The NEW Build Your Own Arcade Controls
Main => Monitor/Video Forum => Topic started by: arcadeswede on August 06, 2020, 10:20:18 am
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Hi!
I'm troubleshooting a Sony PVM-2130QM and the RED color has some bleeding or isn't in focus compared to the other colors. See image:
(https://lh3.googleusercontent.com/wKcZ7V8kF2Gk9v5rfNkk2nSsqD1YH89jaZ1k_8NVn-z2HVidWd5Ck9T-HPghXbNQyBMUPsX_yFGk4ATtJ75rZjIy7RXYNAtRjht1l-O5vmho3Cn8l2S_qEzNJlY9B_kx2Gfv4ogIw_g=w2400)
I've recapped the neck board (C) and PSU board (D). I've tried adjusting the RED Cut Off but that didn't change it. I've reflowed all solder joints on the neck board. Everything looks good. I've measured some test points and they're all within specs.
If you look at the BLUE and GREEN colors, they show good focus and colors. I'm thinking there's a bad ceramic cap or maybe a transistor that's the culprit on the RED channel?
Do you guys have any ideas?
Here's the service manual: https://ia801607.us.archive.org/28/items/sony_PVM-2130QM_Service_Manual/PVM-2130QM_Service_Manual.pdf
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Alright, that's a really ---steaming pile of meadow muffin--- photograph of what i think might be the problem. Can you bring up a test grid, or something with a big red-to-not-red transition? Would it look like the photo below?
Either way, with the power off, check resistor R702 on the neckboard and then probably R703, R704 and R706 just in case. You can replace each of those with a with a metal-film 2W resistor of like value if there's any problems. R702 can be checked in place once the nearby C-3 connector is removed. TBH it might meter fine, but that doesn't mean it isn't the problem. The solid-carbon used in that spot is a known issue on similar models, and i'd recommend replacing it regardless. Just remember that the caps on the neckboard of these might hold charge, i think it is.
(https://www.aussiearcade.com/filedata/fetch?id=1818107&d=1592145310)
Let us know how you get on and we'll go from there.
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Part of the problem with those solid carbon resistors is that they degrade over time a bit like electrolytic caps, and can take a long time to fail completely (vs metal film resistors that usually just fail short), making it hard to diagnose the problem.
If checking/changing those neckboard resistors doesn't help, try swapping colour drive transistors around - see if the same problem transfers to another colour.
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Either way, with the power off, check resistor R702 on the neckboard and then probably R703, R704 and R706
Alright, here's the values:
702 = 691K (680K)
703 = 96.5K (100K)
704 = 524.7K (470K)
706 = 107.4K (100K)
Resistor 704 seems to be acting up. The other resistors looks like they're within specs. It was even desoldered and measured alone.
If checking/changing those neckboard resistors doesn't help, try swapping colour drive transistors around - see if the same problem transfers to another colour.
Are we talking about Q701, Q704 and Q708?
(https://lh3.googleusercontent.com/6HGH8UgdI6Y5tAzPrh-G4VwiY-g6xHH79n5LIBxiUPf6K9HaUsnooxM5FvC2x4p1D8aA0wfI6JG7mil-6wH7cY7hehr7uCc8I9TL0Jeiu24GKM1iZoprbOz-i-U17gwZrk5rRdVebho=w2400)
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Do both the "screen" control RV701 and the sub-brightness control RV706 on the neckboard work normally, out of interest?
No guarantees, but TBH i'd replace R704 with a 2W metal film and see what gives. (If you have to wait ages to get parts, then order all the solid carbon resistor values on the neckboard and just replace them one by one starting with R704). Zeb and I have both seen this problem or a very similar one on the PVM-2730, and it seems to be caused by those 470K solid carbons...
Or really by the fact the grid voltages are too low, and pushing the bias voltage up into the cutoff zone of the red drive, i think. Which is not a transistor problem as such. Technically the drive transistors are Q702, Q705 and Q709. But this set has four transistors for each colour on the neckboard. You can try swapping them one by one if you need to. I'd look at other options first.
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Yeah my suggestion earlier about swapping colour drive transistors is generic advice rather than specific to this model. Same advice still applies but clearly you have several transistors involved for each colour which complicates things a little.
