453 Reverse Relay , Wobble plate solenoid & homing.

[chris1087]

Hi ,
I am a newbie and have gratefully followed some of the help surrounding the gripper arm. That was solid and took quite a lot of work to get it up and running, with heat in the end the only way to even separate the parts! Anyway that is now back together and as soon as it was it came to life. I am able to make selections and the records selects is picked up and plays.

I have the operation manual & spares list. I have identified a number of issues , which are going to need spares , but would like to know if I can make repairs if possible. 

The issues are:


1. Reverse relay is not working. Looked at the manual and it says that when the tone arm trip is activated (or reset switch pressed) it will mute the amp and send power to the reverse relay to trigger it. Cam switch three looks good and the tone arm switch is clearly operating the mute relay. There is 24 volts at the inputs to the reverse relay. Th contacts are all free and everything moves as it should. Its difficult to measure the coil resistance because there is a resistor across the inputs. Manually activating the relay correctly returns the record to the basket as it should. Is there anything I can do to repair this? If not does anybody have the wiring info to use a modern relay instead?

2. The wobble plate solenoid has the power cables broken off the windings. I assume this is what selects A /B sides looking at the manual , does it also affect the home stop ?

[jukenorman]

Hi Chris,

1. You say you are measuring 24V at the reversing relay inputs - do you mean the coil and are you measuring 24V on both sides? In which case the reversing relay is probably OK. If you look at the diagram, there is a diode in series with the coil on the ground side - it's most likely open circuit.

2. The wobble plate solenoid operates when a selection is made, it moves the wobble plate and makes the wobble plate switch which in turn energises the play control relay. When the final selection pin is reset, the wobble plate switch opens and the play control relay is now held energised by the home switch (or homing wiper to be precise) until the record is finished and the mechanism returns to the home position where the home switch opens.


Norman.

[chris1087]

Hi Norman,

Yes I am measuring at the coil & the voltage is only there when the reset switch is pressed or the tone arm is in the record end position, I noted the diode, is there a way to bypass that for testing or would that cause damage?

The wobble plate solenoid is damaged , but it still selects A sides, looking at it closely it looks like someone has put a clip in to hold the wobble plate and switch back. I think Jukebox Revival have a solenoid I will get that as I have no idea on how to connect to the windings to make a repair.

[jukenorman]

That maybe sheds a different light on things - I'm not sure why you're seeing voltage only when the reject switch is pressed? You should be seeing -33VDC at the reversing relay coil before the reject switch is pressed If you're not, that would most likely point to an issue with micro switch 1.

It would be possible to reconnect at the wobble solenoid. The coil winding wire is extremely thin so to solder to it, you need to clamp the end of the thin wire with a pair of pointy nosed pliers to dissipate the heat otherwise the wire just disintegrates with the heat from the soldering iron.


Norman.

[chris1087]

Hi ,

OK replaced all the cam switches today. Not measured the voltage yet , but its still not working. took the wobble plate solenoid out and noticed the wobble plate arm does not retract , it stays forward and does not release the wobble plate switch. Any ideas on how to release it ?

[jukenorman]

Silly first question, are all the selector pins in the reset position? You said in a previous post that a clip had been inserted to hold the wobble plate, is it fully removed? And finally, is there something like a broken selector pin jamming the wobble plate?

With regard to the reversing switch, chasing the voltage through the circuit is probably the best way to determine where the fault lies. The schematic showing the hot circuit is on page 56 of the manual, sequence 20.


Norman.

[chris1087]

Not a silly question, there was a b side still selected. Was not noticed as I have an issue also with the A/B arm being jammed, so b sides not detected.

I made some progress. 1st of all I stripped of the tape on the Wobble Plate solenoid pulled back a little bit of winding, re tapped and attached new cables and also taped over them. So the solenoid, plate and switch now good and finding home.

The reverse relay circuit is not always live. There is no voltage at the relay until the tone arm trips the switch, then I see the full voltage.

[jukenorman]

That was a good job done with the wobble plate solenoid!

I don't understand the reversing relay - are you measuring voltage there with respect to ground? The tone arm switch is applying a ground to the reversing relay which should already be sitting with -33VDC on the other side of the coil.


Norman.

[chris1087]

Hi , This is where I am confused. Looking at the schematic -33v is coming from the Blu / Yell cable that is connected via Microswitch 1. The other side of the coil connects to ground via the tone arm or reset switch. So I assume that is all OK and my understanding of relays is that if you apply a current across the coil it should activate. I am clearly not understanding this. 

[jukenorman]

Hi Chris,
Place the negative probe of your meter on ground (chassis) and use the positive probe to read DC voltage. Before the reject switch operates, you should be reading -33VDC on both connections of the reversing relay coil. When you operate the reject switch, the connection of the reversing relay coil with the diode attached should drop to 0VDC. The relay should pull in at this point of course but if it doesn't and you are still reading -33VDC on the other coil connection, that would indicate the coil being open circuit. Usually the cause of this type of problem is the cam switch (CS1). I am aware that you have changed it out but there could still be an adjustment issue.

The voltage readings should point us in the right direction!


Norman.

[jukenorman]

If everything is OK, yes -33VDC is sitting at the relay coil! The reject switch operates to complete the circuit and the relay should energise. But the relay is not energising - so what we are attempting to do is use the voltage readings to determine where the fault lies.

Norman.

[chris1087]

Right I think I am with you. I will test that.

[chris1087]

Ok blu yellow side 32 volts. Diode side 0 vaults until switch operates

[chris1087]

Actually the penny just dropped. I will check again.

[chris1087]

Hi Norman the results are in.

Not quite getting 33v but 32.

Blu / Yell terminal. 32v
Diode terminal. 32 v

Tone arm across. Diode terminal 0 volts.

As that all works out I guess it’s the coil ?