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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Jun 27, 2010 12:03 am Post subject: HVPS-Updated resistors and now it cycles on 2x and stops |
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Yeah...*sigh*..not sure what went wrong with a simple resistor replacement. No solder splashes, no bridging, just won't stay engaged. I replaced the resistors with flameproofs-not Ohmites like I SHOULD have, all the same values.
The LVPS fans spin as they should. When I energize the pj the fans ramp up like normal for 5 seconds or so but when there's a call for HV the relays (somewhere) click, the fans ramps down, and the it starts all over again one more time and then the pj shuts down. LVPS fans still spin at idle.
I have all new caps from Mouser to install today and I'll try it again. Does it sound like a regulator or opamp couldn't handle the heat from reflowing solder joints? Unfortunately both my HVPS's are different ages so have different IC's at the heatsink. The older one has 4 and the newer one only has 2. (They both have 3 MOSFETS (?) near the vertical daughter board). I can't use the working ps to compare to the newer one.
Any ideas? Does anyone have schematics for the different versions of these?
Thanks guys
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1601
Location: Austin, TX
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| Posted: Sun Jun 27, 2010 12:06 am Post subject: |
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I'm confused. You have one working power supply. Did you swap that back in to see if the problem went away? Just to verify it's a problem with the modified power supply?
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sun Jun 27, 2010 12:08 am Post subject: |
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Was it working before the HVPS resistor and cap changes?
Did you do any other changes at the same time before testing the HVPS upgrades?
See what happens if you unplug one VNB at a time, the PJ should still fire up for a minute or two just to check the
the HV shut down. Remove the umbilical and the g2 lines, video etc.
Athanasios
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sun Jun 27, 2010 12:17 am Post subject: Re: HVPS-Updated resistors and now it cycles on 2x and stops |
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| JustGreg wrote: | Does anyone have schematics for the different versions of these?
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Whats the numbers on them?
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Sun Jun 27, 2010 12:30 am Post subject: |
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did you put the daughter board back on?
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Jun 27, 2010 6:59 am Post subject: |
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| CZ Eddie wrote: | | I'm confused. You have one working power supply. Did you swap that back in to see if the problem went away? Just to verify it's a problem with the modified power supply? |
LOL...that's why I write so much Eddie...even if I fail at being clear and concise I can manage to impart my message SOMEWHERE in the 2000 words. 
1) Both HVPS's worked prior to installing new resistors in the newest one.
2) PJ works with the spare (older) HVPS but not the newer one that got the resistor change
3) The one with all new resistors has the problem I described in the OP
4) Swapped the Control PWB's. The PWB from the now dead HVPS worked in the spare HVPS but the dead HVPS remained so with the spare HVPS's Control PWB.
(LMFAO) That's about as clear as mud right? 
5) Replaced the old poly caps in the dead HVPS with same value Mylars...temporary only to test while waiting for Mouser caps from Nash's Marq Maint thread. It performed (didn't) the same with the Mylars, eg, still powering off after 2 attempts.
The info on the tag from the newer (now dead) HVPS is:
PART NO.:404626-001 REV. B2
MODEL: PTV34.9P143X2532
Electrohome # 10-000310-02P
SERIAL NO.:89851-0864
OUTPUT: 34.9/4.5mA, 1000vdc(X3) / 100uA
INPUT: 390VDC/700mA
Another paper tag under the Spellman tag:
10-000310-02P ISSUE 3
MODEL 2532
(barcode) *1000031002*
S/N *89851 0864*
Nash, I didn't test it after single resistor but that's all I did was a complete resistor change. As soon as I'm done here I'm going to lift one leg of all the resistors and test them. I didn't test all the new ones before installing. My bad and lesson learned. Hopefully I'll find a bad one. If installing the recommended caps doesn't work then later on after some sleep I'll do as you suggested (removing nb's).
And, umm, no I didn't have any spare parts left... like the Control PWB. But that's a valid question. 
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Jun 27, 2010 8:18 am Post subject: |
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Well hell...live and learn I guess. I didn't know soldering iron tips needed to be grounded when soldering; specifically MOSFET's opamps! 
I wonder if I damaged 1 or all of the C4636 (x3) Amp/HV Switching IC's or the (H)G12N60C3D (x2) rectifiers. Sonofa...... 
I'm hesitant to heat the PCB to remove one leg of the resistors to test them. Is there any reason I couldn't cut one lead to test them and solder back together? It isn't how I'd prefer to do it but that PCB is very thick and takes alot of heat to flow the solder through both sides. Somebody has been into it before me. I don't want to rack up any more heat cycles if it can be avoided.
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Sun Jun 27, 2010 10:30 am Post subject: |
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yes i experienced the same thing on the hvps that it needed a lot of heat because of the thick pcb.
the trick to get it flowing quickly is to add a bit solder on your tip while desoldering to get the solder flowing.
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Sun Jun 27, 2010 4:07 pm Post subject: Re: HVPS-Updated resistors and now it cycles on 2x and stops |
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| JustGreg wrote: | Yeah...*sigh*..not sure what went wrong with a simple resistor replacement. No solder splashes, no bridging, just won't stay engaged. I replaced the resistors with flameproofs-not Ohmites like I SHOULD have, all the same values.
The LVPS fans spin as they should. When I energize the pj the fans ramp up like normal for 5 seconds or so but when there's a call for HV the relays (somewhere) click, the fans ramps down, and the it starts all over again one more time and then the pj shuts down. LVPS fans still spin at idle.
I have all new caps from Mouser to install today and I'll try it again. Does it sound like a regulator or opamp couldn't handle the heat from reflowing solder joints? Unfortunately both my HVPS's are different ages so have different IC's at the heatsink. The older one has 4 and the newer one only has 2. (They both have 3 MOSFETS (?) near the vertical daughter board). I can't use the working ps to compare to the newer one.
Any ideas? Does anyone have schematics for the different versions of these?
Thanks guys |
Your description of the fans ramping up and then back down points more to the LVPS than the HVPS. The HVPS shouldn't have anything to do with the fans. Try unplugging the HVPS and turn on the unit, check for how the fans behave then.
Scott
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Jun 27, 2010 5:00 pm Post subject: |
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IMHO, it's REALLY hard to blow up chips. Even static sensitive chips are quite well protected internally. To my knowledge, I've never destroyed a new part that was from a quality manufacturer..... and I've used some pretty archaic soldering techniques on occasion, as in using a soldering gun in the field when an iron wasn't available..
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Jun 27, 2010 8:41 pm Post subject: Re: HVPS-Updated resistors and now it cycles on 2x and stops |
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| tse wrote: |
Your description of the fans ramping up and then back down points more to the LVPS than the HVPS. The HVPS shouldn't have anything to do with the fans. Try unplugging the HVPS and turn on the unit, check for how the fans behave then.
Scott |
Hi Scott...thanks for all the replies in my multiple threads. Gotta love this community!
The spare HVPS in the set works fine Scott. No LVPS issues at all. The HVPS I'm having problems with was fine before installing new resistors. Now it causes the issue I mentioned in the first post. I still have Nashous suggestions to try out; disconnecting and removing one neck board at a time.
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Jun 27, 2010 8:48 pm Post subject: |
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| Curt Palme wrote: | | IMHO, it's REALLY hard to blow up chips. Even static sensitive chips are quite well protected internally. To my knowledge, I've never destroyed a new part that was from a quality manufacturer..... and I've used some pretty archaic soldering techniques on occasion, as in using a soldering gun in the field when an iron wasn't available.. |
Hi Curt,
Yeah it's not like I was rubbing balloons in what's left of my hair before working. Nor did I have my fingers all over the IC's. And I'm well aware of using just enough heat to get the job done. So much so that the entire time I was replacing resistors I was concerned with how long I had to keep the iron to board with the iron at 800 deg F. I was almost ready to whip out the Weller soldering gun for some hard fast heat.
Just a note to others...even though the foil is heavy gauge on these HVPS' prolonged heat WILL lift them. They don't break off like thinner foil does but they lift. That said, if I were to do it all again I think I WOULD use a soldering gun instead of an iron.
And yup...I use solder flow to get the older solder flowing too. Then I wick it out. The leads are so big on these components that a desoldering iron is useless. Another thing that worked well was cutting a piece of thick lead, holding it with needle nose plier, and putting the iron to the base of the lead while it's in the bore. Then gently rotate it out of the hole while it's hot. This leaves a clear opening all the way through without overheating the foil pad and possibly lifting it.
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"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Sun Jun 27, 2010 9:07 pm Post subject: |
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Curt's right here.
Static failing chips have been rare on my benches. The exceptions have been a very few and specific chips that I have not seen in over 20 years of doing this.
And on a Marquee, I don't think there's a need to even use static protection, especially on the HVPS.
The problem you're experiencing may well be the replacement components you're using...
You just can't swap out parts in "Critical Safety Component" circuits and not expect the replacement parts to always work. these circuits operate using current and voltage sensing that is critical to the original components. Changing out components a lot of time thinking it would be a better component could be true, but that would only depend on a circuit that is not TUNED (critical) to the components in use.
I've mentioned this a many time over the years that it's very important to not try any or suggested brands/types of components in those circuits. The G2 circuits require a special resistor, if moving from carbon. A non high voltage approved and safely determined resistor could damage the CRT's.
If the resistors arc (as what would happen if they fail under high voltage) they would also burn (strike) marks on the phorphor of the CRT.
So when the larger resistors in the HVPS, two things are a must. It MUST be HIGH VOLTAGE rated, and it MUST work in and with the protect/fail safe circuits.
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Jun 27, 2010 9:16 pm Post subject: |
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| mp20748 wrote: | Curt's right here.
Static failing chips have been rare on my benches. The exceptions have been a very few and specific chips that I have not seen in over 20 years of doing this.
And on a Marquee, I don't think there's a need to even use static protection, especially on the HVPS.
The problem you're experiencing may well be the replacement components you're using...
You just can't swap out parts in "Critical Safety Component" circuits and not expect the replacement parts to always work. these circuits operate using current and voltage sensing that is critical to the original components. Changing out components a lot of time thinking or would be a better component could be true, but that would only depend on a circuit that is not TUNED (critical) to the components in use.
I've mentioned this a many time over the years that it's very important to not try any or suggested brands/types of components in those circuits. The G2 circuits require a special resistor, if moving from carbon. A non high voltage approved and safely determined resistor could damage the CRT's.
If the resistors arc (as what would happen if they fail under high voltage) they would also burn (strike) marks on the phorphor of the CRT. |
Hi Mike. How've you been lately?
Point taken Mike. I bought the resistors locally instead of ordering the Ohmites Nash listed in his HVPS thread. I got them from a non RatShack electronics parts n pieces store but still, they buy cheap stuff (NTE?) and sell it at a premium just like RatShack. I paid for convenience and got parts that even look chintzy, and therefore don't offer much of a confidence factor.
After mowing the lawn I'm going to order all Ohmites for both my HVPS' and be done with it. The working HVPS already has 6 of the 560K flameproofs and is working fine. I didn't replace the remaining resistors in that one however so that's the only variable.
I'll post here again after replacing them all in both units to prove you right.
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"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Sun Jun 27, 2010 9:31 pm Post subject: |
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I don't what's causing your HVPS, only that you never swap out those resistors unless you're going with replacements that known to work in that circuit.
Even if you have the original CARBON resistors in there, DO NOT replace unless the resistance value has changed. When the Carbons needs replacement, your OHM meter will let you know..
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sun Jun 27, 2010 11:28 pm Post subject: |
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"Shot-gunning" in a bunch of parts for the sake of just getting in new parts is crazy. I also feel the same way about completely re-flowing a board "just to be sure". If I have a problem with a board, the first thing I do is put on my glasses AND inspect it under a magnifying glass. A bad soldered connection can usually be spotted that way. I have found many that way but not enough to warrant re-flowing a whole board.
If you find or suspect a bad resistor, lift one leg and test it. If it's OK put it back.
If a board is calibrated and you swap twenty parts that have a plus or minus 5% tolorance, you can be off a pant load when your done.
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Sparky015
Joined: 12 May 2009
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| Posted: Mon Jun 28, 2010 12:26 am Post subject: |
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Greg, not that this is what caused your problem, but back off on the temperature of your iron. You should never (unless your soldering on a heat sink) be set at 800F. Small components only need 630, 700 for a thick board such as an HVPS. If you need 800, you probably need a new tip, or using the wrong one for that application. That's also a good way to piss through your tips as well. Small components such as FETs ICs can only take so much heat as well. You may not be killing them with ESD, but you can certainly shorten their life with heat. Generally those components can only be heated three times (install and 2 reworks) before they should be thrown away. At 800 degrees I would cut that in half.
Food for thought. 
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Mon Jun 28, 2010 12:30 am Post subject: |
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| stefuel wrote: | "Shot-gunning" in a bunch of parts for the sake of just getting in new parts is crazy. I also feel the same way about completely re-flowing a board "just to be sure". If I have a problem with a board, the first thing I do is put on my glasses AND inspect it under a magnifying glass. A bad soldered connection can usually be spotted that way. I have found many that way but not enough to warrant re-flowing a whole board.
If you find or suspect a bad resistor, lift one leg and test it. If it's OK put it back.
If a board is calibrated and you swap twenty parts that have a plus or minus 5% tolorance, you can be off a pant load when your done. |
OK. I didn't "shotgun" anything.  My mistake evidently was buying parts locally from the only electronic parts store in the city instead of mail ordering them. The other (working) PS that got those 560K resistors is doing fine. That isn't to say I didn't get a bad one but simple fix...I'll replace them all with a better brand. Hindsight and all that.
As far as values go...I replaced them with the same ratings and BETTER tolerances. I find it hard to believe that the best carbon comp resistor from 15 years ago is superior to a 21st century flameproof. Even in the audio forums they'll tell you a resistor is a resistor is a resistor. As long as it is actually at advertised values, tolerances, and features, a $100 resistor is no better than a RatShack $.049 resistor. The same people that will spend $100 on a resistor are the same ones that buy lowland rain forest wooden knobs for their amps that are supposed to enhance the sound.
It will most likely turn out to be something that was teetering on the edge of failure in the first place. I sure as sh*t couldn't do any damage to the PCB in this thing. Not with the iron I was using and the thickness of that PCB.
I take my glasses OFF to see up close. I also use a loupe to inspect before AND after anything I solder. Why? Because I don't "suspect" any one part...I suspect them ALL. This being a hobby...I mosey along at a relaxed pace.
I disagree with not reflowing all the solder joints in something like this. I'm not going to take a device that's been working for 15 years in God only knows what environments and ignore anything. It isn't the easiest thing to remove and bench in my tiny HT so I'm going to cover all the bases. I'll not have to revisit it down the road only to find the problem is something that could have been prevented with a little time and solder when I had it on the bench. Or worse, that thing I didn't do takes it down permanently. If a component in the unpotted section can't take the heat, then I'm kicking it out of the kitchen and replacing it. Simple as that.
I'll get it fixed and I'll be better for the time and effort it will take. Again, the beauty of hobbies is I can walk away from it and revisit it when it pleases me to do so. I'm not working on a cure for killer childhood diseases or a pandemic cure for cripe sakes.
I'm a hobbyist and therefore should be exempt from judgement while learning outside my current skillset. I may never get good at electronics but that's OK with me. I don't work on anything, hobby or otherwise, like a pissed off screeching monkey tossing sh*t all over the place. I plan to the best of my abilities. It takes information to even learn from ones mistakes; which leads me to the reason I started this thread in the first place.
I didn't invent the saying but yeah, sometimes sh*t DOES just happen.  [/b]
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"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
Last edited by JustGreg on Mon Jun 28, 2010 10:13 am; edited 5 times in total
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Mon Jun 28, 2010 12:31 am Post subject: |
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| mp20748 wrote: | I don't what's causing your HVPS, only that you never swap out those resistors unless you're going with replacements that known to work in that circuit.
Even if you have the original CARBON resistors in there, DO NOT replace unless the resistance value has changed. When the Carbons needs replacement, your OHM meter will let you know.. |
Two of them were out of spec Mike. That's the only reason I replaced them all. I originally only planned to replace the caps.
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"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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JustGreg
Joined: 07 Mar 2006
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Location: Kenosha, WI
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| Posted: Mon Jun 28, 2010 10:22 am Post subject: |
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| Sparky015 wrote: | Greg, not that this is what caused your problem, but back off on the temperature of your iron. You should never (unless your soldering on a heat sink) be set at 800F. Small components only need 630, 700 for a thick board such as an HVPS. If you need 800, you probably need a new tip, or using the wrong one for that application. That's also a good way to piss through your tips as well. Small components such as FETs ICs can only take so much heat as well. You may not be killing them with ESD, but you can certainly shorten their life with heat. Generally those components can only be heated three times (install and 2 reworks) before they should be thrown away. At 800 degrees I would cut that in half.
Food for thought. |
I agree. I could very well be wrong with my approach but I found could reduce the time I had heat to the board by adding a little new solder to the foil side and using the tip (1/8" flat blunt) to get the solder wick to rapidly wick the solder up out of the hole. At a lower temp that method didn't work as well and I was spending alot of time trying to get the solder on the component side to flow, thereby releasing the lead.
As I said before, somebody had already been into this thing and I cleaned up alot of piss poor soldering. The down side is the pads had already been heated to death. If I didn't get the solder to flow on the component side the pads wanted to lift if I just heated from the bottom and pushed. I wicked where I could on the component side but many pads are in places where it's too easy to melt the choke wires and such.
I very well could have killed an IC with heat but I've already ordered all the parts for both PS's (the rectifiers are different between the two).
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"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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