630Q - almost working, except for the stop button...

Hi !

Welcome at the Dual hoarders and savers club.

First off: I use this page for references.

http://www.hifi-archiv.info/Dual/630s/

That's the servicemanual for the 630Q.

Zitat von Drooler

The start button works, the lift works, 33-45 works, but the stop button doesn't. It now does this. Is this an error in the electronics? Can it be fixed? Does it need new elcos?

Last question first: not in general.

The elco-problem is a long-term problem and you *might* replace them, because they are already 30+ years old and *do* detoriate over time.

If you take the unit apart to remove the controllerboard you should probably replace the two big cans front / right with two modern radials 1000µF / 40V. They have installed two different ones, but back then high-capacity capacitors were pretty expensive and to save some Cents they opted for one with higher voltage rating than the other one. Ignore it. Buy two with a voltage rating above either of the two and you are off. Modern caps on higher ratings are even smaller than these "beer cans".

About the error itself:

The buttons up front are all controlled by the system microcontroller. They are pretty cheesy pushbuttons with bending heads and there *might* have some corrosion / oxydation going on for the contact surfaces - but I doubt that. The main reason for one function not working when it comes down to the switches is bad soldering between button board and controller board.

Second in place is a solenoid not working. The main errors on this kind of model (includes 620Q, 2225Q and 2235Q which are essentially the same) is a hanging magnet pin within the solenoid that pulls or pushes a lever to start a mechanical function.

If you look here:

http://www.hifi-archiv.info/Dual/630s/630-08.jpg

you will see two magnets marked M1 and M2, where M1 is the Start solenoid and M2 is the Stop solenoid. They pull the same lever to get into Start and Stop. Please examine the solenoids and their corresponding magnet pins. During production the pins have been doused in silicon oil - which over time turns into glue and the pin cannot move. Try to move it by hand. If it works quite nicely and can be pushed in and out with no significant force the problem sits deeper in the electronics. Compare Start and Stop magnets that will give you a better impression on how it should feel, since the Start function works.

I make a break at that point, because it is not clear if it is really neccessary to deal with the dirty electronic details of the solenoid driver circuit and on how to test that stuff.

Mind to tell us your name and where you are located.

For the "old guys" that hang around here for longer there is the footer down below this text - however: you won't see it if you use the mobile version of the forum. So: I am Peter and I live quite a few miles off the dutch border unfortunately.

Hi Hidde !

Uhm ... most likely your message "went under the radar" (of attention) somehow.

This settle-release error might be prone to the control wheel. After all the player is a mechanically operating unit with some processor and magnets assistance, but the main functions on the tonearm *are* mechanical and controlled by the large control wheel.

Obviously the wheels shut-off-lever is still sticking out when the arm has moved towards the record and is lowered.

*Then* the platter comes around and the little catch hooks into the shut-off-lever and pushes the control wheel forward again. The internal path divider is still set to "Start mode" (unlike as when the arm reaches the end of the record, where it is set to "Stop mode"). So the arm lifts up, moves towards the armrest and while Start mode is still engaged it moves back to the start of the record, loweres ... and the cycle repeats on and on.

Mechnical reset: lock the arm on the armrest.

Press "Start" on the front button.

Wait until the clicking and clacking stops and the motor stops (hopefully).

This returns the shut-off-lever and the control wheel path divider into their default positions. It is recommended to run this process every time the unit has been transported or tilted sideways or over the front. Or turned atop.

If *that* doesn't help we need to look deeper inside the mechanism.

Hi Hidde !

All of that looks like a mechanical issue rather than electronic problem.

The lot of the player is still mechanics.

The processorboard just starts the Motor, which controls the arm movements with the cogwheel inside.

The start / stop / lift functions are controlled via solenoids (electro-magnets) that push or pull levers inside - or fail to do so.

The settle / return error is typically for an error related to the cogwheel. The start function is initiated by a solenoid, after the motor started.

That pulls a lever that throws a lever out on the cogwheel, which then gets rotated by the platter motor to carry out the arm movements.

At the end the lever *should* return to the resting point and stay there so that the cogwheel stops and stays in neutral position.

If it doesn't the function "mechanical stop" is carried out and the arm goes back to the armrest.

*Then* the lever also should return to the resting point, but fails either ... and the function "mechanical start" is carried out ... and that's the loop you see.

So you need to remove the platter and inspect the cogwheel.

Unfortunately the 630 Service Manual is -by far- not that complete and detailled as it were for the older Duals.

http://www.hifi-archiv.info/Dual/630s/

But maybe the picture at

http://www.hifi-archiv.info/Dual/630s/630-06.jpg

gives a hint.

In the middle somewhere is the cogwheel (33). The interesting point is the lever on it. It folds out to catch a boss on the platter base to get pushed forward and align with the sprocket gear on the platter base. That then turns the cogwheel forward (counter clockwise). It shoult under normal circumstances stay in that neutral position and only been pushed outwards with the press of either "Stop" or "Start" button - and due to the corrensponding solenoids and the start-stop-levers.

To track that is *a bit* complicated on the 630, since it does not run properly without the platter ... which is needed as a reaction-weight countering the control impulses from the speed control (due to its mass).

(A bit complicated I'd say.)

Hi Hidde !

Well ... unfortunately you live "a few miles away" or I would offer that you'd bring the stubborn thing around, we sit in my storage / workshop, drink some Cappuccino and I'd see what I can do ...

The unloaded motor rotates very erratically and with too high initial speed, which kicks the cogwheel around and throws out the lever on it so that it would *never* show the proper run of it.

Once I'd used a tube spacer (10 cm piece of metal tube with 7mm inner diameter) to elongate the motor axle upwards, put an old BSR middle pin (12cm long) into the tube and placed the platter *atop* of that. That then helped to keep the motor down *and* have enough room between chassis and platter (and have the platter out of the way from the tonearm). With this I could see problem with the cogwheel, which was in fact a sticking lever on the chassis base, which did not retract far enough due to sticky old grease. Wonder where I put that thing ...

I'm about 90% sure that your player suffers a similar problem. It is mechanically, that's for sure.