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!
My teenage sons burn through the cheap Apple earpods monthly, always needing a new pair. We travel a lot for the holidays so I thought they might enjoy a pair of nice headphones but I wanted to find a pair that wasn’t too expensive in case they met the same fate as the earpods historically have.
Insert the Tribit XFree Tune headphones for just $50. I have not heard of this brand before but I found these headphones while researching online and decided to give them a try as a holiday gift for my boys. I read they sound amazing and are very comfortable to wear so I gave it a shot.
I’m happy to say my boys loved them. We travel by car and the way things work is, Dad is boss of the radio and I choose what is listened to while driving and they listen to music on their headphones. Well, the earpods would allow my music to easily bleed into theirs and they would turn the earpods way up in response which I knew couldn’t be good for their ears. After their first listen on the new headphones, the first two things they complimented the Tribits on were the bass response (they love hip hop) and how well they blocked out my music in the car. The headphones were a hit.
I recommended these on my personal Facebook page recently and a few people ordered them and also loved them. The headphones come in a nice carrying case as well which is great for my boys when we travel.
I do not personally have a lot of experience listening with high end headphones so I wouldn’t try to make the comparison here. But, I do love a good bargain and great sound at which point the Tribits are my headphones of choice!
We had the pleasure of being interviewed for one of our favorite podcasts, Vinyl Emergency!
We talk with Jim about hobbies, how to juggle those with a day job, how we got into vintage audio repairs, vinyl collecting and more!
You can listen wherever you play your favorite podcasts but we’re including the Spotify link below. Check it out and be sure to subscribe for more great podcasts from Vinyl Emergency!
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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