CD17 120V unit plugged into 230 V! Help!

[ashok]

Hi,
The super careful me plugged in a Marantz CD17 - 120 V unit into our 230 V mains. I heard a loud hum saw the filaments of the display ( no blue display) and in about 10 seconds realised the mistake and turned of the power at the mains.

Then plugged in the unit to 120 volts through a step down transformer and there was no display. I assumed the transformer was burnt , though in 10 seconds I didn't think that would happen. I opened up the top to find the laser moving when power was turned on.
I put in a disc and it spun and then found that the machine was working OK with normal sound. Even the IR remote works.
But no display. All dc (regulator) voltages seemed to be OK.

Looks like there is no display filament voltage. Where do I measure this and how much should it be ? I see a three terminal connector near the edge of the main board. Is this the supply to the filaments ? Can I check the filament resistance to see if it is blown. If so where ?

Can someone please help me.
Thanks,
Ashok.

[ashok]

OK I found the filament terminals. They have a 3.8 volt ac signal on them and they glow dimly. I can see it when I turn of all the room lights ( its night time here).

So that means possibly no signal on the electrodes . How do I check this out. Any suggestions from our digitals experts ? What else could go wrong in the display circuit ?

Note that I didn't see any disply at all when first plugged in at 230V . The filaments were visible dull red with room lights on.
Now its visible only with lights off which I think is normal.
Thanks.
Ashok.

[apolon34]

hi,

generaly, the display is powered with 5v ac for filaments and something like -26v for electrodes.

check if you have something like this. if yes, the display can be dead

if not, that's a psu problem

[Zombie]

You have subconsiously got rid of the display...what on earth would you need it for?...use the dimmer function and reduce it even more
cheers
t

[ashok]

Hi apolon34 ,

I found 10 volts peak to peak on the filaments. That is about 5 volts peak ac.
The other terminals have pulses of about 5 volts on them. No sign of any higher voltages on any terminal.
Could this display work with lower voltages ? Is there a 24 volt coming down the connector cable from the main board ? I don't see it.
Thanks for the information you gave me.
Ashok.

[ashok]

Can anyone tell me where to check to determine at what point the 24 volts is failing ?
Thanks,
Ashok.

[ashok]

I checked some more and determined that it looks like the connector to the display from the main board does not carry any voltage higher than 5 volts. There is a VF0 terminal which I guess is at 0 volts (?).

I removed the front panel and from the display pcb it looks like there is a chip under the display - that is awful ! Couldn't possibly sit down to remove the multiple pin display . Since the main board to the front panel is very small , it obviously carries only signal and supply lines. Display voltages must be generated on the front panel pcb.
Any idea what chip that is?
Would anyone have a schematic of the display module ?

I couldn't even find any sources for a service manual on the web. Would anyone have a url ?
Thanks.
Ashok.

[apolon34]

maybe there is some displays that work with 5v, but I don't know anything about these.

[Guido Tent]

Originally posted by ashok
Hi,
The super careful me plugged in a Marantz CD17 - 120 V unit into our 230 V mains. I heard a loud hum saw the filaments of the display ( no blue display) and in about 10 seconds realised the mistake and turned of the power at the mains.

Then plugged in the unit to 120 volts through a step down transformer and there was no display. I assumed the transformer was burnt , though in 10 seconds I didn't think that would happen. I opened up the top to find the laser moving when power was turned on.
I put in a disc and it spun and then found that the machine was working OK with normal sound. Even the IR remote works.
But no display. All dc (regulator) voltages seemed to be OK.

Looks like there is no display filament voltage. Where do I measure this and how much should it be ? I see a three terminal connector near the edge of the main board. Is this the supply to the filaments ? Can I check the filament resistance to see if it is blown. If so where ?

Can someone please help me.
Thanks,
Ashok.

congratulations to Marantz for making such robust machine

regards

[Cobra2]

the remains of a CD-14...somewhere....
I guess it uses same display board as CD-17...?


Arne K