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Portable - two steps forward one back

at0z

Well-known member
Non backlit Portable was dead to the world and in need of a recap. Someone wasn't kidding about the nasty fish smell - I thought thai fish sauce was pungent until the hot air cooked up  a whiff of funky bouillabaisse .

But the recap operation seems to be *mostly* successful as I now power up with a chime but hit the Sad Mac code attached. At least the screen is also in reasonable shape save a sing pixel line which starts one third of the screen in.

My Sad Mac coding is a little rough (I guess smartphone apps were a little ways off) but am I right in thinking the "03" means a RAM issue ? Just bare board on the bench at the moment, no peripherals and no RAM expansion back in place. Anybody able to narrow down where to start looking ? Not seeing anything obviously corroded but I have not yet put the board in a nice warm ultrasonic bath - that's next but I don't know if that is going to make the RAM happy.

Any sage advice welcomed.

Stuart

IMG_0144.png

 

at0z

Well-known member
This is bare board, all cards and devices disconnected apart from speaker and keyboard...tried reset power manager and this is the same code each time. Which is good I guess...

in another post I saw someone mentioned that they did something with the NMI but didn’t elaborate?

 
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at0z

Well-known member
Are you using a good main battery ? and battery cover in place ?
Powering the board through the molex connector from a bench lab supply. 6.5v with and a 1.5A current limit. When it powers up it draws about 400mA because none of the peripherals are attached. And yes both positive and negative connections are being fed.

If I made a mistake with the recapping (or have a bad replacement) is there a group/cap which would impact the (apparent) RAM test fail ? On a Portable, which is Bank B ? That might help narrow down my search...

 

techknight

Well-known member
Make sure your using both positive pins on the molex connector. If either one of them come loose, you lose a ton of ICs on the board in one whack. 

With that said, your likely gonna have to start chasing a trace/via issue as thats likely what it is. Especially if the old 9V battery leaked at any point in the past, it tends to corrode/eat the RAM traces away on the back row of ICs. 

 
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at0z

Well-known member
Make sure your using both positive pins on the molex connector. If either one of them come loose, you lose a ton of ICs on the board in one whack. 

With that said, your likely gonna have to start chasing a trace/via issue as thats likely what it is. Especially if the old 9V battery leaked at any point in the past, it tends to corrode/eat the RAM traces away on the back row of ICs. 
Yes, I watched your video and made sure to do that, thanks! When you say "back row" you mean closest to the IO ports ? Still can't find anything that points out Bank A and B on the onboard Portable RAM....

I'm going to give it a bath first and then start looking for trace or through hole issues. Saw your flashlight under the board tip, but not quite sure what I'd be looking for to indicate a wrong un, but maybe it will become obvious.

Thanks for sharing.

Stuart

 

desertrout

Well-known member
The flashlight will reveal whether or not traces are connected to their vias - the vias will appear as dark circles surrounded by a light area, and the trace should be a thin dark line connecting to the via across the light area. Easy to see breaks that way. 

As for the bath, I recommend techknight's method of a cycle in the dishwasher (no soap, no dry cycle), then maybe 15 minutes in a preheated oven at 170 (as low as it will go) to bake out any persistent electrolytic goo. Then leave it to continue to dry for a couple more days to be sure. Has solved weird, hard to diagnose issues for me a couple of times, including on my 5120.

 

at0z

Well-known member
The flashlight will reveal whether or not traces are connected to their vias - the vias will appear as dark circles surrounded by a light area, and the trace should be a thin dark line connecting to the via across the light area. Easy to see breaks that way. 

As for the bath, I recommend techknight's method of a cycle in the dishwasher (no soap, no dry cycle), then maybe 15 minutes in a preheated oven at 170 (as low as it will go) to bake out any persistent electrolytic goo. Then leave it to continue to dry for a couple more days to be sure. Has solved weird, hard to diagnose issues for me a couple of times, including on my 5120.
Thanks for the enlightenment, will get the flashlight out again. Is there any tip for spotting via that are corroded away to the point they aren’t connected at all or just visual check. I assume the Portable is only dual layer pcb ?

 

desertrout

Well-known member
To be honest I'm not sure, but I'd assume that it's at least 4 layers. Checking continuity with a multimeter should be enough if you have concerns about a particular via. Sometimes you can't actually see the break, becomes apparent through process of elimination.

 

at0z

Well-known member
Hmm well maybe need to retitle two steps forward three back.

Not getting a start up chime now. Same power as before from the bench supply direct to the molex on the board (both positives and nagatives).

When I power on, I see a small amount of current draw down which gradually becomes zero or holding the PWR/NMI buttons drops it. Holding the buttons in I can see a small amount of power draw. Checked Q16 and Q20 and I am getting power there, so power is getting to the board outside of the hybrid. Adding the 1M resistor to the IC on the hybrid as I have seen techknight advise hasn't changed anything. Thought I was on to something when I saw one of the regulators on the Hybrid board was missing a middle leg, then noticed everybodys was like mine....

I had already ultrasonic soaked the logic board after the recapping - I did revisit all the caps to check they were secured. The frustrating thing is the board traces look to be in great shape and I am starting to wonder if this is chicken/egg where the board was faulty or intermittent to begin with and that's why it got shelved and the caps needed work due to the storage. It would explain why the case is in very nice shape with no yellowing.

