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Chuck(G)
June 17th, 2012, 10:57 AM
I decided to haul out the old PowerMac 6100/60. And got nothing.

Okay, the PRAM battery was gone--replace it, but still no video--and no sound through the internal speaker. The system boots from the hard disk as far as I can tell, and it also boots from the Network Access 7.5.3 floppy.

But no video--a logic probe test on the DA15 end of the HD45 adapter says that there's no pin wiggling--just static high/low logic levels.

Just in case the thing misunderstood me, I removed the PRAM battery and powered it up, then replaced the battery. Same story (the battery measures 3.66V).

And no sound whatsoever from the speaker. Checking the continuity from the connector, the speaker's good.

PSU voltages are well within margins (+5.06 and +11.88 V).

Apple PowerPC boards are a mystery to me and I don't have any documentation that I can work from.

Any ideas from you more seasoned Performians?

Unknown_K
June 17th, 2012, 11:42 AM
The speaker could be dead because of a leaking capacitor in the audio circuit. Video should work or the system tends not to boot, could you have a bad video adapter or maybe didnt insert it in all the way? Do you happen to have a video cards in the PDS slot? Are you using a good DA15 to VGA adapter?

And then the easy fix:

http://support.apple.com/kb/TA35928

Chuck(G)
June 17th, 2012, 12:18 PM
Thanks, been there. Obviously, if my speaker output is kaput, I'm not going to hear 3 chimes.

The DA15-to-VGA adapter that I'm using is set up for 1024x768 video and that might be the problem, since it seems that the 6100 can do 640x480 tops. I'll try a different monitor ID and see if that helps.

One thing at a time...

Unknown_K
June 17th, 2012, 12:46 PM
640x480 is the default when you change the battery unless you have an adapter then you can also do 832x624 which is not common on the PC side and not sure if LCD monitors like that at all.

Old macs (68k line not sure of the Nubus PPC) like SOG monitors (Sync on green) so you might have issues with an LCD Monitor. I use old Sony Trinitrons that do SOG.

Chuck(G)
June 17th, 2012, 09:30 PM
It seems that the 6100 doesn't like/understand the higher resolution monitor types. My cable is set up for 21" Multisync and the 6100 says nothing doing. If I change the type to VGA/SVGA (S1-S2 jumpered, S0 open), video output comes out fine.

Now, on to the speaker issues...

FWIW, attached is a PDF document concerning video connectors. It also exists as a web page, but occurrences of it seem to be vanishing. Best to keep a local copy.

njroadfan
June 18th, 2012, 04:14 AM
My own 6100 with a dead battery requires a PRAM reset to boot. Just leave adapters on the "multisync" setting, the 6100 is new enough that it supports SVGA video modes. The on-board video uses shared RAM, I think it takes 1MB tops. Some of those adapters have sync splitters in them and allow SoG monitors to work on new Macs, or H+V/composite sync monitors to work on old SoG machines.

Chuck(G)
June 18th, 2012, 07:36 AM
My discovery is that the 6100 doesn't support the type 17 monitor (S0=ground, S1-cathode, S2=anode). VGA/SVGA, type 14, S0=open, S1-to-S2) is fine. I use type 17 with my beige G3, but the same cable doesn't work with the 6100.

njroadfan
June 18th, 2012, 09:10 AM
I have a Belkin HDI-45 to VGA adapter laying around, yes there was enough demand to produce them apparently. I should compare the jumper table with my standard Belkin Mac to VGA adapter and see if its omitted.

Chuck(G)
June 18th, 2012, 10:07 AM
Booted MacOS 7.5.5 from the SCSI drive. Tried to browse this forum with MSIE 4.01--it was hopeless; the display was completely unreadable--IE simply couldn't render it correctly and was clearly straining under the load--it took almost 20 seconds just to close the window!

Any clues on the speaker issue? Any clue on which chip drives it?

Chuck(G)
June 19th, 2012, 05:36 PM
Okay, a bit more on the speaker. The traces are impossible to follow visually, as they're buried in the inner layers of the PCB. However, some probing turns out that they're connected to the output of U7 near the left rear side of the PCB, an SO8 TD7052A one-watt amplifier.

Next job is to see if the IC's getting power and the volume control pin is set appropriately. (Hmmm, is that setting kept in PRAM? Could it be that there's nothing wrong with the board? Just trying to think with my engineer's hat on.

Well, U7 is fine--I can touch a test lead to pin 2 and get a hum out of the speaker. And the sound isn't muted.

