Help My Lighting Education!

holysocks

Well-Known Member
I've just started the restoration process for the MCS 3275 receiver I recently bought. The first thing I did (after spending hours searching and reading about this particular unit as well as the restoration process for receivers in general), was post a question about capacitors. That thread is located here:
http://www.audiokarma.org/forums/showthread.php?t=395226

I've decided to create a separate thread focused on the lighting aspect of this project.

The right power meter light is currently out, and I'm not sure how to go about replacing this bulb. I guess I was hoping the bulb would be in a socket of some sort, however that doesn't seem to be the case. I've got some pics to help outline what's going on here.

Onto the questions!

Is this suitable for an LED upgrade? How would I go about doing something like that? Do I just measure the resistance across this bulb and then pair an led+resistor to achieve a similar resistance? What about voltage, would i have to plug this receiver in to test the voltage across the two wires connecting to this bulb? (I'm a bit apprehensive plugging this in while i've got everything in pieces though in theory it should be okay if I'm nice and careful).

Is LED the way to go? What if i didn't do LED, and just got a bulb -where is a good place to get bulbs? any lessons learned folks would be willing to share?


-And onto the pics!!
MCS3275-D.JPG

MCS3275-E.JPG

MCS3275-F.JPG

MCS3275-G.JPG

MCS3275-H.JPG

MCS3275-I.JPG

MCS3275-J.JPG

MCS3275-K.JPG

MCS3275-L.JPG
 
you want to choose the resistor so that the current through the LED is under the maximum forward current (Ifwd) in the LEDs specifications. most normal LEDs have Ifwd max of about 20mA, so it would probably be best to go with 10 or 15mA for safety (higher current means the LED will be brighter, but you don't want to blow it). superbright LEDs are designed to work at higher currents, so check the data.

btw here's a handy calculator: http://led.linear1.org/1led.wiz. Diode forward voltage and current are from the LED data, measure the power supply voltage to the bulbs (preferably with the bulbs disconnected, as they will load the power supply down more than LEDs so you'll get a different voltage).
 
Quite a substantial looking piece of gear you have there. :thmbsp:

If it was me, I'd choose to replace the bulb with the proper incandescent. My experience with LED's in tight spaces tells me that a lot of experimentation and LED/resistor choices would be in the mix and there is no guarantee that the proper illumination would be the result. LED's are problematic to get the diffusion correct, especially in a small space like a meter housing.

For bulbs, there is only one place to go, IMO, and that is here. Dave is an AK member and has helped me through many a relamp. His pricing and customer service is exemplary.

Good luck with your MCS!
 
Quite a substantial looking piece of gear you have there. :thmbsp:

If it was me, I'd choose to replace the bulb with the proper incandescent. My experience with LED's in tight spaces tells me that a lot of experimentation and LED/resistor choices would be in the mix and there is no guarantee that the proper illumination would be the result. LED's are problematic to get the diffusion correct, especially in a small space like a meter housing.

For bulbs, there is only one place to go, IMO, and that is here. Dave is an AK member and has helped me through many a relamp. His pricing and customer service is exemplary.

Good luck with your MCS!

Substantial is right! I've seen nudes of quite a few amps and this one sure does land on the more complex side of things. I like the idea of LED lighting from a longevity perspective. However with all of the guess and check that comes along with, I think I'll start down the bulb path for now.

Through my search efforts I've seen one thing constant, Dave's name! I best hurry up and contact him.
 
how many volts is the bulb and watts ? it looks very much like an auto bulb may fit from the dashboard lights or clock
 
If you do replace the burned-out light with an LED, you will want to replace the other bulbs as well. The LED's look different.

