Repair your own TU-DST50/51 - AVS Forum
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Old 07-28-2001, 05:53 PM - Thread Starter
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About a week ago I started to experience pixelation and audio cutouts with the Panny combo I use for trolling PBS. It's a fairly elaborate setup with a DST51a, 3 HD1000's and a JVC DH30000 all connected together with an Orange Micro hub. I started unplugging stuff and narrowed the problem down to the DST51. I did the proper checks, tried fresh cables, different recorders, etc., and found that the problem always came back after the 51 was on for about 2 or 3 hours. I replaced it with another 51 and took it to my lab (the living room floor), where I treated it to what I call "Slap It Around".

The procedure is very simple: break and remake every connection in the box. It's a technique commonly used to fix computers. Reseating boards and chips will result in repair about half the time. The other half the time the problem will be a bad hard drive, power supply, or cooling fan. Older computers were more susceptible to connection problems because they used more connectors, ran hotter, and used a lot of socketed dual-inline chips with tin plated pins.

Well guess what!!http://www.avsforum.com/ubb/wink.gif The Panny boxes have no hard drives, and they have lots of connectors. They also run hot, and use socketed dual-inline chips with tin plated leads. From that I'd guess that a good slapping around will fix way more than half these things.

Enough salesmanship. Now for the disclaimer. There's NO GUARENTEE this will fix your box. It's just the most likely thing to fix it, and it worked in my case. If you are a real klutz you could do more harm than good, but I think most of the people here (except one) can handle this with success, or at least do no harm.

The box I fixed was a late model 51. In the process I took it completely apart and photographed both sides of the motherboard. Since then I noticed that several people were having problems with their DST50's, so I opened one of them as well. I did not, however, fix the 50, since it was working fine to start with. I also opened another 51, and got a real surprise, which I'll explain later.

Because several folks here are having problems with 50's I'll start with that first.

http://home.earthlink.net/~rogercc/_...hoto1-51tn.jpg Enlarge
Clear a clean spot on the bench, or floor, or whatever. As shown, you'll need a Phillips screw driver, a chip puller, a large paper clip, and a small crescent wrench or box wrench. The 3-1/2 pound axe may not be necessary in all cases.

http://home.earthlink.net/~rogercc/_...B/photo2tn.jpg enlarge
Remove the 5 screws holding the top. Lift the rear of the top and slid back and off. If your box is a 50 the lid has an inner shield that fits pretty snugly against conductive foam strips on the chassis sides, so expect some resistance as you slid the lid off. It helps to flair the sides of the lid as you take off.

http://home.earthlink.net/~rogercc/_...hoto3-50tn.jpg enlarge
If your box is a DST50 then this is what you will see inside. The inner lid with the fan is next to be removed.

http://home.earthlink.net/~rogercc/_...oto4a-50tn.jpg big http://home.earthlink.net/~rogercc/_...oto4b-50tn.jpg big
http://home.earthlink.net/~rogercc/_...B/photo5tn.jpg big
Remove the 3 screws holding the inner lid. Also unplug the fan connector. You need strong fingernails or a chip puller to do it.

http://home.earthlink.net/~rogercc/_...B/photo6tn.jpg big
The inner lid is attached to the back panel with a piece of copper tape. You can peel it off and restick it later, or you can hinge the inner lid up and prop it or have someone hold it.

I've reached the image maximum per post so...
to be continued

------------------
-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug

-Roger
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Old 07-28-2001, 07:33 PM
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Thanks for another incredibly useful and informative post.
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Old 07-28-2001, 08:09 PM
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"If you are a real klutz you could do more harm than good, but I think most of the people here (except one) can handle this with success, or at least do no harm."

Hey, watch it, I resemble that remark!


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"Better living thru modern, expensive electronics devices"
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Old 07-29-2001, 04:49 PM - Thread Starter
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Continuing...

http://home.earthlink.net/~rogercc/_...hoto7-50tn.jpg big
With the lid up you can get at the 4 eprom chips which will need to be reseated. If I were going to work on this box I would go ahead and peel the copper tape off the back panel and remove the fan/lid completely.

It's not necessary to remove the motherboard. I did on the 51, but then I'm certifiable, and I also wanted to know what was on the underside of the board. To take the board out you'll have to remove the rear panel. It's just a bunch of Phillips screws and the f-connector nut holding it. You'll need the screwdriver and crescent wrench.