You might try checking voltages available (expected values are on the schematic) to see if there is a voltage regulation issue.
Sent from my iPhone using Tapatalk
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Do both the "screen" control RV701 and the sub-brightness control RV706 on the neckboard work normally, out of interest?
Yes, they do!
Ok, I'll try order up some metal-film resistors for 702, 703, 704 and 706 and swap em' out.
Thank you guys! Both you buttersoft and Zebidee.
I've been posting this on multiple forums/facebook groups but no on has giving me this type of answers and knowledge. I really appreciate it!
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Just remember this isn't a guaranteed fix! If it doesn't help, hopefully we can think of something else to try :)
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Just remember this isn't a guaranteed fix! If it doesn't help, hopefully we can think of something else to try :)
Yeah, of course!
Could this also be a symptom of just a tired monitor overall even though blue and green looks ok? I haven’t seen this issue before with just one color so I’m really scratching my head.
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Could this also be a symptom of just a tired monitor overall even though blue and green looks ok? I haven’t seen this issue before with just one color so I’m really scratching my head.
If you mean tired tube, there, then probably not. The repair wizard Zeb consulted once said he'd have expected the blue cathode to wear out first. It could possibly be the cathodes oxidising, which generally calls for a rejuvenator. But the tubes Sony used were great quality, so it's far more likely to be voltage-related as above.
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Could this also be a symptom of just a tired monitor overall even though blue and green looks ok? I haven’t seen this issue before with just one color so I’m really scratching my head.
If you mean tired tube, there, then yes, it can be a symptom. But the tubes Sony used were great quality, so it's far more likely to be voltage-related as above.
Yes, that’s what I meant.
Ok, good to know because I believe so too I mean, blue and green looks good. If the tube is worn out. Wouldn’t green and blue look equally bad?
I’ll order some resistor asap and start from there. I’ll keep you guys posted.
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I think your tube/cathodes are good. The colours are still strong.
Those resistors do age, the values are a little out and replacing them is probably a good thing. I'd expect them to be a lot further out if actually failing, but maybe you're just catching it early.
If it is those transistors failing somehow, voltages at the marked points should be out. So yeah check those points and maybe add some transistors to your order if you get any weird measurements.
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I did some measurments. According to the service manual, there should be some values to check around the transistors B,E and C. So I did. Here's my result:
(https://lh3.googleusercontent.com/DzYI-V27U7P4GxYwvW1_KyCNM51PANsvO0v5Fbd3RGEHWuhjtIqhTKE6YDyPIoHCGiQxf6IbqX11zgxQBDK2k11zYX9dgazGRxGUKGQh75LLXeEX1948aNfB6lRYHRMFCKO0VZ_QwDg=w2400)
Something seems strange around the Emitter of Q707 (RED), only 109V around the diode. I measured the other BLUE and GREEN diode D701 and D704 and their value was not that low, almost the same. I gotta split so I can't measure more right now or dig into it.
Maybe you guys have a clue of what's going on?
Bad diode (D704)?
EDIT: Looking at the image. I might have swapped the values on Base and Emitter for Q707. Or maybe not? I need to check my notes again back home.
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Maybe you guys have a clue of what's going on?
Bad diode (D704)?
Maybe - you'll need to remove the diode to test it.
Worth checking your B+ - if that is low, might explain why other voltages here are a bit low too.
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I measures the B+ voltage going into the D-board. Serive manual says 135V, I measured 136.7V.
A little high but shouldn’t affect my problem enough to have all my values that low on the neckboard, right?
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Always best to make B+ as close to spec if possible
How about that diode? you can just lift a leg to test it too, but sometimes easier to just remove the whole thing rather than bending it up
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Always best to make B+ as close to spec if possible
How about that diode? you can just lift a leg to test it too, but sometimes easier to just remove the whole thing rather than bending it up
The service manual says to adjust +B to 140V (+-0.5V) on board FA, but it's hard to get to a testpoint. Could I instead adjust my 136.7V on the D-board I measured earlier to 135V? Or should I just rely on the actuall test point on board FA (140V)?