The resistor value is important. The value you need is based on the desired drop in voltage. For example, if you measure 8vdc and the LED is rated at 3G, you need to drop the voltage by 5v. Using Ohm's law, if the LED is rated at 20 ma, the resistor should be 250 ohms (5v/0.02a) to obtain the desired 5v drop. Also, the wattage capability required would be (5v x .02a) 0.1watts, so a 1/4 watt resistor would be fine.
 
oooohhhh, looks like you're in some trouble. I hear they don't make replacement bulbs. Guess the whole unit is toast then. Better send it my way and I'll make sure its disposed of properly... While youre at it, I need your SSN, full name, and contact information including full mailing address so it can be recycled and you get your check for parts. My assistant will cut you a bank check plus $200 for the inconvenience... :D:smoke:

*hides and waits*







(seriously though, nice unit, and if you do go LED, make sure you do all the bulbs :thmbsp:)
 
Lights ordered from Dave (dgwojo on AK). Super quick responses, had everything I needed, and a very nice guy. :thmbsp:

Once I've got the lights in, and the MCS back together pics will be posted! Though, that may take a few weeks so don't hold your breath.
 
Will you share the part number of that bulb for the meters please! I have owned my MCS 3275 for 23 years and didnt even know that the thing even had lighting!
 
Will you share the part number of that bulb for the meters please! I have owned my MCS 3275 for 23 years and didnt even know that the thing even had lighting!

First of all, it's great that you've had the MCS 3275 for 23 years. That's definitely a testament to the receiver! :banana: I wonder what speakers you've tried with it? That's my next venture.

Secondly, I don't have a part number for the bulb. I sent an email to Dave (who's website can be found here). I took some macro lens pictures of the burnt bulbs next to a ruler so he could see the exact size/shape of the bulbs I needed. I also took a few measurements with the multimeter. Lucky for you, he now has specs for all the MCS 3275 lighting so the hard work is done for you!

Dave was very fast to respond, and lucky for me had everything I needed at a very affordable price. In fact, I sent him the money via paypal today.

I'll post a few more pics before I put the receiver back together, and then of course the obligatory night shot with all lamps fully functioning as soon as I get everything installed.
 
First of all, it's great that you've had the MCS 3275 for 23 years. That's definitely a testament to the receiver! :banana: I wonder what speakers you've tried with it? That's my next venture.

Secondly, I don't have a part number for the bulb. I sent an email to Dave (who's website can be found here). I took some macro lens pictures of the burnt bulbs next to a ruler so he could see the exact size/shape of the bulbs I needed. I also took a few measurements with the multimeter. Lucky for you, he now has specs for all the MCS 3275 lighting so the hard work is done for you!

Dave was very fast to respond, and lucky for me had everything I needed at a very affordable price. In fact, I sent him the money via paypal today.

I'll post a few more pics before I put the receiver back together, and then of course the obligatory night shot with all lamps fully functioning as soon as I get everything installed.


I was given the MCS when I was 14 it didn't work. My parents didn't have alot of money and I had tons of free time. I got it working by bypassing a "small board" in it. I have read on here its most likely a protection board.

At 15 I got a job just to buy speakers for this receiver. I bought some Marantz with 15" subs. This was a great set of speakers for the MCS.I wished that I known what the model number was but its been too long. I owned the Marantz speakers for 14 years before the foam rotted. I sold them not knowing they could have been re foamed...ohh well lol.

Not knowing what I had with the MCS I bought a Harmon Kardon avr25II. I was never really happy with this unit. I even bought a set of expensive Bose speakers for the Harmon Kardon and was still not happy with it. I used this set up for 15 years all the while I kept the MCS sitting in the closet.

So 2 weeks ago me and my brother was working in the garage complaining how crappy the radio that we was listening to sounded. The light bulb went off in my head! I remembered the MCS hibernating and how I wanted to see if it still worked. After locating a set of speakers and running wiring I have a very nice sounding radio! The MCS fired right up not even a hicup!

I got online searching to see if I could find out anything about the MCS and boy was I shocked to find what I did. I even came across this forum and glad I did. I was so happy that I didnt sell it after all that time not being used. It was almost sold when the Marantz speakers was sold. Now I am on a quest to get it back to OEM specs. I want to fix the protection board (I think thats what its called) and get all the lighting working!

