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Piano, Organ, and Keyboard/Baldwin Fun Machine, 1977, model 121F

Question
Mr. Britanyak
I would appreciate your help with my Baldwin fun machine, Series 121F, 1977.  It stopped working suddenly.  When turned on, the  fluorescent light works and 120v. is present on the primary cell of the power supply transformer.  With the secondary leads disconnected voltage is present on all four leads.  When leads are terminated on the power board, no voltage is indicated on respective pins.  Is this normal?  Also, the circuit board drawing suggest 583v. on the red leads to center tap red/yellow.  We have only 42volts.  Is that sufficient voltage?  Any help or ideas would be appreciated.
Thank you, Susan

Hello Susan,  I am going to have to read between the lines here.  First of all, I will mention the obvious: that measuring the transformer's secondary outputs needs to be measured using an AC meter.  If there is no voltage reading on the secondaries when 120 VAC is applied to the transformer's primary, then we need to assume a defective transformer.  If the voltage were to drop significantly when connecting the secondaries to their intended loads, then we need to look at the loads for shorts.

A common possibility may be the rectifier diodes or electrolytic filter capacitors are bad, particularly knowing the age of the instrument. The voltages measured across the leads of the capacitors needs to be measured with a DC voltmeter.

The voltages applied to capacitors cannot be greater than the capacitor's rated working voltage printed on the side of the capacitor.  So, if you measure 43 DC volts across the leads of a capacitor that is rated for 50 working volts, then the circuit is likely OK.

However, if you read an unusually low DC voltage across a capacitor that is rated for 50 volts, try reading the voltage using an AC meter.  If a voltage is read across the capacitor's leads, then you either have significant DC ripple (suggesting a bad filter capacitor) or a bad rectifier is shorted and passing AC through to the capacitors.

Lastly, I can assure you, there is no such voltage that comes even close to 538 volts anywhere in the organ.

Piano, Organ, and Keyboard

Volunteer

Thomas Britanyak

Expertise

I am a full time organ/piano technician who has been actively involved with the design, building, repair, maintenance and installation of organs and pianos for 35 years. I began as a keyboard instrument apprentice and hold degrees in music and electronics. If you need a piano's date of manufacture, please go to http://www.pianoexchange.com/howold.htm or http://www.bluebookofpianos.com/pianoage.html I am happy to answer musical or technical questions, however, I CANNOT offer appraisals on pianos or organs. Please do not ask what an instrument is worth. For this service please contact an experienced local appraiser or try the following links: https://mmm1100.verio-web.com/blueb1/appraisal.html or http://www.57piano.com/questions.htm

Experience

I am a full time organ/piano technician who has been actively involved with the design, building, repair, maintenance and installation of organs and pianos for 35 years. I began as a keyboard instrument apprentice and hold degrees in music and electronics.

Education/Credentials
I am a full time organ/piano technician who has been actively involved with the design, building, repair, maintenance and installation of organs and pianos for 35 years. I began as a keyboard instrument apprentice and hold degrees in music and electronics.