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SJT 400 repair needed

 
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randallkubin



Joined: 28 Feb 2008
Posts: 12

PostPosted: Mon May 18, 2015 4:10 pm    Post subject: SJT 400 repair needed Reply with quote

Hey you guys.

I bought a broken 400 unit. I knew it was broken when I bought it... He told me so. But, sounded like it just needed a new belt. I bought three, because they were cheap. Cleaned off the old goo and put the new one on. I'll try to describe the problem as best as I can... If I made a video than the disc would get stuck in the player again, and I'd just rather not go through that.

First... when I plugged it in the first time... it made a rapid clicking sound. I messed with the stylus reduction gears a bit, and noticed it was not moving properly on the track it rides on. So, I fixed the rapid ticking.

I believe the turntable needs to be lubricated... I'm sure it woulnd't hurt. It sounds kind of grindy. It's not a gallop noise like I had in my other 400.

When I plug it in and power it on (after I repaired the rapid ticking) the load door doesn't drop down all the way... but if i give it a little push it drops (maybe it's the stylus thing?) and I can load a movie just fine. everything goes into place. BUT, the movie never goes into play mode. I just get the two horizontal red lines on the little LCD panel it has.

I am going to mess this thing up beyond repair if I keep doing things... SO i wondered if one of you more experienced members would like to check it out for me. There's money in it for you. And I'll even throw in a couple j/k load belts Smile
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RCA SJT 400
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jeremybondsf



Joined: 02 Dec 2015
Posts: 6

PostPosted: Thu Dec 03, 2015 3:05 am    Post subject: Reply with quote

My 400 is doing the same thing now (loud rasping sound). Could you please tell me more about what you did to fix it?

Thanks,

Jeremy
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SelectaVision420



Joined: 25 Mar 2012
Posts: 1424
Location: Hartford

PostPosted: Thu Dec 03, 2015 8:32 am    Post subject: Re: SJT 400 repair needed Reply with quote

randallkubin wrote:
Hey you guys.

I bought a broken 400 unit. I knew it was broken when I bought it... He told me so. But, sounded like it just needed a new belt. I bought three, because they were cheap. Cleaned off the old goo and put the new one on. I'll try to describe the problem as best as I can... If I made a video than the disc would get stuck in the player again, and I'd just rather not go through that.

First... when I plugged it in the first time... it made a rapid clicking sound. I messed with the stylus reduction gears a bit, and noticed it was not moving properly on the track it rides on. So, I fixed the rapid ticking.

I believe the turntable needs to be lubricated... I'm sure it woulnd't hurt. It sounds kind of grindy. It's not a gallop noise like I had in my other 400.

When I plug it in and power it on (after I repaired the rapid ticking) the load door doesn't drop down all the way... but if i give it a little push it drops (maybe it's the stylus thing?) and I can load a movie just fine. everything goes into place. BUT, the movie never goes into play mode. I just get the two horizontal red lines on the little LCD panel it has.

I am going to mess this thing up beyond repair if I keep doing things... SO i wondered if one of you more experienced members would like to check it out for me. There's money in it for you. And I'll even throw in a couple j/k load belts Smile


it is possible that the wiring in the stylus arm itself is bad if it only gives the dashes... usually i think thats the deal...
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(2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner
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SelectaVision420



Joined: 25 Mar 2012
Posts: 1424
Location: Hartford

PostPosted: Thu Dec 03, 2015 8:33 am    Post subject: Reply with quote

jeremybondsf wrote:
My 400 is doing the same thing now (loud rasping sound). Could you please tell me more about what you did to fix it?

Thanks,

Jeremy


a loud raspy sound usually means the turntable spindle needs oil, or t
he turntable is too low and its dragging on the chassis...
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(2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner
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dumbchemist



Joined: 27 Oct 2011
Posts: 546
Location: Central New York

PostPosted: Thu Dec 03, 2015 10:32 am    Post subject: Reply with quote

Could you fix the raspy sound of the turntable by turning up the allen screw that is in the brass nut underneath the player?
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Sears 934.54780150 & 934.54810350
CED-1
Hitachi: VIP2000, 3-VIP1000, VIP201P
GEN10301
RCA SJT-200 SJT-400
DiskLord DP-830
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ketonic_dude



Joined: 20 Jul 2012
Posts: 547
Location: Mankato, MN

PostPosted: Thu Dec 03, 2015 11:50 am    Post subject: Reply with quote

For the raspy sound, I assume this is because the turntable is scraping the bottom. You should be able to turn the hex head screw inside the brass ring on the bottom center of the player with a allen wrench. I have found sometimes there is a cover over the screw that needs to be turned. If it's not the turntable than I don't know.

