There are five connections on this oscillator coil, the two on the right hand side are fine but the three on the left have strange readings on the ohm meter, between 1&2 there's 38ohms between 2 & 3 there's 38 ohms , between 1 & 3 there's 5 ohms
Looking at the schematic I can work it out , can you? Sorry I meant to type can't work it out

 

It would (might?) help if we could relate those pin numbers to the schematic. Maybe two of the transoformer wires are (near) shorted to each other or the two capacitors labelled 21 and 22 are short circuit.

 

Thanks for your reply, I have disconnected all the wires from the coil before I took the readings I should have mentioned sorry, do you think the coil is faulty?

 

Hello,

This is already the third thread for the same unit:
https://forum.allaboutcircuits.com/threads/meazzi-echomatic-ecc-83-circuit.169309/
https://forum.allaboutcircuits.com/threads/meazzi-echomatic-help-req.169338/

The original unit is pictured at this french page:
http://jacquesg.brun.free.fr/Chambresdechosmeazzi.html
With the schematic:
http://jacquesg.brun.free.fr/schemaechomatic.html

Do you have the name of the unit?
You might be able to find more info here:
http://meazzi.net/or/schemandlayout1.html

Bertus

 

Is pin 2 the centre tap?

 

no it's not a centre tap, I don't understand the resistance readings , I've atttached the readings between the pins , I need help to put the numbers to the pins, based on the schematic
Which is pin 1.
Which is pin 2
Which is pin 3
Thanks for your help

 

Did you not make a note of the connections when you disconnected it?

My guess would be pin 1 is the tap and pin 3 connects to EL84 anode.

 

OP you're making it too hard- without telling us what you are calling pin 1,2,3,4,5 etc. on the schematic.
You need ohmeter readings between all FIVE pins to properly ID the windings.

Looking like: Pin 1 to B+, Pin 2 to grid, Pin 3 to plate. Pin 4-pin 5 erase head should be low, around maybe 16 ohms with no continuity to any of pins 1,2,3.

 

OP you're making it too hard- without telling us what you are calling pin 1,2,3,4,5 etc. on the schematic.
You need ohmeter readings between all FIVE pins to properly ID the windings.

Looking like: Pin 1 to B+, Pin 2 to grid, Pin 3 to plate. Pin 4-pin 5 erase head should be low, around maybe 16 ohms with no continuity to any of pins 1,2,3.

Ok Thankyou the two pins at right hand side only have continuity to each other and as one is connected to the chassis I managed to work out it’s for the erase head , the other three pins are what’s confusing me , theres a feed in to carry the signal and mix it with the oscillating signal, I just don’t understand the coil 30 ohms 35ohms and 4.6 ohms between the three pins , the coil is drawn in a straight line so I would have thought 30 35 65 ? Does that make sense?

 

One coil of 30Ω and one coil of 4.6Ω So measuring between the ends gets you them in series - 34.6Ω.

 

One coil of 30Ω and one coil of 4.6Ω So measuring between the ends gets you them in series - 34.6Ω.

View attachment 206540

 

Hello,

You could give in the schematic where 1,2 and 3 are:



Bertus

 

View attachment 206544

 

Ok Thankyou the two pins at right hand side only have continuity to each other and as one is connected to the chassis I managed to work out it’s for the erase head , the other three pins are what’s confusing me , theres a feed in to carry the signal and mix it with the oscillating signal, I just don’t understand the coil 30 ohms 35ohms and 4.6 ohms between the three pins , the coil is drawn in a straight line so I would have thought 30 35 65 ? Does that make sense?

I see now, it can’t be 65 it is actually 5
Now all I need to know is where on the schematic would 5.3 be and knowing that it tells me where 31.6 goes

 

OP you're making it too hard- without telling us what you are calling pin 1,2,3,4,5 etc. on the schematic.
You need ohmeter readings between all FIVE pins to properly ID the windings.

Looking like: Pin 1 to B+, Pin 2 to grid, Pin 3 to plate. Pin 4-pin 5 erase head should be low, around maybe 16 ohms with no continuity to any of pins 1,2,3.

 

I’ve got some readings , I need to know what coil on the schematic is 5.3. And 31.6. Thankyou for your help

 

I think this is correct. Note that the record oscillator is usually tuned- with a trimmer capacitor or moveable slug in the transformer core. I think this is why the schematic shows two series capacitors on the (plate) tank, if you can't get decent AC at 50kHz then change the tuning cap.

 

I think this is correct. Note that the record oscillator is usually tuned- with a trimmer capacitor or moveable slug in the transformer core. I think this is why the schematic shows two series capacitors on the (plate) tank, if you can't get decent AC at 50kHz then change the tuning cap.

View attachment 206617

Thankyou very much , would the tuning cap

I think this is correct. Note that the record oscillator is usually tuned- with a trimmer capacitor or moveable slug in the transformer core. I think this is why the schematic shows two series capacitors on the (plate) tank, if you can't get decent AC at 50kHz then change the tuning cap.

View attachment 206617

Thankyou very much, I appreciate your help

 

Thankyou very much , would the tuning cap

Thankyou very much, I appreciate your help

I've got it oscillating at 50khz but there's only 90v ptp on the play head and 3 v ptp on the erase, all three pins on the coil have 330v , which cap is the tuning cap?
Thanks for your help

 

The erase-head voltage is really low at 3Vpp, that's almost like a short-circuit. The original erase-head might be a different part? or the 0.022uF capacitor in parallel I would experiment with. Try go up and down in value and see what happens, you can add series or parallel capacitor to change by say +/-20%. It's OK if the oscillator moves to say 60kHz.

But the oscillator has so many capacitors, five that would affect tuning.
The main ones I think are the two 0.0022uF 100V parts (at the plate) which are too low voltage, they should be good to 400V and the value might be wrong there. Is it two series 0.0022uF to give 0.0011uF (1,100pF)?
I saw another Meazzi use a trimmer capacitor, guessing it is the 220pF/150pF to set amplitude to the record head.