Hey Team,
So I just finished cleaning my Color Classic boards that were very dirty in the ultrasonic cleaner and now when I go to boot them neither boot!
Symptoms:
- Power Button on KB works for both of them
- HV turns on and display turns on with the grey background
- No Chime
What part could the cleaner have broken? I have replaced the crystals and the roms were not present during cleaning. Are there any parts that are particularly suceptible to the ultrasonic?
Any help would be great!
Did you allow the boards to touch the bottom of the tank? That should be avoided as it puts a huge amount of vibration into the board.
Ultrasonic cleaning works by cavitation: small bubbles are created and collapse, blasting debris from hard surfaces. Vibration of the workpiece is an undesired side effect and must be minimized. Cavitation can be a very powerful force: it can even produce temperatures several times the surface of the Sun, as seen in sonoluminescence.
Besides crystals, ceramic capacitors could also be negatively affected by vibration. They might have developed shorts which would show as a low resistance (< 10 Ω) or beep with a continuity tester. It is also possible to damage IC bond wires with vibration.
Nope they sit in a basket a couple of inches off the bottom. I will check some ceramic caps next I guess. Hopefully its not an IC!
Did you remove any/all of the socketed chips? Leaving them in allows the solution to build up in the sockets and that could cause damage. I am assuming you used distilled (ionized) water and not tap water? What cleaning solution did you mix with the water?
Hopefully if you did damage an IC is isn't an ubobtanium one like your SWIM or one of the other custom ASICs.
Yup all socketed chips were removed beforehand.
And used de-ionized water with Shesto UTFLU05 flux and pcb cleaner from Element 14. Let everything dry for 4 days as well.
Thats what I am hoping for as well. Going to reflox some chips and see if I find any bad solder joints.
Something weird happens with the power on these... Leave it plugged into the wall for a day or so and try it again.
A bit of an update. I got 1 of the 2 boards going. It was bad connections on the ram chips. Figured it out after putting in the external ram sticks and it chimed. Reflowed it and its now away.
There is still an issue with the analog board ( the original fault ). Can anyone tell me where a test point is for the B+
I have a working board and want to compare them to see whats going on.
It's amazing how many people talk about "B+" but no one clarifies what it is, and that leaves folks like yourself wondering. Well, I'm please to report B+ is one-in-the-same with the "Horizontal Deflection Voltage" as specified by the Japanese publication, Doping Mac (printed in 1997, it kick started the CC modding crazy in Japan). They never refer to it as "B+" but basically it is the high DC voltage line. It comes through transformer ZP1 and the AC voltage gets rectified by half-wave rectifier silicon diode DP4, a smoothing capacitor, and then goes out choke LP5.
While you could measure at the output of the LP5 coil, I recommend a point closer to the edge of the Analog Board so you don't have to precariously put your meter's probe deep into the machine while its powered. The best place I've found is jumper J66, which is right next to the flyback transformer. J66 looks like a very wide staple. Just put the tip of your meter probe into one of the holes to secure it and put the other meter probe to chassis metal ground.
I currently have the VGA Mod installed. Nominally, it is supposed to be 68.4Vdc, but at J66, I measure a slightly higher 70Vdc. That is with the machine booted. If you shutdown but leave the back power switch set to ON and then measure, you will measure something on order of 79Vdc.
Hi JDW,
The term B+ goes so often without comment because it is very old. In the early days of radio, once vacuum tubes like the Audion were developed, there were multiple voltages that were needed to operate a radio set. The filament heater needs a low voltage, from 1.5 to 7.5 VDC, and the plate or anode needs a higher voltage from 45 to 90 VDC. The grid also needs a bias voltage from –1.5 to –9 VDC. These voltages were supplied by special types of dry batteries called "A", "B", and "C", respectively. Later on, it became more common to use power supplies operating on AC line voltage, which were also called "battery eliminators" (a term that continued to be used for decades, sometimes interchangeably with "power supply"). But the schematics continued to use symbols like "B+" (the positive terminal of the B battery) for plate voltage.
In a tube-based TV set, the horizontal deflection yoke operates from the B+ voltage, to the plate of the horizontal output amplifier tube such as 12BQ6. The same B+ notation then carried over to transistorized TV sets, thenceforth to CRT computer displays.
I am aware of the vacuum tube history and the three batteries named A, B and C. But my point was that whenever people these days talk about B+, they need to make clear WHERE they're talking about on the schematic or PCB they are making reference to.
I spent many hours reading forum posts written by people who are working on their Macintosh Color Classic and they mention B+ without specifying where on the analog board they're talking about. There's absolutely no meaning for somebody to say, "measure B+" and then expect the reader to know exactly where to measure that! The specific point being talked about on the PCB is not common knowledge! And I know it's not common knowledge because when I start asking people what is being referring to when they say "B+", nobody can answer me. So I'm stepping forward to tell people you need to specify an exact leg of a component or jumper when you're using labels like B+ in order for your reader to understand you.
In the case of the Macintosh Color Classic's Analog Board, the place I recommend to measure B+ is jumper J66 (metal stample on the upper component side), which is adjacent to the flyback and near the edge of the PCB. Although you could technically measure at the source, which is in the vicinity of diode DP4's Cathode, it is safer to measure at J66 because the machine needs to be on when you measure it and J66 is easy to access at the edge of the board.
Those are important specifics that tell the reader where B+ is found in that particular board.
The reason this discussion is important is because people do the VGA mod or the 13 inch high resolution mod which require changes to the voltage level called B+. The Japanese book Doping Mac never calls it B+ but instead calls it the Horizontal Deflection Voltage. But that is B+. They are one and the same.
More specifically, the secondary windings of Transformer ZP1 send AC voltage to silicone diode DP4 and its smoothing capacitor for halfwave rectification, and it becomes approximately 60Vdc for a stock CC Analog Board, or about 68.4V for a board with the VGA mod, or close to 84V for a board with the 13" Hi-Rez mod. That voltage leads to the flyback and is called B+. And now that I've just told you exact points on the Analog Board, the location of B+ is 100% clear.
So what I'm telling you right now is the point I was trying to make. We need to be specific when we talk about B+ and not just throw it out there and assume people know exactly what we're talking about on a given analog board, be that a Color Classic or Sony Trinitron CRT monitor. Even if they know the vacuum tube history, that doesn't help the reader when you're talking about a specific circuit board and the need to measure on it. It's not good to assume the reader knows the exact location of B+ because most don't. That's all I was trying to say.
I generally clean boards with rubbing alcohol and q tips...never ran into any problems.
You definitely don't want to be too overzealous cleaning, especially if something is working!
I agree!
It's always going to be in a different place on every device, which is why referring to the specific schematic is the best course of action. Otherwise, the directions will not transfer to other similar devices, even if they use nearly identical circuits.
White that is true, it is simply not possible with the Color Classic ANALOG BOARD because there is no such schematic available.