On to the next suspect. I've got a feeling that there's going to be a big facepalm moment in here somewhere...

Does the HD45 adapter need to loop the sound back if no monitor speakers are being used?

Unknown_K
June 19th, 2012, 06:01 PM
The default speaker setting is NOT mute, so replacing the dead battery would get you back to the default level which is audible.
I had a problem with a LC III where one bad cap killed audio (replaced it and all is well), same thing is common with compacts and other 68K macs.

Chuck(G)
June 19th, 2012, 07:31 PM
Eh, screw it. I'm spending too much time on a "Road Apple". It boots and runs--good enough, I guess.

I'm going to go blind tracing the circuitry on this thing--and then there's the wonderful :puke: Apple technical documentation that doesn't even mention what the various undocumented chips do.

I wonder if Mac sales came from unrepairable Macs being tossed in the bin. I've often wondered how many Mac users have used their system past the lifetime of the PRAM battery.

applefreak
June 22nd, 2012, 09:00 AM
often wondered how many Mac users have used their system past the lifetime of the PRAM battery.
most of them, i think
only replacing the pram battery is not enough - even, many systems don't need a (good) pram battery to boot -
at no boot
first things to do :
removing the ram/vram, cleaning the contacts, replacing the ram
removing and replacing HD's, floppy drives, .....
removing unnecessary extra cards
booting with extentions off (hold down shift key at start up)
PRAM-reset
CUDA-reset, if available

Chuck(G)
June 22nd, 2012, 09:12 AM
Okay, AF, why don't I get sound on my 6100/60? (I don't even get the startup chime). PRAM battery's new, the PRAM's been reset, system boots and runs, but no sound, ever.

ryan42
July 2nd, 2012, 10:33 PM
Check the speaker output port. I believe it mechanically disconnects the audio from the internal speaker so if it's damaged that might be the issue.

Chuck(G)
July 2nd, 2012, 10:39 PM
Speaker is fine--as noted, if I touch the input pin to the audio amp I get a buzz from the speaker, so it's connected. Al K. has given me some of the pinout information on the AWACS chip, so I'm going to get my 'scope out and see what I can see...

Juror22
July 16th, 2012, 09:34 PM
I have a 7600 that had similar symptoms (a 'little' different model and it had an upgrade card installed). I swapped the plain cpu card back in and after that it booted fine, I reinstalled the upgrade card and it was still fine. The upshot of this is that while you are reseating items, reseat the CPU card as well, since I am pretty sure that was the deciding factor. I also did all the standard recommended items before I got to that point (pram, battery, reseating everything else, etc.).

- Juror22

Chuck(G)
July 16th, 2012, 09:50 PM
No CPU card installed--still has the plain 60MHz PPC 601 on the motherboard.

applefreak
July 16th, 2012, 11:19 PM
why don't I get sound on my 6100/60?
leaking capacitors ?

Chuck(G)
July 17th, 2012, 08:14 AM
leaking capacitors ?

Checked every single electrolytic and tantalum on the board. No issues.

applefreak
September 26th, 2012, 12:27 PM
if the sound controller is set to zero,
the next time you power up te mac there is no sound at startup

see the sound controller in control panels

-----
sound
try with external speakers

patscc
September 26th, 2012, 01:12 PM
That setting would be buffered by the PRAM, no ? So pulling the battery would clear it.
Chuck(G), I think they're a typo earlier, you mean TDA7052 , right ? Do you see anything on pin 2 during startup with your scope, and is pin 3 actually grounded ?
patscc

Chuck(G)
September 26th, 2012, 07:05 PM
Pat, I shoved the system back in the pile and don't recall much. The audio amplifier chip was working and I lost interest in getting the audio to work after that. I mean, geez, what am I going to do with the thing?

patscc
September 27th, 2012, 05:35 AM
Use it as a monitor stand ?
At least this thread reminded me that I have some 1 W 8-pin amp chips floating around. I'm not 100% sure they're TDA7052, but if they are, it would make more sense that I hung onto them, since they're pretty useless otherwise. Personally, I think it's cheap to put out a machine that does stereo, and then use mono for the built in speaker.
patscc

Compgeke
September 27th, 2012, 11:38 AM
Just curious, were there ever any NuBus sound cards ever made that would provide you with sound after the OS is loaded?

Chuck(G)
September 27th, 2012, 02:17 PM
There was an NuBus AV addon for this model, if that's what you're asking.