CPC464 - No power, but motherboard works alone

Started by displaced, 15:03, 06 July 22

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displaced

Hi!

I'm new to restoring CPCs, although I've worked on a bunch of other 80s systems.

Picked up a CPC464 on eBay, listed as not powering on.  It's just the computer, no monitor.

I fed 5V DC to the barrel jack and, sure enough, nothing.

Disassembled it and figured out with a multimeter and the schematics that I could get the board to power up without the tape deck by bridging pins 1 and 3 on the internal tape connector.

Did that, and scoped out the address lines on the RAM and CPU.  I'm seeing what looks like good activity, so I *think* the computer is working (I need to build a video cable next!).

So it seems the fault is on the tape deck.  Are there any common faults I should look out for which could be causing the deck not to pass power back to the motherboard?

Thanks!
Chris

eto

Open the power switch and clean it. If no power is delivered to the CPC that's a very likely culprit and so easy to fix.


https://www.cpcwiki.eu/index.php/Fixing_the_power_switch


displaced

That was exactly it, thank you — it's alive!

Now to figure out what's up with the tape deck.  Fast-forward and rewind are fine, but pushing play raises the head and the pinch roller, but the spindle doesn't turn.

And the counter goes backwards on rewind, but stays where it is when fast-forwarding.  Interesting!

eto

Quote from: displaced on 22:00, 06 July 22Now to figure out what's up with the tape deck.  Fast-forward and rewind are fine, but pushing play raises the head and the pinch roller, but the spindle doesn't turn.
The CPC controls the motor. It won't start unless you are really loading a program.

Press CTRL+small Enter, then "press play then press any key" will appear. 

Now you can press play and once you press a key, it will start loading.

displaced

Ooooh! Makes sense!

I only ever used a CPC at a friend's house when I was a kid, so I'm glad I asked before poking around.

In that case, I'll give the head and the rollers a clean, then get building a video cable.

Animalgril987

The tape counter is driven by a pulley on the rewind spindle, so it will only  run forwards if a cassette is inserted.  :)

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