PB 160 sound keeps failing

[Shaddam IV]

Hello, I am renovating a powerbook 160. Its screen has been recapped and works well. The battery is dead; I‘m rebuilding it to house 5 x 1.2 V 700 mAh NiCd cells (which means it won‘t last long but I hope it‘ll last a few minutes). The PRAM battery is also probably dead (date and time, AppleTalk status etc are not retained between sessions with the Powerbook). I dread replacing the PRAM battery on account of having to solder in tight spaces, but I guess there‘s no way around it.

For now, I keep the battery out of the Powerbook and run it from the PSU only.

The sound problem: When I connect the PSU (battery is not in) and switch the Powerbook on on after it‘s been sitting in the dark for a few hours, I get the start sound, the system turns on, and sound play as it should (e.g. when After Dark Star Trek is on). After it‘s played a sound, the sound system (generator? Circuit?) is switched off after a few seconds with an audible “click“. That‘s normal.

But here will come a point in time when the system emits a (relatively quiet) screeching noise, and from then on any sound it tries to make is just a screech. This will last for a few seconds until the sound is switched off. When I reboot, there won‘t be a start sound but only the screech, and the issue persists (screech whenever it should play a sound). When I turn it off and turn it on a few minutes later - not having disconnected the PSU - I get the screeches and no proper sound.

What could be the cause? Is it to do with the PRAM battery? Is the sound generator chip loose? Where is that chip, anyway (I assume somewhere on the motherboard, but where?) What can I do? Gently shake? Wipe? Replace something?

Any help is much appreciated. Thank you!

Kind regards, Karl

 

[luRaichu]

Honestly, if this same thing occurred in a desktop Mac we'd all be screaming caps. However that can't be it, as these PowerBooks use tantalum. I'd carefully check the logic boards for shorts, gunk, etc. if you haven't already. I'd also take care of the PRAM battery. Is the screech replicated on the speaker out aux jack?

Also: Where did you get those NiCd batteries?? From Wikipedia:

Under the so-called "batteries directive" (2006/66/EC), the sale of consumer Ni–Cd batteries has now been banned within the European Union except for medical use; alarm systems; emergency lighting; and portable power tools. This last category has been banned effective 2016.

Unless of course you're confusing NiCd with NiMh. You can use rechargeable AA's in your battery rebuild, here in the US they sell Duracells that are 2,500mAh each. So five of those would create a 12,500mAh battery pack which'll last you about 3 hours from what I'm told. You could put the AA cells in a battery holder like this one:

 

[3lectr1cPPC]

Is the PSU original? If so, has it been recapped? Weird issues can happen when those PSU caps fail. I doubt that's it this time, but it's still worth checking.

 

[Shaddam IV]

Hi, thank you so much.
Screech: The screech is also output by headphones connected to the speaker jack, i.e. I'd also assume something wrong on the Motherboard. I've since discovered the chip ("U16" on the motherboard, it's a smallish square chip called "59152AH, (c) 90 Apple, VI02L245" (at least on the 145B Motherboard, this should be similar on the 160 motherboard). The nearest capacitor is called "C90" and sits on the other side of the motherboard, close to the round hole in the motherboard that's near the sound chip. So I guess I'll try removing the motherboard and cleaning it - and change the PRAM battery while I'm at it (#fear #loathing).
NiCd: It appears they're still legal for medical devices. I got the pack of 5 cells from all-batteries.de, but many outfits seem to have them. When you search for packs, they're often shrink-wrapped in white plastic with a Red Cross on it. The original Apple battery had 2,800 mAh, it seems. The cells in the original battery are slightly thicker (and slightly shorter) than AA.
PSU: I have bought a second PSU on eBay and will test that.

 

[3lectr1cPPC]

If the second PSU is also an OEM, you're likely to run into it failing before long. The originals use ELNA caps that have a 100% failure rate. They won't all fail at the same time, but they all WILL fail. Best practice is to test with a modern generic PSU that fits the requirements (7.5v 2a), or to use a recapped original.

 

[Shaddam IV]

If the second PSU is also an OEM, you're likely to run into it failing before long. The originals use ELNA caps that have a 100% failure rate. They won't all fail at the same time, but they all WILL fail. Best practice is to test with a modern generic PSU that fits the requirements (7.5v 2a), or to use a recapped original.

