QSD3A Restoration.... What have I gotten myself into?

[DavePEI]

Paging DavePEI:  I have a couple of quick questions.

Do you have a scan of an appropriate instruction card for a QSD3A?

Also, on the circuit diagram you posted, it shows a capacitor between the A and X terminals in the upper housing.  I appear to be missing this component; at least I sure don't see one.  Do you have any idea what the value of this capacitor might be, or can I do without it?

I am aware the the brown wires have been cut; I'm going to resolder them and route them appropriately; one to the A terminal, and the other to the BK terminal.

No, I don't have a card specifically made for the QSD-3A.

Alas, we just had another major snow storm, so it will be a while till I am able to get back into the museum to have a look at my QSD-3A. Its been 5 years since I had the phone open, and my memory isn't great on details like that...

Hmmm,,, The Schematic does show the capacitor, but doesn't give a value. You could try .47 or 1 ufd and see if that works.

Dave

[mentalstampede]

Paging DavePEI:  I have a couple of quick questions.

Do you have a scan of an appropriate instruction card for a QSD3A?

Also, on the circuit diagram you posted, it shows a capacitor between the A and X terminals in the upper housing.  I appear to be missing this component; at least I sure don't see one.  Do you have any idea what the value of this capacitor might be, or can I do without it?

I am aware the the brown wires have been cut; I'm going to resolder them and route them appropriately; one to the A terminal, and the other to the BK terminal.

No, I don't have a card specifically made for the QSD-3A.

Alas, we just had another major snow storm, so it will be a while till I am able to get back into the museum to have a look at my QSD-3A. Its been 5 years since I had the phone open, and my memory isn't great on details like that...

Hmmm,,, The Schematic does show the capacitor, but doesn't give a value. You could try .47 or 1 ufd and see if that works.

Dave

Thanks, Dave.  I might see about making up a card of my own when I get that far along.  At this point I'm still stripping paint and sanding and checking out the guts of the phone though, so I'm getting a little ahead of myself.

As for the capacitor, I'm assume it's intended as some sort of audio filter, but filtering what, I can't imagine.  I might try hooking it up without it to see what happens.

Is that a UNICOMP model M in the background? they are great keyboards.

Good eye! Yes, that's a newer Unicomp Model M.  USB, and it has the windows specific keys.

[DavePEI]

Hi Kenn:

Courtesy of Stan Schreier, here is a good description of the action of a QSD-3A....

     "The capacitor across the electromagnet in a Western or Northern prepay
or postpay 3-slot is for audio frequency response. Everything will work
without the capacitor but the payphone won't sound as good.

    The electromagnet in a prepay Western or Northern is different than a
postpay.  In a prepay the armature of the electromagnet pulls in only when
there's current flow regardless of the polarity of the current.  In other
words a prepay electromagnet is a non-polarized device..  When there's a no
current flow the armature releases.

    The electromagnet in a postpay is polarized. The position of the
armature depends on the polarity of the current flow.  The armature does not
return to its previous position when current flow stops. The only way to
release the electromagnet is to reverse the polarity of the current. In
other words the postpay electromagnet is a polarized device.  The direction
of current flow through the electromagnet depends on the state of the phone
call.  Current goes one way when the call is initiated and reverses when the
called party answers. When the payphone goes off hook on the next call the
current flow through the electromagnet goes back to its original polarity
(causing the position of the electromagnet to change) and the routine starts
all over again.

    You can simulate the operation of a postpay electromagnet using a 9V
transistor radio battery.  Momentarily touch the terminals of the battery to
the A and E terminals of the postpay coin track.  If the electromagnet
doesn't move, reverse the polarity of the battery. The electromagnet will
change position.  Reverse the polarity of the battery again and momentary
touch the terminals. The electromagnet will go back to its original position
and stay there.

    You can test a prepay electromagnet in the same way. However, every time
you touch the battery to the A and E terminals the magnet will pull in
regardless of polarity. When you remove the battery the prepay electromagnet
will release."

Also, below is a scan of a suitable Instruction Card...

