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Note: This is about replacing the sound heads in one particular Elmo ST-800, but there is no reason these ideas can’t apply to other machines, especially Elmo ones.
So this thing happened. (These stories always start with some-thing happening!). -and I had to replace my soundhead, it turned out to be a process. Stay with me a while and I’ll tell you the tale!
I got two 400 footers off E-Bay a few months ago: Sunday River Productions’ N&W Articulateds - Class Y6 Part 1 and Part 2. These are prints of films shot in the 1950s of immense Norfolk and Western steam locomotives hauling long coal trains in the high mountains of Western Virginia. These started out as 16mm Kodachromes. The bonus is these were very late Sunday River Productions S8 prints and they were starting to feel the heat from those new VCRs then in the stores, so they bought rights to really good quality sound recordings of the same type of locomotives and dubbed sound tracks where silents would have been good enough a few years earlier These are beautiful prints: from the cuts of the two leaders, I’d say they were never projected before they arrived here.
My standard Super-8 setup is two Elmo ST-800s. These are nice, simple machines that I’ve learned to trust. The 100W lamp is adequate for my screen, the sound is very good monaural and for easily 90% of my Super-8 viewing they get the job done very well.
That night, I worked from the right: ST-800 #2 got part 1, ST-800 #1 got part #2. Part 1 was awesome: wonderful color, sharp image, booming sound.
Then I rolled Part 2...and…something happened! I kept getting these dropouts in audio level. It would be entirely normal, and then all of a sudden get very quiet, for a time and it would randomly bounce up and down in level.
Being very human, I reached the most hopeful conclusion to the question “print or machine?”. I chose “print with bad stripe”. -no big deal: it’s just one print among many and frankly Part 1 was similar enough that losing part 2 wasn’t tragic!
-much better than a wounded projector!.....-Right?!
So I had a theory and the way to prove it (-or not…) was move the “bad” print to a known good machine and see if the bad sound followed. Part 2 went to ST-800#2…and sounded just…fine…oh…no!
ST-800 #1 is my original Elmo sound projector. It first came on-line for me Christmas, 2003 (-gift from my wife!). The entire sound system in there was transplanted in 2009, when the original one died. This replacement system had been working steadily for me 15 years and wasn’t new to begin with.
I took a look at the record/playback head. There was a valley worn in it in the direction of film flow. Next to it, there was a ridge and then an unworn surface over to the opposite edge.
Now, I suppose this could have also been some intermittency in the amplifier, but other prints I have since played on this machine were just fine. It felt like some deadly combination of that one machine and that one print, and the only place that a print meets the sound system is the head. Maybe the stripe on that print was skewed a little towards that ridge worn in the playback head and kept on climbing up and falling off it, losing consistent contact. Tiny fractions of a millimeter can do a lot of harm here!
Still being very human, I went with Denial: “I’ll just avoid pairing that print and that machine. Everything will be fine!”
-until the day another print that had been fine up until then had the exact same problem.
I felt kind of sad about it: I had to break the twins up! I couldn’t trust #1 anymore. #2 soldiered on alone, bravely!
Over the years I’ve installed a new set of guides in #1. I replaced the entire sound system, and I installed a new motor. I also replaced the switch that controls the lamp. It wasn’t so great at the very beginning, but I’ve made it better and better. As a result, it’s been a go-to machine for years. It’s been on vacation with me a few times and to CineSea a bunch more times. When I started building my external sound system, this was the machine I built it around. It has history with me and in the end, for just a piece of machinery, we’ve had almost a “partnership”. I really didn’t want to see this one become just another parts machine!
I wanted to figure out how to replace that worn head, but I had other priorities: family, job, cars, house, etc.). -so I put it in the travel case and gave it a rest for a while.
Around Christmas I started to think about it again: it came down to fixing the head then installed or replacing it entirely.
Other film collectors have shown me a lot of kindness over the years. More than once, I’ve been at CineSea, and some goodhearted soul handed me a dead projector which I could use for parts. Yes: this cleared out some of their own junk, but it gave me parts to do repairs: It’s gotten me out of trouble a number of times.
I looked among my on-hand ST-800 wreckage. There was this one machine that looked like it’s been pillaged by Vikings, but the record/playback head was simply pristine! It seems like early-on this one was involved in some tragedy and the owner decided to shelve it. Normal wear items like guides and the heads looked a lot better than you’d expect from outer appearances: as a matter of fact, they looked very good! (-some might even say “like new”!)
I decided I wanted to bring in the new heads and connect-up to the existing sound circuitry, but how? Maybe I could connect the wiring from the heads where it landed on the sound board (-the board where the volume/tone control and record switch are), but there would be a lot of disassembly/reassembly involved and therefore greater risk that something else could get damaged. I also hate soldering on ancient PC boards: too often, they don’t come out of it intact. I needed a better plan, especially as an opening act. (Let’s not start out doing something that feels desperate!)
