Will this mod work for Panasonic FS-A1WX? | MSX Resource Center (Pagina 2/4)

Van Pentarou

Hero (523)

05-07-2016, 17:36

Alexey wrote:

I am going to measure the temperature of the transformer as well as critical elements in the DC converter circuit.

You should connect a sound cart and test how it sounds.

Van Wierzbowsky

Guardian (3603)

05-07-2016, 17:40

Pentarou wrote:

Alexey wrote:

I am going to measure the temperature of the transformer as well as critical elements in the DC converter circuit.

You should connect a sound cart and test how it sounds.

Yes, will do that too. The +/-12v circuit should work just fine with the transformer. So the amps on sound cartridges should have enough power.

Van Pentarou

Hero (523)

05-07-2016, 17:46

The problem is not the power, the problem is the (electrical) noise. That's the reason they use 2 separated coils.

Van meits

Scribe (6544)

05-07-2016, 18:00

If you check with a sound card, you could play a violin, or any long note and sample it before and after.
Then invert one of the samples and mix them together to find out if they cancel each other out. If so, there's no change.

Van Wierzbowsky

Guardian (3603)

05-07-2016, 18:12

Pentarou wrote:

The problem is not the power, the problem is the (electrical) noise. That's the reason they use 2 separated coils.

The electrical noise in the audio channel pretty much depends on how well the amplifier on the sound cartridge is designed. I designed a few FMPAC boards and noise-wise the difference between the first design and the last one was amazing. So I am not sure that the trick with the sound cartridge will make any difference. However if I hear much more noise from the internal sound output of the computer, I will try to reduce it by adding extra caps to the internal amplifier, the same way I did for FMPAC board.

Van -Neo-

Champion (396)

09-07-2016, 13:34

Did you already try the mod? I am curious as I like to do this mod on the wx too.

Van Wierzbowsky

Guardian (3603)

09-07-2016, 18:08

-Neo- wrote:

Did you already try the mod? I am curious as I like to do this mod on the wx too.

Just did the mod for my TurboR, WX is next. However, after discussing the possible problems with WX conversion to 220v, I don't feel very confident about it. According to our electronics guru the transformer outputs 14v AC that will result in 18.8v DC after the diodes. The voltage tolerance of the 5v converter on the WX board is 20v. Very very close. As a result the voltage convertors will be under constant stress and will heat up a lot.

So that's what I gonna do. I will measure the AC voltages from all transformer's coils on the WX to see what voltages are being output to the board for DC conversion. Then I will talk to our guru again and see if changing the transformer is a good idea.

Van Wierzbowsky

Guardian (3603)

11-07-2016, 15:30

After some discussion with our guru we decided to go for the transformer change. However there's a possibility that the 12v circuit will not get enough power after conversion and the voltages will be falling. We seem to have found an elegant solution for this problem - you just need to remove the D6 and D7 diodes and put a rectifier instead. Only 2 wires will be needed. Here's the schematics:

The following rectifier will be needed:
https://www.conrad.de/de/silizium-brueckengleichrichter-2-a-diotec-b40r-nennstrom-2-a-u-rrm-80-v-501433.html

Physical connection will look like that:

Van -Neo-

Champion (396)

11-07-2016, 20:34

Great stuff. Looks a bit too complicated to do myself. I was hoping the WX would also use +12 - 0 - 12 volts and could be simply replaced but I guess that won't work?

Van Wierzbowsky

Guardian (3603)

11-07-2016, 21:00

It should work. But it might not. The problem is that the 12v regulators receive only part of AC power (with different phases). The original transformer outputs 20v AC to the diodes before the power regulators while the new transformer will output only 14v AC. This may result in voltage drops and will require a rectifier to be installed as shown in the previous post. I will try to install the new transformer once I figure out the problem with FMPAC.