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Old 08-19-2014, 10:23 AM   #301
Lcstyle
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Quote:
Originally Posted by unitron View Post
The caps on a TiVo power supply board, at least all the ones I've seen so far, the ones with both leads sticking out the bottom, are called "radial" as far as the packaging is concerned.

The cap that looks like a lead goes in one end and comes out the other is called an "axial" cap.

In the old vacuum tube point to point wiring days, axials were probably the more commonly used design.

Are all the replacement caps you installed Low ESR and 105 degree (C) rated?



And is this supply out of a 648 or a 652/658?

OK, Thanks for the proper terminology here. Radial vs Axial. Roger that.

Not all of them. The ones I mentioned previously as not having been replaced (the 3 small caps on the right far side) C220 C227 and C306, I replaced with ones that have lower voltage ratings of equal capacitance as stated in a previous post. For example I replaced the 47uF 50 volt with a 47uF 35V temporarily to test.

All the other caps were sourced from the mouser project here, so yes they all are 105 degree low ESR.
https://www.mouser.com/ProjectManage...sID=1a42eea4c1

Finally, this is a 652 unit.

Thanks again for your help
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Old 08-19-2014, 02:46 PM   #302
nooneuknow
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Why is there a cap at JP103 (tends to indicate a jumper wire belongs there)? Some things do just not look right. Did you do things one-at-a-time, or did you remove all and then replace all?

It also appears like a cap is missing, where there should be one.

I need a full board view, from the top, and a full view of the bottom, before I can comment any further.

I guess this must be a true S3 OLED, and not a TiVoHD TCD652___ model, or I wouldn't feel so lost.

I would never use an under-rated cap (voltage-wise), even just for testing, unless it still exceeded the working voltage.

Other than what I had to say about the clicking, and that the power supply NEEDS/REQUIRES a load when being tested (to function, to check voltages, and to prevent damage), I may just defer to unitron and squint on this.
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Old 08-19-2014, 04:32 PM   #303
Lcstyle
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Quote:
Originally Posted by nooneuknow View Post
Why is there a cap at JP103 (tends to indicate a jumper wire belongs there)?
Actually if you look here at this image you'll see C227, because I've used an axial instead of radial the physical placement is a bit different, but the pins are in the correct through hole pads, I've verified that.


Quote:
Originally Posted by nooneuknow View Post
Some things do just not look right. Did you do things one-at-a-time, or did you remove all and then replace all?
I did one at a time on a few, and then a couple at a time in other areas.

Quote:
Originally Posted by nooneuknow View Post

It also appears like a cap is missing, where there should be one.
It does appear that way doesn't it, next to C402 correct? However there was no cap there. Refer to image above for reference layout.

Quote:
Originally Posted by nooneuknow View Post
I guess this must be a true S3 OLED, and not a TiVoHD TCD652___ model, or I wouldn't feel so lost.
It's definitely the TCD 652

Quote:
Originally Posted by nooneuknow View Post
I would never use an under-rated cap (voltage-wise), even just for testing, unless it still exceeded the working voltage.

Other than what I had to say about the clicking, and that the power supply NEEDS/REQUIRES a load when being tested (to function, to check voltages, and to prevent damage), I may just defer to unitron and squint on this.
Ok, I have done some research and figured that as long as the actual voltages don't exceed the rating I should be OK. Worst case the ticking stops, I find the problem and I blow a cap with a lower than spec voltage rating, which means I can just replace it with a spec replacement. I want to figure out what the actual problem is first, and I doubt it's that one or two replacement caps are rated at slightly lower voltages (i.e. at 35V volts versus 50V) for a couple quick power on tests.

I hear you on the load being required. I've run the PS a few times without load and I may have damaged it. No way to tell since it wasn't working, although, the broken behavior (ticking sound) has stayed the same from the time that I initially opened up the case.
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Old 08-19-2014, 05:18 PM   #304
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I've run power supplies without sufficient load (need to be plugged into the motherboard and HDD) and they ended up working just fine afterwards.

I did repair one power supply without replacing any capacitors. Some of the MOSFETs or whatnots bolted to a heatsink had broken solder joints. It was obvious because the whole heatsink and the 3 components bolted to it were loose.
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Old 08-19-2014, 06:14 PM   #305
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Quote:
Originally Posted by squint View Post
I've run power supplies without sufficient load (need to be plugged into the motherboard and HDD) and they ended up working just fine afterwards.

I did repair one power supply without replacing any capacitors. Some of the MOSFETs or whatnots bolted to a heatsink had broken solder joints. It was obvious because the whole heatsink and the 3 components bolted to it were loose.
PC power supplies have built-in protection (prevention) for such scenarios. While they will state a minimum load requirement (which keeps all the outputs steady), they have internal loads, that are just enough to prevent damage (but not enough to operate, or operate properly), when there is no load, or a grossly inadequate one. But, we are not talking about computer power supplies, designed to be handled, and mishandled.
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Cisco tuning adapters should never be used inline (using the TA coax OUT port) to connect a TiVo, if MoCA is in use. Use a splitter w/PoE filter on leg to TA, use other leg for the TiVo. Enjoy!