As far as the double dashes, you can try a different stylus. If you turn the reduction gear does it make the arm come out ok? It doesn't get hung up on anything? If it comes out ok I would try a different stylus. I know Tony and Ryan will tell you the arm is bad and to replace the whole works, but I have found in the past that sometimes just replacing the stylus with a different one will fix the problem. The other thing you can check is if you remove the turntable and take a magnetic screwdriver with a thin shaft and put it down the hole the turntable shaft goes in, there should be a small round washer in there. If there is not you can look on the bottom of the turntable and see if it stuck to the magnet. That little washer will raise the turntable just enough to make contact with the stylus and sometimes when it is missing the stylus won't be able to drop down far enough to contact the disc and you will just keep hearing a click and get the double dashes.

Hope that helps.
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SelectaVision420



Joined: 25 Mar 2012
Posts: 1424
Location: Hartford

PostPosted: Thu Dec 03, 2015 12:38 pm    Post subject: Reply with quote

ketonic_dude wrote:
For the raspy sound, I assume this is because the turntable is scraping the bottom. You should be able to turn the hex head screw inside the brass ring on the bottom center of the player with a allen wrench. I have found sometimes there is a cover over the screw that needs to be turned. If it's not the turntable than I don't know.

As far as the double dashes, you can try a different stylus. If you turn the reduction gear does it make the arm come out ok? It doesn't get hung up on anything? If it comes out ok I would try a different stylus. I know Tony and Ryan will tell you the arm is bad and to replace the whole works, but I have found in the past that sometimes just replacing the stylus with a different one will fix the problem. The other thing you can check is if you remove the turntable and take a magnetic screwdriver with a thin shaft and put it down the hole the turntable shaft goes in, there should be a small round washer in there. If there is not you can look on the bottom of the turntable and see if it stuck to the magnet. That little washer will raise the turntable just enough to make contact with the stylus and sometimes when it is missing the stylus won't be able to drop down far enough to contact the disc and you will just keep hearing a click and get the double dashes.

Hope that helps.



another good point! that little washer is about the diameter of a pencil and as flat as a dime, some times it falls out of place and drops the turntable like 2/16ths, the spindle rotates on it, and sometimes also it spins with the turntable and thats what makes the scratchy noise, thats how i fixed a new in box 300, by just lubing the base of the turntable shaft...


edit... looking in my manual the little disc is called a thrust plate.
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(2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner
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blindfury420



Joined: 26 Jan 2011
Posts: 1036

PostPosted: Thu Dec 03, 2015 11:00 pm    Post subject: Reply with quote

ketonic_dude wrote:

As far as the double dashes, you can try a different stylus. I know Tony and Ryan will tell you the arm is bad and to replace the whole works, but I have found in the past that sometimes just replacing the stylus with a different one will fix the problem.


Double dashes can mean sooooo much. from stylus to internal electronics and more than one ic all the way down to a bad diode or transistor. Never an easy fix sadly.... at least the diagnosis.

I only recommend replacing full stylus arms on f/g players, and only when its in fast forward mode or the dreaded wobbles. Rarely is doing a full stylus arm replacement the answer on j/k players Sad
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McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425
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ketonic_dude



Joined: 20 Jul 2012
Posts: 547
Location: Mankato, MN

PostPosted: Fri Dec 04, 2015 11:35 am    Post subject: Reply with quote

I remember that now that you mention it Tony, Thrust Plate. They are available from John at CEDatum. I ordered some from him once.

So Ryan, are you saying it's easier to replace the circuit board on a stylus arm on a j/k player than just replacing the whole arm? Seems to me like it would just unplug and slide off with just a couple screws removed. But you are the expert so I will take your word for it. I have the J300 new in box that is giving me double dashes. I have not messed with it much but you had said it is most likely the circuit board on the stylus arm. So how easy is it to remove that. I could use some detailed instructions after I have exhausted all other alternatives. Or is there a certain circuit that I can check with the voltmeter to know weather it is the culprit or not? Thanks.