(https://lh3.googleusercontent.com/IZwdAA2vO9Lgq5PQSSHDuSzHv0NLsior-iMw3wMK_lJPkPsklfG7hEoME7FX01u2GaOD8l1OM_STizepVKSADz7-vqErVRhpxIAh_2V7qy_csuZB4oSH0HjY7GzG2NgafLY04ECES98=w2400)
I'm going for the diode next. I had a few minutes to spare for checking the voltages. Will check it and follow up later.
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Everything else relies on B+ being right so sorry but I say test that. Schematic says there is a pot so use it to adjust as appropriate.
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Ok, +B is now adjusted to 140V spot on.
Took out the diode and measured it. The diode is 0.593V one way, and OL the other. Which is good as far as I know.
I will continue to measure and poke around to see if I can find something else that is obvious.
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Alright, did some more measurments and found a couple of mistakes from my part.
The diode that showed bad values before was not D707, it was D712, that was my fault looking at the neckboard the wrong way. But that was the diode I removed when I tested it so it should be fine.
Just out of curiosity I swapped the BLUE Q703 transistor with the RED Q707 but no change. RED still looks blurry.
Here's my measurment values now. Voltage have been going down a bit and the 200V line is now 220V. Don't really know what's going on with my values.
(https://lh3.googleusercontent.com/jbBEcYBf3Tk5HIh7bPStQXs1sF1T9sKgyyWN1naecKWb-Rcs191YmE26WPrAUSRlirtmPeVp23a7eBGmv8DnHxAK8NxX6sTEKaRpoyY5bCu_D2H9wLJaKSh9k-1cwCW6tCcekXtzSZM=w2400)
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The elevated 200V might be a function of the bias voltage pulling high to compensate for the increased value of R704, though at only ~520k rather than 470k I wouldn't expect things to go pear-shaped. Maybe it's going funny under load. Did you replace any resistors yet?
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Did you replace any resistors yet?
No, I haven't got around ordering parts yet.
I just wanted to do some more troubleshooting, hoping to find more components that was bad to add to my order.
I'm thinking about just ordering some of the components for each color channel, just in case I find something strange later (and have some spare ones in the future).
Although, I'm having a hard time finding a new equivilant transistor for 2SA1091, 2SC2611 and 2SC2785. You can find A1091s on Ebay but it's $5 a piece, that adds up!
The diodes are tricky to find too, at least for me since I'm not that great with components :)
I'm looking at the datasheets and comparing parameters trying to find them on Digikey, Mouser, Tme.eu etc but I'm not 100% sure if I pick the right one. Maybe I'll just go with the resistors.
Here's the R704 with bad value (I just soldered it on the other side for easy removal later). The parts list says SOLID resistor but I'm guessing it's some kind of carbon that could be replaced with metal film ones as you guys said?
(https://lh3.googleusercontent.com/xl3WM6hE2y1-E7M1AGtRfiD3QyORNLBjoxoFBrKEc0JcwgC1K4CrSOppmLef1jUnsHqMpvZi_jRK3CTPnKEx4tCFkuc5dOzYtshE_bRlByC4-O89cBKTkbKFK2V-ERc5eTisMQixYCg=w2400)
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https://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc=1.25&ucb=300&uce=300&ueb=5&ic=0.1&tj=150&ft=80&cc=4&hfe=30&caps=TO126
These are a common type of transistor with many possible substitutes. That site lets you review and compare the key data/characteristics for different parts. If you google up for example "2SC2611 equivalent datasheet" you'll find similar information on many site.
Those "SOLID" (solid carbon) resistors can be replaced with metal film resistors that have same-or-higher wattage ratings. I think those SOLID resistors are 1W rated? I got a bunch of 2W and 3W rated for my PVM2730QM. In my case I ended up only having to replace one SOLID resistor (the one on power coming to neckboard was failing slowly but tragicly) and a couple of electrolytic caps.
May as well check everything around Q707,Q718 and Q716 and the diodes, caps and resistors around them including the actual D707. Something there is giving weird voltages. Did these voltages change much after adjusting B+? What do you get where it says 200, up near top of your pic a few posts back?
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https://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc=1.25&ucb=300&uce=300&ueb=5&ic=0.1&tj=150&ft=80&cc=4&hfe=30&caps=TO126
These are a common type of transistor with many possible substitutes. That site lets you review and compare the key data/characteristics for different parts. If you google up for example "2SC2611 equivalent datasheet" you'll find similar information on many site.
Those "SOLID" (solid carbon) resistors can be replaced with metal film resistors that have same-or-higher wattage ratings. I think those SOLID resistors are 1W rated? I got a bunch of 2W and 3W rated for my PVM2730QM. In my case I ended up only having to replace one SOLID resistor (the one on power coming to neckboard was failing slowly but tragicly) and a couple of electrolytic caps.
May as well check everything around Q707,Q718 and Q716 and the diodes, caps and resistors around them including the actual D707. Something there is giving weird voltages. Did these voltages change much after adjusting B+? What do you get where it says 200, up near top of your pic a few posts back?
Great link! I'll check it out.
They are 1/2 W resistors but 2W would do, apart from being a little bit bigger I guess?
I'll replace all those solid resistors while I'm at it.
Hmm, very strange. Went back to measure the B, C, E of Q707 but now Collector shows 129V instead of 100-105V as earlier. Maybe a bad joint? I'm super confused. Red is still the same though.
These are my values as of right now.
(https://lh3.googleusercontent.com/fnjLqQ3qBzce7VvnA3sD4irzaOtAOdJJpwmnlfXYxOC-cvLO4WTrKt5F1whtTWT42ILY3SGwuhI4PCBn0C4sg8pTpU3Qb7heLMKhhQYjumKcJ1azdKJSEN3RmjX1j-0jUxgJC-PG-EY=w2400)
What I've done compared to my last image with values is, adjusted +B voltage to exactly 140V. Switched transistors, the RED Q707 with BLUE Q703. Checked the D712 diode.
Where it says 200, I get 220V.
I'll remove the neck board and start desolder some components. just to check values of resistors. Electrolytic caps are already checked and swapped. Even the old ones was withing specs. What about ceramic caps? Should I bother checking them?
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Oh, I just remembered!
There was a cap (C704) on the neck board that was very close (if not touching) a resistor (R711). The shell off the cap was in contact with the leg going to GND of R711.
I don't know if that was responsible for the low value of the collector on Q707, but I added some electrical tape between the two and got a decent value this time. I can't believe I didn't remember that! I blame the lack of sleep ;)
Before I created this post, I recapped the neck board but the replacement cap for C704 that I had was to big so I ended up using the old one (good and within specs), so maybe I soldered it back on in an angle or something.
(https://lh3.googleusercontent.com/CH0JGfkiR-GL78apCvpQ4f2GHQ4fmveQop74CTYnThwGSNYxZeDIiVssMbZ_LRAnEC-JB41JjzxEjNVG-Xp3sQsPZ6r2T1x68ArwCnJzcH09a8paNUjXiCLKb5G27PplALvStHFUJgs=w2400)
Anyway, enough rambling. I'll do some proper work and order new resistors once and for all.
Thanks Zedibee and buttersoft for your patient! :)
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Some time has passed since I did work on this monitor and I'm done, customer was super happy with it! ;D
Anyway, I got the resistors. Swapped out the bad one, didn't change much, moved on to adjust the convergence and yoke. When that was done, the image looked alright to me.
Some tiiiny misalignment with the red color but wasn't worth the time fixing that. When gaming you can't really tell.
(https://lh3.googleusercontent.com/5JA5FZPbHHiIy-vCAV1lOBN5HST0KyTlnenO3uPTFKBkEMoj-RSYg2ew74UEO3MkL5aviinVeNHh1OQ3X2_nGd_W0MksdPf7npdK2HQaITzYkSHZxkZ6wFpNtYXBXjFocht-DOz-17s=w2400)
Here's some more pics:
https://www.instagram.com/p/CEbMb9ZHzYo/?utm_source=ig_web_copy_link
Thanks everyone for the help! I really really appreciate it.
This was the place that got me the most help out there and I posted in FB-groups, Reddit etc. BYOAC rules!
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Glad to t worked out for you! :)