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#1
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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 |
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#2
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Advice needed - AMI Continental 2 PSU Voltage
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 |
#3
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Advice needed - AMI Continental 2 PSU Voltage
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 |
#4
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Advice needed - AMI Continental 2 PSU Voltage
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 |
#5
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Advice needed - AMI Continental 2 PSU Voltage
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. |
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