• Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.

Recent content by wally

  1. wally

    Lombard/Pismo Batteries

    All of the 4 Pismo batteries I have examined use the Benchmarq, now TI, bq2040 Gas Gauge IC.  In addition there is a Seiko S-8233A Battery Protection IC and a series switch, an NEC uPA1712 MOSFET.  And I think possibly a chemical fuse that gets blown if the voltages or currents sensed get too...
  2. wally

    Capacitor confusion

    You read that correctly. Notice how there is a message with some of the different caps with what current they picked to run the endurance testing. The 321 mA cap has really big hours rated, but be assured that if run at an amp or more of switching supply ripple (commonly encountered in power...
  3. wally

    Capacitor confusion

    Even unabused conventional liquid electrolytic capacitors made by the most reputable manufacturers degrade by loss of electrolyte. There is some gradual loss by evaporation past lead seal(s) even when idle at room temperature. Loss is compounded if seals are thermally abused by soldering...
  4. wally

    Repairing iBook Yo-Yo Adapter

    The one yoyo I have opened was not easy and somewhat risky to the clear plastic top. Controlled prying between the clear plastic top and the white plastic just below it is needed to break a solvent weld. Tool should be wide enough to spread the force somewhat. Some of the clear plastic may...
  5. wally

    Beefier Power Supply for SE/30

    Guide to the Macintosh Family Hardware, Second Edition has more extensive power supply specs for the SE/30 on pages 259-260 that relate to this discussion. In particular on page 259 there is a peak load specification for disk seek servo current on the +12 V disk (4A, with certain duration and...
  6. wally

    Value of L2 on SE-SE/30 Analog Board?

    Needs some experimentation. If two cores are mated there is still a small gap plus chamfer taper of effective cross section at the meeting ends so we can't presume exact equivalence to a single seamless length of powdered iron. The width control has to be able to compensate for variations in...
  7. wally

    Value of L2 on SE-SE/30 Analog Board?

    Major correction! This morning I read my last post again and decided to repeat my measurement of resistance which seemed to me to be too high given the wire size. Turns out in going to post yesterday I did a decimal point error. Sorry, here is the corrected post and value: .066 ohms...
  8. wally

    Value of L2 on SE-SE/30 Analog Board?

    .66 ohms, determined by four terminal measurement of .657 volts across coil component side solder joints while one amp was flowed thru PC solder side terminals. Most people with this problem already have perfectly good copper windings on perfectly good coil forms, once that pesky but quite...
  9. wally

    Value of L2 on SE-SE/30 Analog Board?

    Measurements of an undisturbed, good and properly adjusted L2 in an SE-30 (with yoke plug disconnected, of course): 25 uH. This unit has a black core, 1 inch long; .6 inches remain outside the copper winding area and .4 inches are inserted into the winding area that is about .550 inches long.
  10. wally

    Value of L2 on SE-SE/30 Analog Board?

    Some time ago prompted by some previous posts on jammed width control cores I started to experiment on a scrap analog board I just happened to have, and very quickly cracked and jammed my core quite badly into many fragments while using the correct size alignment tool. After some appropriate...
  11. wally

    MacCon SE/30 ethernet SMD components

    SMD multilayer ceramic capacitors are sometimes marked with two digit EIA code for capacitance value. A5=.1 microfarad. See http://my.execpc.com/~endlr/markings.html for SMD ceramic cap markings. Probably these are capacitors, especially if their positions are marked on the PC board with C...
  12. wally

    Xceed Memory Width and Other Finicky Details?

    Years ago I had to make a cable to get mine to work. After some research, I found that US patent 5,307,083 had most of the necessary information for the cable, and also contained a very informative theory of operation.
  13. wally

    Xceed Memory Width and Other Finicky Details?

    I have only access to a Color 30, not the Color 30HR which has a different video spec. The Color 30 model has a limited video spec, 640x480, 8 bits max pixel depth or 640x870, 4 bits max pixel depth. On the Color 30 board, the memory is four Micron Technology MT42C8128DJ-8.
Top