Urgent help needed for my Powerbook 170!!!

[Cyclone740]

I have a powerbook 170 recently, and thought that it might be a fun thing to work on and restore. But after a week straight of cleaning and plastic repairs, I have finally gotten it to the point of which I am able to test it out and see what I am working with.

Now once I got it all set up I tried it out and found that the device seemed to power on but nothing other than the backlit turning happened.

Then after a lot of random fiddling, I have gotten it to point in the photo that is attached. Even then it is unreliable in when it gets to that point.

I am needing a lot of urgent help with understanding both what is going on and how to fix it.

This is needing to be done as soon as is possible.

If you need Amy more information, please ask. Anything I can do to help you help me out faster.

Thank you.

 

[3lectr1c]

Is the power supply known good or is it the original? The originals always go bad due to failed capacitors, you need to be testing on a modern or recapped supply.

 

[Daniel Hansen]

I agree with @3lectr1c - verify your PSU is putting out somewhere between 7.5-7.8V

A few other things you can try...
- do a power manager reset: unplug the machine and let it rest for a few minutes, then simultaneously press and hold in the two recessed buttons on the back of the machine for 5-10 seconds (with a couple paper clips or similar). Plug in and see if the machine will turn on
- Try booting with the battery installed and not installed
- Try booting with the floppy drive, hard drive, and any expansion / RAM cards disconnected

That might narrow the issue down.

 

[3lectr1c]

If PSU is known-good, next suspect for me would be the interconnect board cable. They’re notorious for going bad and producing this sort of inconsistent behavior and issues.

 

[Cyclone740]

I agree with @3lectr1c - verify your PSU is putting out somewhere between 7.5-7.8V

A few other things you can try...
- do a power manager reset: unplug the machine and let it rest for a few minutes, then simultaneously press and hold in the two recessed buttons on the back of the machine for 5-10 seconds (with a couple paper clips or similar). Plug in and see if the machine will turn on
- Try booting with the battery installed and not installed
- Try booting with the floppy drive, hard drive, and any expansion / RAM cards disconnected

That might narrow the issue down.

Thanks I have tried all that already multiple times. And nothing seems to have changed.

 

[Cyclone740]

If PSU is known-good, next suspect for me would be the interconnect board cable. They’re notorious for going bad and producing this sort of inconsistent behavior and issues.

Thanks for the advice, could you please point out which one is the interconnect board?

 

[Cyclone740]

Thanks for the advice, could you please point out which one is the interconnect board?

Also if worse comes to worse, would I be able to use a powerbook 140 motherboard with the powerbook 170 CPU board?

 

[3lectr1c]

PowerBook 140 and 170 motherboard are the same.
Interconnect board is the one with the gray ribbon cable, speaker, and battery attached.

Again though, have you verified that your PSU works? That is the number one issue that keeps these from starting, those PSUs always have bad capacitors.

 

[Cyclone740]

PowerBook 140 and 170 motherboard are the same.
Interconnect board is the one with the gray ribbon cable, speaker, and battery attached.

Again though, have you verified that your PSU works? That is the number one issue that keeps these from starting, those PSUs always have bad capacitors.

Thank you, I am pretty sure that it is working I might recap the psu as a precautionary measure.

 

[Daniel Hansen]

Thank you, I am pretty sure that it is working I might recap the psu as a precautionary measure.

Well, you can simply test it with a multimeter... check if it's providing a solid output. If it is, then you can move on to checking other things.

Is any part of the logic board getting hot?

 

[3lectr1c]

Also try plugging in headphones and seeing if you’re getting chime out of them. If you are, it’s likely a bad interconnect board.
I’ll ask again though - you said you’re “pretty sure” the PSU is good - do you have another system to test with? If not, absolutely test it with a multimeter. The originals all go bad.

 

[Cyclone740]

Well, you can simply test it with a multimeter... check if it's providing a solid output. If it is, then you can move on to checking other things.

Is any part of the logic board getting hot?

Yes at least two point on the CPU board seem to get hot, the two chips in the red circle.

I have done a bit of adjustment and I have gotten it to a point where I am able to get a solid 7.7v, but when I plug it in I can often get it dropping down to as low as 1.1v.

 

[3lectr1c]

I have done a bit of adjustment and I have gotten it to a point where I am able to get a solid 7.7v, but when I plug it in I can often get it dropping down to as low as 1.1v.

Yeah, that PSU is bad, and likely your problem. Go get yourself a modern supply off Amazon and I'll bet that the 170 fires right up.

 

[Cyclone740]

Yeah, that PSU is bad, and likely your problem. Go get yourself a modern supply off Amazon and I'll bet that the 170 fires right up.

Would it be worthwhile recapping the PSU? Or it pretty much karcked it?

 

[3lectr1c]

You can recap it, yes. Thing is that they're a royal pain to crack open, the ELNA caps' leakage inside is a huge pain to clean up, and when you're done there's a well under 100% chance it will work right. I've had a stone-dead OEM supply for almost 2 years now that I still haven't gotten around to recapping yet just because my aftermarket ones work just fine.
By all means, go ahead, but it will be a lot more work.

 

[Cyclone740]

Also try plugging in headphones and seeing if you’re getting chime out of them. If you are, it’s likely a bad interconnect board.
I’ll ask again though - you said you’re “pretty sure” the PSU is good - do you have another system to test with? If not, absolutely test it with a multimeter. The originals all go bad.

I didn't even think of doing that, thank you I will have to try that out. The headphones didn't even cross my mind, but strange question, would standard cheap in ear headphones work? I am just asking because I tried something like that one time on another computer I own and it didn't work, because it turned out that the sound card didn't really like the newer over ear headphones I was using. Also would using basic PC speakers work as a substitute for the headphone.

 

[3lectr1c]

Try whatever you’ve got.
With what you’ve said now though, you’re not gonna get a chime. Your PSU is bad. It shouldn’t ever drop from 7.5V or thereabouts.

 

[Cyclone740]

You can recap it, yes. Thing is that they're a royal pain to crack open, the ELNA caps' leakage inside is a huge pain to clean up, and when you're done there's a well under 100% chance it will work right. I've had a stone-dead OEM supply for almost 2 years now that I still haven't gotten around to recapping yet just because my aftermarket ones work just fine.
By all means, go ahead, but it will be a lot more work.

Ok thanks, I will give it a go. I have already cracked it open, and quite cleanly I might add if I do say so myself, I can even just pop it back together no problem and open it as well.

Regarding the cap leakage, there doesn't seem to be any leakage, but I can check that when I come to do it.

So if there isn't any leakage is it likely going to be a relatively simple fix?

 

[3lectr1c]

There will be leakage under the caps most likely, it's probably just fresh enough not to have corroded anything yet. If it's in that good of shape, then yes, it will likely be good again after a recap.
Post photos of both sides of the PSU board too, that will be helpful.

 

[Cyclone740]

Try whatever you’ve got.
With what you’ve said now though, you’re not gonna get a chime. Your PSU is bad. It shouldn’t ever drop from 7.5V or thereabouts.

Ok so even if the psu is putting out so.ething between 1.1v and 2.4v would that still be enough to occasionally turn on the backlight of the screen? And also causing the stated chips to to heat up.