HSC Gear Repair

Back in March I broke the reduction gear in the scan motor gearbox of the HSC1. The mechanism jammed on the left side and I forced it to the right. When it went to rest and I made a selection it was like, bump…bump…bump when scanning. The bump being when the spot missing two teeth rode past the driven gear. This is a bad feeling. Especially when I opened the gearbox on the other album unit mech I have and found its gear had a broken tooth as well. Not long ago one of these scan motors came up on ebay and sold for $125 without knowing if the gear in it was any good. Or even, really, if it worked. In the picture below look at the middle gear and the missing teeth are apparent. Note how fully the gears mesh.

I contacted Sean Boyer of Luke’s Jukes about possibly making one of these with his 3D printer. He was very enthusiastic about the project. He’s a young guy that is in this hobby and is intent on becoming really good at it. I’d like to think I mentor him a little bit, so few young people seem to get into this as far as repair. When I first became aware of him I contacted him because I was a bit excited at seeing a young guy wanting to learn. Sean would like to get a line of replacement parts made up and this is quite admirable. He is well on his way. I know he is working with buddy of mine on a Wurlitzer gear of some sort.

We have been working on the gear for a couple months and finally got a good gear. It has been interesting. I sent one of the original gears I had to him and he did whatever you do to replicate the gear. The initial drawing looked promising. He made a couple gears and sent them to me. I would test and make notes and let him know what the outcome was and he would go back to the drawing board. The shaft hole was not correct and I went on my own odyssey trying to find the perfect bit size. 1/8 ” seemed too loose so I turned to metric bits and tried a 3.5mm, 3.3mm and finally a 3.2mm. The 3.2mm seemed perfect. I got a good laugh on me though and am getting a bit ahead of myself. I had been measuring everything with a digital dial caliper that only went to two places. I finally broke out the one I use on engine rebuilds and started getting much more accurate measurements. The shafts of the 3.2mm and the 1/8″ bits were identical at .124. So, a 1/8″ bit will do just fine.

The first gears sent actually worked but induced a ton of vibration and even a squealing noise. The second set worked. When I examined them closely though it was obvious the mesh was not fully engaged. A few days ago I got another batch of gears and perfection!!! V2. red and yellow gears are perfect. These gears are supposed to have a built in washer-like step on the bottom. I thought this was to keep the gear above the bottom case boss. The gears now made don’t have this as it turns out it’s quite difficult to make a .005 step and then build on top of that with a 3D printer. So I went on another odyssey of finding the correct sized washer to put under the gear. It dawned on me that the purpose of the washer was to raise the driving gear enough to fully mesh with the driven gear not just float it off the case boss. With an assortment of small washers with a 1/8″ hole and a little time I found that a .020 washer did the trick. I’m running the gear with the original .005″ gear on top. It runs so smooth. I am so happy! I won’t have to part out the HSC for parts and the fellow, Scott, who has wanted one of these forever will get his wish.

Needle Cleaning Day

I’ve been playing catch-up what with finally getting the SMC1 working. I finished the SMC3 mechanism and installed it in the SMC1. Lo and behold it picked up A/B sides one after the other as it is supposed to. As a reminder the other mech would not play both sides of the same record. Now the juke will with the SMC3 mechanism so I confirmed that the problem was indeed in the mechanism. The beauty of spare parts. And then I proceeded to overthink the problem as I usually do. It’s a good way to learn as I pored over schematics, troubleshooting guides, broke out the meter, ohmed every wire to death…..

I found nothing and finally turned back to the vertical stack of switches. I compared them with the ones on the SMC3 mech and looked at the adjustments. The bottom pair, 1M1 and 1M2, reverse the motor when going from left to right side play when both sides of the same record are selected. The motor was reversing before the mechanism could mechanically switch the tonearm assembly to the right side. It was a matter of adjusting them again, using the SMC3 mechanism as a guide. I had done it according to the book and it just wouldn’t work. The gap needed to be a lot bigger than what Seeburg says.

Now I have a working SMC1 and am at the point of testing. I go out every day and play several records looking for problems to crop up. The ones that did lately are like the tone arm would not land in the play-in space. No matter where I put the Pickup 1 adjustment the tonearm was being jerked forward a bit landing in the music. I had to perform the rest of the Pickup Adjustments 2 through 5 to fix that and then back to 1 to get a good landing spot. Today, most of the time the record clamp won’t clamp flat against the record. When it does this it causes the record to wobble and you can definitely hear a warble. A bad warble that sounds like the speed is off. I did the adjustments for it several times. Most people want to blame the spring but you can add a double-strength spring and it won’t help if the adjustments aren’t right. I will replace the clamp shaft tomorrow. Actually pull it out and put it in the other way. When I loosen the set screw and adjust the horizontal position the clamp works fine until I tighten the set screw. I think the set screw is falling into its old mark instead of setting up a few thousandths away.

Before I broke for lunch I took all the used needles I have and dumped them into a small container filled with “Mean Green”. A couple hours later after finishing with the SMC1 for the day I took them inside to the sink and gently scrubbed each one with a toothbrush. One must be careful to brush only in the direction the needle is pointing or up, as I think of it. I rinsed them off in a small colander in fresh water and then spread them out in the Texas sun. I can guarantee all moisture will be sucked out of them despite the horrendous humidity. After they’re dry I’ll inspect them with a jeweler’s loupe to make sure the needle point is conical and not damaged. Next comes the fun part of selecting and playing a record while installing one needle at a time to listen to it and see if it is usable. That will take two or three days as I don’t have the patience to do fifty at a time. I have a ton of the purple sapphire needles. These are all original Pickerings. I imagine the majority of them will be fine. I had sold quite a few used needles before and had so many people that let me know these original used needles sounded waaay better than the new needles now available. I think most operators changed them out fairly often. In home use these needles will last a real long time. Just keep the tonearm pressure about 3 grams.