Mac Plus high pitched whine

[tanaquil]

My Mac Plus makes a high-pitched singing noise/whine. It is subtle enough that it took me a little while to realize where the noise was coming from. It generally starts a minute or two after starting up the computer; if I leave the computer on for a half hour or so, it goes away.

No unusual smells or anything, and everything is functionally working as expected. Neither logic board nor analog board has been recapped, so either might be suspects. It happens regardless of whether I have an external hard drive attached, so it's definitely internal to the computer.

Thoughts? This machine is due for recapping, but I'm curious to know what I should do first.

 

[BadGoldEagle]

Page 15 from Larry Pina's The Dead Mac Scrolls:

Symptoms: Occasionally, the computer makes a high pitched whining noise (like a mosquito). Otherwise it seems OK.

Probable diagnosis: The problem is on the analog board.

Solution: Replace the flyback transformer (Apple part 157-0026- B) at board reference T1 with later type (157-0042-C)

Can you tell us the part number on your flyback transformer?

The high pitched noise usually indicates a flyback transformer failing. But you should wait other's advice before replacing it!

 

[drybones99]

A similar problem happened to me a while back. If you don't replace the flyback transformer as soon as possible, there is a high probability that it will fail. That whine means that it is just about to fail. If it fails, it will take some other parts along with it, so if you don't want to replace more than one part, which requires lots of soldering, and some troubleshooting, I would recommend replacing the flyback. Does your screen occasionally jitter, and do the sides of the screen bounce a bit? You can buy a replacement flyback on eBay for about twenty dollars, but having the correct model is important. The model number should be written on the transformer itself. 

This list should be helpful: https://docs.google.com/spreadsheets/d/132RwzC8HM5ask-BdY_31txErOCwJDSkz099GY2XLpE0/edit?hl=en&pref=2&pli=1#gid=0

The flyback transformer is board reference T1.

 

[BadGoldEagle]

So the flyback is dead. You can replace it with a later type. Version C is better.

 

[uniserver]

http://www.ebay.com/itm/157-0026B-Flyback-1570026B-Replaces-Apple-HR-42031-/400922654856?hash=item5d58da3888:g:xs4AAMXQgwNSJyrC

wow shame last one at 23 bucks free shipping.. from there the prices just go up.

 

[tanaquil]

Thanks all! What makes version C better than B? I see the last one at $23 is a B version, looks like there are several C version for about $30.

I will check my machine when I get home tonight for the part number and order accordingly.

 

[uniserver]

the b does not have an internal bleeder, pretty sure there is a bleeder externally on the AB////  just the ones with internal bleeders, bleed down fast... like 15-25 seconds fast.   but that is the only difference.

 

[uniserver]

it doesn't matter though...  I always Discharge the tube every time anyways no matter what, its a good habit to get into.

 

[techknight]

the ring is a loose core. You can probably wiggle it. But the cause is glue breakdown from constant usage in the past. 

 

[tanaquil]

Checking back in on this thread:

I finally (finally!) had a chance to open up my Mac Plus and look at the label on the flyback. It is currently a 157-0042-C model.

From reading up a bit, I understand that 157-0042-C is theoretically superior to the older 157-0026-C, although both have bleeders. The only 42 model (of any kind, that I'm aware) on ebay is currently 157-0042-B for $50 plus shipping. There are several 157-0026-C for $30 free shipping. (And a 26-B for $23, but I'm willing to step up for the bleeder, which 26-B doesn't have.)

I don't object to paying the higher price if it is really important, but can I get away with the cheaper item (that is, 157-0026C) and still do just as well? I just wanted to check before committing to a purchase.

 

[uniserver]

personally i always go for the cheapest… as far as using the word superior ..lol     i mean its a coil of wire….   So you get one for 23 and it takes 3 minutes to bleed down instead of 25 seconds…    The only thing that really got these flybacks is heat. the better ventilated the longer your flyback is going to last...

that is why you rarely get a Mac SE with a dead flyback...

sometimes you can pick up a used SE analog board on ebay for less then a flyback its self and its alrady got the upgraded C flyback.. and updated rectifier and regulator that you can all use to fix your 128k-plus ab.

here is a whole SE superdrive unit for 29 bucks….  buy it now… and you know the parts on the ab are good.

at least i would trust they are. -- probably just has a dead PSU,  the PSU in my se/30 test machine died last night…. lol  

what good timing…  the caps in that thing were toast… nasty leakers. was a freakin mess...

http://www.ebay.com/itm/Vintage-Apple-Macintosh-SE-Superdrive-All-in-One-PC-M5011-68000-8MHz-parts-/381629103717?hash=item58daddfe65:gtMAAOSw2x1XJ6oy

 

[techknight]

I just did a video on replacing the caps in an SE/30 sony power supply. the 2nd part of a series on restoring an SE/30 from the ground up. I need to find time to upload it. My bandwidth is shared with another cabin so that gets tough sometimes. 

they do go. it really depends on how heavily it was used though, thats what I am finding. The machines with the most flyback cookage, and burn-in have the worst caps in the power supply. 

 

[tanaquil]

Good point! There is shipping too but I should consider it. Parts is parts.

I just bought an entire PB 160 (bad screen) just to get the I/O cover that is so hard to find. Hey, it was $25 shipped, and the only parts source I have been able to identify sells the I/O covers for $91 plus shipping. The danger is, once I have a machine I've robbed for parts, I start wanting to repair/restore the parts machine. It's never ending!

 

[techknight]

I had the same issue with parts machines, But I eventually convinced myself to stop. I have the machine for parts, and THATS IT. its hard, i know. 

 

[Johnnya101]

I know this is an old thread, but thats an awesome list and I had o idea they still sold new flyback for compacts! With lots in stock too! Gonna have to stock up at some point.