I took off the loop restorer and found the connections at the back of the two heads (record/playback and erasure) and saw this underneath:
.
-just solder connections: I can deal with that! The only thing better would have been some kind of plug-in connection, but this was still an easy enough connection to break and re-make.
It’s important to stop here and consider exactly what’s needed when changing out a sound head. These are two terminal devices, so it’s natural to think “Just unscrew and replace the old heads, then solder in the new ones and it will be fine.”, but it’s just NOT that simple! There is a very critical spatial relationship between the head and the sound stripe so that the head can pick up the stripe’s tiny magnetic field variation and make a usable electrical signal for the pre-amp and amp to amplify to become sound in our ears. These sound heads were aligned at the factory, probably with procedures and tools that we don’t have access to, that may not even exist these days. Elmo discarded even things like manuals when they stopped making film projectors: the idea that a box of alignment jigs is in Tokyo in somebody’s desk drawer, especially someone who understands what they are, is not at all promising in 2025.
I’ve heard tales of people trying to do a simple head swap that never get this re-alignment correct. As a result, they never get good sound out of the replaced head. I won’t go there! It’s a waste of otherwise good parts, maybe even the death of a once-fixable machine. (Too many “parts machines” are a BAD omen!)
So, it's not enough to simply transplant in a new set of heads: their alignment needs to be transplanted in too. Fortunately there is a way. The heads mount on a metal plate. This plate also holds the film guides below the gate around the heads all the way to the lower sprocket. It holds the presser too. This plate is held onto the chassis by a couple of machine screws. By unsoldering the pins from the wiring that connects to them and removing those screws, the whole thing can be lifted out as a unit and a new one installed.
.
Sometimes people long for the days back before cellphones. In many instances they do have a point, but these are great when doing a project like this: I like to take a lot of pictures so things end up exactly the way Elmo started them.
Before I started demolition here, I’d compared the two sets of heads and their signal connections: everything looked identical. It was time to get going for real.
I uninstalled the “bad” plate and the “good” plate from where they started out. I just held a hot soldering iron on the wires until they let loose and held them back with a small pair of needle-nose pliers until the solder cooled. I literally hid the “bad” one away as soon as it was loose. It could get re-installed in the good machine by mistake: stranger things have happened!
So this thing happened. (These stories always start with some-thing happening!). -and I had to replace my soundhead, it turned out to be a process. Stay with me a while and I’ll tell you the tale!
I got two 400 footers off E-Bay a few months ago: Sunday River Productions’ N&W Articulateds - Class Y6 Part 1 and Part 2. These are prints of films shot in the 1950s of immense Norfolk and Western steam locomotives hauling long coal trains in the high mountains of Western Virginia. These started out as 16mm Kodachromes. The bonus is these were very late Sunday River Productions S8 prints and they were starting to feel the heat from those new VCRs then in the stores, so they bought rights to really good quality sound recordings of the same type of locomotives and dubbed sound tracks where silents would have been good enough a few years earlier These are beautiful prints: from the cuts of the two leaders, I’d say they were never projected before they arrived here.
My standard Super-8 setup is two Elmo ST-800s. These are nice, simple machines that I’ve learned to trust. The 100W lamp is adequate for my screen, the sound is very good monaural and for easily 90% of my Super-8 viewing they get the job done very well.
That night, I worked from the right: ST-800 #2 got part 1, ST-800 #1 got part #2. Part 1 was awesome: wonderful color, sharp image, booming sound.
Then I rolled Part 2...and…something happened! I kept getting these dropouts in audio level. It would be entirely normal, and then all of a sudden get very quiet, for a time and it would randomly bounce up and down in level.
Being very human, I reached the most hopeful conclusion to the question “print or machine?”. I chose “print with bad stripe”. -no big deal: it’s just one print among many and frankly Part 1 was similar enough that losing part 2 wasn’t tragic!
-much better than a wounded projector!.....-Right?!
So I had a theory and the way to prove it (-or not…) was move the “bad” print to a known good machine and see if the bad sound followed. Part 2 went to ST-800#2…and sounded just…fine…oh…no!
ST-800 #1 is my original Elmo sound projector. It first came on-line for me Christmas, 2003 (-gift from my wife!). The entire sound system in there was transplanted in 2009, when the original one died. This replacement system had been working steadily for me 15 years and wasn’t new to begin with.
I took a look at the record/playback head. There was a valley worn in it in the direction of film flow. Next to it, there was a ridge and then an unworn surface over to the opposite edge.
