Restoring a pretty old -and dirt- Technics SL-1200Mk2
- Thread starter morfeora
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- restoration sl-1200 mk2
morfeora
Active Member
Well I did reflow those joints and also check the FG coil for continuity and looks fine, but I have my doubts, I don't know if maybe to check it for continuity is not enough. I will remove all the motor assembly to inspect very carefully visually just in case, but I already de-solder the joints and checked the FG coil disconnected from the board and seams OK.
Cheers,
Rodolfo
BillWojo
Addicted Member
I don't work on these Technics tables but if your supposed to get 30VAC on the transformer secondary and your getting 60VAC that that tells me the transformer is either wired for the wrong input voltage or it's a 120VAC transformer and your feeding it 240VAC.
Something seems seriously off there.
BillWojo
morfeora
Active Member
Hi BillWojo, yes is very weird to find such voltage difference... I was asking because maybe someone new about a series of SL-1200 that probably came out with a 60V AC transformer instead of a 30V.
Cheers,
Rodolfo
PD: Still working on this project but a series of events step in the way... in other words, I am going to be a father in the next few months
The transformer is connected to 120VAC so this is not the case.
Cheers,
Rodolfo
PD: Still working on this project but a series of events step in the way... in other words, I am going to be a father in the next few months
morfeora
Active Member
I finally had some time to keep going with this restoration.
Today I have found something that might be the responsible for the non stop and running away issue. Looking around on YouTube about possible solutions, I found a guy checking all the coils on the main board. I followed him to figure out that one of the coils was not giving the same measure others did. To make a better measurement I desolder the entire coils assembly to confirm one of the little position coils was weird. All the other position coils were 0.12mH and 10 Ohms, this one, the defective one, was 0.06mH and 16 Ohms. I am assuming that this coil is damaged.
I already ordered from a seller I already bought, another coil assembly. In the worst case scenario, I hope I can get at least one little coil in good condition.
Here at side is the little defective position coil.
The measure of a supposed good coil. In total there are six position coils, five measure like this.
And the measure of the one I think is defective
And this is how the defective coil measure when out of the iron nucleus:
Now as is used here, to wait until this piece makes its way to south America.
Let's hope this is the fix for my problems, honestly I was losing my hopes to was able to get this thing property spinning.
Cheers,
Rodolfo
Today I have found something that might be the responsible for the non stop and running away issue. Looking around on YouTube about possible solutions, I found a guy checking all the coils on the main board. I followed him to figure out that one of the coils was not giving the same measure others did. To make a better measurement I desolder the entire coils assembly to confirm one of the little position coils was weird. All the other position coils were 0.12mH and 10 Ohms, this one, the defective one, was 0.06mH and 16 Ohms. I am assuming that this coil is damaged.
I already ordered from a seller I already bought, another coil assembly. In the worst case scenario, I hope I can get at least one little coil in good condition.
Here at side is the little defective position coil.
The measure of a supposed good coil. In total there are six position coils, five measure like this.
And the measure of the one I think is defective
And this is how the defective coil measure when out of the iron nucleus:
Now as is used here, to wait until this piece makes its way to south America.
Let's hope this is the fix for my problems, honestly I was losing my hopes to was able to get this thing property spinning.
Cheers,
Rodolfo
neuralrevolt
Member
I would check that little coil for resistance before anything else. If it's shorted (which it seems it is) it will show a lower value than the rest. Next, I would just rewind the coil instead of getting another entire assembly. Can't be that hard even though it is small. Measure the wire gauge count the turns when unwinding the old one and take note which way the winding goes and which way you install it. This is important.
I would also check the large coils as well, just as a matter of course.
Those transistors you're chasing don't need to be changed if they measure well. But if you do want to change them, they are nothing special, you can replace them with any similar modern equivalents.
But I don't think the transistors are the problem.
Chase up the transformer problem and see what's up with that.
Fix the problem with the coil and see what happens before you venture further.
If problems persist I would have a look at the ICs. If these don't do their job properly you will never get the motor to work properly. And again, those ICs are nothing special, modern equivalents should be readily available and drop straight in.
I would also check the large coils as well, just as a matter of course.
Those transistors you're chasing don't need to be changed if they measure well. But if you do want to change them, they are nothing special, you can replace them with any similar modern equivalents.
But I don't think the transistors are the problem.
Chase up the transformer problem and see what's up with that.
Fix the problem with the coil and see what happens before you venture further.
If problems persist I would have a look at the ICs. If these don't do their job properly you will never get the motor to work properly. And again, those ICs are nothing special, modern equivalents should be readily available and drop straight in.
Last edited:
morfeora
Active Member
Hi! I already changed the coil, actually the entire coils section. And that solved the problem. Finally, after more than a year, I have an almost new Turntable, most of the things have been changed, and now I hope it will last another 50 years. I also changed the transformer and the new one have the proper voltage, It might be that the old one was rewound, and they did it wrong.
It was a long delay to update this threads and I apologize to those where waiting updates... but my first son arrived for months ago, and we are still in the very happy adaptation process... means, no much free time
I will have to go back and fount the pictures of the last part of the process....
morfeora
Active Member
This are some pics from the last part of the process:
The old coil part:
The New:
This is the change and adaption of the target light using a led:
Painting sanding and making the platter shinny again:
The inside without the new transformer
And this is how it is now... still have to thing about the top cover, but migth be in the future I build a beautiful wood and glass cover, I really dont like the original plastic one.
... as use to be before:
I am very satisfied with the result. Nor I am playing records using a Technics EPC-270II cartridge using a Nagaoka elliptical stylus and for my taste sounds very good.
Cheers,
Rodolfo
The old coil part:
The New:
This is the change and adaption of the target light using a led:
Painting sanding and making the platter shinny again:
The inside without the new transformer
And this is how it is now... still have to thing about the top cover, but migth be in the future I build a beautiful wood and glass cover, I really dont like the original plastic one.
... as use to be before:
I am very satisfied with the result. Nor I am playing records using a Technics EPC-270II cartridge using a Nagaoka elliptical stylus and for my taste sounds very good.
Cheers,
Rodolfo
KentTeffeteller
Gimpus Stereophilus!
Rodolfo,
Beautiful repair/restoration of this classic workhorse. You did superb work, and got it running. I love this thread. AK at it's very finest.
Beautiful repair/restoration of this classic workhorse. You did superb work, and got it running. I love this thread. AK at it's very finest.
Have seen where people sanded the paint of the aluminum wet sanded the aluminum with 600 grit and bugged out to a polished finish and bought new control stencils looked really cool they also make covers of different collars or chrome finish that goes on the turn table lots of cool stuff for those ! I have the pl120 Chinese knock off of that table ! While not as durable it performs pretty decent ! Have a sumiko pearl cartridge I put on a definite inprovement ! Over the stock cartridge ,Hello friends,
Some months ago I was bitten by the idea of buying a turntable and to start a record collection. My first choices were mostly Technics turntables which are very common over here in my city, but after realizing the price for a second hand Technics SL-1200MK2 I wanted to give a try to restore this very old one that I have since 20 years ago. I thought I would prefer to spend the money restoring this one that to buy one.
The entire tone arm assembly was missing (I used in another turntable 20 years ago when I was DJ), also foots were, and the worse... not spinning.
So far I have spent some days buying things and also was checking all the circuit with help of the manual. Bought a second hand AN6675 drive IC that turn out to be shorted (it seems I am not learning from experiences and some of you which already told me not to do that on that known site), whether because it arrived like this (shorted) or because I did the mistake and put a wrong transistor as rectifier... any way I learned a lot, and now I am waiting for a new AN6675 (from 1200.com). I hope this solves the not spinning problem, if not, has to be the AN6680. I already check some voltages and every thing seams fine with the AN6680 (I don't have an oscilloscope, so I only check voltages). The other little transistors around seams ok.
So far these are the things I have bought:
1. A complete tone arm assembly (second hand with the arm bent). Apart from the arm bent, is in a good condition, and bearings are ok
2. Arm tube.
3. Tone arm balance
4. A new start stop button
5. New AN6675
6. A set of feet
I don't have a dust cover, but I have no plans to buy one. My idea is to create a wood base and in the way also some kind of cover too.
After I have this table working I will change all the electrolytic capacitors. Also have heard of an external Power supply mod, but it seems the only noise thing in the power supply is the Transformer, so I have plans to leave it outside and build an external wood box for it. (what do you think about these guys?). I am also thinking if I try to find the original color to paint it (Something that will be difficult here specially because I am limited to spray paint), or to paint it in black.
This turntable was given to me for parts from my brother 20 years ago, before that the turntable was in a radio station, it suffered a lot there. I am a little afraid, because I am putting too much work and money in this, when with may be the same money I was able to buy one in a very good condition, but I like to restore things instead of put them in the garbage...
Well guys thank you for the reading and for the future company in this new project.
Cheers,
Rodolfo
These are some pics before disassembly (today wile I wait for the AN6675 to arrive (I order to be shipped to my sisters house in The States, and then she sends it to me to Colombia, as everything I need, so this is mainly a waiting game
View attachment 2172276
View attachment 2172275
View attachment 2172274
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And this is the second hand tonearm I got:
View attachment 2172278
View attachment 2172279
View attachment 2172280
More pics of the disassembly in the next post...
morfeora
Active Member
Yes, I so that kind of finishing and I thought it possible for my TT, but at the end I choose to remain loyal to the original painting. I already have the stencils, but I think I kind of like it without them. I will add the sumiko pearl to my list, but first I have an Ortofon OM (a gift from my dear friend @Bratwurst7s ) needing a stylus... but still not sure -or not able- to spend $534 USD (LP Gear price) on the OM40 stylus (My ambition always wanting the best :S). Not only that, but I also have a possible Denon MC DL-301 (Not sure if it's the right reference) to retip, BTW, I am receiving advice whether this repair worth the money it could cost.
Thank you guys! I am still looking forward to the perfection... KAB damping, external power supply, wood and glass dust cover, etc. But as a good friend of mine taught me, "Seeking perfection is not always good, and sometimes good can be very, very good"
Thank you all of you, this task would be impossible without all the help, support and inspiration from you, the AK community.
Now I am looking forward to finishing my new project... the Altec speakers: https://audiokarma.org/forums/index...t-ferrite-magnet-511b-902-8t-and-more.996080/
Cheers,
Rodolfo