Sanyo M7880k Mini Boombox Led Mod

[Maxx134]

Hello I am posting this to make known the optimal location for a LED mod for this unit.
Unfortunately this unit like many small units does not use a glass or plastic Dial.
Instead it has a shiny metal background with FM dial imprint.
So we have to go with light to shine onto the metal surface.
Instead of using two directional LEDS on either end,
I chose a more bold approach of a 4" cool white LED strip overhead, hiding above the display
Resulting in a more brightly lit unit.% looks blu-ish on camera.
Using this approach we are able to light up the controls as well!
This was my first LED mod on radios, but I have been Modding my car lights before even LEDs were out,
using sequential Christmas lights on tinted glass! lol.

Here is a result of using LED strip over the dial:

 

[Maxx134]

Next is a pic of the optimal location for using the Led strip or any other LED around 12v.
The reason for this location is that it will turn on with the unit in whatever mode (radio/tape/line) it is in and off when off,

At the time I did not think of toggling it with any of it's buttons.
It works just fine and have not had any issues for the months I have had it installed.
here is pic of primary location on main board, as you will see that I have soldered the wires there:

 

[Maxx134]

And here are the youtube links of it in action:
https://www.youtube.com/watch?v=OZeIg4RYddY&feature=plcp
and here:
https://www.youtube.com/watch?v=7cTgqFI4zTI&feature=plcp

 

[redbenjoe]

nice

 

[superlew]

Looks great.
Your mod is very similar to my Panny Frankestein:
viewtopic.php?f=47&t=15539&hilit=panny+led
I did end up adding a tiny switch a couple of weeks ago. I mounted it in the recess for the power supply, so it's still very trick.
Great job! Small boxes are tough cuz space needs to be used wisely.

 

[goodman]

Good work!!!

 

[Maxx134]

Looks great.
Your mod is very similar to my Panny Frankestein:
viewtopic.php?f=47&t=15539&hilit=panny+led
I did end up adding a tiny switch a couple of weeks ago. I mounted it in the recess for the power supply, so it's still very trick.
Great job! Small boxes are tough cuz space needs to be used wisely.

Your Panny is very cool and looks considerably more difficult than this one. Nice touch with red.

 

[chrygore]

lookin good

 

[Maxx134]

Here we go again.. this time full mod on an almost new one:

 

[Maxx134]

LED on:
Dial
Tunning dial
controls
cassette area
tape counter
volume

unit was new without box when I attained it and is still mint and up for sale on ebay as well..
If I hold onto it any longer I may keep it lol.

8hrs painstaking operation with trial and error on LED placement to get just the right effect and glow..

This mod totally different as every area has its own dedicated lighting.
Super hard as there is virtually no space at all for conventional LED so I had to modify the LED itself.

up next for LED mod is a National rs-4360
hopefully tomorrow..

 

[Superduper]

Be very careful. These sanyo mini's have a very weak power switch. Basically, the function switch doubles as a power switch. Unfortunately, the function switch is really only suitable for signal level circuits and not power level circuits. Eventually, the arcing inside the switch causes the foil feelers to vaporize necessitating the replacement of the switch, or more likely, the foil feeler which you'll need to cannibalize from another boombox. You won't know what you'll need until you actually take the switch apart and compare to feelers within other switches, which you'll also need to take apart. The function switch looks like a record bar.

In any event, all sanyo mini's are prone to this problem. I've seen this problem in several examples already. Anyhow, if you want an idea on what I'm talking about, you should look at the restoration video here:

https://boomboxery.com/forum/index.php?/topic/10746-one-rare-bird-sings-once-again/?hl=m7830k

Ideally, the power switching function should be offloaded to a relay or solid state switch which may be better suited for higher power level switching. In the meantime, any added load to the circuit could exacerbate or accelerate switch wear. Just FYI.

 

[Maxx134]

Piont taken.
didnt know the switch had problems
The load is on the motherboad I tapped far away from that power switch and LED require low power.
I hardly use my minis and almost never used this one I should say is like new but I will keep an eye on my old unit.
So better to pull the plug huh.
EDit:
just finished watching video pretty amazing work in restoration..

 

[Superduper]

The load is on the motherboad I tapped far away from that power switch and LED require low power.

The power switch powers the motherboard. So tapping onto the mainboard only serves to increase the load on the switch which is why I said to be careful. It's true that LED's consume little power but most ultra brights are rated at 20mA each. 5 LED's at rated current will consume extra 120mA. There's also something else you should know. LED's that are connected directly onto the power rails will consume current until all residual power is drained. When you initially power on a boombox, there is a current surge that charges the storage capacitors. These caps usually retain a residual charge after device is powered off, and the next time you power up the box, the surge will be far less on a full (or partially full) cap. Unfortunately, if the LED's drain the caps completely after each cycle, then the power switch will bear the brunt of full surge current each time it's powered on. So basically, there's several issues here:

1) Depending upon the number of LED's there will be extra current consumption in operation.
2) There is an increase in surge current upon every power up event. Add rated current times number of LED's to figure added surge current.
3) LED's that drain the residual system charge will ensure that every power up event requuires maximum surge current.

Now, like on all things electronics, there is no way to know exactly how much this will affect the life of the switch. However, I only caution that the Sanyo mini's seem to utilize switches that are already undersized for their application, therefore, any extra load only exacerbates the problem. As I said, ideally, the high current switching duties should be offloaded to a switching device that is better able to handle the high current loads for longest life although Sanyo can certainly argue that these boomboxes have already outlived their intended lifespan. That is a pretty serious upgrade though and perhaps except for the rarest and most valuable minis, maybe not worth such a retrofit.

 

[Maxx134]

I believe surge currrent is inescapable whether unit has leds or not.
I can switch the leds to the power suppy and have the LEDs contrioled by the tiny "beats" switch off to the side.
thank you very much for this input

 

[Superduper]

I believe surge currrent is inescapable whether unit has leds or not.

Yes, but you are missing the point. Drained caps are very power hungry and loads a circuit until they charge up. Once charged up, they stay charged for a period of time and their affect on the circuit is minimal. The discharge period after power/off can be minutes, hours, days, or even months.... all depends if there is a drain, and how much of a drain. If you don't believe me, charge up a large capacitor (or power on a boombox). Shut off the boombox (or remove power to the cap) and wait awhile.... up to you how long. Then short the two cap leads with a screwdriver and you'll likely see a big fat spark that might even eat a bite out of your screwdriver tip. The presence of the spark proves the existence of residual charge. So on a boombox that is played daily, the discharge might be minimal and upon next power up cycle, the circuit might not experience quite the surge as with empty hungry caps. Where the LED's come in is that they act like a controlled short between the cap leads and drain off any residual charge thereby guaranteeing that the caps will be fully empty on the next powerup cycle. Up to you if you want to believe me or not. I can tell you that on my M70 lamp kits, the controller I supply has a power-on reset function. However, depending upon the boombox, most examples will not actually reset if the boombox is powered off for only a short period of time, and turned back on later. It retains the previous state even though hours have passed. This is because the residual power remaining in the caps is enough to keep the controller alive. Of course if the boombox is off for a long period of time, the controller will in fact power-on in the reset mode which is the expected state when tested on the bench. Anyhow, that's my observation and I'm only providing you some advice based on what I've observed with these Sanyos. Of course if the boombox is only played once/month, then current surge would be, as you say, inescapable.

 

[kraftmatic]

Nice mod, Maxx! Very pretty.

And thanks for the knowledge, Norm. I always learn a lot from your posts.

 

[Maxx134]

ok to appease members and to put to use helpful ideas.
I took the LEDs off the power switch and used instead the beat button off to the side.
the good it that any extra surge to main power switch can be thus eliminated atpowering on,
if Leds are switched off before shutting down box.
Another good is that you have a choice to turn light on or off..
The bad is that I had to hard wire the beat function so I set it at 1..

ALSO:
the LEDs are not blue..
They are actually cool frosty white but my stupid camera captures it incorrectly as blue..

 

[Maxx134]

Finnally got a video uploaded

https://www.youtube.com/watch?v=6M2rOv9-gTg&feature=youtube_gdata_player

 

[Maxx134]

2days left on ebay .
Will post in sale section.