19-01-2023, 12:15 AM
Right, back on topic with electronic organs. This one is not so historic, but it's a good'un, a Wurlitzer 950TA from 1979. Top model in their range at the time, right at the end of the analogue era. I got it for dad about 15 years ago, bought online for one pound. Ludicrous, considering it cost a five-figure sum new, but there are two clear reasons. One is the glut of home organs available second-hand at the moment, as many were bought in the 1960s and 1970s by a generation no longer with us. Their successors are not so likely to be players, and few of them will give space to 'grandpa's organ' any more, so home organs are widely available second-hand. Granted, not many of them are of this calibre, indeed many are mediocre, but with the larger instruments of this age comes teeming complexity and maintenance headaches and that is the second reason that buyers who simply want to play music are unwilling to shell out for them.
I bought this knowing it to be faulty, expecting it to be very faulty in many ways, and I was not wrong. The actual number of faults present on arrival now escapes me, somewhere between 20 and 30. The previous owner had tried to get it repaired, but could not find an organ technician prepared to tackle it at all, let alone at a practical price. Such techs are thin on the ground now; they know that these behemoths have ongoing issues with unavailable ICs, recurrent contact problems etc, so it's unsurprising that they are considered borderline unserviceable. I.e, enthusiasts' territory only, not a realistic commercial proposition.
Given the component-count, it is not the kind of thing you could or should 'shotgun' repair; certainly not something you would enjoy re-capping as a precaution. A barely-legible photocopy-reduced service manual was going to set me back £50 so I decided to try and live without one, as I had some prior knowledge and experience with these and similar models. As things turned out, most faults were bad semiconductors including leaky transistors, dead CMOS switches, opamps, bucket-brigade delays, and some shaky soldering and PCB damage from ham-fisted repairs in the past. At that time, thankfully, none of its few dozen custom LSI ICs was faulty and there were no ususual parts to source. I ploughed through it one fault at a time in the workshop, got it 100%, and with some effort six of us carried it up the stairs and squeezed it through the front door into the house.
Dad and I had some fun with it over the years, during which a few further repairs have been done. Since I've been ill, the faults have been gaining on me; there are now half a dozen, of which one or two are rather elusive and subtle. Indeed, if one didn't know exactly how a 950 was supposed to sound, one probably wouldn't spot them. I will come back to those in the next instalment but first a few views of what's inside, or at least what you can get at by folding things up layer by later. There's more hidden round the back and in the pedestal, but I'm not pulling it away from the wall until ready to start the repairs.
I bought this knowing it to be faulty, expecting it to be very faulty in many ways, and I was not wrong. The actual number of faults present on arrival now escapes me, somewhere between 20 and 30. The previous owner had tried to get it repaired, but could not find an organ technician prepared to tackle it at all, let alone at a practical price. Such techs are thin on the ground now; they know that these behemoths have ongoing issues with unavailable ICs, recurrent contact problems etc, so it's unsurprising that they are considered borderline unserviceable. I.e, enthusiasts' territory only, not a realistic commercial proposition.
Given the component-count, it is not the kind of thing you could or should 'shotgun' repair; certainly not something you would enjoy re-capping as a precaution. A barely-legible photocopy-reduced service manual was going to set me back £50 so I decided to try and live without one, as I had some prior knowledge and experience with these and similar models. As things turned out, most faults were bad semiconductors including leaky transistors, dead CMOS switches, opamps, bucket-brigade delays, and some shaky soldering and PCB damage from ham-fisted repairs in the past. At that time, thankfully, none of its few dozen custom LSI ICs was faulty and there were no ususual parts to source. I ploughed through it one fault at a time in the workshop, got it 100%, and with some effort six of us carried it up the stairs and squeezed it through the front door into the house.
Dad and I had some fun with it over the years, during which a few further repairs have been done. Since I've been ill, the faults have been gaining on me; there are now half a dozen, of which one or two are rather elusive and subtle. Indeed, if one didn't know exactly how a 950 was supposed to sound, one probably wouldn't spot them. I will come back to those in the next instalment but first a few views of what's inside, or at least what you can get at by folding things up layer by later. There's more hidden round the back and in the pedestal, but I'm not pulling it away from the wall until ready to start the repairs.
