Help me find the source of the mysterious PSU ticking noise

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geerlingguy's picture
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Help me find the source of the mysterious PSU ticking noise

Our Apple II project keeps hitting little speed bumps...

Today after my Dad spent a couple hours re-seating almost all the chips on the board (cleaning with Deoxit), we had turned it on a few times and it was fine.

But then after the final few chips were re-seated, and everything was plugged in, the PSU started ticking, maybe a few times per second.

Pulling off the PSU cover and listening relatively closely, we couldn't determine exactly where the ticking is coming from, but it seems to be coming from the side more near the back (where the power plug is).

We tried bypassing the socket that has it's little built-in capacitor circuit, and supplying 120v straight from mains to the PCB, but the ticking persisted, so it seems to not be the AC socket itself.

See video with sound amplified in this GitHub issue: https://github.com/geerlingguy/retro-computers/issues/15

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If this is an original power

If this is an original power supply, it's 30+ years old, and it has no good place to go.  I replaced my //e PSU with an easy internal upgrade from ReactiveMicro, it is cooler and I have no qualms about leaving it running telnetting to my email account overnight or for days in a row.  You are also assured that there will be plenty of steady reliable power for any expansion boards you may throw at it. 

geerlingguy's picture
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Yeah, we just invested a good

Yeah, we just invested a good amount of time recapping it and replacing the power switch, tidying everything up. It's sad to see it go :)

I've ordered a PicoPSU Adapter kit, and we'll put that in. Might also do the other one at some point so we can re-install the original PSU for that original aesthetic. when lifting the cover...

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The ReActive Micro kit is

The ReActive Micro kit is good and super easy to install but I am a fan of the Mean Well PT-65B + LM7905 swap that you can find a thread here on AppleFritter about.  It is a bit more work than the ReActive kit but it produces basically similar results -- a power supply that looks stock from the outside but has a brand new board that supplies more juice than original -- and at about 1/2 the price.

 

Seriously, I can do the swap all-in for around $35.  I've done it on an original Apple supply, an AE power supply and a Franklin power supply so far.

 

 

 

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Here is a link to the
ggb
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Ticking power supply

The ticking sound is usually the power supply protecting itself from an overload/no load situation.
If the power supply has been working since the recapping, it is possible there is a component on the motherboard that is now causing an overload of the power supply.

If you had a known working power supply you could swap and see if the issue is gone.

As it appear you don't have a spare power supply try the following.
I would remove any/all installed cards in the slots.
Consider removing all the RAM and the 74S195 you mentioned was very warm/hot and then turn on and check if the PSU is still ticking.

If the ticking stops then you can install 74S195 first and test, then install the RAM a bank at a time and test.

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I'm less of a tinkerer and

I'm less of a tinkerer and prefer more of the (but not totally) drop-in solution of the ReactiveMicro.  But the Mean Well setup does look interesting.

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mreg376 wrote:I'm less of a
mreg376 wrote:

I'm less of a tinkerer and prefer more of the (but not totally) drop-in solution of the ReactiveMicro.  But the Mean Well setup does look interesting.

 

Totally understandable.  I've rebuilt several power supplies using the ReActive Micro kit and it's a really great solution that is super easy.  But honestly, the Mean Well conversion the way I do it, which is a slightly modified version of Uncle Bernie's method, mainly in how I attach the Mean Well power supply board to the case using a piece of plexi cut to the size of the original board and drilled to fit in the case really isn't much more difficult.  The only additional work really is the cutting and drilling of the plexi and soldering in the LM7905 voltage regulator to get the -5V.  My method is also very adaptable to clone supplies even ones like the AE supplies with very different board mounting or the Franklin power supplies which are a completely different form factor.  For those the ReActive Micro kit probably would require a bunch of effort to adapt.

 

 

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