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Realistic Lab 420, Tonearm Drops Too Fast

Scott Roark said:
Well, I hosed it up. Unfortunately, in my attempt to loosen the top, I ended up messing with a hidden screw....and this was a TERRIBLE idea. It affects where the tone arm will drop on the record and another screw controls where it will pick up.
I'm BEYOND frustrated with my mistake, but cannot figure away to resolve it. I hate to say 'Live and Learn', but I guess I'm going to have to.
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I don't think you did.
When you lose the tonearm, that's what happens. I should have pointed this out before..... every time I had to unscrew the tonearm, I had to realign those two screws you mentioned that drops and pick up the tonearm.

This is how I do it.
1. On screenshot below where the red circle is, use a flat screwdriver and set both screws all the way to the left (counterclockwise), to leave them by default.
2. Then I unscrew a bit those two screws that hold the tonearm from below (second screenshot on yellow). That way I can move the tonearm guide (on blue) freely and set it on starting position all the way to the left. Then I hold it on this position and screw again those two screws on the yellow circles (not too tight though)
3. Finally, you can start the turntable and see where the tonearm drops and picks up. You go back to the first screenshot where the red circle is and use the same flat head screwdriver, and start moving those two screws clockwise until you find the correct position. This is trial and error but not complicated to do.
Keep in mind that the first screw you find, is for the pick up function. Then you slide the tonearm to the end until you find the second screw, and this is the pick up function.


Screenshot_20220417_172059.jpg

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WOW! That is AMAZING Detail and I GREATLY appreciate it. I'm going to give it a shot. Thank you!!!!

P.S. I'm re-reading your steps, and the two screws. It looks like you wrote that the 1st screw is for pick up function and the 2nd screw is for pick up function. I realize one of them is actually drop off and I think I read it somewhere.
 
Scott Roark said:
WOW! That is AMAZING Detail and I GREATLY appreciate it. I'm going to give it a shot. Thank you!!!!

P.S. I'm re-reading your steps, and the two screws. It looks like you wrote that the 1st screw is for pick up function and the 2nd screw is for pick up function. I realize one of them is actually drop off and I think I read it somewhere.
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My bad, yes you are right. I will correct that here:

Keep in mind that the first screw you find, is for the pick up function. Then you slide the tonearm to the end until you find the second screw, and this is the drop function.

Another tip. On step 3, when you start the turntable the first time (when on default position), if the needle drops outside the record area, then you are good. So you can adjusting with the second screw turning clockwise to fix the drop off function.
 
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Bad_boo, I can't thank you enough for providing these detailed instructions. I'm so gun shy from being out of my element and thinking I've totally messed this up. But I'm going to give it a shot over the next week and I'll let you know the results. Thanks!
 
Scott Roark said:
Bad_boo, I can't thank you enough for providing these detailed instructions. I'm so gun shy from being out of my element and thinking I've totally messed this up. But I'm going to give it a shot over the next week and I'll let you know the results. Thanks!
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Awesome, my pleasure to help.
I'll check out my notification this week in case you have some questions.

This was the part I also got stuck when I serviced this turntable, and it was because of these alignment screws.

Anyway, looking forward to hear back from you to hear the good news.
 
Well, after about 5 hours, and multiple considerations of throwing this thing in the trash, I finally KIND OF got it working.

At this time I'm able to auto place the needle on the record. It drops softly and plays perfectly. BUT, at the end of the record the needle stays on the record. I realize that the 2nd screw is what should control this, but I'm SOOOO gun shy now.

For me, ultimately, to get the needle to drop in the proper place was all based upon the placement of that blue bar (screen shot 2). It seemed like every time I messed with those 2 top screws that are accessed from the top (screen shot 1) didn't every truly, accurately work.

So, I can live with this set up. Thanks for you help @bad_boo
 
I am officially addicted.... I've fine tuned this turntable as much as I can. There is literally ONE thing I cannot figure out how to resolve....The auto pick up. When the needle gets to the dead wax at the center of the record it will not auto return. I have to manually pick up the needle or use the cue arm. I have adjusted both screws on the top. The most I was able to do was better fine tune the drop off of the needle, and this by adjusting screw #2, which only becomes visible when the tone arm is near the dead wax near the label. None the less, those screws did nothing to handle the auto return. (Please see the video if my description isn't clear)

So, any insight would be truly appreciated. I'm 95% satisfied with how it's operating now. But I'd love to be able to take advantage of the auto-return and programmable repeat. Thanks in advance to @bad_boo , @Montycat and @likebike23
 
Tried to upload it here for you but apparently the file is too large.

Anyway, go to Vinylengine and download the Lab-420 service manual (you'll need an account but it's all free). It explains, in detail, how all the auto mechanisms are supposed to work. It should at least get you on the right track on what you should be looking for/at.

https://www.vinylengine.com/library/realistic/lab-420.shtml
 
Scott Roark said:
I am officially addicted.... I've fine tuned this turntable as much as I can. There is literally ONE thing I cannot figure out how to resolve....The auto pick up. When the needle gets to the dead wax at the center of the record it will not auto return. I have to manually pick up the needle or use the cue arm. I have adjusted both screws on the top. The most I was able to do was better fine tune the drop off of the needle, and this by adjusting screw #2, which only becomes visible when the tone arm is near the dead wax near the label. None the less, those screws did nothing to handle the auto return. (Please see the video if my description isn't clear)

So, any insight would be truly appreciated. I'm 95% satisfied with how it's operating now. But I'd love to be able to take advantage of the auto-return and programmable repeat. Thanks in advance to @bad_boo , @Montycat and @likebike23
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Hey, Just ruling out, does the tonearm return by itself when you press the off/start reject switch, when playing a record?

If the above is all good, then going back to your video, when the needle is on that dead wax, can you lift the cue and slight push the the tonearm with your finger to the center, until the autoreturn function clicks? If so, then that should be an issue with the adjusting screw that has not been done properly most likely

The way I adjust this autoreturn function is by leaving up the cue lifted, and starting from the end of the record (or before that dead wax), I keep pushing the tonearm to the center until the autoreturn clicks. That way I can see how misaligned I am. Then I keep turning clockwise the adjusting screw for the pick up function until the autoreturn clicks around that dead wax. Then I drop the cue and check the autoreturn is adjusted properly.

Last case scenario, if all that doesn't adjust it, it could be and issue of not leaving its adjusting screw all the way to the left (or default position) when adjusting the "blue" guide to the starting position. But let's look into this if the above doesn't adjust it.
 
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Yes, the tonearm will return when I flip the 'Start/Reject' switch.
I've tried what you recommended regarding lifting the tone arm with the cue and then pressing towards the center, but it doesn't trigger that auto return. I then played with screws A & B but it has NO effect.

So, it may be that I've done something else that's causing this issue.

But I can live with this. Thanks!!!!
 
Ok sounds good if you are Ok with that. It's not a big issue.

If you ever feel like checking on it at some point, I would suggest to do this whole readjustment again. With that blue guide on that second screenshot.

There has to he something you may have missed, as you mentioned. I've been there and I've had to start again this whole part.

Anyway, good luck with that and enjoy the tt.

Cheers
 
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