Technical and Repair Assistance

[Lorfarius]

The multimeter has a huge dial with the following:

V ~

600, 200

A--- (This has a straight line with 3 black dashes underneath next to the letter)

200 u, 2000u, 20m, 200m, 10A

hFE

Omega Symbol

200, 2000, 20k, 200k, 2000k

V --- (This has a straight line with 3 black dashes underneath next to the letter)

200m, 2000m, 20, 200, 600

Each number is a setting on a dial and the bold letters are divided up into sections around it. Not sure which to set it too and the instructions for this thing are pretty poor  But it did recommend using the lowest setting if you werent sure. Any ideas which number I should be going for?

[133MHz]

V --- (This has a straight line with 3 black dashes underneath next to the letter)

200m, 2000m, 20, 200, 600

[Lorfarius]

The LED shows 10.60, sometimes flicking to 10.61

[133MHz]

Good. That means that power is reaching the voltage regulator. Now test 2

[Lorfarius]

Good. That means that power is reaching the voltage regulator. Now test 2

Yay some good news!    Will let you know the results of 2 later 

[Lorfarius]

Results for these test, copied exactly results in bold:

Test 1:
   ___
  |  o  |
|¯¯¯¯¯|   
| 7805 |   
|_____|   
| | | | | |
| | | | | |
T  T  ¯
  |    ¯¯¯¯¯¯  Black lead here
  ¯¯¯¯¯¯¯¯  Red lead here
1  2  3

-0.58

Test 2:
   ___
  |  o  |
|¯¯¯¯¯|   
| 7805 |   
|_____|   
| | | | | |
| | | | | |
¯  T  T 
      |    ¯¯¯¯¯¯  Red lead here
       ¯¯¯¯¯¯¯¯  Black lead here
1  2  3

-11.17

[133MHz]

I should've asked first: Did the Twin suddenly stop working or it never worked at all as far as you're concerned?
Because if you're getting negative voltages, you either have the test leads reversed on your multimeter or you're using the wrong AC adapter (reverse polarity).

Also, the tests should be done with the front side of the regulator facing you (the side with the numbers printed on it).

[Lorfarius]

I should've asked first: Did the Twin suddenly stop working or it never worked at all as far as you're concerned?
Because if you're getting negative voltages, you either have the test leads reversed on your multimeter or you're using the wrong AC adapter (reverse polarity).

Also, the tests should be done with the front side of the regulator facing you (the side with the numbers printed on it).

It suddenly stopped working. I'm currently using a Universal Unregulated AC/DC power adaptor which lets you select the voltage but there doesnt seem to be anyway to change the polarity on it just a switch for the voltage. I did have a Japanese convertor to use with the original TF plug but when the console stopped working a few days ago I sent it back to the eBay seller in the hope it was down to that failing. He's going to test it when it arrives.

Edit. Scratch that. Managed to find a way to change the polarity on it! More results:

Test 1 = 1.78
Test 2 - 2.48

Edit AGAIN  :

It works!! The Japanese adaptor must have died. Ive just changed the polarity on the Universal adaptor and its started loading a disk in the drive. Hooray! Famicom games ahead!

I feel like a right idiot  Thanks for all of your help 133MHz as I wouldn't have got any of this without you

[133MHz]

Glad to be helpful

BTW, you were pretty lucky for not killing your Twin Famicom with reverse polarity. It is known that Twin Famicoms do not have reverse polarity protection (that's why you got negative voltages at the regulator terminals). Somebody here tried an AC adapter with the wrong polarity on his Twin, and the main filter capacitor went *BOOM*

[Lorfarius]

Glad to be helpful

BTW, you were pretty lucky for not killing your Twin Famicom with reverse polarity. It is known that Twin Famicoms do not have reverse polarity protection (that's why you got negative voltages at the regulator terminals). Somebody here tried an AC adapter with the wrong polarity on his Twin, and the main filter capacitor went *BOOM*

Tell me about it  Its time I had some luck with this thing. Off to play Challenger 

[a121729243]

I just got a not working Famicom from Japan.
It was fine when it was in Japan, but now there is no any response on TV screen when I turn on the power.
The TV screen even doesn't have a "wave" when I turn on/off  the power switch.
I have another Famicom, so I am sure the AC adaptor and the signal cord are fine.
My guess is either the power on/off switch or the AC adaptor connector is dead....
Any suggestion for me to do the quick check??

Thank you all.

[133MHz]

It may have a fuse on the RF board. If it does, it could've blown. This is what it looks like:

          ^   
          It's the black thing

[Lorfarius]

It may have a fuse on the RF board. If it does, it could've blown. This is what it looks like:

          ^   
          It's the black thing

Just as a point of interest. How difficult is it to replace such a fuse? I take it you need to solder it back on?

[wolf9545]

I didn't replace mine I just soldered a piece of wire jumping from one side of the fuse to the other.  It looks like a typical electrical component.  That means that all you should have to do is get an exact replacement, remove the solder on the existing component and remove it.  Then just place the new component back in and re-solder it (direction should not matter because it is a fuse.

[a121729243]

Dear 133MHz
Thank you for your quick answering.
I just had our engineer checked on my Famicom (...don't tell my boss....: ) ), and the layout of the RF board in my machine is different than what you are showing me.
There is no such a fuse on my RF board, and the engineer couldn't find anything on the RF board looks like a fuse.
Our engineer also confirm that the on/off switch is fine, and the 5V voltage does go to the mother board, so there must be something wrong after the power supply system....
Anymore suggestion??

Old Game Lover