Got a Modem Blaster DE-5620?

I need to know what AC-adapter it uses.

If you have one of these external modems, could you check the markings on
the AC-power adapter for me?

I don't know if it's 12 VAC, 9 VDC with center pin +, or 6 VDC center-pin
negative, or what...

I opened it up to see if the PC-board had it painted on there.
(Sometimes they do.) No luck.

No luck on Creative Labs site, either.

You're my only hope. It's not going to work too well until it gets power.

Thanks in advance,

- Ralph

On Fri, 10 Jun 2005 16:20:13 GMT, Ralph Innes
<haruspex(NOSPAM)@shaw.ca> put finger to keyboard and composed:

Can you post a photo of the circuit board on your webspace? A simple
analysis of the components near the power socket may tell you what you
need to know.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Thanks for the response, Franc.

Here's the component side of the board, with detail on the lower section.
The yellow arrow points to the pwr connector. Not much to go on, but maybe
you can glean something from it. (I hope.)

http://members.shaw.ca/haruspex/DE5620.jpg

The wiring side of the board has a copper shield (I assume it's insulated)
covering the entire side, soldered at each corner.

Thanks again,

- Ralph

Franc Zabkar <fzabkar@optussnet.com.au> wrote in
news:gbmma11a71ckvija90brgb1iovtttpgl4i@4ax.com:

On Sun, 12 Jun 2005 03:02:08 GMT, Ralph Innes
<haruspex(NOSPAM)@shaw.ca> put finger to keyboard and composed:

Short version - I'm guessing 9VAC, 500mA. Use a multimeter to confirm
that there is no continuity between each of the pins in the power
socket and pin 7 of the serial DB25 connector.

Here's the long version.

The three large components (U12, L20, C6?) which are located in a
direct line between the on/off switch and power socket comprise a +5V,
500mA switchmode power supply. I can't see the markings on the chip at
U12 (?), but I believe it is an AP34063:

http://www.anachip.com/downloads/dat...eg/AP34063.pdf
http://www.anachip.com/downloads/app...01_AP34063.pdf

The maximum power output of this regulator is 2.5W. Assuming an
efficiency of 80%, this translates to a power input of ~3W.

The bridge rectifier, BR2 (?), to the left of capacitor C72 suggests
that the modem's power requirement is AC. It appears that one of the
AC terminals (~) of BR2 goes to the power socket while the second
connects to the switch, probably via a copper track on the solder side
of the PCB. It would help to know the voltage rating printed on C72
(horizontal cap), but I expect that the modem should work with a 9VAC,
500mA (4.5VA) adapter.

The two capacitors, C74 and C75 (?), are a bit of a mystery, but I
suspect they may be involved in generating the +12V and -12V required
by the serial interface. It would help to know the part number on the
20-pin chip to the left of the DB25 socket.



- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Wow! That's a truly comprehensive response, Franc. Much appreciated.

The male pin reads "open" to pin-7.

The outer rim contact reads, variously 50K and 15K, depending on lead-
polarity with a DVM. And reads 50 Ohms or 120 Ohms, similarly, with an el-
cheapo analog meter. I'm not sure what I'm seeing here...
I guess you'd be referring to U12, L20 and C69. I've posted a better pic
of these components:

http://members.shaw.ca/haruspex/C69-U7.jpg

U12 is, indeed, an AP34063, also shown on link above.

C72 is a 1000uf 25V cap. ZD7 is located between C72 and L20. (Would that
be a zener diode?)
U7, the chip west of the DB25 socket has markings "LGS S29 GD75323D",
which I take to mean it is a GD75323D, also shown on the new pic I posted.

I want to thank you again, Franc, for taking the time & trouble to repond
to my plea. It's very generous of you.

I repair camera lenses as a hobby, and offer all the help and parts I can,
to people who're similarly engaged. And, the internet is a great vehicle
for exchanging information.

It's nice to be on the receiving end this time...

- Ralph

On Mon, 13 Jun 2005 14:21:44 GMT, Ralph Innes
<haruspex(NOSPAM)@shaw.ca> put finger to keyboard and composed:

Pin 7 connects to circuit ground. The fact that there is no continuity
suggests that the power input is AC rather than DC. The resistance
readings are consistent with (1) and open on/off switch and (2) a
diode in the bridge at BR2. You should get the same readings for both
contacts of the power socket if you close the switch. A digital
multimeter will show high resistance on the resistance ranges because
the current is insufficient to turn on a PN junction. However, it
should show a voltage drop of about 0.6V on the diode range, if it has
one. An analog meter will show a lower resistance because it puts out
a much higher current.

I suspect that the modem would easily tolerate a 12VAC supply. After
rectification, and allowing for voltage drops in BR2, the 12VAC supply
would become ~16VDC (= 12 x 1.414 - 2 x 0.6). This would provide
plenty of margin for C72.

