Home |
Search |
Today's Posts |
![]() |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
![]() |
|||
|
|||
![]()
Hi,
I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. The power supply that came with the unit is an adapted computer psu with output voltages of +/-12v and +5v - but only 3 outputs are used. Looking at the resistor to the 'on' LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on this line. I just want to be 100% sure if possible. The transformer is one of those impossible to open things (sealed - cant see any screws) and as its not mine, I'm not overly keen to take a hacksaw to it. Anyway, hope someone out there knows, tho I guess its a long shot ![]() thanks in advance for your help. Colin |
#2
![]() |
|||
|
|||
![]()
Colin,
While I'm hardly a Theremin expert, here are a few ideas... An LED powered from 12V thru 220 Ohms is going to draw about 47 milliamps which is pretty high. I think 220 Ohms is more typical for an LED that's run on 5 volts. If you're sure it's *either* +5 or +12 (and not some other voltage), there's probably no harm in hooking to +5 and giving it a try. Most circuits will be okay if powered from a significantly lower voltage than they were designed for - they won't work, but won't be damaged either. If the power supply is the kind used inside a PC, the wire colors are pretty standardized. Black is 0V, yellow is +12, and red is +5. Eric Law Wilmington, MA "Colin Swift" wrote in message ... Hi, I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. The power supply that came with the unit is an adapted computer psu with output voltages of +/-12v and +5v - but only 3 outputs are used. Looking at the resistor to the 'on' LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on this line. I just want to be 100% sure if possible. The transformer is one of those impossible to open things (sealed - cant see any screws) and as its not mine, I'm not overly keen to take a hacksaw to it. Anyway, hope someone out there knows, tho I guess its a long shot ![]() thanks in advance for your help. Colin |
#3
![]() |
|||
|
|||
![]() "Colin Swift" ) writes: Hi, I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. The power supply that came with the unit is an adapted computer psu with output voltages of +/-12v and +5v - but only 3 outputs are used. Looking at the resistor to the 'on' LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on this line. I just want to be 100% sure if possible. The transformer is one of those impossible to open things (sealed - cant see any screws) and as its not mine, I'm not overly keen to take a hacksaw to it. You do realize that those computer power supplies expect a decent load on the output(s)? If they aren't loaded properly, you won't see the voltages it is supposed to supply. Before assuming the power supply is bad, you'd better make sure it is properly loaded. And if the power supply is bad, it's likely simplest to replace the whole thing. It surely can't be "adapted" very much. If the power supply is bad, you can't really assume anything. If you think it's adapted, then you really need to know what voltages it was supposed to put out. Micahel Anyway, hope someone out there knows, tho I guess its a long shot ![]() thanks in advance for your help. Colin |
#4
![]() |
|||
|
|||
![]() "Michael Black" wrote in message ... "Colin Swift" ) writes: Hi, I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. The power supply that came with the unit is an adapted computer psu with output voltages of +/-12v and +5v - but only 3 outputs are used. Looking at the resistor to the 'on' LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on this line. I just want to be 100% sure if possible. The inline LED resistor is 220 ohm, LED's dropping voltage is about 1.2 V. With 5 V that is about 17 mA, for 12 V that would be about 50 mA and that amount of current would kill most LED's rather sooner than later. Bottom line... that 'on line' should be + 5 Volts. |
#5
![]() |
|||
|
|||
![]()
Ok...so lets get this one straight....you accepted someone's Theremin to
repair...with absolutely no idea how to repair it?. After your done thoroughly killing it to the point of no return, send it off to me. -- Kim..."A Man Of True Frankenstinean Proportions" "Colin Swift" wrote in message ... Hi, I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. The power supply that came with the unit is an adapted computer psu with output voltages of +/-12v and +5v - but only 3 outputs are used. Looking at the resistor to the 'on' LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on this line. I just want to be 100% sure if possible. The transformer is one of those impossible to open things (sealed - cant see any screws) and as its not mine, I'm not overly keen to take a hacksaw to it. Anyway, hope someone out there knows, tho I guess its a long shot ![]() thanks in advance for your help. Colin |
#6
![]() |
|||
|
|||
![]()
Colin Swift wrote:
Hi, I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. The power supply that came with the unit is an adapted computer psu with output voltages of +/-12v and +5v - but only 3 outputs are used. Looking at the resistor to the 'on' LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on this line. I just want to be 100% sure if possible. The transformer is one of those impossible to open things (sealed - cant see any screws) and as its not mine, I'm not overly keen to take a hacksaw to it. Anyway, hope someone out there knows, tho I guess its a long shot ![]() thanks in advance for your help. Colin ---------------------------- I dunno, but if you ever get it fixed, please feel free to yell "Beam Me Up, Scotty!!" 'motsco' |
#7
![]() |
|||
|
|||
![]() "motsco_ _" "motsco_ wrote in message ... I dunno, but if you ever get it fixed, please feel free to yell "Beam Me Up, Scotty!!" What does that have to do with a Theremin? N |
#8
![]() |
|||
|
|||
![]()
I've been given a wavefront travel case Theremin to repair.... seems the
power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. Hi, Have got the Theremin working, tho I'm still unsure as to the correct operational voltage. I used a 7 volt battery on the non-working +V line and lo and behold the thing lights up and plays just fine. as folks have pointed out, the LED resistor points to the +V line being 5 volts. The LED is actually a panel mount LED unit which has written on the side 5V, 20MA - though this still means the resistor is a bit low for 12V, also a bit high for a 5V supply. There is an IC which is fed off the two supply lines which ( LM13600, according to the data sheets) requires +/- 15volts. I guess the main thing is its working and building a PSU for it will be no problem. Thanks for your help. Colin |
#9
![]() |
|||
|
|||
![]()
"NSM" bravely wrote to "All" (01 Mar 05 06:31:46)
--- on the heady topic of " Wavefront travel case Theremin Repair" NS From: "NSM" NS Xref: aeinews sci.electronics.repair:42073 NS "motsco_ _" "motsco_ wrote in message NS ... I dunno, but if you ever get it fixed, please feel free to yell "Beam Me Up, Scotty!!" NS What does that have to do with a Theremin? Sargent had a theremin in the original Star Trek TV show theme music. BTW the Beach Boys' "Good Vibrations" used one too. A*s*i*m*o*v .... Guitar smashing doesn't bother me. Some "need" smashing. -Chet Atkins |
#10
![]() |
|||
|
|||
![]() I've been given a wavefront travel case Theremin to repair.... seems the power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure as to what the voltages should be on these pins? Is there anyone out there who knows? I tried e-mailing the company however haven't received a reply. You might ask on Levnet, I don't own that type, but I'd be VERY surprised if one of us dosen't have the info you seek. So far the voltages measured on the pins on the din connector are -12, 0 and -0.71V - I guess the latter pin should be +12v. Almost certainly. FWIW, how did you come by it? |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
GE refrigerator warranty repair misery | Home Ownership | |||
HELP Crack in brand new TV case - Best way to hide the repair ???? | Home Repair | |||
HELP Crack in brand new TV case - Best way to hide the repair???? | Home Repair | |||
OT Guns more Guns | Metalworking | |||
Panasonic CD player "F15" display code repair tips | Electronics Repair |