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Mitsubishi LT-30 restoration

Thanks for the replies. Kotofei-I think you misunderstood the problem but I appreciate your effort in describing a solution. The tone arm unit is not sliding whilst it is playing, creating the issue that the tone arm floats to it's max position and then skips. It seems like Pio1980 has the idea. Not sure where the "tracking servo light gate" is but I will poke around and see what I can find. It seems the issue is the tone arm is not tracking once it is positioned at the beginning of the record.
Thanks for the replies!
 
I think it's inside the carriage block under the arm gimbal. You need to download the manual from TVE and refer to arm disassembly page 4 and 5, I think the tracking servo light gate assembly is in figure 7.
Again, simplest first. Check the cable board plugs off the arm unit and work them with a contact cleaner fluid like DeOxit, WD-40, or even naphtha lighter fluid (NOT alcohol!!).
 
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OK, I see. Looks like I really misunderstood what's going on. Sorry.

PIO1980 has a good suggestion to test and clean the connections first. If this wouldn't help, check the lamp with the DMM. Look at the schematics what wires go to that lamp, unplug the connector and measure resistance accross these wires. It should be 7 or so Ohm; an open connection means the lamp is toasted and has to be replaced. This is the most likely reason for malfunctionning.

MitsuLT said:
Thanks for the replies. Kotofei-I think you misunderstood the problem but I appreciate your effort in describing a solution. The tone arm unit is not sliding whilst it is playing, creating the issue that the tone arm floats to it's max position and then skips. It seems like Pio1980 has the idea. Not sure where the "tracking servo light gate" is but I will poke around and see what I can find. It seems the issue is the tone arm is not tracking once it is positioned at the beginning of the record.
Thanks for the replies!
Click to expand...
 
It may not be the bulb, it could be the photo detector. I burned out one with a Zerostat gun by accident. Hope that's not it, as they are about impossible to find. Same design as in an LT-20. Easy o trouble shoot, just monitor volatge at he car dinput, and if there is no change when swinging left to righ, and the bulb is good, then the detector is bad.
 
Thanks guys! First, thank you for all the advice and offer for parts koseltri. I'm relatively new to repair on these types of things, so if you could clarify a few things, that would be very helpful. I replaced all three tracking bulbs in my first round of repairs, but in order to narrow it down to the photo detector, I need a little clarification as to where the "card input" is so that I can test for voltage change.

Also, when you refer to the "tracking servo light gate assembly is in figure 7" do you mean it's inside the arm assembly or are you referring to the series of three lights and detectors easily accessed without getting into the arm assembly?

The tracking lights all seem to be lighting but the problem of no consistent tracking motion when playing is still the problem.
Koseltri-it looks like I might need that detector?!
Thanks again for the help!
 
"Also, when you refer to the "tracking servo light gate assembly is in figure 7" do you mean it's inside the arm assembly or are you referring to the series of three lights and detectors easily accessed without getting into the arm assembly?"

Inside the arm base, an SOB to access from what I can see/not see in the pix.
 
Pio1980 said:
"Also, when you refer to the "tracking servo light gate assembly is in figure 7" do you mean it's inside the arm assembly or are you referring to the series of three lights and detectors easily accessed without getting into the arm assembly?"

Inside the arm base, an SOB to access from what I can see/not see in the pix.
Click to expand...

It is a PITA to get to and work on, mine did the same thing, the tracking would respond in 'reverse' but not 'forward'. If you have to go in there you might as well replace the lift belt. Cheap insurance. Other than Perry's 'induced' failure, every other time I know of is a burned-out bulb. You have the SM from VE I presume? The three bulbs on the bottom of the tonearm are for size/positioning only.
 
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koseltri said:
It is a PITA to get to and work on, mine did the same thing, the tracking would respond in 'reverse' but not 'forward'. If you have to go in there you might as well replace the lift belt. Cheap insurance. Other than Perry's 'induced' failure, every other time I know of is a burned-out bulb. You have the SM from VE I presume? The three bulbs on the bottom of the tonearm are for size/positioning only.
Click to expand...

I do have the Service Manual from VE. And I have already replaced the lift belt in my first round of repairs, so I know how to get into the tone arm section with minimal cursing. I will have another look into the tone arm to see if I can find the last remaining "old bulb" in the entire unit. hahaha!
Side note FYI, the arm does manually track in both directions when the play/stop buttons are pushed. Does that change your diagnosis?
Thanks again for all the help!
 
OK, i have finally dug the farthest reaches of the tonearm and found the tracking servo light gate assembly. Any idea what volt/amp bulb i should use? I have one 12v .006amp bulb left from the size/positioning assembly and control panel bulb changes and can pick up another at the Shack (since there are two in there) if that is the correct one to put in...
 
LT-30 Alignment Template

I don't know if anyone has this, but I have seen a couple posts about not having one.
I was looking in my folder that came packed with my LT-30 a couple years ago, and behold, here was the Alignment Template. It is a hard, glossy, almost plastic material.
I scanned it into a jpg format so it can be printed out as needed.
Other that the original owners manual, that was all I got.
regards
Mike

Well, I must be doing something wrong. It is not showing up or printing in the actual size. Any ideas? I can email the original copy if anyone wants it.
 

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Thanks Pio1980! I went ahead and replaced both bulbs this afternoon. Re-assembled the unit and plugged her in...Good news is she now tracks!
BAD NEWS is I now have no signal coming out of the Red RCA (aka left? channel), which was not an issue prior to the tracking bulb replacement. Another f*&$ing setback. Assuming i dislodged a wire during the tracking arm dis-assembly, I went back, re-dis-assembled the entire unit and it appears all of the wire connections are still intact. What's the best next step for diagnosing this latest problem?
Thanks. I was hoping the tracking was going to be my last hurdle.
Anybody live in Denver? hahaha
 
Signal line, that should be easy. If the dead channel has noise it's probably and open circuit/broken wire. If the dead channel is nearly silent it's probably a shorted/grounded signal wire or possibly a muting switch problem. Measure resistance at the RCAs when cued up and stopped and when playing, it should be very low to zero ohms when cued up /stopped and a few hundred ohms when playing. If open it's a broken circuit somewhere between the plug and the cartridge. If low/zero it's a shorted/grounded signal wire. Follow the wires from the RCAs to the arm. The mute switch is in the base of the arm with the cueing limit switches in the area with the cueing belt. Used to live in SLC, fat lot of good that does you.
 
It's definitely a silent left channel. So "a shorted/grounded signal wire or possibly a muting switch problem." as you diagnose. What visual issue should I look for in a "grounded/shorted" wire? I recall seeing the muting switch, I will go back and investigate that as well.
Thanks Pio1980!
 
I would also check continuity between the relevant pins in the tonearm socket and the board where the tonearm wires and the RCA cables meet. You may have nicked/broken one of the tonearm wires.
 
steel Band

Does anyone have a picture of the steel band inside the TT?
I need to see how it is wrapped and looped around the wheels.
I thnk mine is to stretched out to be effective anymore.
I may have to try the steel bead cord another poster talks about.
Thanks
Mike
 
I believe there is one or two springs that connect this steel band to moving carriage (?) They keep it stretched properly.

My pics are on another comp, I'll post a picture if I find one.



Jobman said:
Does anyone have a picture of the steel band inside the TT?
I need to see how it is wrapped and looped around the wheels.
I thnk mine is to stretched out to be effective anymore.
I may have to try the steel bead cord another poster talks about.
Thanks
Mike
Click to expand...
 
kotofei said:
I believe there is one or two springs that connect this steel band to moving carriage (?) They keep it stretched properly.

My pics are on another comp, I'll post a picture if I find one.
Click to expand...

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These are kotofei's from the 1st page, perhaps they are of use?
 
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