• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

SL1600mk2 Pitch Control LED Repair

H

hatman

Active Member
Technics SL1600mk2 - Control Board /LED Pitch Control problem

Problem with 'Pitch Control' LEDs (total 12 Red & 1 Green);
Center Green LED works, as does control of motor/ platter speed via Pitch Control. When control is moved to any + or – position, the green LED goes out as expected, and the far right (red) LED goes on.

Repair 6/20/12: Replaced IC427, (TD4011BP Toshiba) with CD4011BEE4 (Texas Instruments) from Mouser Elec. @ .50¢ (14 pin PDIP, through hole).

PM me if you want detailed info on this repair or my other post today regarding small gear replacement on the SL1600mk2.
 

Attachments

  • Repair Pics_IC427 001.jpg
    Repair Pics_IC427 001.jpg
    128.6 KB · Views: 283
  • Repair Pics_IC427 022.jpg
    Repair Pics_IC427 022.jpg
    99 KB · Views: 271
Register to hide this ad
Pitch Control LED

Hi There,

I was wondering if you knew if the fix you did will work the same on a SL-1800MK2 with the same problem.

Thanks
Jack
 
I was wondering which LED would work for one of the red ones that is out on my 1600 II. Nice report on the solution to the problems you had.
 
The IC that fixed my SL-1600mk2's problem was IC427,part # SVIMSM4011 and marked as TD4011. I used a CD4011BEE4, made by Texas Inst. and sold at Mouser for about .50. This IC is 14 pin DIP.

BlueShadow, I would first check for cracked solder joint and dirty control. Then maybe suspect a failed red LED. The 12 red LEDs are; D429-434 & D436-D441, part# SVDGL-9PR2, (Green LED is D435, SVDGL9NG2). Not familiar about replacement possibility, but a used or new one may be an option.
IC429 has direct connections to the LEDS and measuring the ICs pin voltages might help to determine where the problem lies. But, I am a novice and could only guess on your findings. Pins 2-6 & 11-16 all show .03VDC, with pin#7 at .07VDC. Seems these are the 12 red LED voltages.

In circuit testing of a LED that is suppose to be lit but isn't: With your DMM measure the voltage across it. If you measure more than 3 volts or so, the LED is open.


Technics part numbers give you an idea of the generic part number.
An example; SL-1600mk2, IC429 part# SVIMS1901P. I found the IC marked as a Mitsubishi IC, with a part# M51901P. Available as NOS at LittleDiode in UK at about $14.00 plus ~$13 shipping.
 
Last edited:
Does anyone have a main board out there for parts or to sell for a SL-1800MK2..Seems there are no specs for a NEC D4011C......ANYONE!!
 
Last edited:
This worked for me; Replaced IC427, (TD4011BP Toshiba) with CD4011BEE4 (Texas Instruments) from Mouser Elec. @ .50¢ (14 pin PDIP, through hole).
 
I replaced IC427, (TD4011BP Toshiba) with CD4011BEE4 (Texas Instruments)

Same problem persists: LEDs don't show correct position, but I can see they all work because when I turn the power on and turn the pitch adjust, I can see the LEDs run quickly to the left or sometimes to the right. After the power is on, the rightmost LED stays on or the leftmost LED stays on.

Any ideas?
 
Adding info to this old thread, for future searchs.

I've fixed this same problem, replacing IC 427 (TD4011) AND IC 426 (CD4013BE).
 
Resurrecting this thread with the same problem. On my sl-1700 Green led lights up when at 0 and the far right red led at any other setting. Actual speed is good at 0. I have replaced every IC and every transistor on this board except for the led driver 1901. I've found one on ebay and currently waiting for it to arrive. This is the first table I'm trying to fix so if anyone has an idea of what I might be missing or something I could try please help!
 
My SL1600mk2 is just about to go on my bench too- it's far right red led doesn't work. All others ok. I'll update the thread with pics and fix when done.
 
Aelfine, the SL1600mk2 Service manual list IC's 428, 429 and Diodes 429 ~440 for Pitch LED Illum problems. Although, replacing IC427 fixed my LED problem. My symptoms were exactly as you describe on your SL1700mk2.

You state"speed is good at zero" but, does the speed of platter change + or -, when you move the pitch control? If it does not, then you have a pitch control malfunction and the leds may be affected by that issue.
 
I have a green led that recently got very dark light. Almost dead. I can get many different green leds at 3v or 2v and different mcv values of emitting power.
Is 16mct strong enough? Or 8mct?
These run at 2.2volts the one rated 560mct i think runs at 3volts.
Service manual says 8Volts at pin 1 of IC where green led goes but that can't be right?

I see it gets current from a 100 Ohm resistor stripped down from 12v line.while red ones get it from 680 Ohm resistor.
 
I checked the voltages.
Green LED shows 2.02V and Red LED shows 1.9V.
I just cannot guess the light intensity.
The available green LEDs at 2.3V offer 8 or 16 or 76mcd of light intensity. The stronger ones all operate at 3.3V.
 
You must log in or register to reply here.
Back
Top Bottom