take a lot of photos as it’s common for a little connection wire to break loose somewhere on the board which will cause sound to disappear completely.
I love these little Sherwood receivers and their sound. A lot of people swear by them and enjoy the warm, tube-like sound they provide.
If you find one in the wild that’s priced cheap due to a weak channel, consider picking it up!
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The P-700 phono board in model 22 Marantz units is prone to noisy output, mostly due to leaky transistors and diodes. I recently rebuilt a phono board on the Marantz 2230 receiver and decided to post a how to for anyone with soldering skills to attempt.
If your Marantz 22XX receiver is experiencing noise on the phono output or, you have soldering skills and want to go ahead and rebuild the board before it does, this post is for you.
I recently picked up this Pioneer SX-780 receiver from a local record store. I brought her home, hooked her up and she powered on fine but there was no relay click and I couldn’t get any sound to play. Bummer.
I hit up the trusty AudioKarma message boards and found this solution and decided to give it a try.
In short, over the many years these have been operating, the solder joints on the voltage regulator run hot and develop cold/cracked solder joints.
I removed the old solder, cleaned the board, applied fresh solder and everything came back to normal!
A friend of mine recently asked me to take a look at his Marantz 2238b receiver. When I met him to pick up the receiver, he said overall it “sounded bad” and one of the channels was possibly out.
Thankfully the receiver simply needed a good cleaning and some lights replaced. See before and after in the video below:
From static channels and burned out lights to clean sound and bright lights.
Please note – I am still teaching myself how to repair vintage audio gear and would not consider myself an expert. This guide is not meant to repair all vintage audio gear, only point out how to handle cleaning and replacing lights.
If you are a beginner and want to follow this guide, please take your time and go slow. There are some steps that I will not include because they require soldering knowledge. But everything else just requires a screwdriver, some Deoxit, new lights, (a lot of) patience and a steady hand.
Let’s begin.
FIRST THINGS FIRST: UNPLUG THE UNIT!!!
These receivers pack enough of an electrical punch to cause serious injury so please unplug the unit before following any of the steps below. We can’t be held responsible for any damage to your equipment or more importantly yourself so please unplug the unit and if any of the steps below feel dangerous to you, please have a professional handle instead.
Let’s Replace Those Lights!
With the unit unplugged, we need to remove the top of the unit which is easily handled by unscrewing four screws on each side of the unit. In the photo above I have already removed two from the left side.
Also, there are four screws on the top of the unit to remove: two in the front, two in the rear. See photo below with screws circled…
Remove the cover and you’ll find the above view of the unit…
First, let’s replace the lights for the Signal Strength and FM Tuning meters on the left side of the unit.
In the photo below you will see two plastic tabs circled.
PLEASE NOTE: Both of these tabs snapped off when I attempted to unhook the light’s base. I was able to glue them back after I replaced the lamps but it took some patience.
Broken tabs. I think these break fairly easy since after the first one broke, I took extra special care on the second to no avail.
What you need to do is remove the lamps from their casing. As you can see, it should be as simple as sliding them up and out of the plastic tabs mentioned above but remember, these are over 40 years old and those pieces get fragile with age. Hopefully they will not break on you.
Once you have them released from those tabs, simply pull the piece back to reveal the bulbs as shown in the photo below. In this case both bulbs are burned out.
All you have to do now is replace them with your bulb of choice. In my case I had some extra LED lights lying around as replacements in the photo below.
Now, simply secure the lights back in place and you are ready to move to the tuning dial lamps!
The best way to approach the tuning dial lamps is by removing the board from plastic pieces very similar to the ones for the meter lights. I’ve circled the spots in the photo below. I was able to take a screw driver to one end of the green circuit board and push slightly up until it came loose. Thankfully, none of the plastic holders broke on me like they did on the meters!
I’m not sure why the scotch tape is present on this unit. I left it in place after changing the lamps.
Once the circuit board is free, simply tilt backwards to reveal the lamps as shown below:
Simply replace each with a new bulb…
Once the lights are replaced, insert the circuit board back into place.
Please note, since this is a beginner’s guide, I’m not including how to replace the tuner pointer light, stereo light, etc., as those require soldering.
Lastly…where do you buy lights? I use www.dgwojo.com where I email David the name of the unit and model number and he provides me with the options needed.
Cleaning Pots. Eliminate Scratchy Sounds For Good!
To eliminate scratchy sounds on your receiver, you need to clean all of the potentiometers or “pots”. These can vary from knobs you turn to buttons you push or slide.
The Marantz 2238b has the following pots and switches to clean:
Five pots to clean: Bass, Mid, Treble, Balance and Volume (the most important).
Eight push button selectors to clean: FM Muting, FM 25, Tape 1 Monitor, Mono, Hi Filter, Loudness and Speakers 1 – 2. The most important button to clean is the Tape 1 Monitor.
Below are instructions on how to access and properly clean.
First, with the power still unplugged from the receiver, remove the bottom casing from the unit. You might want to keep a bowl or container close by to keep the screws safe as they have a tendency to run away. I count twelve total screws.
