Sl-7 Disassembly Problem

by **fscl** » 08 Jan 2010 22:55

flavio81 wrote:
fscl wrote: however I spied a bag of black, almost square cross section, a bit tighter / smaller OD RUBBER BANDS than the original belt. Of course at $0.99 I bought them and they WORKED.... no sound when driving. I mean I had thousands / hundreds of thousands..... so my SL-7 would live forever.....

You're THE HERO!! Can you measure the inner diameter (unstreched) please?

Finally got to taking and posting the picture..... :oops:

Fred

by **xactifan** » 19 Jan 2010 12:15

My SL-7 stay asleep...at least I cleaned all switches and contacts with
Deoxit. I've checked optical sensors with a Multimeter and found no
continuity but it's just the same with another SL-7 tested and working
well.
The Stop button don't respond,and with the Start button I can Start and
Stop pressing once more.
Sometimes the platter start turning when I push Power On.
"I'm really stumped on this one and would be grateful for advice from
anyone who has a working solution"!

Fred,I like your photo: bubbles champagne ? Cheers!
o

by **fscl** » 19 Jan 2010 13:56

xtifan writes:

The Stop button don't respond,and with the Start button I can Start and
Stop pressing once more.
Sometimes the platter start turning when I push Power On.

You're getting there..... try cycling the Start / Stop buttons....while the unit is off, they respond to repeated usage and eventually become "positive" (execute the desired function).

Did you clean and cycle the power switch?

Fred,I like your photo: bubbles champagne ? Cheers!

, No, like Frank, I still "get no kick from champagne"

This picture show the bag of rubber bands which served as a temporary repair / replacement for the tonearm drive belt. :shock:

which got displaced with a "real" O-ring drive belt sourced from a TV/VCR repair shop.

Fred and thinking your SL-7 is almost there to "fully working" status......

by **Damien Taylor** » 19 Jan 2010 15:49

Another Technics linear owner dropping in to say hello (SL-J3 '85). Just finished reading the whole thread. My machine runs great now, but it's good to know if I ever have issues, you guys are here!

by **ATHERMOS** » 19 Jan 2010 16:50

xactifan wrote:My SL-7 stay asleep...at least I cleaned all switches and contacts with
Deoxit. I've checked optical sensors with a Multimeter and found no
continuity but it's just the same with another SL-7 tested and working
well.
The Stop button don't respond,and with the Start button I can Start and
Stop pressing once more.
Sometimes the platter start turning when I push Power On.
"I'm really stumped on this one and would be grateful for advice from
anyone who has a working solution"!

Fred,I like your photo: bubbles champagne ? Cheers!
o

Hi,

Please give us a step by step account of what happens after you turn the turntable power on and try to play a record.

Cheers,

by **xactifan** » 19 Jan 2010 20:12

Hi,
Thanks again! Yes I tried cycling the Start/Stop buttons while it is off.
To clean the switch is it necessary disassembly the plastic bloc inside
the unit ?
Now my step by step:
Power On/light On
sometimes the platter get running automatically
if not:
press Start,it is running, the tonearm lift down on the record (30) but
stay at the same groove
No forward/backward movement possible
To Stop,it is very difficult, or not! I must cycle the Start/Stop buttons
the tonearm lift up when i press Start again or Stop
It seems to me that the Stop button is softer to the touch than the Start
button,I don't feel clearly the difference (clic) between the 1/2 positions
unlike the Start button.
Is it an understandable picture of the (puzzling) situation ?
Hopefully!

by **ATHERMOS** » 20 Jan 2010 09:05

Hello again, it seems that the belt driving the tonearm horizontally is out. As in this case the tonearm is integrated in the turntable cover,lift up the cover , open the required screws , get access to the motor and check the condition of the belt. If it is out, initially put a rubber band of suitable dimensions to check proper functioning of the arm. Get a proper belt later.

Cheer up, it is fixable.

by **xactifan** » 20 Jan 2010 10:31

Athermos Salut, Comme je l'ai dit plus haut J'ai nettoyé tous les engrenages et remplacé la courroie
  avec un nouveau. J'ai vérifié le moteur du bras de lecture avec une pile 9V et
  l'avance du bras de lecture a été OK. Bouton d'arrêt ne fonctionne pas, aucune idée sur
  ce que c'est?

by **xactifan** » 20 Jan 2010 11:20

Sorry it was in VO! :roll:

Hi Athermos, AS I said above I cleaned all gears and replaced the belt
by a new belt. I've checked the tonearm's motor with a 9V battery and
tonearm's advance was OK. The Stop button doesn't work,have you
any idea about this ?

by **ATHERMOS** » 20 Jan 2010 14:45

Hello xactifan,

To check the functionality of the switch first determine what are the PCB foils it is connected to , then manually while running the table make and break (i.e. short and release) that circuit as if you are duplicating the switch. If you are confirmed about switch's fault , (it is a tactile switch) try cleaning with the same fluid you have used before, if a replacement is required, try to source a similar switch from an electronics part shop, or, you might choose to source it from a junk TV or other similar device.

Cheer up again.

by **xactifan** » 20 Jan 2010 16:04

Hi Athermos,
would you give me more details,step by step if possible,I am afraid it is
hard enough for me because I have no experience working with this
components.
May I touch this copper foils without damage ? Is it with power off ?
Thankfully!

by **fscl** » 20 Jan 2010 16:13

xtifan gives step by step:

Now my step by step:
Power On/light On
sometimes the platter get running automatically
if not:
press Start,it is running, the tonearm lift down on the record (30) but
stay at the same groove No forward/backward movement possible

Appears that the tonearm advance / offset angle detection is not working. :?:

What happens when you lift / cue the tonearm and use "Start" and "Stop" buttons to move the tonearm?

It does appear as AMOS says, that the switch(s) may have a problem.

From the service manual it appears the front (top) panel control switches are directly attached to the board :?:

Both the "Start" and the "Stop" are 2 step buttons, when you push the "Start" 1/2 way down does it only light 1 left pointing arrow? All the way down lights 2 left pointing arrows? Same for the "Stop"?

ATHERMOS wrote:Hello xactifan,

To check the functionality of the switch first determine what are the PCB foils it is connected to , then manually while running the table make and break (i.e. short and release) that circuit as if you are duplicating the switch. If you are confirmed about switch's fault , (it is a tactile switch) try cleaning with the same fluid you have used before, if a replacement is required, try to source a similar switch from an electronics part shop, or, you might choose to source it from a junk TV or other similar device.

Cheer up again.

EXACTLY...... what AMOS ? /\ said.

Refer to pages 24 of 33 of the pcb for the switch(s) in question and foils where they are connected (soldered?) to.

As the unit starts automatically when you push the "Power" on button, I'd first concentrate on the "Start" switch. Remove (desolder) and install 2 wires as jumpers in their place. Cut the wires and strip the ends. and pull them out the front / top of the tt.

1. Push the "Power" button on. Hopefully nothing will happen only the tonearm LED and the strobe light comes on.
2. Touch one pair together and release and see if she starts and tonearm tracking works and plays;
3. Touch the same one pair together and hold and see if she lifts and starts slow advance;
4. Press "Cue" then touch both pair together and hold and see if she lifts and advances quickly.

These pairs of wires are simulating what is being done with the "Start" switch. So use your other SL-7 as a guide for proper operations.

You can identify which pair is 1/2 and 1/1 using a continuity tester on the switch and make sure to use / touch the correct pair together.

Hopefully it's a faulty "Start" button that's causing all of the problems. If there is any continuity in the "dirty" "Start / Stop" buttons, the circuit is not released and the rest of the logic programmed into the chip cannot proceed.

From your descriptions, I'd concentrate on the "Start" button first as it statistically gets used more. If pushing "Stop" has the desired / correct effect in any of 1-4 above, then you've isolated the problem with your other SL-7.

Good luck.

Fred and then you can try sourcing a replacement button and you'll have 2 working SL-7s.

by **ATHERMOS** » 20 Jan 2010 16:14

Hello xactifan,

Play the turntable and short and let go of the terminals of the stop switch (NOT the power switch connected to the mains power).What I am trying to say is that we are trying to replicate the stop switch manually.

Cheer up,

by **xactifan** » 20 Jan 2010 20:54

Thank you both for your helpful explanations.

- For buttons START/STOP : lights 1/2 are ok.
- For LIFT/CUE : the tonearm doesn't move forward with START 1/2.
- Switches are soldered to the mainboard. They look like two squares of plastic that I worked directly without the buttons... with the same bad result.
I've never done soldering in my life, but if it is the only solution (I'm afraid) it'll be an opportunity to learn.
Could the failure come from elsewhere ?

"My" other SL7 is my sister's one, running after cleaning and replacement of the belt