Last edited by nooneuknow : 08-19-2014 at 09:29 PM. Reason: context correction
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Old 08-19-2014, 06:33 PM   #306
nooneuknow
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Quote:
Originally Posted by Lcstyle View Post
Actually if you look here at this image you'll see C227, because I've used an axial instead of radial the physical placement is a bit different, but the pins are in the correct through hole pads, I've verified that.

Ok, I have done some research and figured that as long as the actual voltages don't exceed the rating I should be OK. Worst case the ticking stops, I find the problem and I blow a cap with a lower than spec voltage rating, which means I can just replace it with a spec replacement. I want to figure out what the actual problem is first, and I doubt it's that one or two replacement caps are rated at slightly lower voltages (i.e. at 35V volts versus 50V) for a couple quick power on tests.

I hear you on the load being required. I've run the PS a few times without load and I may have damaged it. No way to tell since it wasn't working, although, the broken behavior (ticking sound) has stayed the same from the time that I initially opened up the case.
Now that I got a full view, my brain has reoriented itself (I sold all my 652 power supplies, so I can't hold them in-hand). The angles were playing tricks on me.

I'm going to recommend examination in a pitch-black room, and carefully look for any arcing. It could be arcing at a solder joint, between traces, or I'm thinking the most likely place is inside the flyback-like transformer. If you can't see any arcing, it's probably internal. There are no relays, or moving part components to finger as suspects.

If your work is all done correctly, and all the solder joints are good. it's down to knowing what happens where, and tracing through the flow of the design, until you find a fault/faulty part.

I'm actually familiar with ticking/pulsing/strobing power supplies. When it is not due to a bad solder joint, it is either a byproduct of the protection mechanisms, or it's often really bad news. You might have one of the rare power supplies that developed a fault inside the high-frequency transformer. Other than rechecking all your work, it's down to how much time you want to spend tracing your way through, and how well equipped you are to measure as you trace through.

I might consider taking all the filtering caps out (only ripple filtering), and rigging up a dummy load, for further testing. I'm not great at walk-throughs at this level.

I'm going to sit the rest of this one out. Sorry.
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Cisco tuning adapters should never be used inline (using the TA coax OUT port) to connect a TiVo, if MoCA is in use. Use a splitter w/PoE filter on leg to TA, use other leg for the TiVo. Enjoy!
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Old 08-19-2014, 08:16 PM   #307
Lcstyle
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Quote:
Originally Posted by nooneuknow View Post
I'm going to recommend examination in a pitch-black room, and carefully look for any arcing. It could be arcing at a solder joint, between traces, or I'm thinking the most likely place is inside the flyback-like transformer. If you can't see any arcing, it's probably internal.
I think this might be it. There are Several Voltage Regulator IC's that are attached to fairly large heat sinks. I am thinking that due to dust one of them has overheated and internally shorted.

Quote:
Originally Posted by nooneuknow View Post
If your work is all done correctly, and all the solder joints are good. it's down to knowing what happens where, and tracing through the flow of the design, until you find a fault/faulty part.
Yeah, I do have an oscilloscope and test equipment. I'm not completely ignorant to electronics, I've just never troubleshot an UNKNOWN circuit (one that I didn't put together), much less a power supply circuit.

Quote:
Originally Posted by nooneuknow View Post
I'm actually familiar with ticking/pulsing/strobing power supplies. When it is not due to a bad solder joint, it is either a byproduct of the protection mechanisms, or it's often really bad news. You might have one of the rare power supplies that developed a fault inside the high-frequency transformer.
Do you have knowledge on which component is which here? I am trying to run some of these Sparkle Power components (Marked SPI) through digikey to ident the IC's and the large transformer. I've Identified the SBL 1045 CT which is a 10AMP rated schottky diode array.

So identifying any of the following highlighted components would be most useful:


Quote:
Originally Posted by nooneuknow View Post
Other than rechecking all your work, it's down to how much time you want to spend tracing your way through, and how well equipped you are to measure as you trace through.
Quite honestly, I don't think at this point that it was any of the caps to begin with. My work was fairly minimal, and I have an ESD safe soldering station. There was only one cap that was slightly bulged when I first opened the unit, and while I am aware that caps can go bad without bulging, obviously replacing all of them didn't result in any change in behavior.

None of what I have done has resulted in any different behavior whatsoever, so I am thinking that it's either the big transformer, or one of the IC's has shorted or arced internally.

So now how to troubleshoot that, I could sit here and calculate what I think all the values are supposed to be using some fundamental circuit analysis but I'd rather just be a 'mechanic" and replace parts till I find the bad one.
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Old 08-19-2014, 09:09 PM   #308
Lcstyle
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Here's some component reference images for everyone else.