Also when are you guys going to start a database of service manuals so everyone else can just download them. Wink Thanks.
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blindfury420



Joined: 26 Jan 2011
Posts: 1036

PostPosted: Fri Dec 04, 2015 12:26 pm    Post subject: Reply with quote

ketonic_dude wrote:
I remember that now that you mention it Tony, Thrust Plate. They are available from John at CEDatum. I ordered some from him once.

So Ryan, are you saying it's easier to replace the circuit board on a stylus arm on a j/k player than just replacing the whole arm?

The stylus arm is a pain on j/k cause you have to do a lot to free the bar that the arm rides on. Plus there is no need to replace the arm on a j/k player when its just the arm stretcher coil. Its the coil right behind the stylus. You see it every time you change a stylus in the j/k players! I will explain more about replacing it if its something you want to try. You need a good digitally controlled soldering iron at the very least.

F/g players its just way easier to replace the whole arm. Its also rarely coil behind the stylus on f/g players. That is not what causes auto fast forward.



I have the J300 new in box that is giving me double dashes. I have not messed with it much but you had said it is most likely the circuit board on the stylus arm.

I honestly don't remember saying that Sad I know double dashes is almost always something like the video demodulator on the main board not the stylus arm. As long as you have tried other working styli.

Also when are you guys going to start a database of service manuals so everyone else can just download them. Wink Thanks.

One day! It would take a ton of time to do it! i know easiest way would be to copy any schematics, voltages and service notes!

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I dont own

McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425


Last edited by blindfury420 on Fri Dec 04, 2015 12:35 pm; edited 1 time in total
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ketonic_dude



Joined: 20 Jul 2012
Posts: 547
Location: Mankato, MN

PostPosted: Fri Dec 04, 2015 1:28 pm    Post subject: Reply with quote

I guess I don't have a digitally controlled soldering iron, just a plain one. I'm not real good at soldering either but if it's not too small a spot I can usually get r' dun. Sure it wouldn't be easier to take the arm off? Anywho, I'll cross that bridge when I come to it. lol

As far as creating an online database, it probably wouldn't take as long as you think. I would just clear off a table or desk and create a contraption to hold a camera looking down a couple feet from the surface of the desk. Then just lay the manual on the desk, take a pic, turn the page, take another pic, etc. all the way through. Then upload the pictures and use a photo to PDF creator program to make a PDF of it all. If you had a really good camera and it didn't move at all when the pic was being taken it would be just as good as a scan but in a fraction of the time. If the camera had a B&W picture setting it would be even better cause you would have smaller file sizes for the pictures and PDF's. At least that is how I'd probably do it.
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blindfury420



Joined: 26 Jan 2011
Posts: 1036

PostPosted: Fri Dec 04, 2015 1:42 pm    Post subject: Reply with quote

The arm stretcher coil is not easy. You have to pop a lil o ring clamp on it, then take of the stylus kicker mechanism (black plastic that lowers and raises stylus) and desolder the two connecting wires and it has to be a low temp otherwise it will melt the plastic the coils posts are attached to on the old and new one!

In your case I would say its easier to remove the arm but you still have to basically disassemble the whole top structure in order to get the bar free to take the arm off. In your case its worth a try! Although I wouldn't recommend it to a novice though!

I never thought about pics, always thought scan. Just wanted everything to be clear if I ever did it, but I think the camera trick would work!
_________________
I dont own

McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425
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dumbchemist



Joined: 27 Oct 2011
Posts: 546
Location: Central New York

PostPosted: Fri Dec 04, 2015 4:06 pm    Post subject: Reply with quote

I sent a message to Tom Howe's personal e-mail address asking him if he wanted the pdf files of the SJT-100/101/200/300 manual that I had scanned. So far, there has been no answer.

FYI:
The office supply store that did the scanning of the SM had an 11/17 inch scanner. They removed the staples from the spine of the SM before scanning and restapled the SM back to its original condition. For me, the cost of $30 was still cheaper than buying a scanner.

Also, I sent the SM pdf files to manual@lddb.com so that it would be posted on the laserdisc web site (lddb.com). So far, no answer has been received.
_________________
Sears 934.54780150 & 934.54810350
CED-1
Hitachi: VIP2000, 3-VIP1000, VIP201P
GEN10301
RCA SJT-200 SJT-400
DiskLord DP-830
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