SEWALL@UCONNVM.BITNET (07/04/87)
Before getting to the main topic: I tried to answer Steve Sloan
and got the mail back from the "Deamon." What it said was that
sloan@cadovax.uucp is an "unknown user." Did I spell something
wrong (unfortunately, I discarded the original request). The
messages will hang around in my in basket for a few days; I'll
resend if I get a correct address from bitnet.
POWER SUPPLIES
Funny you should mention that. Tom Weishaar has a LONG answer
to a letter on that very subject in the July Open-Apple (p. 3.45).
The gist of it:
Symptoms: stange characters on the screen at, evidently, random
intervals. Unexplained trashing of track zero. CPU hangs that
won't replicate. Often "fixed" by removing a card or two. The
TransWarp accellerator and Central Point's 3.5 disk controller
are 2 power hungry cards that often are blamed.
Replacement power supplies (bad news generally)
Although they have higher ratings than the original Apple units,
experience indicates that have significantly shorter life spans
than Apple's. All of the sources (listed below) actually are
selling Taiwanese units that vary in quality from shipment to
shipment. That is, you may get a very good one and be extremely
happy. I expect some of the messages posted here have already
puzzled a few readers as being quite different from their own
experience (both better and worse).
Apple's power supplies have two ground wires running to the
motherboard. Some (not all) of the Taiwanese clones only have
one (beware those especially as the single ground wire models
have some other problems that may lead to failure to properly
ground the motherboard).
Suppliers (prices as of June 12)
"Heavy"
duty
Applied Engineering (214) 241-6060 $69
P.O. Box 798
Carrollton, TX 75006
BTE Computers (602) 867-8962 $59 (regular for $44)
14644 N. Cave Creek #6
Phoenix, AZ 85022
Jameco Electronics (415) 592-8097 ?? (regular for $35)
1355 Shoreway Rd.
Belmont, CA 94002
JDR Microdevices (408) 866-6200 $50
110 Knowles Drive
Los Gatos, CA 95030dryfoo@bloom-beacon.UUCP (07/07/87)
I have recently purchased a power supply from BTE: BTE Computers 14644 N. Cave Creek #6 Phoenix, AZ 85022 (602) 867-8962 $59 (regular for $44) I bought the $44 model, which still had twice the amps of Apple's own. It also had only one ground wire. It also had an interesting flaw. The symptoms: a startup disk (AppleWorks or any DOS or ProDOS disk) would boot just fine, but typing any single keystroke gave many repeats of that character. Since I was replacing a burned-out power-supply, I feared that some keyboard chip had fried. No chip replacement could solve the problem. We finally, in desperation, plugged in a spare Apple supply. No problems! Everything was fine. Why? I tested the voltage on all four lines from the BTE supply (a Seasonic) and found that the two negative lines (-5v and -12v) had been reversed in the plug. I called BTE, and then sent back the supply, along with two copies of my diagnostic report and the unit's serial number. They sent me another supply via UPS Blue label (next day service), which is the way I'd ordered the original one. The new one is not a Seasonic (I don't see any brand name on it) and the housing looks different. In any case, it works just fine. They are very friendly on the phone, and anxious to avoid hassles. Evidently, importing Apple power supplies is NOT their main line of business, and they don't want to have to spend a lot of time mollifying unhappy customers. In short: I am glad I did business with them, and I hope they used my diagnostic report. By the way, what is the problem with only one ground wire?
kamath@reed.UUCP (07/08/87)
In article <1086@bloom-beacon.MIT.EDU> dryfoo@athena.mit.edu (Gary L. Dryfoos) writes: > >By the way, what is the problem with only one ground wire? The main problem is that some components on the motherboard are not properly grounded, leading to minor errors and/or major ones. AS noted, I am going to wait for mine to die before I replace it. Also, when a friend of mine's power supply died, he bought a new one and gave me the old one. I took it apart and saw that the fuse had blown in it. It's an awfully tiny one, but it so happens that the Imagewriter spares kit has a fuse about the same size. I replaced it and it seems to work just fine. I think it was due to flipping the on/off switch to rapidly (yeah, I'm the one who fried it :-(), and this caused the fuse to overload. Moral of the story, you can fix a power supply (but DON'T tell 'em who told you you could) and don't cycle the on/off switch too fast. Sean Kamath -- UUCP: {decvax allegra ucbcad ucbvax hplabs ihnp4}!tektronix!reed!kamath CSNET: reed!kamath@Tektronix.CSNET || BITNET: reed!kamath@Berkeley.BITNET ARPA: tektronix!reed!kamath@Berkeley <or> reed!kamath@hplabs US Snail: 3934 SE Boise, Portland, OR 97202 (I hate 4 line .sigs!)