Thanks for the quick reply and hope you dont mind me asking a few questions on removing the front!
Trevor

IMAG0288.jpg
 
Awesome pictures! I can even see the broken filament. Be a good application for an LED but might be better to keep it as original though. Good luck with the overall project too.
 
I was given the MCS when I was 14 it didn't work. My parents didn't have alot of money and I had tons of free time. I got it working by bypassing a "small board" in it. I have read on here its most likely a protection board.

At 15 I got a job just to buy speakers for this receiver. I bought some Marantz with 15" subs. This was a great set of speakers for the MCS.I wished that I known what the model number was but its been too long. I owned the Marantz speakers for 14 years before the foam rotted. I sold them not knowing they could have been re foamed...ohh well lol.

Not knowing what I had with the MCS I bought a Harmon Kardon avr25II. I was never really happy with this unit. I even bought a set of expensive Bose speakers for the Harmon Kardon and was still not happy with it. I used this set up for 15 years all the while I kept the MCS sitting in the closet.

So 2 weeks ago me and my brother was working in the garage complaining how crappy the radio that we was listening to sounded. The light bulb went off in my head! I remembered the MCS hibernating and how I wanted to see if it still worked. After locating a set of speakers and running wiring I have a very nice sounding radio! The MCS fired right up not even a hicup!

I got online searching to see if I could find out anything about the MCS and boy was I shocked to find what I did. I even came across this forum and glad I did. I was so happy that I didnt sell it after all that time not being used. It was almost sold when the Marantz speakers was sold. Now I am on a quest to get it back to OEM specs. I want to fix the protection board (I think thats what its called) and get all the lighting working!

Thanks for the quick reply and hope you dont mind me asking a few questions on removing the front!
Trevor

IMAG0288.jpg

Wow, I haven't seen it all together for quite some time! This sure is a good looking receiver isn't it. I can't wait till mine is up and running!

I loved reading your story and history with your 3275, that's just too cool!!!!

Removing the front is very simple. All of the knobs simply pull off with exception of the two largest knobs, the tuning and volume. Each of those have very small set screws, and each knob has two set screws. You'll need a small allen wrench to loosen the set screws. Don't even worry about the push button switches like the speakers A B A+B those knobs can stay on.

My volume knob was on there real tight, so I had to wrap a piece of torn t-shirt around the knob to help pull it off. You gotta get the cloth underneath the knob and twist to wrap around the knob, it was a PITA!

After knobs are off, take off the wooden case (8 screws) and then the 3 screws at the top and 3 screws at the bottom of the metal face. From there it should just slide off.

Accessing the meters requires taking off that black plate that surrounds them, simple rubber pieces hold it in place. I used a toothpick to pry them out.

I'm pretty sure the board you are referencing is located underneath the receiver, where the fuses are mounted. I'm not a circuit guru, and know very little more than is on my threads about bulbs and capacitors, so I can't give guidance further for you on that.

I'll keep this thread updated when my bulbs arrive. And I hope to hear more about your newly rediscovered MCS3275! Feel free to PM me if you have any specific questions or picture requests while I've got it on the operating table.

Looks like all your LEDs are working well, but your filament bulbs are all out. The receiver takes 3 larger bulbs that mount in a reflective hood. I've posted a few pics of this.

MCS3275-M.JPG

MCS3275-N.JPG

MCS3275-O.JPG

MCS3275-P.JPG


And lastly, welcome to AK!!!!!
 
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Thanks for the great pics that will help greatly! Ok so maybe that small board is not the protection board. In the picture you have with the transformer and amp is showing.....its the small board in the middle...with the two sets of twisted red and white wires. There is also a yellow and gray wire at tha top. The amp wiring runs to this board and the over to the speaker connections. When I got the MCS the sound was getting to the board but would not leave it. So I just bypassed it. Any ideas what this board is or does?
 
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