CD63 display problem

[Chivvyp]

I made some mods to the power section of my CD63KIS at the weekend.

As I'm an idiot I put +12v and -12v voltage regs in with wrong orientation.

I corrected this but now I have no display and the control panel buttons (and rc) don't work. I am getting audio output though.

I've traced the power lines and seem to be getting power through the ribbon cable to the display.

Anyone got any ideas where to look next? Is it possible I've fried a component somewhere?

[martin clark]

If it turns out you have fried it - I've got a complete and working front panel from a CD63 you can have for the cost of postage. Drop me an email if interested.

[poynton]

Originally posted by Chivvyp
I made some mods to the power section of my CD63KIS at the weekend.

As I'm an idiot I put +12v and -12v voltage regs in with wrong orientation.

I corrected this but now I have no display and the control panel buttons (and rc) don't work. I am getting audio output though.

I've traced the power lines and seem to be getting power through the ribbon cable to the display.

Anyone got any ideas where to look next? Is it possible I've fried a component somewhere?

Since you have audio, you do not have a problem with the +-12v supply. [ The +-12v supply is audio only ]

First place to start is the VFTD supply at Q851, [close to the transformer] the voltage on its pins, to ground, should be-31.5v, -24.4v, and -6.8v.

Next, check the voltage either side of resistor, RF01. This is next to the big chip by the display. Voltage to ground should be +5v both ends.

Andy

[Chivvyp]

Andy,

I checked Q851, viewing from front, l > r I got -6.9, -34.4, -24.6.

RF01 I got +5 going in but 0 coming out. Guess this may be the problem. I'll replace it at the weekend and see what happens. Or are there other things I should check first?

Not sure how this would have been affected by the changes that I made but maybe it was just coincidence?

Thanks for your advice.

Pete

[poynton]

Originally posted by Chivvyp
Andy,

I checked Q851, viewing from front, l > r I got -6.9, -34.4, -24.6.

RF01 I got +5 going in but 0 coming out. Guess this may be the problem. I'll replace it at the weekend and see what happens. Or are there other things I should check first?

Not sure how this would have been affected by the changes that I made but maybe it was just coincidence?

Thanks for your advice.

Pete

The readings round the regulator are OK.

RF01 is the 'safety' resistor feeding the +5v to QF01, the uP.
This should not have been damaged by the 12v supply problem !!

Check for solder splash or other foreign bodies from your previous soldering.

Andy

[Chivvyp]

Thanks Andy, will do.

Any idea where I can get a suitable resistor for RF01. I checked on Maplins site but the only 4.7 resistor I could find was rated 0.6w rather than 0.25.

Regards

Pete

[SimontY]

Hi Pete, you could just replace it with a piece of wire for now. Or use a similar small resistor, whatever wattage you like: it just won't fit in flat.

Regards
Simon

[SimontY]

I also broke my display, hehe. And I did before one time, which was caused by lifting a solder pad under the big cap near the 7805 (+5v regulator).

This time the problem is elsewhere, but sadly it's a different problem to yours, so we can't help each other much

Simon

[Chivvyp]

Simon,

thanks for the advice, I think I'd better use something "blowable" to start with in case I havent solved the root problem completely.

Pete

[poynton]

Originally posted by Chivvyp
Thanks Andy, will do.

Any idea where I can get a suitable resistor for RF01. I checked on Maplins site but the only 4.7 resistor I could find was rated 0.6w rather than 0.25.

Regards

Pete

Hi.

Half watt will do. Definately not a short in case there are problems as you said.

RD01 and RD04 near the opamps are also 4.7ohm. [ you could short here as no problems.]

Andy