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Old 08-19-2014, 09:09 PM   #309
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Last Two



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Old 08-19-2014, 09:19 PM   #310
nooneuknow
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Quote:
Originally Posted by Lcstyle View Post
I think this might be it. There are Several Voltage Regulator IC's that are attached to fairly large heat sinks. I am thinking that due to dust one of them has overheated and internally shorted.

Yeah, I do have an oscilloscope and test equipment. I'm not completely ignorant to electronics, I've just never troubleshot an UNKNOWN circuit (one that I didn't put together), much less a power supply circuit.

Do you have knowledge on which component is which here? I am trying to run some of these Sparkle Power components (Marked SPI) through digikey to ident the IC's and the large transformer. I've Identified the SBL 1045 CT which is a 10AMP rated schottky diode array.

So identifying any of the following highlighted components would be most useful:

Quite honestly, I don't think at this point that it was any of the caps to begin with. My work was fairly minimal, and I have an ESD safe soldering station. There was only one cap that was slightly bulged when I first opened the unit, and while I am aware that caps can go bad without bulging, obviously replacing all of them didn't result in any change in behavior.

None of what I have done has resulted in any different behavior whatsoever, so I am thinking that it's either the big transformer, or one of the IC's has shorted or arced internally.

So now how to troubleshoot that, I could sit here and calculate what I think all the values are supposed to be using some fundamental circuit analysis but I'd rather just be a 'mechanic" and replace parts till I find the bad one.
Ugh. Rough forum day... Most of the parts up to, and including, the diode array/rectifier are run of the mill inrush limiting, surge protection, and safety components. From the time I used to spend full-time around the power supply threads, I can't recall anybody sourcing the flyback (The really large one, with the really large lead to the board). If that's shot, well, that does more than the rest of it all combined.

It sounds like you're equipped with the tools and the knowledge to trace it out. It has to be one of the least complex ones I've worked with. I traced one out for fun, but never documented it (oops).

I hear you on the caps. It's cap replacement frenzy here, with some so bit by the bug, they do it for free. I had initially thought you meant the output filtering caps as the "small ones", which was why I was "AYFKM?" on that. But, now that I'm not just passing through, I see the context of why you didn't think the problem was related to the caps. I doubt even the one bad one killed it. I think it just was unlucky #whatever out of a batch.

Have you considered trying to test individual components off-board? My Fluke meter/scope-in-one can run varying frequencies through and see how components react. The only way you can test a transformer is by running waves through it and seeing what comes out. I would guess it's still as simple as if there's a broken winding, you might catch that with a simple resistance test.

That's where I'm at... Either try to trace the path and try to test along it, or just do at at a component level. You'll want a dummy-load for each output, rather than risk the TiVo board. Speaking of which, have you tried a dummy load to eliminate the mainboard as being an overload, triggering the overcurrent protection? Back to protection, I'm beginning to wonder if that PS has any more protection than what is required. It is pretty minimal. When you've worked with so many, but it's been awhile, it all gets foggy.

There are more power supply threads than this one. Many don't even have power supply in the thread name (just the operating malfunction that leads down the rabbit hole to a power supply with bad filtering caps). I think there's a thread devoted just to the parts sourcing (or even two).

PM unitron for links, or search around. I lost my bookmarks for all this when my old PC retired itself (massive power supply failure with a cascade effect).

I can't vouch for the guys offering at-cost repair. unitron's been around, and stuck around with this older stuff. He knows enough to be helpful, for sure, as long as "it's the capacitors", beyond that, I just don't know.

That you have me, half-awake, yammering on, and aren't being flooded with help, makes me think the forum "experts" haven't seen your dilemma. It's unlike them, not to be tripping over each other...

Gotta run. Good luck.
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Cisco tuning adapters should never be used inline (using the TA coax OUT port) to connect a TiVo, if MoCA is in use. Use a splitter w/PoE filter on leg to TA, use other leg for the TiVo. Enjoy!
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Old 08-22-2014, 11:17 AM   #311
Lcstyle
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so I replaced the board with one from Ebay, now it works. Looks like the new board has a few caps replaced, and it might have a different LT7231 IC (labeled D500 on the board). Those were the only two differences I noticed from the original.

Hope this helps someone else.

the SBL1045 CT IC can be found here:

http://www.digikey.com/product-detai...CTDI-ND/164934

Last edited by Lcstyle : 08-22-2014 at 11:31 AM.
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Old 08-23-2014, 05:08 PM   #312
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Quote:
Originally Posted by HerronScott View Post
I actually ordered enough caps to repair my 2nd S3 OLED as well since it has a few bulging 3300uF caps so the S&H was for both sets although the way it was boxed and shipped, I'm not sure it would have been any cheaper for just 1 set of caps.
OK so after 2 years I finally got around to replacing the capacitors in the 2nd S3 OLED. It was still working but I was upgrading from a 1TB drive to a 2TB drive so I took the opportunity to take care of this too.

Only the same 2200uF cap (C701) was still bulging although it might have been a bit worse that the last time I checked it. I was surprised that it had gone this long without causing any issues.

Voltages after replacement:

12.45V
7.55V
5.04V
3.26V



Scott
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