no power but tape deck motors are working. Any ideas

No power and the tape motors are still moving!! I suggest you apply for a grant to study this further!! You may have discovered a way to create energy from nothing! There may be a way to harness this and provide power to a small city with a great Helix array!!!

Some boxes will allow you to run the cassette without actually turning the the power switch to "on." The Sharp GF-777 is one example. My GF-777 was the same way - power to cassette / no power to radio. The problem for me was a dirty power switch.

I guess you could say no amp power but the deck motors work

So, no sound when playing a cassette?

No lights or power to amp. When power switch is on and I touch ground wire to ground I can hear crackling through speakers. The guy I got it from said preamp is powerless

Now I have power light and humming noise but still cant get radio or sound from deck

Hey Bobby power switch seems to be working I did clean it 3 times

quote:

Originally posted by Fatdog:
Some boxes will allow you to run the cassette without actually turning the the power switch to "on." The Sharp GF-777 is one example. My GF-777 was the same way - power to cassette / no power to radio. The problem for me was a dirty power switch.

Can you check the DC voltage at the input ?.
Hum is realted to a supply problem.
It may be caused by

1) Bad main capacitor
2) too much current consumption (because some part of the circuit ir shortening the supply).

If the boombox have voltage regulators inside, the DC voltage most be above a certain value to allow them to work.
If the DC voltage is below than the expected by the regulators, they wont work, and so the circuit parts they supply.

But since theres a DC voltage and many thing don't need regulation, like the motor or bulbs the will work, event at a low DC voltage.

Post a picture !!!

Would this cause no power at pre amp

Fact:

The only boombox where I've seen voltage regulators is the Panasonic RX-DT680.

This boombox uses a power amp, which also provides two DC "well-regulated" voltages, 5V and 9V. A bit crazy, but not too much.

The 9V line was used to feed the preamp, equ, and volume motor

When the amp blown, the boombox stop sounding.
Ok, the main amp blown .... no sound is expected !!!!
But this boombox is bi-amp, that's it has two power amps, one for lows and one for mid/highs. The blown amp was used to drive low frec.
But the mid/highs amp wasn't damaged. I tested it and it was rigth, but no sound, even at mid/highs !!!!!!!!!
That was because the preamp was DEAD.
But some sections keep working like LCd, leds, CD and turner !!!!. That's because there were another regulators around ... a complex boombox for sure.

So, no sound is posible, even while some parts get power and the amp is working fine.

So what do I need to check

A shematic would be great to see where the problem would be and if the boombox has voltage regulators.
If you have heard a hum through the speakers, the power amp is working. But if there's still no sound looks like a preamp issue.
Try to get the schematics .....

Well with the help of Pedro (sucess) I got the pre amp working on this helix 4636. I ended up having to replace a transistor and capacitor. Thank You again Pedro. Pictures to follow I am also looking to get a bottom deck door.