tc-k555 plays for a second - stops (Idiot needs help redux)

You need to determine whether it's a mechanical problem, or electrical. Most decks, and surely this one, have some form of motion sensing. There might be a small belt run off the take-up hub, turning a ring magnet near a Hall sensor. This is one method. Another method is to have a mechanical oscillation which stops if the take-up stops, thus triggering the auto-stop. Still others use photo-electric sensing. On these, a lamp could be burned out.

Mark Z.

Good morning,

The auto stop in the Sony TC-K555 uses a lamp (PL1, 5V 60mA) on a pair of photo transistors. The schematic shows a 6V supply running this 5V lamp, so the schematic may have an error. I've got 2 of these machines that I bought new around 1983, and have never had to deal with these lamps. I believe the sensors work off the take up reel, but unfortunately the manual does not show it in the exploded diagrams.

I've found these decks to be pretty good sounding, and very reliable over the years. Not as good sounding as the Tandberg they replaced, but work every time I turn them on. (Something I could not say about the Tandberg.) Considering the machines currently available, the TC-K555 is worth putting some money and/or effort into if you want a good sounding workhorse.

Regards, Tim Schwartz Bristol Electronics

Thanks to both of you for replying.

I found the burnt out lamp. It sits directly above the cassette and is just almost accesible through a hole in the cross-brace of the interior frame. Not quite though, as it is mounted in a white rubber sleeve that won't move out of the way. So I took out the circuit boards and snipped the two wires running to the lamp.

The bulb is unmarked. I haven't checked the circuit voltage yet, but even once I do, I don't know where I am going to find the bulb. I went to Radio shack, Fry's and a stereo repair shop and none of them have it (Fry's, surprisingly, had NO small incandescents at any voltage.) The Stereo Repair shop referred me to mcminone.com. They have this:

Product Details: SUB MINIATURE LAMP 6.3 70MA Lamps, Subminiature, Voltage: 6.3 V, Current: 0.07 A

Assuming it is a 6 volt circuit, do you think this will work? If not, where else could I look for the lamp?

Thanks again,

Adam

Ought to work, assuming it will mount like the original.

Mark Z.

Adam,

I agree with Mark about the replacement lamp. However, if you want to get really ambiscious, the Sony part number for the lamp is

1-518-313-00. You can try any Sony parts distributor. I use Andrews Electronics (phone 800-289-0300, fax 800-289-0301).

But first, I'd measure the voltage across the lamp and make sure there is some! The problem could be no voltage rather than a bad lamp.

Regards, Tim Schwartz Bristol Electronics

I'll double check, but the lamp is visibly burnt out, so it is at least part of the problem. Thanks again, Adam

Update: MCMInone has the lamp in stock but they will only ship via ups for $8.50. Sony has the lamp in stock, and only charges 2.50, but the lamp costs $7. I went back to Radio Shack and got a 6V, 25mA bulb for $2.50. I don't really understand electricity well enough to predict how long this bulb will last, but I wired it in (using elec.tape to the old leads, which I had left soldered to the boar) and it is working fine for now. Many thanks, Tim and Mark. Now I'm off to get those cassettes onto cd's!