800XL: No video output, loud hum!

[LordVaderUK]

Have just received an 800XL in good cosmetic condition, together with an original power supply. I confirmed on a different thread here that this particular PSU was safe to use. Connected everything up, the 800XL power light comes on but the unit is emitting a noticeable humming noise. No output from the composite video. I've switched it off to avoid blowing anything up, and I await a new USB-based power supply.

 

Is the hum normal? Or does it indicate some issue with the unit?

[gs80065xe]

Is the hum coming from the unit itself or the TV speaker?

[LordVaderUK]

3 minutes ago, gs80065xe said:

Is the hum coming from the unit itself or the TV speaker?

From the 800XL...

[gs80065xe]

Just wanted to be sure. My first time hooking up an old composite cable I had, I learned it didn't match modern composite cable colors. I plugged the red into TV's red audio port and got a hum and no screen. Later learned that was connected to the the chroma pin.

 

I'll have to defer to the more experienced tech wizards on what would cause the actual computer to be humming.

[TGB1718]

Does it hum with no cable connected ?

[Rybags]

Hum from the computer itself - not right.  Maybe there's some AC coming through the power supply.  Or maybe there's some sort of user modification that's playing up.

[+DrVenkman]

24 minutes ago, LordVaderUK said:

From the 800XL...

From inside the machine? There’s nothing whatsoever inside that box that should produce any sound. I’d be concerned you have some kind of internal short or something. Open it up and see if anything is amiss. 

[TGB1718]

As @DrVenkman says, there's nothing in an 800XL, only the 800 has an internal speaker, so if it's humming, there's something rather unwell with it.

 

Check for leaking capacitors, they are the only thing I can think of that might make a noise if they are breaking down

[LordVaderUK]

Thanks all, I have done some more checking and on closer analysis the humming was coming from the TV ? Sorry to send you all off on the wrong direction.
 

Seems as though the telly doesn’t like the composite signal coming from the monitor cable (I bought a proper one from a retro computing supplier). I’ve tried all three connectors from the cable (yellow, red, white) in turn in each of the three composite inputs, but nothing. I can only assume the telly doesn’t have the right sort of inputs. I’ve attached a photo of the back of the TV.

[+DrVenkman]

The inputs of your TV there are COMPONENT video, not Composite. Many TV’s do allow you to input a Composite signal into one of the Component jacks - I believe it’s usually the Y/V (green colored) input.

 

Now, the cable plugged into your Atari may or may not correspond to usual standard (Video = Yellow, Audio = Red/White, etc). You’ll have to experiment to see.

[+Nezgar]

The Jack labelled "Y/V" (V = Composite Video?) may have a dual function as a Composite input, but you might have to use a different display to confirm first. Worst, it should at least show a greyscale picture...

 

I'd pin-out (continuity test) your cable to verify what pins on the DIN connector map to the RCA connectors on the other end... ie Pin 4 should map to the tip of the composite video RCA connector, Ground to the ring.

 

 

[StickJock]

The above picture of the DIN 5 is the jack at the computer.  Remember to mirror it when you beep out your cable.