Stu's Onix

laatsch55

laatsch55

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It doesn't sound like babble to me and you know way more about some stuff than you let on. you are absolutely correct about the -volt supplies, it does cool down after the spin motor shuts down, i have swapped Platter/laser assemblies twice and I get the same results. When the heat gets to a certain point I swear i can hear some "wow" and flutter going on, very slight but its there.
 
laatsch55

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All out going voltages are on separate harness plugs, so that should be doable!! Why haven't you spoke up before, this is a big help, thanks Robert, as I've said before, i wouldn't make a pimple on a real tech's butt, but I learn fast.
 
rtp_burnsville

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If the regulator is one of those three terminal IC's most have a thermal limit built in which can create some interesting side-effects..... The Wow and flutter effect could very much be happening, more likely an oscillation, sorta like on-off-on-off....... Can you see anything on your scope?

Do you have a stash of known-good-assemblies?

I am not really a tech but have played being a hands-on design engineer for years.... Have designed lots of digital stuff in the past and usually have a knack for finding the solution to the problems nobody else wants to deal with. Currently just wasting life doing crappy software and baby-sitting outsourcing to India, hopefully that will change soooooon!

Glad to help if I can,
Robert
 
laatsch55

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Haven't even broke out the scope Robert, don't know what I'm lookin for ..yet. Can the heat be from a tired component, the regulator itself?? And yes it's a 3 terminal 7805A, made by JRC.
 
rtp_burnsville

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It's Friday, we all are.....

7805 is a positive, 5 volt regulator, If a t-220 pkg I would guess good for 1.0-1.5 amp if heat-sinked. Most have an internal temp sensor in the IC which puts the regulator into a current limit of sorts to try and protect itself. High current in time equals high heat so they cheat and use a temp sensor to detect overcurrent. They are pretty hard parts to destroy.

My guess is that something downstream is drawing more current than it should which is why I suggested seperating the pieces and try to test each standalone. The supply by itself should not get hot unless there is an issue with a component in the supply (shorted filter cap for example). Linear supplies usually don't need a minimum load so no problem running it stand alone, unlike switchers.

:)
 
laatsch55

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Hookay, Thanks Robert, that helps, a lot. It is a TO-220 package. All the Shanling built are exhibiting the same hot regulator. When you open your's up Robert it is the 2nd one from the left in the row closest to the front.
 
rtp_burnsville

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Is my CDP similar???? I think Stu's is a -2 rather than a -3..... I'll see if I can find a minute to pull the top on mine over the weekend that should help so I have a clue as to what may be going on.

Robert
 
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laatsch55 said:
OK, still not sure about this CD-2, think I can detect some wow and flutter?? Is that the correct term for Cd speed variance?? One of the voltage regulators is getting very hot. Web and rtp, if yours start doing this let me know would ya?? A schematic would be a godsend, if i can't find one soon i'm just gonna shotgun the power supply.
Click to expand...

I haven't listened to it yet. Will try this weekend hopefully.
 
rtp_burnsville

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laatsch55 said:
Hookay, Thanks Robert, that helps, a lot. It is a TO-220 package. All the Shanling built are exhibiting the same hot regulator. When you open your's up Robert it is the 2nd one from the left in the row closest to the front.
Click to expand...
Could it be that the original design is 'right on the edge' of failing??? It would be good to see if you can measure the actual current draw for that regulator in an 'assumed to be good' unit. With that info you could see if the power supply is under-rated. Many people don't consider environmental changes in their designs, such as sticking a hot part in a sealed box. Maybe you can easily fix the issue by just adding a larger heat sink to the regulator or a similar minor tweek. Power supply problems cause lots of systems to fail. I'll bet well over half of all the things I have fixed can be traced back to power supply or grounding issues.

Robert
 
laatsch55

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To measure current draw of DC my 179 fluke has to be in series with the current path. I can desolder and jumper to accomplish that if there's no other way, none that I'm aware of.

Robert, when you open yours up I think you will agree it's a very robust power supply. At first glance "on the edge" is not what comes to mind.
 
laatsch55

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Web Police said:
laatsch55 said:
OK, still not sure about this CD-2, think I can detect some wow and flutter?? Is that the correct term for Cd speed variance?? One of the voltage regulators is getting very hot. Web and rtp, if yours start doing this let me know would ya?? A schematic would be a godsend, if i can't find one soon i'm just gonna shotgun the power supply.
Click to expand...

I haven't listened to it yet. Will try this weekend hopefully.
Click to expand...

Thanks Web.
 
rtp_burnsville

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Yep, that is one way..... Can you get your meter in series at the wiring connector or harness between boards?

There are clip on current probes but most people don't have one..... If there is a series resistor in the power supply (part of a RC filter maybe) one could measure voltage and compute the current.

Brute force is usually what is required. It sounds like you are on the right path.

I could not find the exact NJR/JRC datasheet but there are a couple different max current output devices using the same generic part number and package type. Some parts were rated at 1.0 amps and others at 1.5 amps. Don't know what the JRC part is so the real world measurement would be helpful. You could try searching the net for an exact datasheet (I am sure its out there someplace). The more info you can gather the better solution to be found.

Wish you were here (or I there) as it would make this all so much easier. I really need to look inside my box to see things at this point.

Robert
 
laatsch55

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I have quite a collection of terminal accessories for the Fluke. There is an abundance of harnesses and points to access. For total cummulative desoldering is called for,, now , that being said, the heatsink cools markedly when the CD quits turning and wires going to the motor are very accessible.
 
rtp_burnsville

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laatsch55 said:
I have quite a collection of terminal accessories for the Fluke. There is an abundance of harnesses and points to access. For total cummulative desoldering is called for,, now , that being said, the heatsink cools markedly when the CD quits turning and wires going to the motor are very accessible.
Click to expand...
Boy, it sure sounds like that regulator is dropping out........ Do you have a bigger heatsink you could attach, or even stick some small ones on the current setup. Do you know what the input voltage is into that 7805? You need 2-3 volts for it to regulate, When it's greater there is more heat being generated.

Looks can be deceiving, what looks massive may not be in-so-far as heat removal goes.

I really need to look at mine, you have my interest....



Robert
 
laatsch55

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They play just fine when opened up Robert, wheres the small Phillips...............
 
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