Dave

[DavePEI]

Here is another photo from Stan comparing Postpay and PrePay relays:

[mentalstampede]

Interesting..... In that case, my phone has a prepay cointrack electromagnet.  It looks like the one in the picture, and it behaved like a prepay is described when I checked it with a battery on the terminals. But the phone is clearly marked QSD3A.

Strange!

[G-Man]

7.00 DIAL POSTPAY SERVICE (CDO)

7.01 In dial postpay service, dial tone is received,
the called number is dialed, and the called
party answers before a deposit is required. Refund
of deposits is not necessary. Dial postpay service
has central office equipment which, when the called
party answers on nonfree calls, automatically
splits the connection and sends a deposit-coin tone
to the calling party. Deposit-coin tone is a low tone
to inform the calling party that the called party
has answered and that the required coins should
be deposited. During the time the connection is
split, the battery supply to the coin station is reversed
in direction. This current reversal prepares
the coin collector for the 10-cent initial coin deposit.
The first coin, passing through the coin
hopper, opens a pair of contacts on the spring
assembly, which places a 4450-ohm resistor momentarily
in the circuit. The increased loop resistance
will cause the central office equipment to
remove the split connection and prepare the circuit
for conversation.

7.02 The central office line circuit for dial postpay
service furnishes battery on the ring
side and ground on the tip side of the line. This
requires only a completion of the loop through the
primary circuit to operate the line circuit and prepare
the line for dialing as indicated by dial tone
(loop start).

7.03 For dial postpay service, the coin hopper is
equipped with a coin trap and a coin vane.
The coin vane is positioned permanently to the [snip]

[poplar1]

Interesting..... In that case, my phone has a prepay cointrack electromagnet.  It looks like the one in the picture, and it behaved like a prepay is described when I checked it with a battery on the terminals. But the phone is clearly marked QSD3A.

Strange!

Is it possible that someone changed out the coin chute to a prepay one? Another CAN P894263 chute was found in a NE 233QF by a forum member, jjacob:

http://www.classicrotaryphones.com/forum/index.php?topic=10199.0  Reply #1

The 233QF is a prepay set.

[mentalstampede]

Interesting..... In that case, my phone has a prepay cointrack electromagnet.  It looks like the one in the picture, and it behaved like a prepay is described when I checked it with a battery on the terminals. But the phone is clearly marked QSD3A.

Strange!

Is it possible that someone changed out the coin chute to a prepay one? Another CAN P894263 chute was found in a NE 233QF by a forum member, jjacob:

http://www.classicrotaryphones.com/forum/index.php?topic=10199.0  Reply #1

The 233QF is a prepay set.

That seems likely that it was changed at some point; The phone is dated 68, with numerous yellow 1970 stamps on the back, but the chute assembly is dated 72.

The phone does have the correct postpay hopper with the vane fixed in position.  Perhaps whomever did the hackjob conversion swapped out the cointrack?

[mentalstampede]

Quick Update:

Finally managed to get the paint satisfactory on the upper housing. i was obviously not cut out to be a painter.

Anyway. I'm slowly working out were all the wires should go, and hopefully I should have decent paint on the vault sometime this week.

[WesternElectricBen]

Looks good, I cannot see any imperfections.

Ben

[mentalstampede]

They are definitely there; luckily the worst bad place is hidden under the instruction card.

Looks good, I cannot see any imperfections.

Ben

[mentalstampede]

Now I just need to figure out what wires need to go where!  Hooking this up without the relay has me a bit confused on what needs to go where.

[mentalstampede]

Well, I haven't updated this thread in awhile, but here's how things stand with my phone. It's getting very close. The only issue I'm having is nickels occasionally getting stuck in the coin mech. Usually, pressing the coin release will clear the jam.

Aside from that, It works beautifully, and all I'm looking for is a more correct handset.

Also, here's the schematic I used to hook it up--Since all of the post-pay specifics were gone anyway, wiring it like a 234 was the more straightforward way to do it.

[mentalstampede]

It's finally all done!

Thanks to all of you guys who have helped me with technical questions, and especially for those who have helped me acquire the pieces I needed.

Here's the necessary pic showing the results:

[WesternElectricBen]

Looks great, man.

Ben