Hi all I am new to this forum so please be kind:)I have read here and other places about my specific problem so I think I know what I need to do but before I bust in and start removing chips I wanted to get the correct service manual as well as some advice. My specific unit is similar to many others but is a bit different. It was an earlier HD that came out before DVI and way before HDMI. I have 2 different Component video ins and where the HDMI is on most units like mine, there is a 15pin DIN connector. So question 1) I want the correct service manual and Question 2) I would like to know if I could swap out one or more system boards to get the HDMI interface. I would like to upgrade this thing if possible. I downloaded the manual for the DPTV400 series training from this site. It looks like it may be correct but it shows HDMI inputs so it is clearly using a different interface board than my unit. I may be wrong but I may have gotten a special boned down version for sale only through The Good Guys.The specific problem I am having is the convergence is not working anymore which is typical. I have read many posts about what to change...some stating "by this chip instead because it is an upgrade" and others stating don't buy that chip. I am an electrical engineer and work on boards all the time so naturally I went to look up the chips and couldn't find proper datasheets for these. So Question 3) is there a table somewhere I could look at that shows which are compatible with which chips? I assume by now there are newer versions that run cooler and won’t burn out as fast.Q4) Also while I am in there are there other components that typically fail that I should just swap out? I got an email from a guy off Craig’s list who had pics of his board and one of the chips did not have heat sink compound between the chip and sink...would that be typical or his botched repair job? I assume it can't hurt to be there and should be added.Are there any gotchas..ya know "make sure not to do this" or "unscrew this one first" I should know about before diving in?Thanks a ton…my division at work is shutting down so I am losing my job in a few months so self repair is my only option unless I find a new job between now and then.
Use the 300 series manual for the 60PP935217. Common problems are the convergence stk's and return resistors 3149 thru 3160, often 3159 and 3160 red, cold solder joints, coolant drips, coolant contamination in blue and green tubes.
Mark all connectors both ends and take before pics. Use the stk's specified in the manuals parts list for your model, always with heat sink compound. Convergence resistors are 6.8ohm 1W 5% flameproof.
Thanks!!! So looking at the manual I noticed that the STK392 is called out but no other numbers. At the site I found these are running about 6- 8 bucks each but there are multiple 392’s…again I was unable to find datasheets before for these. Should I just crack open my case and see which ones I have? Does anyone know what the differences are and if there are compatibility issues? I was hoping some newer ones would run cooler…I plan to add a fan anyway …why not.
As a board designer call me crazy but if those resistors are commonly failing then if we could find ones that fit, wouldn't it be better to scale up and get a 5 watt version or jumper in 2 / 13.6 ohm 1 watt in parallel? I am gonna look around for these. I can get probably bulk pricing through my purchasing department. It seems looking at the schematic that there are other 6.8 ohm power resistors being used in the current path to power supply to the STK392 chips. I am thinking about swapping them all. Specifically 3172 and 3173 are filtering and biasing the power to the STK (funny I just found a bug in the schematic used in the manual I downloaded...Reference designator 3171 is called out for 2 different resistors LOL). Anyway thanks for the feedback.
I can't figure out fonts on ths board...
The DPTV305.pdf (Philips/Magnavox 300 series) service manual has all the model parts lists in addition to chassis training. The 60PP935217 stk392-120's are listed on page 870 , #7044 and 7045. Buy Sanyo brand stk's only, they are still available, I use Acme Enterprises Orlando, but there are many good suppliers.
http://www.techlore.com/forum/thread/22659/
The best way I know to keep a RPTV running cool is keeping contrast and brightness settings at very modest levels, 33 to 50%. Same goes for lcd and especially Plasma sets. Some models default to 100% brightness and constast when they loose power, and some have to be set for every input or resolution.
Your analysis of the circuits would be very interesting, Please let us know what you find, and how you would power the stk fans and do any air ducting.
yeah I think the manual I found on this site isn't the detailed one you are referring to. It is only 68 pages...
I am the sole EE on an entire laboratory appliance product line. So I have access to tools and parts. I grabbed a couple of fans out of some of my knock around units that run 24V DC. There don't seem to be any 24V places to tap into so I may just add another power supply board for these...probably the right thing to do anyway.
I just opened it up and noticed the heat sinks are really not a type that is really good at conduction. My set is almost 10 years old and dusty so I figure I should be getting in there once a year and cleaning off the heat sinks to help them work. First thing I did was bust out my vacuum.
As far as the resistors go I am gonna try to take the whole board out and into work, see what parts I have in the lab and probably place an order for those on Monday. I have done plenty of circuit design and repair. I can guaranty that using better parts will work better. The problem is different types of materials have different characteristics. So a wire wound resistor will perform differently than a film resistor for non DC signals. Essentially not all resistors of the same value are equal. All of those 6.8 ohm resistors have non-steady current through them and need to have rapid (enough) response. the problem is higher current spec'd resistors are expensive. So manufacturers spec in the lowest type they can to save on cost. $2 *10 resistors * 10k sets = $200k...enough to pay for an engineer to spend the time figuring it out. But we only have one set so for a few extra bucks we can over build and it shouldn't fail. I just need to get the board into my shop so I can inspect them to figure out what kind they are. They are probably ceramic and using a resistor of the same material but capable of higher current is a no brainier. The issue really is size and can you make it fit. There appears to be plenty of space. I usually design and work on surface mount multi-layer boards. This is a 70's type of design that is real easy to rework assuming I can get it out without damaging something.
So once get it into work I can measure the dimensions of the parts. Then I will see if I can figure out what kind we have and find out what is available that will fit that is an improvement. I will find something even if it is 2 in parallel but hopefully I can find a drop in better part and I will post them after my set is up and running.
Thanks for the link...hopefully there is something good there about what the best STK's are for my set. I noticed mine are the 120's.
Incidentally my father in law just bought a new LED-LCD Samsung top of the line bad boy and gave me his DLP...So the priority of this project has dropped on my honey-do-list.
Again thanks for the reply
The DPTV305.pdf (Philips/Magnavox 300 series) service manual is on this site in the downloads section.
Okay this is too funny... For all of you circuit geeks this may make you laugh...
I finally found the data sheet for the STK392-120's and got the service manual for my model so I have the schematic (still has the same typo). I was mentioning earlier in the post that if the resistorss are wearing out then maybe we should try using better ones. Well Philips already did that and they are still wearing out. I think I figured out why...
So for the tech details the Data sheet calls out 3.3ohm 1 watt resistors where the board has 2 6.8ohm 1 watt resistors in parallel. So the board was already laid out as I suggested using 2 double sized resistors in parallel. Since they are now capable of running 2 watts safe and the part is spec’d for 1 watt per channel these must be running way over budget.
So then I looked more at the datasheet and found out what the real problem is. The parts are designed to run on a power supply of +-44V not +-35V. So since they are under powered in voltage the current mirrors cannot provide the input supply necessary and the output buffer has to run up the current to compensate.
I am not sure that cooling better will fix it but it will make it easier on both the current mirror and output buffer. Just upping the resistor quality AGAIN may prevent the resistors from failing but then the weakest link is the chip…Since the design is already running 2x the manufacturers spec. it is probably overkill to up those but I will do it anyway.
I’ll probably do both running 5 watt resistors…high end heat sink compound…additional fans on the heat sink. Hopefully I get some more life out of this but you know as soon as I fix this something else will break. But it is a good project.
i have the 60pp935217 philips tv i had the convergence prob as well so i gave it to a friend to fix he ended up PCSing and loosing the board in the process. Now im in need of the board and i cant fig out what boards are what to replace it. If you are looking from the rea of teh tv with the panel off it would be the far right board and everything with it
I believe the far right one is the power supply if you are looking in from the rear. The service manual can be found on this web site if you dig hard enough. Page 26 has a general layout that should tell ya.
yes i know the far right one is the power supply but that is no the one i was looking for it the one on the left if looking from the back
3159 and 3160 (red vert) are usually the resistors that burn, if any burn, sometimes it is the traces between 3159,60 and the stk's that burn. There have been reports of what appear to be factory installed larger (physically) resistors there, color codes charred beyond reading, but no known service bulletins or manual updates for anything other than 6.8 1w.
The stk's are not hard to change, but the heat/desoldering is hard on the circuitboard, what about putting those stk's on 18 pin headers in addition to upping the resistor quality, fans ?
yodave, I would recommend downloading, from this site, the service manual to figure out exactly what you are missing. The "other" right or left most board is the SSM board which has multiple daughter boards. The ACS and HOP both plug in and the back panel interface and SSB are all interconnected. It is a lot of stuff. If everything is missing that was connected to that board and may not be worth repairing. I would suspect it costs anywhere from 150 - 200 for the parts alone assuming you can find it. This model of TV is working order goes on Craigs list for less than 200. So you could buy an entire unit for the same cost. In the DPTV305.pdf manual on page 26 all of the boards are pointed out and the previous few pages explain what each board is.
Alnp, Sorry for taking so long to get back but I was out of the
country without internet access.
I have not yet taken out my board as I was given a suitable
replacement TV and I just got my parts in the mail a few days before leaving
the country. So I can respond only to what you are describing…but what
you describe is very typical for problems where novices are trying to do
Soldering work. Soldering looks Very easy but in reality it is moderately
easy and at times can be very difficult. So novices can quickly and
easily do sever damage before they know it, they may in fact not even recognize
the damage. Even experts damage parts and boards depending on the layout
and material types used.
1) Regarding the resistors: When I pull my board Hopefully tomorrow
( I am jet lagged today after 16 hours of Red eye travel) I will verify the
components there match the schematic. As I previously wrote however the
board designer already laid out the board as I suggested with 2 resistors in
parallel to half the current through each making it capable to buy cheaper
(physically) smaller ones. We can keep "Halving" the current
but it is probably not the resistors rather more likely (based on what you are
describing) a botched Desolder repair job. I would be interested to hear that
people have problems first with the resistors as the main and only source of
failure not as a secondary problem. If people only have problems with
these after a repair job then it is someone trying to desolder a broken part
incorrectly.
Also many parts can be sourced from many suppliers and function just as
good. The physical size of the resistor
is not the best indication of the quality.
Most parts on all boards in all appliances are spec’d by the designer to
allow for the board stuffers to buy parts as a commodity at best pricing. So it is common over the long haul to have
part changes.
2) Header stakes: Probably Okay but I prefer not to use these on
high current devices. The electrical contact surface area will most
likely be reduced increasing resistance and therefore heat and reducing energy
transfer (VI losses). Using sockets is okay for logic IC's where the
current is small but these STK's are really current amplifiers running slightly
biased off of +- 35V which means 70V DC at peak. I'd be surprised if this
wasn't pumping out huge current and the heat sinks these are using is a good
indicator that these are dumping current in a controlled fashion to a low
load.
Based on my assumption that the majority of resistor failures happen after a
repair job was completed (based on your description) I would think the problem
is people are not using Diagonal cutters ;) to clip off the broken chips and a
solder sucker to clear the holes. More likely people are trying to remove
the chip intact. Removing chips intact that have more than a few pins
soldered in place is a bad idea and not something a novice has much of a chance
doing successfully. By that I mean they will probably remove the chip
eventually but the damage to the board may be hard to spot and very
serious. Almost anything can be reworked but if you don't know you broke
it... Also Cold solder joints from damaged pads from incorrectly removing
the chips will cause heat and damage or failure to function. There is a
long list of failure modes associated with over heating during the removal
process.
So getting back to the point...The design currently
goes above and beyond using both a low pass filter and 2 watts capability where
1 watt is recommended so in theory this should be more than enough. What
percentage of people have these resistors fail as the primary fault (first and the
only thing they ever replace)?
yodave...
Resistor burning and trace damage found along with stk failure,like this pic:
http://www.techlore.com/forum/thread/26696/Possibly-not-your-average-con...
You can crack the plastic cover off the old stk and likely see the failed component