Help with a non powering Apple iie

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Help with a non powering Apple iie

Hello!

Although I'm new here I have been on the 68KMLA forums for a while. Anyways, I've mentioned this because the problem I'm having had also been discussed over on that forum, but since they're more 68K Mac oriented, help has been a bit scarce.  

https://68kmla.org/bb/index.php?threads/buzzing-noise-from-apple-iie-transistor.48497/#post-544983

 

So! My problem is, my Apple IIe won't turn on, and there was a buzzing noise coming from the transistor. Originally, the transistor was making a clicking noise, and the power led would blink on and off, then the clicking got faster and the led didn't turn on at all. Eventually the transistor made a pop and now nothing turns on it seems. I've replaced C15 and C17 with an equivalent 16V 10UF capacitor and still no dice.

 

Any thoughts? Thanks :)

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You either have a short in

When you say  "noise was coming from the transistor", what transistor are you referring to?

Are you talking about the power supply?

 

You either have a short in the low voltage section of the power supply or a short in one of the four voltage rails in the computer motherboard.

If it is a motherboard voltage rail short, then most likely it is in the +5volt rail.  

I would wager a guess, though, that if your machine was working properly before and it suddently stopped, that the problem is in the power supply itself.

But since your power supply is probablty toast now anyway, I would suggest getting another power supply, or better yet, buy a Universal Power Supply Replacement Kit from ReActive Micro.

I am not affiliated with RM nor am I earning money off of this advice, but the link is here:

https://www.reactivemicro.com/product/universal-psu-kit/

 

 

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baldrick wrote:When you say  
baldrick wrote:

When you say  "noise was coming from the transistor", what transistor are you referring to?

Are you talking about the power supply?

 

You either have a short in the low voltage section of the power supply or a short in one of the four voltage rails in the computer motherboard.

If it is a motherboard voltage rail short, then most likely it is in the +5volt rail.

yes, the power supply. Where is the low voltage section of the board? Another thing, you say the psu is likely toast, is that true? I wouldn't mind buying the new psu you recommended, but if it's possible to replace a few diodes, I'd do that as well. I've replaced C9-17 on the motherboard, which didn't fix the problem.

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The low voltage section is

The low voltage section is the section after the switching section that regulates the +/-5 volts and +/-12 volts.  It is on the output side of the power supply.

I would recommend if you don't have a good knowledge of how the power supply works to simply replace it altogether, rather than throwing parts at it.

 

I can't elaborate further or offer any more repair advice without knowing if you have an Astec power supply or a DynaComp power supply in your IIe.  

 

My advice for the universal power supply replacement kits stands regardless of which power supply you have - the kit will work in both.

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baldrick wrote:The low
baldrick wrote:

The low voltage section is the section after the switching section that regulates the +/-5 volts and +/-12 volts.  It is on the output side of the power supply.

I would recommend if you don't have a good knowledge of how the power supply works to simply replace it altogether, rather than throwing parts at it.

 

I can't elaborate further or offer any more repair advic

Whoops, it's a Dynacomp

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Anonymoose wrote:Whoops, it's
Anonymoose wrote:
Whoops, it's a Dynacomp

 

Then get rid of it! It's a cheapified version of the ASTEC which is a tank. The Dynacomp is crap, at least that's my $0.02.

 

Your problem very likley can be fixed, but it's clear you don't know what you're doing so that will be an uphill trek. Safest for all to just say get something else.

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Anonymoose wrote:Whoops, it's
Anonymoose wrote:
Whoops, it's a Dynacomp

 

 

If you don't yet have the knowledge and/or equipment and want to save the original PSU, you can always try a recap. 

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Anonymoose wrote:Whoops, it's
Anonymoose wrote:
Whoops, it's a Dynacomp

 

 There is very little information about Dynacomp supplies out there.  I don't have a schematic for it, and I know from experience that when they fail it's often with the feedback optoisolator section and repairing that is tricky.

I treat Dynacomp power supplies as disposable units.

That said, I have a working Dynacomp PCB in my spares pile that I removed in favour of a Universal PSU kit.  

Message me if you want to buy it.

 

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Dynacomp PS untrustworthy
baldrick wrote:
Anonymoose wrote:
Whoops, it's a Dynacomp
I agree with Baldrick and in general with others in this thread.  Dynacomp PS seem to be not only less common , but far less reliable and trustworthy tha ASTEC PSs.  The manner in which you have asked the questions in this thread indicate you don't have a lot of knowledge related to PS repair and it can be dangerous.  Furthermore, stable power is a necessary basis for more advanced troubleshooting.  I love the modern RM replacement PS and own several, especially if I'm going to load the machine with 4+ interface cards.  It slides right in the original case and nobody will ever see it and you would be confident you have reliable power. I second replacement rather than repair in this situation.
 
 
 
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