Hi Guys My DD3 cannot maintain speed - only by un-soldering the link pictured in service manual. If I un-solder link I can get 3000hz but with 0.6% w+f = sounds a bit wobbly. Once I solder Link speed drops to 2700 hz. However if the FG coil doesn't see motor movement the walkman shuts off in 2 seconds (normal) - so I think the chip is partially working I have ordered new IC601 Sony servo chip CX20084 already Will try scope the DC supply to the motor and see if I can find source of un stable supply - Maybe also SMD Capacitor shorted What do you guys think
The DD3 has an external quartzed oscillator to drive the PLL that locks the capstan rotation. The quarts X601 generates a frequency of ~27 kHz which can be tested at pin 1 of IC602; that frequency is divided by 32 by IC602 and fed into IC601 Pin 4 as a reference to lock the signal from the the capstan FG. Desoldering the test point as in the procedure to set RV601 basically kills the reference signal from the quartz oscillator: if you have an oscilloscope, you can check that reference signal is correct on both IC pins
Thanks I will check this The voltage to the motor is a smooth 1.97 - 2.05 volts RMS If I stop the capstan the compensation works and the volts rise to 2.7v and then shuts off supply Does that mean the chip is potentially ok?
According to the service manual, the input voltage to the motor is expected at ~1.45 V (output of Q601), but I have no idea if ~2 V is still acceptable. Surely with age the mechanics stiffens a bit so the motor might be required a bit more torque. The input signal to the motor must also have an AC component as a result of the feedback from FG, I would not expect a stable voltage (unless the mechanics is perfect which is never the case)
Hi you are correct I remember now my D3 was 1.45 Volts-ish on the motor. So would you think my DD3 is higher voltage because of increased resistance in the mecanism and the chip is doing its job of increasing the voltage? Only thing is the Milliamps are about 90mA with no cassette and I think 120-ish mA with a cassette - which I think is correct for these Thanks
service manual indicates between 65 and 80 mA for play, FFW and REW. There is no indication if it is measured with a cassette, but it would be reasonable to assume no cassette. Anyway you have 2 V and 90 mA with no tape ? Is the capstan screw too tight ?
Hi it's 2v 120mA with a tape in I'll check it without a tape later tonight or tomorrow and post what it says
Hi the voltage to the motor with no tape is 1.45 volts and 65 mA Today when playing a tape 1.6 volts and 85 mA But wrong speed and 0.6% w+f
1.45V is correct according to service manual... have you checked the reference signal from IC602 ? You previously said that if you disconnect the quartz you get the correct speed but high W&F; what is the voltage on the motor terminals in that case ?
ive not checked the frequency yet, i have a dso scope but i cannot get it to display the frequency on pin 1 or 4 the voltage is slightly higher with the solder link missing
Quartz frequency is 27.7 kHz. The frequency used by IC601 is 27.7/32 = 866 Hz. The numbers look good to me so actually you were right about IC601 being defective; all other components look fine.
Spare should be here tomorrow but I'm out all day so will report back asap I already removed ic601, then ultra sonic cleaned the board, I've checked every cap none are shorted, the crystal is ok and the mechanics are silky smooth and quiet ** every through hole cap
Ok ... this is where I must confess up the truth Changed the chip.... exact same issues... Applied light pressure onto the pinch roller.... correct speed and 0.12% wrms w+f. Try not to laugh too hard at my expense....
I put the walkman on some digital scales and zeroed them. It requires approx 200 grams of force on the pinch roller to bring it in speed and w+f specs. I cannot see any adjustment in DD3 service manual? On disassembly I remember a tiny piece of metal (now I think was a shim) on the FG Coil. I think Sony realised something wasn't in spec and shimmed out the Fg coil. The only thing, is it already fell off, so couldn't even photograph exactly where it went. Could this part be the missing link all this time?
The pinch roller pressure specification calls for 170+/- 20 g; the spring on the left of the pinch-roller is responsible for pushing it against the capstan. There is no adjustment, I think the only option back then was to replace the whole assembly. But I think that most likely the pinch-roller itself is the problem: how is the rubber ? glossy, hard ? a rubber rejuvinator might help in that case.
Hi mate the rubber is nice I already cleaned it with RRR Sadly I'm now back to square one and no matter how hard I press on the roller makes no difference This machine has had liquid damage and specs of rust all over the places I'll rebuild the mechanics again soon and hopefully sort it once and for all My problem is I don't have any donor machines All my walkmans are really mint and I'm not taking them apart again unless I have to Got a Wm-dd and another wm-f5 coming soon so will have a bit of trial and error I'm very confident the electronics are fine I spent hours today tracing most of the links using the service manual and measuring caps, all is good
It surely has been an excellent exercise in understanding the inner of a DD walkman, but maybe this DDIII is not worth the salvage. Rust is typically a death sentence. I would keep this walkman as a donor for other future walkman's
I try win every one on eBay bids that spares and repairs but I've managed to fix all but this Yes a bit sick of the dd3 now, I go drink lots of beer now lol
