Macintosh Performa 5200CD

[joshc]

I do indeed still have it in pieces, in fact more pieces than last time I posted.

It's a Rev A - the speakers are not in their own housings.

Everything in this machine has a coating of thick dust. The analog/video boards seem to be the worst affected.

I wasn't expecting this machine to be quite as much of a faff to take apart as it is, there are so many connector cables, separate boards and separate pieces of RF shielding in this machine...

OK, so after a little bit of foul language, the analog and video boards are out...



And after cleaning...



I forgot to take a photo, but the rear of the video board wasn't messy, but there was some yellow residue around the solder joints, which I cleaned off with IPA.

So far, I haven't seen anything which would suggest there are problems with the capacitors on either of these boards -- so I am starting to wonder what might be causing the CRT issues. Obviously you cannot always just tell by looking at the components and there are many components that can fail other than just capacitors, but I actually don't know where to even start with this...I know someone mentioned about the flyback transformer possibly having issues because of dust but that part wasn't that dusty.

This is before I removed the video boards and did any cleaning...



Gradually getting emptier.... This is after brushing all the dust off the yoke/CRT assembly - I tried to be gentle with these parts as they look very fragile indeed!



It looks quite cool from the front with the bezel removed, just looks like a TV...I actually prefer this look 8)



I gave up trying to remove the CD-ROM drive, and yes I did break the plastic tab - the floppy drive came out easily and is full of dust.

 

[Trash80toHP_Mini]

Nice mess!  :approve: So which connectors/wires head from the A/B down to the FOXCONN Logic Board connector harness setup?

 

[joshc]

Nice mess!  :approve: So which connectors/wires head from the A/B down to the FOXCONN Logic Board connector harness setup?

Sorry for the delay (and for initially missing that question) -- I might get some time at the weekend to look at this project again!

 

[Trash80toHP_Mini]

Supergreen, some high res pics of the A/B so I can read the legends on the ICs to ID of the Amp(s?) would be much appreciated. Especially important would be the area surrounding P803, the speaker connector.

View attachment 29838

My current thinking would be that left and right channels are discrete connections on the harness and are are tied together on the Audio/Monitor Connection Subassembly in the Q630-6500 series pictured below, but not listed as a part as it is in the tower versions? I'll have to buzz that on both versions.

Has anyone got both versions of this machine? I'm wondering if the housings make a noticeable difference in sound quality? In Rev. A, metal chassis and plastic case parts appear to have functioned as a housing, but Apple went to the trouble of tooling two parts for each complex speaker housing to fill that cubic in Rev. B. I always liked the sound of the housed speaker in desktop machines. If there's not much of a difference, that'd be too easy, there's all kinds of cubic available for mounting a speaker without the housing between Front Panel.Control Board 661-0139 and PSU. Left speaker would be mounted on the left side in the same position. pointing out that side of the case. It looks like there might be just enough room in the Q630 sheet metal between floorpan and underside of the Chassis Shield 922-1154 to poke the housed speaker out in the same position. Methinks sound wouldn't be all that great without the ad hoc chamber of Rev. A or plastic housing of Rev. B if Speaker 922-1175 housing is left out of the mix.



Note that the FOXXCON wiring harness above isn't illustrated/listed as a part in the AIO versions. That's similar to the towers where it is illustrated w/o the part number as it was bundled with the entire metal chassis replacement part! The same appears to be the case in Powermac.Perf_5400.5500, the exploded diagram for which appear to be the same, only the part number were changed to  pro  confuzzle things. I'll need to check that out too. :huh:

View attachment 29834

View attachment 29835

Hope you don't mind the comparison/detail graphics and commentary. I'm tempted to add a screen shot of the exploded diagrams of the tower versions so we have everything in one place? I find this stuff fascinating anyway.  []

edit: didn't notice it before, but only Chassis Assembly (Rev. B] 922-2043 is listed as a replacement part. That makes me wonder about differentiation between Revisions for the part?

 

[Trash80toHP_Mini]

More info on what I'm looking for in your new pics when you get a chance to do more documentation of your Rev. A system:

Took a break and finished up taking pictures of the Audio/Monitor Connection Subassembly PCBs of the 630 series and the 6x00 machines. Searching IC legends yield Op-Amp (Operational Amplifier) hits. TI's LM386 Low Voltage Audio Power Amplifier comes up at every turn. Basic operation seems to be tying left and right channels together for amplified mono output? Not a clue here, gotta buzz connections there to see what might be going on.

In addition to the 630 and 5xx0 series front panel sound-control push buttons, the towers have a subwoofer balance control added to the backside. Guessing that's gain control on the IC? It's set at 20 normally, but variable resistance gives a gain range of 20 to 200. Dunno about the older IC in the PDS machines, all that's way too techie for now, theory is you'll find a pair of Amp chips or a stereo Amp IC on your A/B as opposed top an Op-Amp? Clueless there as well.

I'm still looking at the converse of my 6x00 stereo output hack, strapping a Sub to the ass end of your 5200.  [}]

 

[Trash80toHP_Mini]

Took a break and buzzed some connections on the 6360/6290 +INPUT and -INPUT both run through a resistor, then a capacitor and out to discrete pins on the wiring harness. Op-Amp ties the two together and OUTPUT goes straight to one speaker pin. The other speaker pin is connected to GAIN (Pin 8 on the Op-Amp) and I'm clueless again there.

It appears that my guess that Left and Right Stereo Channels are present on the cable harness was correct. Each should head to a Stereo Amp or to individual Amps on your A/B? Oh so curious about that, but enough for now, what I use for a brain is in pain. :blink: