Technics SL1200 / 1210 Speed Fluctuation Problem

Hi

I've found this site whilst trying to research a problem I have with my technics SL1210 Mk2. I've searched the forum but can't find anyone describing the subtle speed changes I am experiencing.

I have two of these decks, for DJ'ing, but recently one of the decks has developed a fault where the speed constantly oscillates around what I presume is the speed it should be turning at.

This isn't audibly noticable, but it causes huge problems when trying to beat match records as one record drifts all over the place and continual correction of this 'drift' means the mix will never actually sound cohesive.

The fluctuation is in the order of tenths of a percent, and occurs at all positions of the pitch fader, including at the zero position. I have come to this conclusion by playing two copies of the same record and hearing it drift from being in time, to too fast, to back in time, to too slow, etc., etc., so I'm pretty certain this is what is happening.

I've put a new pitch fader in the deck anyway as it is 15 years old and never needed servicing, but I guess something else is wrong and causing this problem... I am very willing and able with a soldering iron, but I don't have anything other than basic test equipment, i.e. a multimeter. I'm up for replacing as much stuff as it takes to fix this problem and have a bit of a stock of capacitors, etc.

If anyone can offer any advice it would be seriously appreciated as I don't have the time to send the deck off for repair anywhere.

Thanks.
 
Never needed servicing? What a joke, so you never oil your car parts or put oil in the engine
, it has to break down first?.... Your spindle has never been old, tonearmclean and servived, so you have the cheap rca's. Never changed some elco's en the cheap potentiometre on the board, which a few people change but is a throw away thing. Just clean or better replace the pitchfader and clean the table, but after 15 years , i just would place new bearings in the tonearm and replace the tonearmwire and rca's and don't take technics ones. Your car also needs to be serviced every year by law.....
gr.richard
 
Hi,

if You switch on Quartz lock is there still fluctuation?
If not, one can already exclude Magnet weakening and FG-coil related probs.
Then the issue may be related to the circuitry around IC301 (AN6682) and IC302 (MN4011B) on the Motor-PCB including the Pitch-Fader-PCB.

For Service manual look at the VinylEngine´s Database.
Additionally You can find a "Help-Sheet" with pics of the Motor-PCB and the location of components at deckdoctor.com.au and djsdeckdoctor.com
Also have a look at KAB Electro Acoustics http://www.kabusa.com and the Problem#1, related to Diode D301.

jauu
Calvin

ps. KAB erred with their correction schem of the Pitch Fader".
Compare the schematic and the PCB-Layout and You´ll see that the Technics Manual is correct.
 
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Interesting thread with a lot of useful info - thanks!

Not sure if my problem is quite the same so wanted to put it out there...

1210mk2 that has barely been used in anger since new - had an Origin Live tonearm fitted for home listening. I use it now and again to play my 90's dance vinyl and relive my youth :D

Not been used for a while and recently upgraded to an onyx tonearm and an MP-110 cartridge so i can make good use of the deck again.

Everything was fine for about 15-20 minutes playing at around _2% when it suddenly started slowing down slightly - almost like the power had been pulled for a fraction of a second. put it down to a dodgy record so put another on and this was fine for a bit then starteddoing the same thing. quartz lock was perfect. moment i moved the fadr, the speed jumped all over the place - and at -8% it is constantly fast/slow.

Replaced the fader with one from technics-service (the repro -2 fader), plus a new D301. checked solder joints and reflowed a couple. put it all back together again and calibrated using a scope. All good.....or 10 minutes. at which point the same problem happened!

The only other odd thing is the strobe - the dots seem a little fuzzy and unfocussed - although i believe that may be due to dimming LEDs (or maybe linked to this issue?). both 6680 and 6682 are running quite hot, so i plan to replace R307 with a 10k (currently using a 2.7k) - but has anyone got any suggestions please?
 
Check this handy vid out
Technics SL-1200/1210 MK2/3/4/5/6 - Mother Board Troubleshooting - YouTube

Diagnoses a load of motherboard issues very well

My money is on your an6675 acting up, be worth comparing the temp of the chip to a working deck by letting both deck run for 10 mins then put your finger one each and seeing if the bad deck is hotter than the other. This part can also cause a very feint clicking when it trips out after it heats up so worth checking for that
 
Is there really no 1 with the correct answer ?

Here the same problem......

all 4 ic.s are good

all capacitators are recaped

d 301 d3 replaced

coil is ok

vr's are ok

q 2 3 201 202 203 are ok

.......still running at 100 rpm........

i tried it all...... ANYONE with the right answer?
 
Hi,

the FG-coil is a flexible PCB ´wound´ on the outer aluminum ring, covered by the white plastic ring.
Two pins connect the FG-PCB with the brownish interface-PCB.
Due to moving the motor assembly several times in and out of the plinth microcracks had devolped around these pins, leading to a high-speed revolving platter.

jauu
Calvin
 

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Hi

I've found this site whilst trying to research a problem I have with my technics SL1210 Mk2. I've searched the forum but can't find anyone describing the subtle speed changes I am experiencing.

I have two of these decks, for DJ'ing, but recently one of the decks has developed a fault where the speed constantly oscillates around what I presume is the speed it should be turning at.

This isn't audibly noticable, but it causes huge problems when trying to beat match records as one record drifts all over the place and continual correction of this 'drift' means the mix will never actually sound cohesive.

The fluctuation is in the order of tenths of a percent, and occurs at all positions of the pitch fader, including at the zero position. I have come to this conclusion by playing two copies of the same record and hearing it drift from being in time, to too fast, to back in time, to too slow, etc., etc., so I'm pretty certain this is what is happening.

I've put a new pitch fader in the deck anyway as it is 15 years old and never needed servicing, but I guess something else is wrong and causing this problem... I am very willing and able with a soldering iron, but I don't have anything other than basic test equipment, i.e. a multimeter. I'm up for replacing as much stuff as it takes to fix this problem and have a bit of a stock of capacitors, etc.

If anyone can offer any advice it would be seriously appreciated as I don't have the time to send the deck off for repair anywhere.

Thanks.


Did you happen to repeatedly remove the platter with the tt still plugged in? You should unplug it before removing the platter.