Advice needed - AMI Continental 2 PSU Voltage

Hi all
Advice please....
On my Cont 2 I have a very weak pin pusher, so this is whats done to
date
When I restored a while ago I changed the cap for a new one, the
resisitor checked out ok, it worked ok for a bit but never selected
the pins all that well im places
Just doign a good clean and minor tidy up and I with some input from
the team here I checked and thought the voltage was low under load
(below 20v) so I just popped a bridge rectifier in and now at rest I
have 28v and under load with the carousel going 25v min but still the
pin pusher is pathetic, could it be the coil? The carosel does not
seem to zoom round but it has a fair bit of strength.
On the recctifier change I did some reseatch but no definitive so I'll
ask here please. I took the 20v 20v taps onto the AC feed, left the
centre tap as the ground and simply used the +ve output as the feed,
gives me close to but not quite 30v (28v in fact). The tranafomer is
almost dead on 20v from each end of the tap so that looks healthy
enough, if my taps still work after 50 odd years I'll be a happy
chappy
As always thoughts, ideas very welcome
Cheers all
Shaun

You've addressed the power supply, there are several other causes for
poor write-in punching.

Sticky, rusty or just dirty pins.

Punch interval is too short. this one involves an electrolytic
capacitor in the search unit (front of mech) From memory the value is
around 100mfd. When I rebuilt one of these in 1989 I experimented with
adding capacitance here to lengthen the punch and found that adding
approx 22 mfd was a good choice.

This assumes a washed pinwheel and new 100mfd cap are already present.

Do not add too much capacitance, this will result in blown fuse.

The power supplies in these old mechs were never that great and if the
unit is scanning or changing, voltage can drop even more for the
punch. Sometimes this is exacerbated by the motors developing some
shorted turns in their armatures and thus drawing higher current. AMI
motors were -much- better than Rock-Ola in this regard, but it can
happen to any aging motor

Rob/NYC

You've addressed the power supply, there are several other causes for
poor write-in punching.

Sticky, rusty or just dirty pins.

Punch interval is too short. this one involves an electrolytic
capacitor in the search unit (front of mech) From memory the value is
around 100mfd. When I rebuilt one of these in 1989 I experimented with
adding capacitance here to lengthen the punch and found that adding
approx 22 mfd was a good choice.

This assumes a washed pinwheel and new 100mfd cap are already present.

Do not add too much capacitance, this will result in blown fuse.

The power supplies in these old mechs were never that great and if the
unit is scanning or changing, voltage can drop even more for the
punch. Sometimes this is exacerbated by the motors developing some
shorted turns in their armatures and thus drawing higher current. AMI
motors were -much- better than Rock-Ola in this regard, but it can
happen to any aging motor

Rob/NYC







On Apr 17, 2:42*pm, shaun wrote:
Hi all
Advice please....
On my Cont 2 I have a very weak pin pusher, so this is whats done to
date
When *I restored a while ago I changed the cap for a new one, the
resisitor checked out ok, it worked ok for a bit but never selected
the pins all that well im places
Just doign a good clean and minor tidy up and I with some input from
the team here I checked and thought the voltage was low under load
(below 20v) so I just popped a bridge rectifier in and now at rest I
have 28v and under load with the carousel going 25v min but still the
pin pusher is pathetic, could it be the coil? The carosel does not
seem to zoom round but it has a fair bit of strength.
On the recctifier change I did some reseatch but no definitive so I'll
ask here please. I took the 20v 20v taps onto the AC feed, left the
centre tap as the ground and simply used the +ve output as the feed,
gives me close to but not quite 30v (28v in fact). The tranafomer is
almost dead on 20v from each end of the tap so that looks healthy
enough, if my taps still work after 50 odd years I'll be a happy
chappy
As always thoughts, ideas very welcome
Cheers all
Shaun

On Apr 18, 11:37*am, Rob in NYC wrote:
You've addressed the power supply, there are several other causes for
poor write-in punching.

Sticky, rusty or just dirty pins.

Punch interval is too short. *this one involves an electrolytic
capacitor in the search unit (front of mech) *From memory the value is
around 100mfd. When I rebuilt one of these in 1989 I experimented with
adding capacitance here to lengthen the punch and found that adding
approx 22 mfd was a good choice.

This assumes a washed pinwheel and new 100mfd cap are already present.

Do not add too much capacitance, this will result in blown fuse.

The power supplies in these old mechs were never that great and if the
unit is scanning or changing, voltage can drop even more for the
punch. *Sometimes this is exacerbated by the motors developing some
shorted turns in their armatures and thus drawing higher current. *AMI
motors were -much- better than Rock-Ola in this regard, but it can
happen to any aging motor

Rob/NYC

Hi Rob

Thanks that really helps, the pin wheel is another second hand one I
got which I cleaned well with thinners and air dried with a air line
The pins are not easy to push but I think easy enough,

I wonder then if the caps as you say in the caps may be weak? They are
old and original

I'll replace them now as a matter of course, cheap and removes one
more issue

Will let you know how it goes

Cheers
shaun

On Apr 18, 8:37*pm, Rob in NYC wrote:
You've addressed the power supply, there are several other causes for
poor write-in punching.

Sticky, rusty or just dirty pins.

Punch interval is too short. *this one involves an electrolytic
capacitor in the search unit (front of mech) *From memory the value is
around 100mfd. When I rebuilt one of these in 1989 I experimented with
adding capacitance here to lengthen the punch and found that adding
approx 22 mfd was a good choice.

This assumes a washed pinwheel and new 100mfd cap are already present.

Do not add too much capacitance, this will result in blown fuse.

The power supplies in these old mechs were never that great and if the
unit is scanning or changing, voltage can drop even more for the
punch. *Sometimes this is exacerbated by the motors developing some
shorted turns in their armatures and thus drawing higher current. *AMI
motors were -much- better than Rock-Ola in this regard, but it can
happen to any aging motor

Rob/NYC


If the scanning motor under load is pulling the supply down to the
point that the pin
pusher is being starved of sufficient current to operate reliably,
depending on the circuit
it could be possible to put a diode in series with the search unit
28vdc supply, and
a filter capacitor across that supply - after the diode (assuming that
the cap mentioned above doesn't
do that already). A 3A diode such as an IN5408 should be more than
sufficient for this job.