Normally that would be the case. But the diode appears to be a 1N5817,
which is a fast Schottky rectifier, not a zener.

http://www.onsemi.com/pub/Collateral/1N5817-D.PDF

This chip requires three supplies, +5V, +9V (typical), and -9V.
See http://goodwork.ru/chips/slls213a.pdf

This would tend to confirm an AC requirement. I'd go for 9VAC, 500mA
or better. 12VAC would probably be OK, assuming the voltage ratings of
the caps at C74 and C75 were up to it.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

On Tue, 14 Jun 2005 08:48:21 +1000, Franc Zabkar
<fzabkar@optussnet.com.au> put finger to keyboard and composed:

Correction. A 12VAC adapter may produce voltages which exceed the
absolute max supply requirements (+/-15V) for the GD75323D IC.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Thanks for this, Franc.

As you suggested, both tip & ring of the pwr connector read similar
resistance to pin-7 when the pwr switch is "on".

Though C74 and C75 are both rated at 25V, I'll heed your warning and scare
up a 9VAC supply.

I think it's important to keep problem resolutions like this one in the
public arena. The temptation is to take it to private email, but then it
is lost to others who follow, and may be looking for the same solution.
Somebody, some day, will be looking for an AC-adapter for a Flash56 modem,
and Google will turn up this thread. And the wheel won't have to be
reinvented...

When I find a 9VAC adapter, I'll post the outcome.

Many thanks for all of this, Franc. Definitely above and beyond the
call...

- Ralph

Franc Zabkar <fzabkar@optussnet.com.au> wrote in
news:2m3sa1ha29fuh9p7q3mmp8grv7an4vgh6v@4ax.com:

I found a 9VAC 400ma supply, and the modem comes alive on it. I'll keep an
eye out for one with a little higher current rating, though.

Thanks again for all the help, Franc.

- Ralph

Franc Zabkar <fzabkar@optussnet.com.au> wrote in
news:2m3sa1ha29fuh9p7q3mmp8grv7an4vgh6v@4ax.com:

On Wed, 15 Jun 2005 23:56:52 GMT, Ralph Innes
<haruspex(NOSPAM)@shaw.ca> put finger to keyboard and composed:

Just to give yourself a little extra confidence, I'd check the
voltages on the output pins (eg pins 2 and 6) of the modem's DB25
connector.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Hi Franc,

Relative to pin #7, pin #6 measures +11.85VDC, pin#2 measures +0.07VDC

Pin #6 measures +11.74VDC, relative to pin#2.

Kosher?

- Ralph

Franc Zabkar <fzabkar@optussnet.com.au> wrote in
news:i222b19cq91pfq575lup5eb27jn01nu0m4@4ax.com:

On Thu, 16 Jun 2005 14:50:38 GMT, Ralph Innes
<haruspex(NOSPAM)@shaw.ca> put finger to keyboard and composed:

Yep, all's well, although I got it wrong with pin 2. I should have
asked you to measure pin 3. I was looking for a result of around
+/-10V to +/-12V which IME is the most common range for RS232
voltages.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Pin #3 reads -11.4VDC relative to Pin #7, -23.0VDC relative to pin #6

Guess that's what you were looking to see?

- Ralph

Franc Zabkar <fzabkar@optussnet.com.au> wrote in
news:io04b11942mslgm4quld7bgr80906mh1qv@4ax.com:

On Thu, 16 Jun 2005 23:46:02 GMT, Ralph Innes
<haruspex(NOSPAM)@shaw.ca> put finger to keyboard and composed:

I wanted to confirm that the voltages at pins 3 and 6 (relative to
ground) were within the operating limits (+/-15V) of the GD75323D IC.
So, yes, all is well. Just make sure the AC adapter doesn't get hot.
My total wattage calculations were based on the absolute maximum
rating of the internal +5V switchmode PS, so 400mA may be more than
adequate. In fact, there is an earlier thread in this NG regarding an
external GVC Rockwelloid. Its user manual states that its power draw
is only 0.75W, and its rating sticker specifies a 5V 300mA (1.5W)
adapter. Your modem probably has similar power consumption (it is also
a Rockwelloid), so 9V @ 400mA gives 3.6VA which is about double that
of the GVC.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

I've been keeping an eye on the adapter, and it's running just above body
temperature. If I come across one with a higher rating, I'll replace it.
Meanwhile, I'll keep this one in an exposed area, where it can dissipate
heat well, and where I'll notice any problem right away.

Thanks for all your help on this, Franc.

Now, I can work on the next task: configuring SuperVoice. The object is to
set up a voicemail system on a phone line with Distinctive Ring and Caller
I.D. I'd tried this whole process about 3 years ago, but SuperVoice said
that the USR V. Everything Courier wasn't a voice modem. It seems the
software will work with this Modem Blaster.

Take care,

- Ralph

Franc Zabkar <fzabkar@optussnet.com.au> wrote in
news:7hf6b1leuurqkffs5ekoerrrl2qj0mlou1@4ax.com: