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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Thu Dec 01, 2016 6:03 am Post subject: aliognment fixture |
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has any seen a turntable bearing alignment fixture for sale? _________________ An analog kind of guy forced to live in a digital world:>) |
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jsdspif
Joined: 16 Jan 2016 Posts: 279
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Posted: Sun Dec 11, 2016 1:59 am Post subject: |
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I don't think I've ever heard of that. Is there a photo of one somewhere? If I could see a pphoto and get a rough idea of what it does I may be able to make something up. (I'm a machinist) |
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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Sun Dec 11, 2016 12:30 pm Post subject: |
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[quote="jsdspif"]I don't think I've ever heard of that. Is there a photo of one somewhere? If I could see a photo and get a rough idea of what it does I may be able to make something up. (I'm a machinist)[/quote]
what it does is allow the new bushing (bearing) assy to be adjusted true vertical so the inserted tuntable is true flat.
i guess w/luck, trial and error i could try w/o it. last i saw one was mid 1990's _________________ An analog kind of guy forced to live in a digital world:>) |
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SelectaVision420
Joined: 25 Mar 2012 Posts: 1424 Location: Hartford
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Posted: Sat Dec 17, 2016 8:27 pm Post subject: |
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for an F/G model? _________________ (2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner |
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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Sun Dec 18, 2016 12:31 pm Post subject: |
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[quote="SelectaVision420"]for an F/G model?[/quote]
should have included model number.
its an SGT 250 _________________ An analog kind of guy forced to live in a digital world:>) |
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jsdspif
Joined: 16 Jan 2016 Posts: 279
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Posted: Sun Dec 18, 2016 1:11 pm Post subject: |
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I have one opened up now. on mine there's a top and bottom brass bushing and they sit on pieces of plastic and on mine there is glue (or something) poured all over the screws that hold those 2 pieces in place. So are you saying you have somehow removed those 2 pieces? Because other than that it's pretty much aligned automatically, as long as the 2 bottom pieces haven't been moved. I don't know how they would ever be moved, at least how I could move them. I'd have to get rid of all that glue holding it in. Can you take a photo of what you have going? |
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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Mon Dec 19, 2016 6:20 am Post subject: |
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good to know
years ago i was led to believe removing the assy for any reason required
a fixture to true it vertically
thanks for the heads up. now i can remove it for repair.
if there's any problem i'll take a pict and post it _________________ An analog kind of guy forced to live in a digital world:>) |
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jsdspif
Joined: 16 Jan 2016 Posts: 279
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Posted: Mon Dec 19, 2016 7:07 am Post subject: |
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I took mine apart , not the 2 bottom pieces but the tops of each bushing to lube the turntable shaft and lube the bushings themselves but that's not really needed. I ended up putting the bushings back in place and I applied some synthetic grease that I've been using for years on small motors and what not. Anyway I applied very sparingly in the bottom bushing and then ran a swab in and out quick so basically there is just a very thin film in the bottom bushing. Then I applied again very sparingly grease to the top of the turntable shaft where it rides in the bushing. I figured that way you slide the shaft thru the top bushing and at this point there's still no lube until the end of the shaft reaches the bottom bushing and at that time the top of the shaft (that is lubed) is sliding into the top bushing. The idea being there's no need to lube the entire shaft and I didn't want lube all over , just where the shaft is inside the bushing. I also disassembled the motor to lube it, it runs alot quieter now. Before it just sounded a little dry. Those bushings are probably an oil impregnated bronze or something but over a period of 35 years they dry out. I tried a special oil for guns that's supposed to leave a coating that lubes and protects but I didn't like it. I kind of like knowing the lube is there and it's going to stay there. This synthetic grease never dries out and stays pretty much the same feel whether it's 0 degrees or 100 degrees. I've done a few small motors like in the players for years with it and have never had problems. |
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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Tue Dec 20, 2016 5:53 am Post subject: |
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i don't think i'm going to be that lucky
there's lateral movement/wobble to the turntable which like w/a phonograph
means a worn bushing. _________________ An analog kind of guy forced to live in a digital world:>) |
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Daxi Don
Joined: 24 Dec 2006 Posts: 75 Location: Indiana
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Posted: Thu Dec 22, 2016 6:29 am Post subject: Alignment Fixture. |
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I have looked carefully through the RCA Service data for the SGT250 and the Addendums and Service notices. I see no reference to an Alignment Fixture. There is no instruction to align bearings in the service data Mechanical Adjustment section. The player parts list under Tools does not list an Alignment fixture or Tool.
71 ChevyVan, are you sure that the Alignment Fixture you describe is for an RCA CED player ? |
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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Thu Dec 22, 2016 7:15 am Post subject: |
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although in the day i never had to replace an assy, i could have sworn the fixture had slots that allowed a screw driver to turn screws to true it vertically.
its possible that after many many years i have had a brain fart or two
and have my facts wrong. my bad :>(
so your saying to replace just unscrew the old and (if available) screw the new one in place. _________________ An analog kind of guy forced to live in a digital world:>) |
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Daxi Don
Joined: 24 Dec 2006 Posts: 75 Location: Indiana
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Posted: Thu Dec 22, 2016 3:06 pm Post subject: |
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The SGT250 service data shows the 2 turntable bearings. The upper and lower bearing are identical RCA Part 149052. No alignment is needed if the bearing are replaced. Wear sometimes shows on the turntable spline. I have never changed a bearing.
A slight turntable wobble is normal and not a sign of wear, The wobble and disc run out are corrected during play by the player time base correction circuits. An important part of the time base correction is the arm-stretcher coil, found at the back of the stylus. This coil rapidly changes the stylus tip position on the disc to counter play timing errors.
.RCA F and G line player models use the same parts. |
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SelectaVision420
Joined: 25 Mar 2012 Posts: 1424 Location: Hartford
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Posted: Sat Dec 24, 2016 9:21 am Post subject: Re: Alignment Fixture. |
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Daxi Don wrote: | I have looked carefully through the RCA Service data for the SGT250 and the Addendums and Service notices. I see no reference to an Alignment Fixture. There is no instruction to align bearings in the service data Mechanical Adjustment section. The player parts list under Tools does not list an Alignment fixture or Tool.
71 ChevyVan, are you sure that the Alignment Fixture you describe is for an RCA CED player ? |
if anything, the sync plate gauge ( the one that is a partial turntable with relief cut in it to aid in gauging ) may be what he is referring to, since it does have a spindle... _________________ (2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner |
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71chevyvan
Joined: 29 May 2004 Posts: 52
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Posted: Wed Nov 08, 2017 12:15 pm Post subject: Re: Alignment Fixture. i think thats exactly what i remembe |
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[quote="SelectaVision420"][quote="Daxi Don"]I have looked carefully through the RCA Service data for the SGT250 and the Addendums and Service notices. I see no reference to an Alignment Fixture. There is no instruction to align bearings in the service data Mechanical Adjustment section. The player parts list under Tools does not list an Alignment fixture or Tool.
RCA CED player ?[/quote]
if anything, the sync plate gauge ( the one that is a partial turntable with relief cut in it to aid in gauging ) may be what he is referring to, since it does have a spindle...[/quote]
i think that was exactly what i remembered _________________ An analog kind of guy forced to live in a digital world:>) |
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