Pianotech

Hello all, 

I just signed up to this community and appreciate the opportunity. I am working on an old PianoDisk system that uses the PDS-128 controller and the "generation 8 powersupply". The powersupply seemed to power up the low voltage line but not the solenoids. I believe that is supposed to be around 40V. I have taken the powersupply apart. There is a handnote on it stating that the transformer was replaced. I noticed right away that "fuse 2" which is internal to the motherboard is blown which would explain the symptom I am dealing with. However, I am not able to find the root cause of the blown fuse. None of All the power components such as the transistors and diods on the board measure to be shorted. Capacitors measure OK and the two transformers also dont seem to be shorted out as they both measure expected resistance. Also, the other component attached to the heat sink (seemingly a thermostat) measures 0 ohm in room temp. I tried to heat it up with my soldering tip but it did not change resistence. However, before all of this I noticed the fan kicked in when needed so I assume the thermostat is just open at room temp and doing its job. 

Does anyone have a schematic / diagram for this powersupply please? If not, does anyone know what components might cause fuse 2 to be blown? 

Thank you so much 

Joey

There may have been a power surge that took out fuse 2. Maybe try replacing that fuse and see if you can get 40v to power the solenoids. The newer power supplies have two transformers instead of the large heavy auto battery size dual supply. There are also different cables. The PDS 128 is a very old first generation system I think it will be next to impossible to get schematics

Hello all, 

I just signed up to this community and appreciate the opportunity. I am working on an old PianoDisk system that uses the PDS-128 controller and the "generation 8 powersupply". The powersupply seemed to power up the low voltage line but not the solenoids. I believe that is supposed to be around 40V. I have taken the powersupply apart. There is a handnote on it stating that the transformer was replaced. I noticed right away that "fuse 2" which is internal to the motherboard is blown which would explain the symptom I am dealing with. However, I am not able to find the root cause of the blown fuse. None of All the power components such as the transistors and diods on the board measure to be shorted. Capacitors measure OK and the two transformers also dont seem to be shorted out as they both measure expected resistance. Also, the other component attached to the heat sink (seemingly a thermostat) measures 0 ohm in room temp. I tried to heat it up with my soldering tip but it did not change resistence. However, before all of this I noticed the fan kicked in when needed so I assume the thermostat is just open at room temp and doing its job. 

Does anyone have a schematic / diagram for this powersupply please? If not, does anyone know what components might cause fuse 2 to be blown? 

Thank you so much 

Joey

Great to hear from you James and thank you. Yes I have been hoping a power surge being the cause too given that I can't really identify any real culprit components. Based on that, I did go ahead and ordered a bunch of BussMann 250V, 4A MLD glass fuses. It my best guess. Please let me know if that passes your giggle test. So I will replace one and see if we can be that lucky. 

I hear what you are saying about finding a schematic. But frankly, a newer schematics would be more helpful to me right now than no schematics. Any advice on how to get something reasonable please? 

thank you much 

Joey

There may have been a power surge that took out fuse 2. Maybe try replacing that fuse and see if you can get 40v to power the solenoids. The newer power supplies have two transformers instead of the large heavy auto battery size dual supply. There are also different cables. The PDS 128 is a very old first generation system I think it will be next to impossible to get schematics

Hello all, 

I just signed up to this community and appreciate the opportunity. I am working on an old PianoDisk system that uses the PDS-128 controller and the "generation 8 powersupply". The powersupply seemed to power up the low voltage line but not the solenoids. I believe that is supposed to be around 40V. I have taken the powersupply apart. There is a handnote on it stating that the transformer was replaced. I noticed right away that "fuse 2" which is internal to the motherboard is blown which would explain the symptom I am dealing with. However, I am not able to find the root cause of the blown fuse. None of All the power components such as the transistors and diods on the board measure to be shorted. Capacitors measure OK and the two transformers also dont seem to be shorted out as they both measure expected resistance. Also, the other component attached to the heat sink (seemingly a thermostat) measures 0 ohm in room temp. I tried to heat it up with my soldering tip but it did not change resistence. However, before all of this I noticed the fan kicked in when needed so I assume the thermostat is just open at room temp and doing its job. 

Does anyone have a schematic / diagram for this powersupply please? If not, does anyone know what components might cause fuse 2 to be blown? 

Thank you so much 

Joey

there are a number of technicians that do a significant amount of piano disc work but I am not sure if any rebuild the power supplies. Piano disc was buying back old PD equipment but I am not sure why unless they where thinking of refurbishing equipment. The new wireless Prodigy systems are great but they are not cheap . I have installed several and it is time intensive as well as challenging. I had a customer who thought he could do a wireless setup because he had an ipod interface. Eventually he called me but only after blowing the power supply which he claimed had a power surge hit it . A new power supply with two separate components plus the correct cables fixed the power issues. In addition an airport express made the unit totally wireless. You could try Piano Disc on the West Coast tech support for schematics. Also post something on the player piano community thread 

Great to hear from you James and thank you. Yes I have been hoping a power surge being the cause too given that I can't really identify any real culprit components. Based on that, I did go ahead and ordered a bunch of BussMann 250V, 4A MLD glass fuses. It my best guess. Please let me know if that passes your giggle test. So I will replace one and see if we can be that lucky. 

I hear what you are saying about finding a schematic. But frankly, a newer schematics would be more helpful to me right now than no schematics. Any advice on how to get something reasonable please? 

thank you much 

Joey

There may have been a power surge that took out fuse 2. Maybe try replacing that fuse and see if you can get 40v to power the solenoids. The newer power supplies have two transformers instead of the large heavy auto battery size dual supply. There are also different cables. The PDS 128 is a very old first generation system I think it will be next to impossible to get schematics

Hello all, 

I just signed up to this community and appreciate the opportunity. I am working on an old PianoDisk system that uses the PDS-128 controller and the "generation 8 powersupply". The powersupply seemed to power up the low voltage line but not the solenoids. I believe that is supposed to be around 40V. I have taken the powersupply apart. There is a handnote on it stating that the transformer was replaced. I noticed right away that "fuse 2" which is internal to the motherboard is blown which would explain the symptom I am dealing with. However, I am not able to find the root cause of the blown fuse. None of All the power components such as the transistors and diods on the board measure to be shorted. Capacitors measure OK and the two transformers also dont seem to be shorted out as they both measure expected resistance. Also, the other component attached to the heat sink (seemingly a thermostat) measures 0 ohm in room temp. I tried to heat it up with my soldering tip but it did not change resistence. However, before all of this I noticed the fan kicked in when needed so I assume the thermostat is just open at room temp and doing its job. 

Does anyone have a schematic / diagram for this powersupply please? If not, does anyone know what components might cause fuse 2 to be blown? 

Thank you so much 

Joey