This is the point where you do the "Reseating" thing. The list of priorities is as follows:

http://home.earthlink.net/~rogercc/_...hoto8-50tn.jpg big
1) The four eproms (M27C801-100F1 on the TU-DST50's, and AT27C080-10PC on most DST51's) These things are CMOS devices with solder plated leads. They are ESD sensitive, so you should use ESD precautions. Take off your shoes and let your sweaty feet ground you to the carpet. Touch the chassis with your hand before attempting to remove, or reinstall one of these chips.

http://home.earthlink.net/~rogercc/_...oto10-51tn.jpg big Here is an EPROM being yanked. Use the chip remover to firmly rock the chip out of the socket. Don't bend those leads.http://www.avsforum.com/ubb/wink.gif If you do, straighten them. As soon as it's out, reinsert it. Don't mix them up or install them backwards or upside down.

Next installment will be the chassis connections...

------------------
-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

[This message has been edited by gridleak (edited 07-29-2001).]

-Roger
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Old 07-29-2001, 09:06 PM
 
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Warning. Panasonic does read the forum! If you disassemble unit...repair can and will be denied. I have a pvhd1000 which was looked at by panasonic dealer Murray TV in delray Beach. They will not even honor free evulation arraged personally by Steve Saluka. They told me the unit was tampered or "tampered unit estimate"!! Oh yes. They have keept it in IL for TWO FULL months!!

There is more.

1) I believe a forum member or CBS is somehow involved in this! Since when does Panasonic do anything free!!

2) Now my OTHER record will NOT record!! It can play back. the on screen display says record. Tape track moves. Glitches every 30 seconds!! Now i can kill myself!!!
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Old 07-29-2001, 09:18 PM
 
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Let me stress again. If your STB works do not play around with it. Only if your unit is DEFECTIVE should you consider doing this.

Gridleak,

One of my STB's 51a has broken firewire connector. I opened unit. It appears it is connected to motherboard. Yes, panasonic i did open the hood! How can i replace this connector without panasonic stress. I tried computer repair shops. They stutter with words like 1394, HDTV or 8VSB!!
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Old 07-29-2001, 10:48 PM - Thread Starter
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Ken, what are you doing in my Klutz-trap? Now I have to reset it.

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-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

-Roger
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Old 07-30-2001, 02:58 AM - Thread Starter
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Ok, it's time for a break...

Rodmanbra,

1) Any Panny box I work on is like-new when I'm done and works perfectly. Not even a pimply-faced Panasonic Technician, in a white lab coat, and with pizza sauce dripping from his chin, would be able to tell I worked on a machine.

2) Believe it or not, "gridleak" is not my real name. I use another (untraceable) name when I buy parts from Panasonic.

3) I'm protected by an aluminum foil hat.

4) You are in luck. I happened to photograph the iLink connector when I fixed the DST51 that is the subject of this thread (which machine is now back in service and performing perfectly thank you).

Here you go:
http://home.earthlink.net/~rogercc/_...TB2/bra1tn.jpg big This is the underside of the motherboard showing how it's soldered in place.

http://home.earthlink.net/~rogercc/_...TB2/bra2tn.jpg bigger Top view of motherboard.

CLOSEUP of socket. It can't be removed from this side.

By the time this thread is done you'll know how to get the motherboard out. The only other thing you'll need, besides a new iLink socket from Panasonic, is a good soldering iron and some "solder wick" to pull up the old solder. It's easy. You might end up with your first fully functional Panny box.http://www.avsforum.com/ubb/smile.gif

... to be continue

------------------
-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

[This message has been edited by gridleak (edited 07-30-2001).]

-Roger
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Old 07-30-2001, 09:32 AM - Thread Starter
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One more intermission topic...

The two different EPROM's mentioned above, are really both the same. The M27801-100F that's found in the DST50's is made by STMicroelectronics, and is a commercial grade (0-70 deg C) 100nsec UV EPROM. It has a window and is UV erasable, which explains why it is covered with copper tape. The other chip, AT27C080-10PC, found in DST51's is made by Atmel, and is the same in all respects except it is an OTP (one time programmable) device with no window.

I don't know if this is the change that fixed the blue sparkles problem, but it's certainly possible.

Reseating motherboard connectors is next...

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-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

-Roger
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Old 07-31-2001, 12:53 PM
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I can report my experience with a DST50 which I think gives strong corroboration that gridleak is on the right track.

I had a sealed box DST50 and concluded that it was unwise not to test it before the warranty ran out. The unit displayed terrible pixelation and audio distortion and noise. It was so bad you could not make out the picture nor the sound. I was running this unit with an external fan right from the start. I gave the unit a couple of light taps on the top of the case with my hand--and it now works perfectly. I wonder if most of the problems encountered are simply due to poor contacts.
What would you think of the wisdom of using Caig Deoxit and Progold GL on the contacts and connectors?

gridleak-
Your inputs on this forum has been absolutely invaluable and I want to express my appreciation to you for all your efforts and the enormous help it has been to me.

Chazz
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Old 07-31-2001, 01:05 PM
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I bought a Panasonic TU-DST50 which works without blue sparkles or distorted audio, but it's reception sensitivity and channel locking is far poorer than my accessDTV card.,

Can a TU-DST50's reception and ability to stay locked be improved with any sort of additional UHF amplification beyond the CM 7775 preamp I have on the antenna now?

Murray Kerdman

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Old 08-01-2001, 12:28 AM - Thread Starter
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Quote:
Originally posted by chazz:
What would you think of the wisdom of using Caig Deoxit and Progold GL on the contacts and connectors?
I've been tempted. From my bad old audio (single-crystal cables, clean all the vacuum tube pins before each listening session) days, that stuff really worked good. But I had the feeling it was like drugs: once you started using it you couldn't stop.

To be more specific, I think that stuff reduced some of the energy barrier effects at microvolt levels that messed up very low level sounds. Not so sure about the hi millivolt levels in computers. Might help with firewire which is really analog on the cables and runs around 200 millivolts.



------------------
-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

-Roger
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Old 08-01-2001, 09:35 AM
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As long as we're talking about repairing DST50/51's, does anyone know which chips supposedly get replaced by Panasonic to fix the blue sparkly problem?

I have a DST50 with no signs of the problem yet. I'm using an external fan. I haven't opened up the unit yet; but, thanks to this thread (and gridleak of course) I'm not afraid to do so. I'd like to be proactive and replace the hot chips with cooler ones if it's not too difficult. Of course, it ain't broke yet, so maybe I won't fix it.

mdv

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Old 08-14-2001, 04:41 AM
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The DST50 unit in which I was able to fix a severe pixelation problem by a few taps on the chassis has unfortunately reverted to its original behavior. It is time to try the chip and connector reseating technique using gridleak's instructions.

gridleak- any chance on seeing your next installment on reseating motherboard and chassis connectors? Thanks a million in advance. Also, any advice on how to remove and then reseal the copper tape without leaving a trail?

Chazz
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Old 08-14-2001, 03:09 PM - Thread Starter
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Chazz

I had intended to finish this up much sooner, but my other hobby (work) got in the way. Should be up in a day or two. I think I'll have to shrink some of the thumbnails too, since the thread loads rather slowly.

------------------
-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

-Roger
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Old 08-17-2001, 04:40 PM - Thread Starter
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continuing

Ok, I shrunk all the previous thumbnails substantially, and, of course, I shrunk the thumbnails for rodmanbra even more, so that he would have something else to complain about.http://www.avsforum.com/ubb/wink.gif

I left off with the reseating of the EPROM chips. Next in priority is:

2) Reseating of the main board connectors. There are 6 all together, 2 on the left side connecting to the power supply, and 4 on the right connecting to the "S-Board".
http://home.earthlink.net/~rogercc/_...hoto9-50tn.jpg Big The upper three on the right carry control signals to the tuner and digital block, and lower most connector carries the all important Transport Stream from the digital block to the main board. That's obviously the most important connector to reseat, but as long as you're in here you should do them all.

http://home.earthlink.net/~rogercc/_...oto11-51tn.jpg Big This is how to disconnect one of these connectors. An oversized paperclip works perfectly. What I'm attempting to show here is the finger of one hand supporting the wires while the other hand pries the orange side out of the socket. Don't try to pry up the white side because that's soldered in place. The picture shows me doing it all with one hand, but that's because the other was holding the camera.

Pry up each end of the orange connector until it pops loose. There's no need to bend the wires very much. Reconnect immediately, unless you intend to remove the main board.

http://home.earthlink.net/~rogercc/_...onnectortn.jpg Big There's one more connector that connects the front panel to the main board. This one is the least important. You can work it out of it's socket using the chip puller or by pulling on the leads while rocking the plug lengthwise. This photo is from a DST51 so things look slightly different.

one more installment follows...

------------------
-Roger
Analog -- Always out of adjustment.
Digital -- Always one more bug.

-Roger
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