OK, thanks. Yes, the second PSU is also original. I'll look for a "modern" one, then, at least for testing purposes; if that works out ok, I might get into recapping... Never done it before.

 

[3lectr1cPPC]

Hardest part of recapping an original is getting the case open - best way seems to be to use a vice and two pencils until it pops open. This worked well with mine and they'll generally go back together ok after.

I haven't even recapped my OEM supply yet though, I just use two generic modern ones. They're cheap, and probably not terrible well made, but they work fine for me. Just search amazon for "PowerBook 160 power supply" and a bunch of them will come up.

 

[Shaddam IV]

I've just ordered one (made for "Powerbook 145") from Amazon. Thanks!

 

[Shaddam IV]

I killed the machine. After I soldered a new PRAM battery to the interconnect board, half the screen is missing pixels: The upper screen half is showing vertical white stripes every 7 or so pixels. I have another interconnect board which shows the same phenomenon (actually worse: The whole screen is now showing white stripes)(, so I guess that I managed to damage the interconnect board. Hm! Any ideas…?

 

[luRaichu]

I killed the machine. After I soldered a new PRAM battery to the interconnect board, half the screen is missing pixels: The upper screen half is showing vertical white stripes every 7 or so pixels. I have another interconnect board which shows the same phenomenon (actually worse: The whole screen is now showing white stripes)(, so I guess that I managed to damage the interconnect board. Hm! Any ideas…?

Oh no! Do the dead pixels appear on the external monitor as well?

 

[3lectr1cPPC]

Post a photo of the condition and I’ll see if I can help.

 

[Shaddam IV]

Post a photo of the condition and I’ll see if I can help.

I'll post pictures asap (machine is in the basement right now). Thank you!
I believe that the video output to an external monitor is not affected, as it's just the upper half of the LCD that's showing the stripes. But I'll test as soon as I can (probably mid week).
I have just bought a (relatively cheap) apparently dead PB 180 just now off eBay, and will try to use its (hopefully still working) interconnect board when it comes in (middle of the week).
I don't think that the flat plastic connector "cable" from the interconnect board to the LCD is damaged. I can't see any damage on it.
The screen used to work fine before I messed with the interconnect board. As described, another interconnect board (which had a new battery soldered on) showed the missing stripe in both halves of the screen, so I switched back to the unit's own board (with a dead battery). All was good with the screen. Only when I soldered a new battery to the unit's own interconnect board did the stripes appear.
So maybe it's the battery...? But how...?

 

[Shaddam IV]

Hi, this is the broken screen. Note that the problem occurs in the upper half of the screen. When I switch the interconnect board to another one that I have, the problem becomes worse and the white vertical lines lines occur in both the upper and the lower half of the screen. Help please!

 

[Shaddam IV]

Post a photo of the condition and I’ll see if I can help.

Thanks! I've just posted a photo.

 

[3lectr1cPPC]

Either you have two bad interconnect boards or the LCD ribbon cable is loose. Take the display apart and reseat the cable display-side and see if that solves it. A very similar (if not the same, don't quite remember) thing happened to my 145 when the cable was loose there.

 

[Shaddam IV]

Thank you! I'll try reseating the cable on the display side of things. (I have now repeatedly re-seated it in the interconnect board.) The (flat ribbon) cable of the floppy drive hadn't been properly connected on this computer when I got it, and the floppy would not reliably work - until I fastened the cable (to the motherboard). Maybe there's a similar issue with the display ribbon cable.
Incidentally: I have a LCD ribbon cable from a (very broken, very cheap) PB 145. It looks very much like the cable of the 160. Do you know whether they are interchangeable? Thanks!

 

[3lectr1cPPC]

I believe the 140/145/160/165 cables for Sharp LCDs are all interchangeable.
Edit: 165 cables may not be compatible with the rest actually.

 

[Shaddam IV]

Oooh kay. Sounds like my week-end will be busy. Thank you very, very much!

 

[3lectr1cPPC]

No problem. I hope you get it solved!

 

[Shaddam IV]

I reseated the cable, but the problem persists :-( I’ll try switching out the cables next - but I guess it is the interconnect board after all. Thanks!