Now, I suppose this could have also been some intermittency in the amplifier, but other prints I have since played on this machine were just fine. It felt like some deadly combination of that one machine and that one print, and the only place that a print meets the sound system is the head. Maybe the stripe on that print was skewed a little towards that ridge worn in the playback head and kept on climbing up and falling off it, losing consistent contact. Tiny fractions of a millimeter can do a lot of harm here!
Still being very human, I went with Denial: “I’ll just avoid pairing that print and that machine. Everything will be fine!”
-until the day another print that had been fine up until then had the exact same problem.
I felt kind of sad about it: I had to break the twins up! I couldn’t trust #1 anymore. #2 soldiered on alone, bravely!
Over the years I’ve installed a new set of guides in #1. I replaced the entire sound system, and I installed a new motor. I also replaced the switch that controls the lamp. It wasn’t so great at the very beginning, but I’ve made it better and better. As a result, it’s been a go-to machine for years. It’s been on vacation with me a few times and to CineSea a bunch more times. When I started building my external sound system, this was the machine I built it around. It has history with me and in the end, for just a piece of machinery, we’ve had almost a “partnership”. I really didn’t want to see this one become just another parts machine!
I wanted to figure out how to replace that worn head, but I had other priorities: family, job, cars, house, etc.). -so I put it in the travel case and gave it a rest for a while.
Around Christmas I started to think about it again: it came down to fixing the head then installed or replacing it entirely.
Other film collectors have shown me a lot of kindness over the years. More than once, I’ve been at CineSea, and some goodhearted soul handed me a dead projector which I could use for parts. Yes: this cleared out some of their own junk, but it gave me parts to do repairs: It’s gotten me out of trouble a number of times.
I looked among my on-hand ST-800 wreckage. There was this one machine that looked like it’s been pillaged by Vikings, but the record/playback head was simply pristine! It seems like early-on this one was involved in some tragedy and the owner decided to shelve it. Normal wear items like guides and the heads looked a lot better than you’d expect from outer appearances: as a matter of fact, they looked very good! (-some might even say “like new”!)
I decided I wanted to bring in the new heads and connect-up to the existing sound circuitry, but how? Maybe I could connect the wiring from the heads where it landed on the sound board (-the board where the volume/tone control and record switch are), but there would be a lot of disassembly/reassembly involved and therefore greater risk that something else could get damaged. I also hate soldering on ancient PC boards: too often, they don’t come out of it intact. I needed a better plan, especially as an opening act. (Let’s not start out doing something that feels desperate!)
I took off the loop restorer and found the connections at the back of the two heads (record/playback and erasure) and saw this underneath:
.
-just solder connections: I can deal with that! The only thing better would have been some kind of plug-in connection, but this was still an easy enough connection to break and re-make.
It’s important to stop here and consider exactly what’s needed when changing out a sound head. These are two terminal devices, so it’s natural to think “Just unscrew and replace the old heads, then solder in the new ones and it will be fine.”, but it’s just NOT that simple! There is a very critical spatial relationship between the head and the sound stripe so that the head can pick up the stripe’s tiny magnetic field variation and make a usable electrical signal for the pre-amp and amp to amplify to become sound in our ears. These sound heads were aligned at the factory, probably with procedures and tools that we don’t have access to, that may not even exist these days. Elmo discarded even things like manuals when they stopped making film projectors: the idea that a box of alignment jigs is in Tokyo in somebody’s desk drawer, especially someone who understands what they are, is not at all promising in 2025.
I’ve heard tales of people trying to do a simple head swap that never get this re-alignment correct. As a result, they never get good sound out of the replaced head. I won’t go there! It’s a waste of otherwise good parts, maybe even the death of a once-fixable machine. (Too many “parts machines” are a BAD omen!)
So, it's not enough to simply transplant in a new set of heads: their alignment needs to be transplanted in too. Fortunately there is a way. The heads mount on a metal plate. This plate also holds the film guides below the gate around the heads all the way to the lower sprocket. It holds the presser too. This plate is held onto the chassis by a couple of machine screws. By unsoldering the pins from the wiring that connects to them and removing those screws, the whole thing can be lifted out as a unit and a new one installed.
.
Removed mounting plate for soundheads, guides and head-presser
. Closeup of removed soundheads showing solder terminals
.Sometimes people long for the days back before cellphones. In many instances they do have a point, but these are great when doing a project like this: I like to take a lot of pictures so things end up exactly the way Elmo started them.
Before I started demolition here, I’d compared the two sets of heads and their signal connections: everything looked identical. It was time to get going for real.
I uninstalled the “bad” plate and the “good” plate from where they started out. I just held a hot soldering iron on the wires until they let loose and held them back with a small pair of needle-nose pliers until the solder cooled. I literally hid the “bad” one away as soon as it was loose. It could get re-installed in the good machine by mistake: stranger things have happened!
) He's my own resource when the thing is causing ME grief!
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