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.
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.
Also, don’t forget to shop our Discogs Store to purchase used records, CDs and 45s!
All I wanted was a Marantz 2270 receiver but prices were escalating between $750-$1,000 for used units and that was just too far out of my budget.
I’d been researching vintage receivers for over a year, having decided I wanted to completely rebuild my stereo system from the ground up with all vintage gear. I have owned several stereo systems in my life but never with any vintage pieces included. All my research led me to Marantz, specifically the 2270.
A few years ago, while visiting family in Alabama during the Christmas holiday break, I went hunting for Marantz receivers on craigslist. I found someone in Manchester, TN, selling a Marantz and a couple other receivers for $600. I immediately contacted him and we went back and forth a few times before finally he told me if I wanted these I could have them but he had another buyer behind me bugging him. The next buyer didn’t want all three so in order for me to do the deal I had to purchase all three at $600. I jumped on it.
I had to meet to him very early on a Monday morning at a Cracker Barrel in Manchester, TN, which is a 45 minute drive in the opposite direction of my office. The man was very nice, explaining his elderly father was a hi-fi nut and he was cleaning out his collection.
The receivers included in the purchase are pictured above, a very clean Marantz 2270, a Sansui 2000 and a Pioneer SX-450. He told me the Pioneer was not working properly but the Sansui 2000 was still in the original box and even included the receipt from where his dad had purchased the receiver brand new in the 1970’s. The one thing I’ll never forget was picking up the Marantz receiver and placing it in my car. The receiver weighs almost 40 pounds and I had never picked up a piece of stereo equipment that heavy before.
I finally had my Marantz 2270 and it sounded great. I was so nervous hooking it up, worried it wouldn’t work properly after paying someone $600. Thankfully it did and I’ve used it as my every day receiver since. As for the $600 price tag, I sold the Sansui and Pioneer receivers for around $200 so really my Marantz 2270 only cost me $400. Of course, once I had the Marantz in place, I then had to upgrade all of my other stereo components, a story for another day, especially how I came to own my Pioneer HPM-100 speakers.
This one purchase started my love affair for vintage audio gear and I’ve been buying and reselling ever since.
This website is our homage to great vintage analog gear of all kinds: receivers, radios, turntables, film cameras, speakers and more.
Sign up on our mailing list to receive 15% off your first purchase in our Etsy store.
