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Help ! - Marantz 2285B LED conversion

Pauljuhn

Pauljuhn

Active Member
Hi,
This topic seems to be discussed many times earlier but I still want some clarification before ordering LED's for my 2285B.
I would like to replace all lamps for Signal Strength meter(V001), Center Tuning meter(V002) and all VZ01-VZ05(8V 200mA) with LED which has 3 LED's in one lamp tube - they are on ebay.
They are supposed to be better than 2 LED's in a tube.
My question is
1.In order to maintain the 10 white dots on the FM scale dial, should I buy warm white LED?
- Some people buy blue LED - why?
2.Do I still have to change the Vellum paper for the meters to get the same blue color for meter as well as dial?
3.Any suggestions on this topic?
Thanks very much.
 

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1. Yes, white LEDs, My source is on the links page of my website.

2. It may not be absolutely necessary but I always do.

3. I go in from the front by removing the black piece the dial pointer slides on and the silver bracket below the dial. Then remove the dial, it's glued on the top edge and the sides, be careful not to scratch it. Once it's off, you can just pop the old lamps out and the LED replacements in.
Then tape the dial cord to the black drum on the tuner (front end) so it doesn't come off and remove the small screw holding the left dial cord pulley so that you can get the meter lamp shroud off.

Tom
 
I just posted this to another member who had LED questions.

For my two Marantz 2238B's I bought 12V warm white automotive fuse LEDs each with three SMD 5050 leds. Then, I unsoldered the 8VAC wire to the lamps on the right side of the dial housing and installed 2 silcon diodes in series to change it to DC and also reduce the voltage a bit. I applied shrink tube over the diodes and it is neat and tidy. I also added a 100uf capacitor across the the now rectified 8VAC which ends up about 8.3VDC with no flicker and a more subdued light output. The 12V automotive LED fuse lights run fine at 8.3VDC and should last forever.

The resulting light output is brighter than incandescent by a bit, but illuminates the dial evenly and allows the nice blue color of the dial.

I will have to try aiming the fuse lamps backwards and see how I like that. It might warm the dial up a bit more.

Attached are two pictures of my LED mod. The red arrows point to the diodes I inserted into the 8VAC supply to the dial lamps and also the 100uf 20V capacitor across the dial lamp supply terminals. By doing it this way I can revert back to original by simply removing the diodes and capacitor at any time.




 
Thanks very much for the tips...
I also want to know how good they look when LED's installed facing backwards.
 
is it relatively easy to remove glued dial?
how did you re-glue when you put dial back?
what about access from the back?
Thanks
 
Pauljuhn said:
is it relatively easy to remove glued dial?
how did you re-glue when you put dial back?
what about access from the back?
Thanks
Click to expand...

You really do not want to access the lamps from the back because the white plastic lamp housing is held on by small latch prongs that will break if you try and unlatch them. Ask how I know this. . .LOL This is because the plastic has gotten very brittle from age.

It also is just a good idea to remove all knobs and clean and polish them and the front panel anyway. Also, once the front panel is off, you may see a lot of dust and a smudgy film on the back side of the dial glass. BTW.. . clean the dial glass only with a damp soft cloth. . . . and wipe dry. No strong cleaners.

The dial glass can be pried off fairly easy starting on one end and working slowly. The glue on mine was actually very sticky yet and after I installed the LEDS I just stuck it back on and also applied some extra cement on each corner of the dial glass.
 
Thanks...
I ordered 7 LED's on Ebay.
One bad news is that no lights are tuning on all of a sudden.
No needle light no stereo light nothing.....
Amp still works as I can hear music from speakers.
Any idea why? all lights will go off if there is one blow-up?
 
Phase700b said:
I just posted this to another member who had LED questions.

For my two Marantz 2238B's I bought 12V warm white automotive fuse LEDs each with three SMD 5050 leds. Then, I unsoldered the 8VAC wire to the lamps on the right side of the dial housing and installed 2 silcon diodes in series to change it to DC and also reduce the voltage a bit. I applied shrink tube over the diodes and it is neat and tidy. I also added a 100uf capacitor across the the now rectified 8VAC which ends up about 8.3VDC with no flicker and a more subdued light output. The 12V automotive LED fuse lights run fine at 8.3VDC and should last forever.

