AboutThomas Britanyak Expertise I am an 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
Question Hi Tom,I have a 4116W President.When I got the organ the power supply was spot on with the correct outputs.
The power supply has now failed due to a leslie amp fault.I wasn't aware that the faulty resistors in the amp were actually fuseible ones and had failed due to the amp fault.So I created the problem.
I lost the +&-35v unregulated supply and the all the 8 rectifier diodes. I replaced the diodes and got the +/-35 volt supply back but it was actually and still is about 38v.
However the fuseable resistor in the negative leg failed.I replaced its electrolytic with a temporary one which restored the +/-35 volt supply.When I reconnected the regulator board (no.413032)the -35 volt(38v) fuseible resistor failed.If I left the +/- 35v capacitors isolated the regulated voltages(25v & 20 volt supply's)were Ok but when I replaced the fuse the -35v capacitor fuse fails.I am bewildered as to why this fuse fails when it has its own 4 diodes in bridge pack formation and its only common point with the 2 regulated supply back to back diodes/electrolytic/capacitor/regulator board is the common ac supply from the transformer.
During these procedings Q2(a BC108 which was a replacement transistor for 801536 when I got the organ also failed.I replaced it with a BC548 then presumed that Q1 an 801522 was faulty.
My aim was to get the regulated supply working and then replace the temporary capacitor with the correct replacement.The 801522 is however a PNP germanium transistor (TO3)and I can only get a MJ2955 Silicon (out here in Australia).I believe that would require a change in biasing and if you have access to a drawing could you give me some indication as to which resistors I would have to change and what would be the new values required or better still could you recommend a direct replacement No. for the 801522.The remaining transistor Q3 has a TT3055-1 fitted (silicon I think) and the original part No. was 801537 (germanium I think) but strangely enough all the resistors on the board match up with those on the drawing.So the situation now is that I have fitted a BC548 npn at Q2 and a MJ2955 at Q1.
All the voltages around both these transistors are about 38 volts so the transistors are not regulating because of incorrect biassing and the 20 volt test point is reading 30v. and R14(130 ohm 5W is running hot.
I would be pleased if you can help to solve this problem and perhaps list some alternative direct replacement transistors for those with Gulbransen part numbers.None of the original electrolytics were running warm but the -35v one would dissipate its voltage at shutdown whereas the others held their voltage until I discharged them thru a 220 ohm resistor(about 20 seconds)
It would be helpful if you could tell me where I could buy the capacitor and fuseible resistors and the transistors.
Thank you for the opportunity to seek your help.
By the way I am a 74 year old retired electrician from Bulli (50 miles south of Sydney) N.S.W Australia.Where are you from?
Answer Hello Ron! In the scheme of things, when jobs get complicated in the field and you are faced with a problem that seems to take you in circles, the best advice came from one of my professors: "If you can't resolve the problem in a timely manner, then start thinking about what it is you are going to do about it." I realize this doesn't seem like much help, but what he was trying to say is forget the problem of "why", think out of the box and decide what you are going to do to get the system (in this case the organ) up and working. You have a tremendous balancing act right now where lots of components will need to be reengineered so that things work dependably. If you are up to that, fine. However, in reading over the complicating factors involving mixing germanium and silicon, fuseable resistors, capacitor fuses, blown diodes, etc, etc, I start thinking "forget the problem, what are you going to do about it?" The answer I come up with is this: You need a regulated 20 volt supply? Then just get one. You need a regulated 25 volt supply? Then just get one. You need a -/+ 35 volt supply? Then just get one (or build one). Tie all the 0V lines together, make the appropriate connections and you are out of there, with a better product and the boss is no longer breathing down your neck demanding to know what is taking so long.
I had to deal with a very large church organ that had shut down a while back. The instrument was so large much of the electronics was housed in large remote cabinets. With all the 10's of thousands of parts, wires and boards to contend with, I managed to narrow the problem down to one tiny zener diode. It turned out all the various voltages throughout the entire organ were dependant upon that one failed part. I was told to make certain the problem would not happen again. OK, so I located the problem but in my opinion, plugging in another zener was only setting a time bomb to go off at another very inopportune moment. So I asked myself, "OK, but what am I going to do about it?" I chose to gut the ancient power supply complex and replace it with new, dependable power sources. I can sleep at night though knowing full well some other section of the organ could still fail. Nonetheless, my power supply fix would not.
My concern is, your project could keep you busy indefinitely. This is precisely why I became an organ technician. In my high school years in Southern California, my first organ was an electronic amplified reed organ with tubular pneumatic keying. It was the only thing I could afford. As much as I wanted to learn to play it, to do so, I had to spend most of my time fixing it. Hence, I learned more about organ repair than I did about organ performance, and I learned it, initially, the hard way.
