baz@cbnewsk.att.com (Bruce Zenel) (07/12/90)
I need some hardware help. I turned on my Mac Plus today and all it did
was click. No beep, no screen, it just repeatedly clicks.
I have a feeling that it is the flyback transformer, which I've read about
in the past.
Is there any way to replace this myself? Is there a replacement
transformer that I can buy somewhere? I have no problem with desoldering
a piece and putting in a new one. Every Mac shop I have talked to today wants
to replace the whole analog board, which is a real waste.
Any help would be appreciated.
Bruce Zenel
Uucp: att!lzsc!baz
Internet: baz@lzsc.ATT.COM
--
Bruce Zenel
AT&T Bell Labs
(201)576-2853
Uucp: att!lzsc!bazwerner@cs.utexas.edu (Werner Uhrig) (07/12/90)
analog board repair is more than just swapping the flyback (sometimes it is even less :-); sometimes it is only cold solder, sometimes it requires replacing a couple of caps, too ... here is my official recommendation again: 1) check for cold soldering on the connector for the cable to the yolk for the 'smoking' (and smelling) cap 3) if you can see sparks at the flyback, you know that's not right ... 4) if you are endangering your life by doing 1 to 3, you are probably not getting to 4 ... 5) call a place that does repair mail-order, my recommendation (because he is local) is Rick Allphin at Omnitek, phone (512) 345-4339 expect to pay between $50 and $80. I never heard of a repaired board break down again ...
briand@tekig5.PEN.TEK.COM (Brian D Diehm) (07/12/90)
> I need some hardware help. I turned on my Mac Plus today and all it did >was click. No beep, no screen, it just repeatedly clicks. > I have a feeling that it is the flyback transformer, which I've read about >in the past. Probably the wrong conclusion. The flyback transformer would prevent the display from lighting up (or it would be a very narrow vertical line). It would NOT prevent the processor from operating normally, and thus it would NOT prevent the bell from dinging. -- -Brian Diehm Tektronix, Inc. (503) 627-3437 briand@tekig5.PEN.TEK.COM P.O. Box 500, M/S 47-780 Beaverton, OR 97077 (SDA - Standard Disclaimers Apply)
gordon@milton.u.washington.edu (Gordon Davisson) (07/12/90)
In article <1990Jul11.194216.1939@cbnewsk.att.com> baz@cbnewsk.att.com (Bruce Zenel) writes: > I need some hardware help. I turned on my Mac Plus today and all it did >was click. No beep, no screen, it just repeatedly clicks. > I have a feeling that it is the flyback transformer, which I've read about >in the past. > Is there any way to replace this myself? Is there a replacement >transformer that I can buy somewhere? I have no problem with desoldering >a piece and putting in a new one. Every Mac shop I have talked to today wants >to replace the whole analog board, which is a real waste. > Any help would be appreciated. It probably isn't the flyback. Flybacks don't fail nearly as often as their reputation would suggest, and when they do, they usually don't cause the symptom you describe. The ticking you're hearing is the power supply resetting itself due to incorrect loading. The most common fail- ures that leads to this symptom are the GI854 diodes at board locations CR1 and CR5; they tend to short themselves out, and overload the power supply. You can test for this by pulling the diodes and looking at them with ohmmeters (be sure to remember which way around CR1 goes). You can get repair parts (diodes, flybacks, and pretty much anything else you'll find in a Mac) mail order from Soft Solutions: Soft Solutions 907 River Road, Suite #98 Eugene, OR 97404 (503) 461-1136 -- Gordon Davisson Westwind Computing (206) 632-8141 4518 University Way NE, Suite 313, Seattle WA 98105
hawley@adobe.COM (Steve Hawley) (07/12/90)
In article <1990Jul11.194216.1939@cbnewsk.att.com> baz@cbnewsk.att.com (Bruce Zenel) writes: > > I need some hardware help. I turned on my Mac Plus today and all it did >was click. No beep, no screen, it just repeatedly clicks. > I have a feeling that it is the flyback transformer, which I've read about >in the past. > Is there any way to replace this myself? Is there a replacement >transformer that I can buy somewhere? This clicking is from the speaker and might not be related to the flyback transformer. The Mac Plus has some ciciutry in the power supply to check if the power is at an acceptable level to run the beastie. Anything out of this range and the machine will click and not power up. This is a diagnostic. To fix/adjust this: Open up your case, set the mac on something insulated, plug it in and turn it on. It will start clicking. Look at the side of the power supply board with paper on it. There should be a label that says "Voltage Adjust" or something similar that is right by a trim pot. Get out a screw driver and turn this until the machine boots (you might want to mark its original position first). I had a similar problem when 2 meg was put into my old plus. The power supply just couldn't cope because of how much current the memory was drawing (the machine was being upgraded from a 512K to a plus at the time). The service being did exactly the steps above with the exception that he also connected a fluke volt meter first to measure what the voltage was first which was about 4.2 volts in my case -way too low. Steve Hawley hawley@adobe.com -- "A blow on the head is... ...worth two in the bush." -Basil Fawlty
cramer@sun.com (Sam Cramer) (07/13/90)
In article <4985@milton.u.washington.edu>, gordon@milton (Gordon Davisson) writes: >You can get repair parts (diodes, flybacks, and pretty much anything else >you'll find in a Mac) mail order from Soft Solutions: > > Soft Solutions > 907 River Road, Suite #98 > Eugene, OR 97404 > (503) 461-1136 I recently dealt with Soft Solutions and highly recommend them. Another item that they carry is "Macintosh Repair and Upgrade Secrets," by Larry Pina, which goes into lots of detail regarding diagnosing and repairing Mac analog boards. It is excellent, and should be considered to be the "FM" that you are referred to when you have MacPlus/SE hardware problems. Sam
werner@cs.utexas.edu (Werner Uhrig) (07/13/90)
> There should be a label that says "Voltage Adjust" or > something similar that is right by a trim pot. Get out a screw driver and > turn this until the machine boots (you might want to mark its original > position first). do NOT use a (metall-)screw-driver! Radio-Shock sells a color-TV plastic tools set for $3 ($2 on sale) or you can use a home-made gizzmo with a flat end made of plastic or wood (I've used cherry sticks, those wooded sticks girls use to do their nails ...:-) you also should not do this without a voltmeter attached somewhere (the goal is to adjust the 5-volt-level as exact as possible; ignore the 12-volt level completely) like a DB-9 port, pins 2, which has 5v and 1 or 3, which is ground (I know this is not the best place to get exact readings, but, hey, I'd like my neophyte net-friends to be around a while longer ... :-) pin 6 and 7 of the cable linking the analog with the motherboard also have 5 volts and ground .... (there. kill yourself or your motherboard :-)