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My EX618 is here! (Pics and step by step)

davisneil - 2012-11-28 11:07

Well, the EX618 is here.

 

7 quid for this bad boy on ebay. Belt clearly gone and knew that in the first 20 seconds...capstan post that just spins in your fingers cant be good. So, DocP is on it like a car bonnet on that one.

 

Visually, hmmm. A few battle scars and a little dent but not affected the transport. Pinch rollers look great, as does the mechanism and the fixed azimuth playback head.

 

I get the feeling though that when the belt went and thus stopped playing, the user pressed the buttons quite hard to try and get it to play, because they all dont click. 

 

Popped its armour off and got it naked. PCB...good. Buttons....yep, dented inward. Flywheels...good. Motor...fine. Belt...all bunched up and tangled in the corner, like a little  frightened snake in the motor well, caught in the rotor. Pulled it out, yep thats knackered.

 

So, yeah, let's get that belt and get the black beast fired up and working.....guess i need to find replacement buttons though.

 

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cooldude - 2012-11-30 14:50

That's a good find  

I think I have one of them stashed, will have to look.

davisneil - 2012-12-01 01:25

So first of all, belts ordered from doc p. 

 

They are 0.8mm square section belts, he thinks 60mm but hes sending me a kit. Ill let you know what belt i use.

 

Secondly, I needed to find the surface mount switches, which as you can see, are damaged through being pressed too hard. I did some searching and needed switches that are about 5mm square and less than a mm thick. I found these:

 

C:GB:3160" target="_blank">http://cgi.ebay.co.uk/ws/eBayI...me=ADME:LC:GB:3160

 

4.8mm square and 0.75 mm thick. they should work perfectly, and i can shave a bit of the 'pokers' on the back of the buttons to fit it.

 

Next, time to lift the pcb. Because things look goog on the pcb, im ONLY GOING TO LIFT ENOUGH TO INSPECT AND OIL MECH. No point risking damage if it looks clean and only needs oil/ service.

davisneil - 2012-12-01 02:42

Right...pcb lifted. I undid a screw by the headphone jack, one just above the buttons, two by the positive battery terminal, and one where the tape position switches are.

 

This model has no solenoids. It relys on back and forth motor motion to switch the modes. Therefore i could lift the pcb with no desoldering, watching out not to damage the motor flexi connector.

 

Be aware also of the positions of the fwd/rev switch on the mech, and the blank skip/dolby switches in the cassette well.

 

Next..oiling.

 

Im lucky enough to be diabetic and i get syringes with tiny needles on prescription. So I use these 'U100 insulin' needles to load with sewing machine oil, and apply directly to the gears and bearings in tiny drips. STAY AWAY from the centre clutch. oil will reduce the tape wind tension of the slipping clutch.

 

When doing capstans, LESS IS MORE. dont swim it in oil because it will give a whole world of pain when you put a tape in and oil gets on it.

 

Oiling done and mech looks great, so refitted PCB making sure all the switches are in the right place. 

 

Ive desoldered the little gold power connector that is next to the motor, so its ready for the belt when it arrives.

docp - 2012-12-01 04:06

Always nice to have a step by step run through with pics to help the community. So hope this helps too The service manual :
http://elektrotanya.com/sony_w...18.pdf/download.html
Happy mending N
P.S : Do cell phones have tiny switches that might suit your purpose?

davisneil - 2012-12-01 05:04

possibly...but ive ordered 50 switches new for a few pounds. much easier

 

thank you very much for the manual

davisneil - 2012-12-03 06:50

buttons removed. No pads ripped (there is one thats looks a bit suspect on the pic but i inspected it and it looks fine).

 

I cleaned the tape transport with an isopropyl wipe, paintbrush and air, as well as the belt grooves and the flywheels. For that i simply folded the wipe and slotted it in the groove, rotating the wheel until clean.

 

All ready for belt and new buttons

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davisneil - 2012-12-04 11:44

A little further hint here: it is impossible to desolder/solder on the buttons without ruining the flexible plastic decal which protects the pcb from the metal case. It stops the metal shorting out the electronics. 

 

So prior to working on the buttons, i used a hairdryer to soften the adhesive, and SLOWLY peeled the black plastic decal off. Keep it stuck to a piece of sticker backing away from hair. it can be stuck back on.

 

If you ruin it, dont worry, you need to cut a new one out from sticky wrap or similar.

davisneil - 2012-12-04 11:50

using an insulin syringe to add a drop of oil to the belt idler.

 

the needle allows a tiny drop to be applied. less is more. 

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