The resulting light output is brighter than incandescent by a bit, but illuminates the dial evenly and allows the nice blue color of the dial.

I will have to try aiming the fuse lamps backwards and see how I like that. It might warm the dial up a bit more.

Attached are two pictures of my LED mod. The red arrows point to the diodes I inserted into the 8VAC supply to the dial lamps and also the 100uf 20V capacitor across the dial lamp supply terminals. By doing it this way I can revert back to original by simply removing the diodes and capacitor at any time.




Click to expand...

Looks beautiful. If I may... I am trying to learn from the community, and wanted to retrofit LED's to a Kenwood. I was successful with the stereo and meter lamps and LED's. But the dial lamps have me baffled. I bought 8v LED's from fleabay, and when installed, the fuse blows. Finally figuring out I have 8vac (not dc, my fault for not checking) I am very interested in your simple solution of diodes and cap. Researching diode theory, I stumbled on this...



Diodes in series with the same polarity each behave no differently than a single diode. The voltage drop and current capabilities of each diode remains the same. The overall voltage drop of the series combination of the diodes will be equal to the total of all of the diode voltage drops. The current capability of the diodes does not change.

Diodes in parallel with the same polarity each behave no differently than a single diode. However, due to the fact that the current into each diode is lower because of the current divider rule, each diode will have less current flowing through it, and therefore its voltage drop will be lower, as this is a characteristic of diodes. Therefore, assuming the diodes are all identical, the overall voltage drop of the parallel combination of diodes will be lower than it would be for a single diode. Although each individual diode's current capability does not change, the parallel combination of diodes can handle more current overall, once again because of the current divider rule."
My question, would one diode accomplish the same thing, or do two in series do something I cant understand? And to clarify, you assembled them like this: AK-AK or --|<--|<--?
 
You have it pretty much correct. The 2 diodes I used were in series. Each diode when conducting current (AKA forward biased) will have a constant voltage drop of about 0.6 volts. So, I put two diodes in series, cathode to anode, to obtain a 1.2 volt drop across the pair. I did this because the 8VAC supply to the previous incandescent bulbs would be a bit high. This is complicated a bit since the resultant DC current is now only half wave rectified. In other words, only half of the supplied AC voltage passes through the diode, while the other half is blocked when the AC polarity is reversed during the "other" half cycle of AC current flow.

Further, this resultant half wave DC current is pretty unrefined and I added the capacitor to "smooth" out the pulsating 60 cycle DC from the diodes. But, when you filter this pulsating DC, the average voltage the load (LEDs in this case) see, is higher since the capacitor has that effect. Also, since the LEDs do use much less current than the original 8VAC incandescent bulbs, the filtered DC effect provided by the capacitor results in a higher average voltage applied to the LEDS. I wanted a total DC voltage of about 8 volts to the LEDS. Without the second diode and using the capacitor the LEDs were getting about 6.7 volts of unfiltered DC from the diodes. After adding the second diode and a 100uf 20 volt cap, I eneded up with about 8.3 volts DC to the LEDs. . . . which were actually 12VDC automotive LED fuse lamps. But they gave more than enough light output and work fine at 8.3 volts.

You see, with LEDs, it isn't so much the voltage alone that is supplied, but how much current that voltage will cause to flow through the LEDs. You want to supply a voltage to the LEDs that keeps the current flow at or a bit lower than the rated operating current of whatever LED you choose. In my case I think it was 0.060 amp or 60 milliamps. I found that the LEDs worked fine at even about 45 milliamps, so they should last even longer with this reduced current flow. In some applications, a designer may just add a resistor in series with the supply voltage so that will limit current flow through the LEDs. I have done this in a few instances, but where a supply voltage is close to what the LED lamps need, using a diode or two is a more elegant solution.

There are some other intricacies to this whole scenario, but this is the gist of it. Diodes, like transistors, are generally current operated devices so this must be remembered. That said, the supply voltage to these devices, will have some of a determination of the current flow through the device. The goal is to control supply voltage to a solid state device (diode, transistor, etc) in order too keep current flow through them within safe operating ranges.
 
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Phase, I thank you for the explanation. I do appreciate the time you took to spell it out for me. You put it so I could understand better. I'm certainly going to try it and mimic what you have done in my Kenny.
 
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