I'll keep digging around the schematics and see what might bring inspiration but I hear the caution that the survival rate can be 50% with these Hybrid board (but I think my readings suggest my Hybrid is probably not guilty) which maybe leaves the PMU....

As always, any cheering from the sidelines with helpful tips is always welcomed....

I'm holding off investing in a SCSISD upgrade until the motor turns over ;-)  It may end up in my Color Classic instead, which is also on the bench for recap.

 

techknight

Well-known member
I believe you have a bad PMGR. its a known issue and theres no fix except to replace it from a donor board. It can also be the Hybrid IC as well, they both work in tandem. 

 

at0z

Well-known member
I believe you have a bad PMGR. its a known issue and theres no fix except to replace it from a donor board. It can also be the Hybrid IC as well, they both work in tandem. 
Thank you sir,  I also tried removing the SWIM and starting up, no change. I may pull the PMGR and see if anything amiss underneath from the nearby caps.

If any philanthropist souls out there have a donor PMGR from a wrecked board, or a wrecked board, please make themselves known. It’s such a fine condition case it would be a shame not to get it actually working. No plan to flip it, it’s in my collection now so will sit next to the ANS700. 

 

at0z

Well-known member
Well here’s the before pic of the PMGR and VIA and they don’t look obviously eroded by capacitor venom. Pulled both and cleaned up the pads, no eaten tracks under the chips so I fear I have reached a temporary hiatus until I can try another PMGR. Oh well,  Color Classic time...
 

0E26150E-8933-47ED-A491-42026A09BC92.jpeg

 

at0z

Well-known member
Until I can get a PMGR chip to test, maybe it's a good idea to post the current sit rep and see if something jumps out at somebody

So, applying 6.5V to the on board molex (both +ve and -ve connected), no extra peripherals, just speaker and keybd. No sound from speaker and initial current draw is tiny 5mA which fades to zero in a few seconds. Pressing both RST and NMI displays again small 5mA draw which reverts to zero when buttons released. No startup from keyboard, no sound from speaker.

With power still applied to the board, I get the following voltage readings .

Q20 5.9,0,6.5

Q16 2.9,5.2,6.5

Q14 6.4,0,6.5

Q15 6.4,0,6.5

Q1 6.41,6.49,6.48

VR1 zero

Q10,11,13,  5.17,5.20

Q8,2 5.13,5.20

Q21,22,23 zero

Q9 zero

Q5,6,7 zero

Q18,19 zero

Q4 5.17,5.20

With power removed, I get four buzz connections from the NMI and RST pin to the MISC GLU, one on each side about middle.

From the NMI and RST pins I get 250k ohm to the 5v pin in the power molex. I think I saw a post saying it should be maybe 10K but I don't know if I got the same +5v rail.

I don't know if VR1 is expected zero given there are no 12v demand devices attached on the bench.

I do have replacement 74AC02/10/157 on the way, but I don't detect any heat either with my finger or an IR camera. But they're cheap as chips to replace so why not....

Someone on a FB group mentioned testing Y1 as they mention they can go pfut in the bath but according to my scope, we're good.

I may yet try reflowing the Hybrid with some fresh flux and hot air. What's to lose at this point ?

Hoping someone has a Eureka moment I'm missing :)

 

techknight

Well-known member
when I get time, I would have to stare at the schematics for those numbers above to mean anything. at first glance, nothing stands out, but.... 

the PMGR is entirely responsible for powering up the system by turning on/off the various transistors. so if pressing a key on the keyboard does not wake up or start up the system, the PMGR is not working. Assuming your 5.2V DC supply is present. There is the possibility the PMGR is seeing 0% battery voltage, and it wont turn on either. That line goes straight between the Hybrid and PMGR, so you can check this. 

 
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at0z

Well-known member
when I get time, I would have to stare at the schematics for those numbers above to mean anything. at first glance, nothing stands out, but.... 

the PMGR is entirely responsible for powering up the system by turning on/off the various transistors. so if pressing a key on the keyboard does not wake up or start up the system, the PMGR is not working. Assuming your 5.2V DC supply is present. There is the possibility the PMGR is seeing 0% battery voltage, and it wont turn on either. That line goes straight between the Hybrid and PMGR, so you can check this. 


I have 6.5v going into the board molex from the bench supply. After "resetting" PMGR

On the PMGR

P57 2.74v (A/D_FILTER),

P57(PMGR_PWM) 0v

Back at the Hybrid

P62 (A/D) 2.74v

P39(HICHG) 0v

P25(BATTSENSE) 6.49v

P19(CHRG_ON) 5.15v

P41 6.43v

P8 2.99v

P11 5.20v

 

techknight

Well-known member
well A/D line was what I was most interested in. 

Seems fine. Sounds like a bad PMGR, or an open trace from the PMGR to the SYS_PWR line. 

 

at0z

Well-known member
well A/D line was what I was most interested in. 

Seems fine. Sounds like a bad PMGR, or an open trace from the PMGR to the SYS_PWR line. 
I see multiple SYS_PWR on the schematic, like Q10,11,13 but is there a particular one more important?

 
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