3COM US ROBOTICS 56K INT ISA-Slot Modem Type 0613 repaired

[Johann]

To all who want to try to repair their broken Modem 3COM US ROBOTICS
56K INT ISA-Slot Type 0613 themselves a tip that may help: I got a
broken one for free, which could be installed as usual with driver
from http://www.driversguide.com.
When trying to connect, it was dialing, but it did not establish a
connection to the server. I found out that the transistor Q7 used for
switching the relay coil of the 5 Volts Fujitsu SY-5-K relay was
broken. I tried out an ordinary general purpose PNP transistor
Motorola 2N4403 instead and it worked. The emitter must be soldered to
the soldering point of the replaced surface mounted transistor, which
is on the side of the ISA-slot, the collector in the mid (connected to
the relay coil) and the base to the one soldering point which is on
the side of the relay.

Good luck,

Johann

 

[techforce]

Good Work. If there is no Diode accross the C-E of that Transistor, it will
fail again down the road because the Counter EMF of the Coil in the Relay
will gradually degrade it. You may want to throw a 1N4148 Type Diode accross
C-E in a manner that its reverse the polarity of C-E th Help Absorb some of
that Energy.



| To all who want to try to repair their broken Modem 3COM US ROBOTICS
| 56K INT ISA-Slot Type 0613 themselves a tip that may help: I got a
| broken one for free, which could be installed as usual with driver
| from http://www.driversguide.com.
| When trying to connect, it was dialing, but it did not establish a
| connection to the server. I found out that the transistor Q7 used for
| switching the relay coil of the 5 Volts Fujitsu SY-5-K relay was
| broken. I tried out an ordinary general purpose PNP transistor
| Motorola 2N4403 instead and it worked. The emitter must be soldered to
| the soldering point of the replaced surface mounted transistor, which
| is on the side of the ISA-slot, the collector in the mid (connected to
| the relay coil) and the base to the one soldering point which is on
| the side of the relay.
|
| Good luck,
|
| Johann

 

[Franc Zabkar]

Good Work. If there is no Diode accross the C-E of that Transistor, it will
fail again down the road because the Counter EMF of the Coil in the Relay
will gradually degrade it. You may want to throw a 1N4148 Type Diode accross
C-E in a manner that its reverse the polarity of C-E th Help Absorb some of
that Energy.

The diode should go across the hook relay coil in a reverse biased
direction. Just to be safe, make it a 1A rectifier, eg a 1N4001, not a
1N4148 signal diode.

| To all who want to try to repair their broken Modem 3COM US ROBOTICS
| 56K INT ISA-Slot Type 0613 themselves a tip that may help: I got a
| broken one for free, which could be installed as usual with driver
| from http://www.driversguide.com.
| When trying to connect, it was dialing, but it did not establish a
| connection to the server. I found out that the transistor Q7 used for
| switching the relay coil of the 5 Volts Fujitsu SY-5-K relay was
| broken. I tried out an ordinary general purpose PNP transistor
| Motorola 2N4403 instead and it worked. The emitter must be soldered to
| the soldering point of the replaced surface mounted transistor, which
| is on the side of the ISA-slot, the collector in the mid (connected to
| the relay coil) and the base to the one soldering point which is on
| the side of the relay.
|
| Good luck,
|
| Johann

- Franc Zabkar

 

[techforce]

That Would be nice, but the Smaller Leeds in the 1N4148 give less chance of
lifting a land on the SMD Stuff if by chance something brushes up against
it.. I guess if you are a Very good Solderer its not a concern.


|
| The diode should go across the hook relay coil in a reverse biased
| direction. Just to be safe, make it a 1A rectifier, eg a 1N4001, not a
| 1N4148 signal diode.
|

 

[techforce]

I have a Rockwell PCI type Modem that wont detect a Dial tone. Drivers
install ok. Do you think this could be the same problem?

I dont remember if the Relay Clicks or not on this one.


| To all who want to try to repair their broken Modem 3COM US ROBOTICS
| 56K INT ISA-Slot Type 0613 themselves a tip that may help: I got a
| broken one for free, which could be installed as usual with driver
| from http://www.driversguide.com.
| When trying to connect, it was dialing, but it did not establish a
| connection to the server. I found out that the transistor Q7 used for
| switching the relay coil of the 5 Volts Fujitsu SY-5-K relay was
| broken. I tried out an ordinary general purpose PNP transistor
| Motorola 2N4403 instead and it worked. The emitter must be soldered to
| the soldering point of the replaced surface mounted transistor, which
| is on the side of the ISA-slot, the collector in the mid (connected to
| the relay coil) and the base to the one soldering point which is on
| the side of the relay.
|
| Good luck,
|
| Johann

 

[Franc Zabkar]

That Would be nice, but the Smaller Leeds in the 1N4148 give less chance of
lifting a land on the SMD Stuff if by chance something brushes up against
it.. I guess if you are a Very good Solderer its not a concern.

I just checked a typical Rockwell modem circuit. It uses a 1N4148, so
it looks like you are right. If the relay coil is a 500 ohm, 5V type,
then it should draw 10mA max, which is well within the range of a
signal diode.

| The diode should go across the hook relay coil in a reverse biased
| direction.

This is the way the circuit has it, so I got this part right

Just to be safe, make it a 1A rectifier, eg a 1N4001, not a
| 1N4148 signal diode.

- Franc Zabkar

 

[Hawkeye]

I had two brand new USR PCI modems that failed in a matter of days in
the same fashion. Same cause, bad transistor, but due to the SMT
construction I couldn't repair them, besides, I just returned them
under warranty.

