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Sunday, October 24, 2010

Repairing a Mickey Mouse Lamp - UPDATED !

My daughter has a nice Mickey Mouse lamp.
We bought it years ago and it worked nicely for many years, until "somebody" connected it to an X10 Lamp module.
After few times, the lamp stopped to work completely.
In this article I'm documenting the repairing process.

The lamp


Here the lamp.  Mickey is pulling the cord every time the big red button is pressed, while some sentences are spoken, turning the lamp on and off.

The circuit

Inside the base of the lamp, are present four PCBs.
  • Main control module
  • lamp activation module
  • pushbutton support
  • main power support

The LAMP control module feeds the transformer via a main fuse, and it  receives from the Main control module the command to activate the bulb.
Here a picture of the inside :



On the left lower corner, it is located the main control module, just below the transformer.
On the right side, the LAMP control module.

Main control module

The main control module circuit, is the main PCB of the lamp.
The main controller module performs these functions :

  • it power supply the circuits
  • it controls the bulb  via the LAMP control module
  • it controls a motor for some motion effects
  • it generates sounds/voices when the lamp is activated/deactivated
  • it handles the main on/off pushbutton

LAMP control module

The bulb  control module (called LAMP in the block schematic) feeds the transformer that power the main control module via a fuse, and it receives via photocoupler the comand to turn on/off the bulb.

Here a schematic of the LAMP module :
 


Open the lamp

It is quite easy to open the lamp.
On the base there are 4 adhesive pads. Under each pad there is a hole containing a screw that connect the base with the main body of the lamp.
After the screws are removed, the bottom of the base is coming out.
The PCBs and the transformer are screwed to the upper part of the base.
The only annoying thing is that all the wires are soldered to the PCBs, no connectors. 
 



The problem

The lamp was totally dead.
Measurement made on the LAMP  control module didn't show up any problem.

The diagnosis

Since all the functions of the lamp, motion, voice and lamp, were dead, as the first thing I checked out the  power supply.
Hooking a voltmeter to the transformer secondary (blue wires) showed up 0 volts.
Then I disconnected the transformer secondary from the main control boards and did again the tests.
Still 0 V.
So it seemed the transformer was gone.
To be sure of that, I disconnected also the primary of the transformer (cutting out the red wires) and removed it from the base.
The primary resistance of the transformer was infinite, the secondary one 0.6 Ohms.
So the primary of the transformer was broken, thus no power to the entire circuit.
I then hooked up a DC power supply to the main board control, when the secondary  of the transformer was connected.
Around 7V the circuit started to work.  Pushing the ON/OFF button the character spoke and moved as usual.
However connecting the main power (110V) to the lamp, the lamp remained OFF
Possible reasons :

  • a) also the circuit that control the bulb had problems (SCR dead or some diodes broken)

    OR
  • b) the LAMP control module needed to be driven with a signal in sync with the AC line
    Since I used a DC power supply to test the main control board, I didn't have any AC signal

    OR
  • c) the bulb was broken
The last one was correct.
The bulb was broken.

The  repair

Since all the functionalities of the lamp were present when powered with the DC power supply, in order to repair the lamp, the transformer had to be substituted.
In order to do so, I had to figure out  what transformer to use.
The original transformer was labeled "HUNG KAI 4104".
A search  with google showed only a Chinese company who produce it (Hung Kai Electric Co) and that the model 4104  belonged in the category of transformers below 15W, with max. voltage of 42V.
Clearly the original transformer was  NOT sending out 42V, a main line capacitor on the main control board  was a 16V max electrolitic.
Since the main circuit board was working with 7V DC, my first guess was that the transformer had to be a 6V one.
I found on Jameco a 6.3 V transformer, 1.2 A , with dimensions "close" to the original one. 
Approx 6.3 V AC, once filtered  become around 8V DC

Here the "fix".
The transformer is little bit bigger than the original one, so it is attached upside down, with  some high heat hot glue on the top and a velcro support (not in the picture) on the base to avoid movements (safety must be always the first concern when repairing electric appliances).
It is also possible to see the rewiring (yellow and white wires) connected to the original wires (red and blue).
The small gray wire is the one in parallel to the original pushbutton, connected to a jack.
This is used to command the lamp with an X10 Universal module  (see below).
The unused wires on the transformer, were cut and insulated and glued to prevent short circuits.



The improvement

Since the lamp was open, I decided to add a jack to "bring out" the push button ON/OFF function.
In this way it is now possible to control the lamp with a remote push button or connect the lamp to a X10 Universal Module .

Broken .. again

Well, the lamp did broke again few years ago (now is 2020).
I did write the original article 10 years ago !!! WOW !!!!!