The secret to clean pots is in the sauce and you will want to have a can of Deoxit on hand to spray into the pots to clean. Deoxit can be found at your local Guitar Center or simply via Amazon.
I do not recommend using any other cleaner besides Deoxit. Please do not take any liberties here and try something different. Deoxit is the only product to use.
Where do I spray? In the photo below you will see all of the pots to clean.
Spray right into the openings of each pot as shown below. You do not have to spray a lot. A little squirt goes a long way with Deoxit.
After you spray the Deoxit in, simply turn the volume knob on the front of the unit back and forth, back and forth many times to work the Deoxit in. I usually go back and forth about 100 times which sounds like a lot but since I have the unit open I may as well get her as clean as possible.
To clean the push button switches on the front of the unit, you will need to locate the circled area in the photo below. Once the Deoxit is applied, I simply the push the button in and out around 100 times to make sure it cleans properly.
The most important push button switch to clean is the Tape Monitor one. A dirty Tape Monitor switch can cause all sorts of problems, including a loss of sound. Just remember to not keep the switch activated when you eventually power the unit back on or you will not have sound.
Congratulations, you have cleaned all of the pots and switches needed.
WARNING: DO NOT POWER THE UNIT UP TO TEST FOR 24 HOURS.
I usually give the Deoxit PLENTY of time to dry before I power the unit back up to test. Even though Deoxit dries quickly, it’s still liquid based and we know how electricity and liquids mix. So, pat yourself on the back for all the work so far and just be patient, knowing you can power her up the next day.
One last piece of advice, before you plug the unit back in and power her up to test everything, go ahead and turn the volume knob all the way down and make sure your balance knob is correctly centered. Just give the unit a quick eyeball to make sure you will not blow yourself (or your speakers) away when you turn the unit back on.
If everything was cleaned properly, the unit should light up nice and bright from the new lights and the scratchy sounds should be eliminated. If so, turn the unit back off, unplug again and reinstall the bottom and top covers.
If this doesn’t fix the problem, take the unit to a professional for repair. These instructions are meant for a beginner to clean the unit, not attempt a professional repair.
In the video I posted above, all that was needed were clean pots and new lights to get the unit playing properly again. These vintage units can still need a lot of adjustments or to be recapped for optimum use, but for now at least this will get it playing. Any further maintenance or repair should be taken to a professional.
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Also, don’t forget to shop our Discogs Store to purchase used records, CDs and 45s!
A few weeks ago I received an estate sale notification containing a few blurry photos of all the items for sale. I could spot a receiver in the pile but couldn’t tell what model it was. I assumed it was a Pioneer and that it would sell quickly as vintage gear usually sells on the first day. The only plus was the sale was over 40 miles outside of the city, in a very rural area, so maybe it would still be there Saturday.
I made the long drive on Saturday, leaving later than planned, telling myself the entire way it was a waste of time and the receiver would have been sold.
I pulled up to the house and noticed from the long driveway that they still had a lot of items for sale. As I walked up the driveway, I saw the receiver immediately only to discover it wasn’t a Pioneer but a Marantz! And even better, they had it priced fairly at $115. I plugged her in and she powered on properly so I offered $100 and they accepted. I was excited.
Upon first testing of the receiver at home, I knew immediately it needed a thorough cleaning and a few lights were burned out. As I adjusted the volume knob, the music would completely drop out and make awful scratchy noises.
Below is a before and after video showing how she looked and sounded when I first brought her home and after I cleaned her up and installed new lights.
These issues are common with old receivers and people often ask me how to clean up an old receiver. I’ve spent the last two to three years researching these methods through YouTube videos and audio forums and decided to put together this step by step guide for beginners.
Please note – I am still teaching myself how to repair vintage audio gear and would not consider myself an expert. This guide is not meant to repair all vintage audio gear, only point out how to handle cleaning and replacing lights.
If you are a beginner and want to follow this guide, please take your time and go slow. There are some steps that I will not include because they require soldering knowledge. But everything else just requires a screwdriver, some Deoxit, new lights, (a lot of) patience and a steady hand.
Let’s begin.
FIRST THINGS FIRST: UNPLUG THE UNIT!!!
These receivers pack enough of an electrical punch to cause serious injury so please unplug the unit before following any of the steps below. We can’t be held responsible for any damage to your equipment or more importantly yourself so please unplug the unit and if any of the steps below feel dangerous to you, please have a professional handle instead.
Let’s replace those lights!
With the unit unplugged, we need to remove the top of the unit which is easily handled by unscrewing four screws on each side of the unit. In the photo above I have already removed two from the left side.
Above is just an overhead view of the unit. This is what you will see once you have removed the top.
The lights for the dial face are underneath that long silver piece in the top photo. I’ve circled the two screws you need to remove in order to access the lights. Please note, these units are almost 40 years old and some of the plastic pieces crack easily. You can see in the bottom left photo that the plastic is cracking. When you remove and return the screws, go easy so those pieces do not break further.
With those screws removed you can slide the lights out by gently pulling it away from the front of the unit. In the photo above I’ve already replaced the lights with LED bulbs. What you will find are lights that look like fuses as shown in the bottom left photo below. Simply dislodge the old light and replace it with the new ones. Be careful, the old fuse lights can often break with too much force. I usually pry one side loose with a screwdriver and pop out of the socket.
Once the new lights are installed, the dial face should light up nice and bright like the below photo. Please note: if the dial pointer on your unit is burned out and you are a beginner without soldering skills, find someone else with the proper experience to handle replacing it for you. A hot soldering iron around the dial string could result in serious damage you want to avoid. I’m not including instructions on how to replace the dial pointer since this is a beginner’s guide.
Next, we need to replace the tuning meter light below. This photo is after I installed the new light.
The two screws below need to be removed but before you do, please read below…
CAUTION: THE DIAL STRING IS ATTACHED!
With the screws removed you run the risk of the dial string coming loose. (The dial string is what allows you to tune in radio stations and if it is cut, you will loose that function on your receiver.) I was able to keep pressure on the string so it didn’t come off the plastic guide. It might not have mattered but I was worried the string would fall off the other guides leaving me have to restring the dial which would not be fun. Just take it VERY SLOW here. There is one light bulb inside the plastic piece which can be gingerly swapped out.
Once the tuning bulb is replaced, you are finished and can put the top of the unit back together.
Lastly…where do you buy lights? I use www.dgwojo.com where I email David the name of the unit and model number and he provides me with the options needed.
Cleaning Pots. Eliminate Scratchy Sounds For Good!
To eliminate scratchy sounds on your receiver, you need to clean all of the potentiometers or “pots”. These can vary from knobs you turn to buttons you push or slide.
The Marantz 2215b has the following pots and switches to clean:
Four pots to clean: Volume, Selector, Treble, Bass
Four push button selectors to clean: FM Muting, Hi Filter, Tape Monitor and Loudness
One slider to clean: Balance (Left to Right)
Below are instructions on how to access and properly clean.
First, with the power still unplugged from the receiver, you need to remove all screws underneath the unit. You might want to keep a bowl or container close by to keep the screws safe. These screws have a tendency to run away. I count 11 screws in the above photo that need to be removed.
The secret to clean pots is in the sauce and you will want to have a can of Deoxit on hand to spray into the pots to clean. Deoxit can be found at your local Guitar Center or simply via Amazon.
I do not recommend using any other cleaner besides Deoxit. Please do not take any liberties here and try something different. Deoxit is the only product to use.
Where do I spray? In the above photo you will see where to spray behind the volume pot. You do not have to spray a lot. A little squirt goes a long way with Deoxit. After you spray the Deoxit in, simply turn the volume knob on the front of the unit back and forth, back and forth many times to work the Deoxit in. I usually go back and forth about 100 times which sounds like a lot but since I have the unit open I may as well get her as clean as possible.
Next you will want to spray the Deoxit into the tone control pots which I’ve circled in the photo above. They are tucked away but reachable with the straw provided with the Deoxit can. Just find the same openings you sprayed into on the volume pot, give a little squirt in each and beginning turning the knobs back and forth.
To clean the push button switches on the front of the unit, you will need to locate the circled areas in the above photos. I slightly push in the button and the little metal bar moves which is where I give a little Deoxit squirt. See photo below. Once the Deoxit is applied, I simply the push the button in and out around 100 times to make sure it cleans properly.
The most important push button switch to clean is the Tape Monitor one. A dirty Tape Monitor switch can cause all sorts of problems, including a loss of sound. Just remember to not keep the switch activated when you eventually power the unit back on or you will not have sound.
Now we want to clean the Balance sliding bar on the front of the unit. If you look closely, you will see a long skinny box with a couple of square shaped openings. See above and below photos. I spray a little squirt of Deoxit into just one of the openings and then slide the balance switch back and forth on the front of the unit.
Congratulations, you have cleaned all of the pots and switches needed.
WARNING: DO NOT POWER THE UNIT UP TO TEST FOR 24 HOURS.
I usually give the Deoxit PLENTY of time to dry before I power the unit back up to test. Even though Deoxit dries quickly, it’s still liquid based and we know how electricity and liquids mix. So, pat yourself on the back for all the work so far and just be patient, knowing you can power her up the next day.
One last piece of advice, before you plug the unit back in and power her up to test everything, go ahead and turn the volume knob all the way down and make sure your balance knob is correctly centered. Just give the unit a quick eyeball to make sure you will not blow yourself (or your speakers) away when you turn the unit back on.
If everything was cleaned properly, the unit should light up nice and bright from the new lights and the scratchy sounds should be eliminated. If so, turn the unit back off, unplug again and reinstall the bottom and top covers.
If this doesn’t fix the problem, take the unit to a professional for repair. These instructions are meant for a beginner to clean the unit, not attempt a professional repair.
In the video I posted above, all that was needed were clean pots and new lights to get the unit playing properly again. These vintage units can still need a lot of adjustments or to be recapped for optimum use, but for now at least this will get it playing. Any further maintenance or repair should be taken to a professional.
If you enjoyed this post, please consider subscribing to our newsletter below. First time subscribers receive 15% off in our Etsy store.
We design shirts for fans of all things analog – visit the store and order yours today.