 

[Franc Zabkar]

I have a Rockwell PCI type Modem that wont detect a Dial tone. Drivers
install ok. Do you think this could be the same problem?

I dont remember if the Relay Clicks or not on this one.

Does it actually have a relay? Many newer modems use silicon
(transformerless) DAAs.

Here's a way to test the operation of your hook relay. Disconnect the
modem from the phone line and measure the voltage between tip and
ring. It is usually around 50VDC. Now reconnect the modem. In the
on-hook state, the voltage should not change much, if at all. In the
off-hook state, ie when the hook relay is closed, the voltage should
drop to around 10V or so.

You can set the modem to ignore dialtone by adding X3 to your Extra
Settings.

| To all who want to try to repair their broken Modem 3COM US ROBOTICS
| 56K INT ISA-Slot Type 0613 themselves a tip that may help: I got a
| broken one for free, which could be installed as usual with driver
| from http://www.driversguide.com.
| When trying to connect, it was dialing, but it did not establish a
| connection to the server. I found out that the transistor Q7 used for
| switching the relay coil of the 5 Volts Fujitsu SY-5-K relay was
| broken. I tried out an ordinary general purpose PNP transistor
| Motorola 2N4403 instead and it worked. The emitter must be soldered to
| the soldering point of the replaced surface mounted transistor, which
| is on the side of the ISA-slot, the collector in the mid (connected to
| the relay coil) and the base to the one soldering point which is on
| the side of the relay.
|
| Good luck,
|
| Johann

- Franc Zabkar

 

[Johann]

The SMD-transistors need some special technics for removing them from
the board, without destroying the soldering points on the board or the
transistor. Usually I borrow a third and fourth hand from my
girl-friend and we are working with three fine soldering irons, one
for each soldering-point. At the same time the SMD transistor is held
with a pincette in its place and lifted away as soon as the tin is
molten. You need a pincette, since these lightweight pieces tend to
adhere on the tip of one of the soldering irons and may then be
thermally destroyed.

Besides: Does someone now a chemical etching liquid, by which
soldering tin can be removed from non-repairable boards, in order to
recover all SMD-chips from it. I am not very much in favour of
technics using a hot flame, but would like to put them in a glass and
let do an etching liquid this job (without destroying the integrated
circuits)?


With kind of regards,

Johann

 

[Ken Weitzel]

The SMD-transistors need some special technics for removing them from
the board, without destroying the soldering points on the board or the
transistor. Usually I borrow a third and fourth hand from my
girl-friend and we are working with three fine soldering irons, one
for each soldering-point. At the same time the SMD transistor is held
with a pincette in its place and lifted away as soon as the tin is
molten. You need a pincette, since these lightweight pieces tend to
adhere on the tip of one of the soldering irons and may then be
thermally destroyed.

Besides: Does someone now a chemical etching liquid, by which
soldering tin can be removed from non-repairable boards, in order to
recover all SMD-chips from it. I am not very much in favour of
technics using a hot flame, but would like to put them in a glass and
let do an etching liquid this job (without destroying the integrated
circuits)?


With kind of regards,

Johann

Solder wick?

Ken

 

[Ricky Eck]

Solder wick?

Ken

A Solder Wick is solder removal device. It is fine braded wire, that will
effectively remove solder from the source you intend. It is actual better
then a solder bulb (solder sucker), but is not reusable. Therefore can
become expensive if you do a lot of solder removal. However, it usually
does it in one shot, therefore reducing the amount of time you have to keep
heat to a connection to remove the solder.

Hope that helps,
Rick

 

[Michael Black]

The SMD-transistors need some special technics for removing them from
the board, without destroying the soldering points on the board or the
transistor. Usually I borrow a third and fourth hand from my
girl-friend and we are working with three fine soldering irons, one
for each soldering-point. At the same time the SMD transistor is held
with a pincette in its place and lifted away as soon as the tin is
molten. You need a pincette, since these lightweight pieces tend to
adhere on the tip of one of the soldering irons and may then be
thermally destroyed.

Besides: Does someone now a chemical etching liquid, by which
soldering tin can be removed from non-repairable boards, in order to
recover all SMD-chips from it. I am not very much in favour of
technics using a hot flame, but would like to put them in a glass and
let do an etching liquid this job (without destroying the integrated
circuits)?

If this is just to reuse the ICs (rather than repairing a board where
you want the board intact), you might try a hot air gun, the type used
to strip paint. It gets the ICs off, you can heat up the board and
shake the surface mount devices off, but there's not the open flame
of a torch.

Micahel

 

[Ken Weitzel]

A Solder Wick is solder removal device. It is fine braded wire, that will
effectively remove solder from the source you intend. It is actual better
then a solder bulb (solder sucker), but is not reusable. Therefore can
become expensive if you do a lot of solder removal. However, it usually
does it in one shot, therefore reducing the amount of time you have to keep
heat to a connection to remove the solder.

Hope that helps,
Rick

Hi...

I agree it's expensive, but you can make your own if you've
a mind to.

Braid is very cheap. Just buy a few lengths of differing
sizes, and using your fingers smear a little rosin into
it. Then (before washing your hands) wind it into one
of your empty spools.

Take care.

Ken

 

[JURB6006]

I have a Rockwell PCI type Modem that wont detect a Dial tone. Drivers

install ok.

If it has a transformer, it might be the culprit.

JURB