I did left the lamp in garage for some time, then I decided to at least see what the problem was.
I did re-open the lamp and I immediately noticed the fuse be dark .. clearly the fuse did blow up, maybe due to a defective lamp (at least I hope).
The fuse is a 125V 1A (ehm .. years ago I did speculate that the fuse was 15A in a message answer, wrong !!), with solder terminals (it can be easily spotted on the picture above) and OF COURSE on my junk box or around the lab I didn't have one.
So I did remove the broken fuse and ordered a new one, with a fuse holder.
I did order a 250V 1A fuse and is OK, it is OK to use a 250V fuse instead a 125V one, as long as the current is the same, not the opposite though !!
i.e. if a circuit requires a 250V fuse you CAN NOT substitute it with a 125V one !
Anyway, as I said, I did order the new fuse and soon will arrive.

.........

I did receive my fuse kit with some fuse holder and the 250V 1A fast fuse.
As predicted I was able to embed the fuse holder somewhere in the lamp base and fortunately not other components were damaged.
The lamp once again did come back to life :)




Click here to see an interesting article about fuses from my preferred magazine, Circuit Cellar Ink, the only magazine I still regularly read since 1989 !!!
Enjoy !

13 comments:

  1. Do you have any information on the specification for the fuse? I have the same lamp with a blown fuse and I'm not sure what to replace it with.

    ReplyDelete
    Replies
    1. No, I have to open the lamp and see if there are some indications.
      You can look for the resistance of the lamp you want to use, pay attention that the filament change resistance with the temperature, usually when cold is much lower, so you can expect a "pike". For example a 100W lamp when cold has a filament around 9.5 Ohm, about 11 A pike.
      When hot the filament is around 144 Ohm, so about 1A. The fuse must sustain the initial pike, so 15A ?
      Look for info about the lamp you want to use.

      Delete
  2. Ӏt's going to be end of mine day, except before end I am
    rеading this wonderful article to іncrease
    my know-how.

    ReplyDelete
  3. Wow, here l am in exactly the same situation as you were when it first happened. I just found this page and it is amazing that l did the exact same process as you had and came to the same conclusion. I even told my wife and then l found this page. Thanks so much. Now l need to find a transformer. Everything else seems to be giving the correct readings on my meter. Thank you for your page.

    ReplyDelete
  4. Hey man i opened mickey time ago but i can't remmeber conect a little spring in his arm could you show me a photo? please!

    ReplyDelete
    Replies
    1. Hi Daniel, well I never actually opened the mechanical part of the character, I don't have any picture of the arm or inside the arm, I always worked on the electronic at the base.
      Sorry

      Delete
  5. Hi There,
    I have a similar lamp, but it's a goofy version. I sent it to A-1 telephone and they did the repair, but it cost me a bit plus a lot for shipping-that was a few years ago. Well I went to turn it on and with a quick flash it shorted out. Now it isn't working. Do you have anyone you would suggest for repairs?

    ReplyDelete
  6. Thanks for this, attempting to repair a goofy lamp for a friend. Has the same circuity. This is really helpful and confirms my diagnostic that the transformer is out. Also explains why the lamp doesn't work since it is optocoupled, I couldn't figure that one out at all, and was causing much confusion.

    ReplyDelete
  7. Im a dummy and not an electrician. I have lost the cable to this while moving house. Can i ask is there any way I can purchase a generic cable with the adaptor online?

    ReplyDelete
    Replies
    1. What cable are you talking about ?
      The lamp has no external adapter and the cable is attached to the lamp, can't be removed.

      Delete
  8. Hello from Spain. I have this lamp and we always connect it to a current autotransformer because the current in Spain is 220V and the lamp is 125V. Unfortunately, a visiting relative connected the lamp directly to the 220V curremt and now it does not work. We are looking for a internal power transformer to replace the HUNG KAI 4104 because we believe that is was damaged because the fuse does not appear damaged. We have found a internal Power Transformer with 220V input and 6V and 10W output. My question is: with this internal Power Transformer... would the lamp work without having to use an external autotransformer 125-220 or we need to find an internal 125V input power transformer and continue using the external autotransformer? I do not know if I explained well. Thanks in advance.

    ReplyDelete
    Replies
    1. ¡Hola!
      Well, yes, the transformer could do the trick, however there is a problem.
      The lamp is controlled by a SCR and all the circuit is designed for the 110V, not 230V.
      So you will end up to power up correctly the base circuit, the one that handle the voice and the animation, but the lamp itself could still have problems unless you adapt the SCR circuit for the 220V.
      Btw, it is possible the SCR circuit and the lamp are fried.

      I would proceed in this way :
      - remove the very probably burned out transformer
      - with a power supply try to give 7 V to the circuit and see if at least voice and movement is coming back. If not ... all the lamp is to trash away
      - if OK, change the transformer similar to the original one
      - since the fuse seems intact, change the lamp, connect it to the auto-transformer and see if is turning on
      - if not the SCR is probably fried as well, try to change it and if still has problems probably is not worth continue

      I would continue to use an auto-transformer in order to keep all the lamp under 110V.
      Just my 2 cents.

      Good luck

      Delete