Cause for CRT Monitor Jittering? - Page 1
Forum section: electronics / repair

author: sideburn
author_rank: Regular Contributor
timestamp: February 02, 2017, 05:39:04 am
content: Does anyone know what might be causing this old CRT monitor to be jittering like it is in this video?https://youtu.be/_FlFdDvYHpABad capacitors maybe?

author: Armadillo
author_rank: Super Contributor
timestamp: February 02, 2017, 07:17:02 am
content: Suspect Internal Loose Connection - Check deflection yoke plugs into the main PCB or at the base of the flyback transformer. Check for poor soldering joints and bad connections near high wattage components. Examine the solder connections on the PCBs, particularly in the area of the deflection circuits and power supply. Look for hairline cracks between the solder and the component pins - mostly the fat pins of transformers, connectors, and high wattage resistors. Just re-solder anything that look suspicious.

author: JFJ
author_rank: Regular Contributor
timestamp: February 02, 2017, 11:22:01 am
content: The jitter only appears to be in the horizontal direction, which suggests that there are fluctuations in the line sync. Have you tried a different monitor (to eliminate the video signal source as being the cause of the problem)?

author: Rasz
author_rank: Super Contributor
timestamp: February 02, 2017, 11:56:07 am
content: dont you mean TV?I have pretty much zero TV knowledge, but this looks like tv(pll?) is unable to catch sync in shitty NTSC composite signaltry connecting something using proper signal -RGB with separate sync (Euro connector).

author: sideburn
author_rank: Regular Contributor
timestamp: February 02, 2017, 05:03:25 pm
content: Yes I tried another tv to rule out the signal.It is a sony monitor. Not a tv. Has BNC composite video input on the back.

author: Twoflower
author_rank: Frequent Contributor
timestamp: February 02, 2017, 08:23:10 pm
content: That could be even outside the monitor. I've seen similar influences on CRT caused by electric trains passing by in a distance of 300ft. Not just that, as this problem was known half of the monitors in the office were covered in passive shielding, the other half they tried some active shielding (worked less effective).So see if you can run the monitor in a different orientation to see if it changes. And or check any nearby electric gadgets.

author: Rasz
author_rank: Super Contributor
timestamp: February 03, 2017, 04:14:14 am
content: does it have other inputs? even svideo could be better

author: james_s
author_rank: Super Contributor
timestamp: February 03, 2017, 04:51:41 am
content: That looks like a hum bar, if the screen background weren't black you would probably see a bar scrolling down the screen. It can be caused by a ground loop, bad connection, or tired capacitors in the monitor. What sort of input does the monitor take?

author: martinator
author_rank: Contributor
timestamp: February 03, 2017, 08:48:24 am
content: Is that an Apple II?I had the same problem with a IIe PAL machine I had. I think it's probably a timing issue. I can remember replacing caps and all sorts and it didn't make any difference. How modern is your crt? Newer crt's are not as tolerant to out of spec signals I suppose? Try to find one without a digital tuner. Ifitis an old crt and doesn't have a digital tuner then it sounds like it's scope time.

author: james_s
author_rank: Super Contributor
timestamp: February 03, 2017, 08:51:14 am
content: I see now where it was mentioned that this is a composite monitor. Try feeding it video from another source to rule out timing issues or other problems with the computer.

author: Armadillo
author_rank: Super Contributor
timestamp: February 03, 2017, 09:49:14 am
content: Quote from: sideburn on February 02, 2017, 05:03:25 pmHow about a signal source from another computer showing Window on the Sony Monitor.The signal seems to be from old computer like 6502 or Z80? What signal source is that?

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 12:48:46 am
content: I have the same issue when I connect it to my art 800xl as well so I don't think it is that Apple II.I have relocated the monitor and tried different outlets and it doesn't make a difference either.

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 12:49:27 am
content: It does but they all have the same issue.

author: drewscruis
author_rank: Newbie
timestamp: December 22, 2018, 05:10:14 am
content: Looks like failing caps to me.Sent from my KFSUWI using Tapatalk

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 11:36:43 am
content: I think it’s caps too. Just not sure which ones. I’ll have to find a schematic and seee if I can get the values.

author: drewscruis
author_rank: Newbie
timestamp: December 22, 2018, 11:51:07 am
content: I have rebuilt plenty of arcade crt's, you should Google to see if someone has a cap kit available to make life easier. I'd replace them all as there pushing their service life at this point.Sent from my SM-N910V using Tapatalk

author: drussell
author_rank: Super Contributor
timestamp: December 22, 2018, 12:24:47 pm
content: Unplug the degaussing coil to make sure it isn't intermittently getting a bit of power fed to it after the initial power-up when it should stay off. If that isn't it, check all the supply voltages to be sure they are stable and you don't see any fluctuations of the voltages when the wiggle happens.If those are all stable then, yeah, it is probably a bad capacitor somewhere with the same kind of fault that can cause sizzles and noises in things like audio amplifiers that are often one of those great times to use an old timey audible "signal tracer."

author: PKTKS
author_rank: Super Contributor
timestamp: December 22, 2018, 12:47:02 pm
content: It looks like you have a SECOND SIGNAL superimposed over the sweepBy the speed of the symptom I would guess that the SYNCH SEPARATORblock is faulty and the Hsynch is mixed with some ammount of VsynchEasy to check w/SCOPE on the output of the HSynch separatorShould have **ONLY** the proper high freq part - not the low (vertical seep)Block faulty is not filtering the synch properlyWild guess without the scope probe attachedPaul

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 22, 2018, 12:51:26 pm
content: My knowledge of CRT's is also limited but i would check all connections inside first to see if something has got a bit loose or look suspicious.Sometimes solder joints etc can also break if you move crt's.Like someone said it might be number of things maybe caps also .Good luck !

author: drussell
author_rank: Super Contributor
timestamp: December 22, 2018, 02:15:53 pm
content: Quote from: PKTKS on December 22, 2018, 12:47:02 pmYeah, if it seems to repeat at a predicable rate then it is likely a rogue signal pathway somewhere rather than the typical power filtering issues, though I suppose it could be an interaction between the power line frequency and the video refresh rate.That is one of those times where having a variable frequency AC supply is handy to quickly determine whether something like that is the case by being able to observe any generated beat "note."

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 22, 2018, 02:20:53 pm
content: Quote from: drussell on December 22, 2018, 02:15:53 pmMaybe AC line is picking signal and filter caps are bust ?

author: PKTKS
author_rank: Super Contributor
timestamp: December 22, 2018, 02:39:56 pm
content: Quote from: Bashstreet on December 22, 2018, 02:20:53 pmYes quite possible as wellTHAT DEPENDS a **LOT** on the MONITOR YEAR (technology used)Some old mutisynch monitors used to have separated V/H pathsbut they do MIX internally on some blocks (PSU and/or video MCUs)More recent better monitors started to use a dedicated MCU to handle theexternal synch signals which they would just "resynch" as possible to passthat to the video controller IC2 FIGURES of these 2 different approach attachedNote that on the ancient one the PSU also uses the SYNCH signalsto synch itself switching freq.SCHEMATICS will be very handy to see how the 2 separate inputsare used along the synch path.. they do got mixed some howand may be the AC PSU noise as welllOn the recent one the MCU handles the synch and the PSUis not using the external synch entries as interface..Paul

author: PKTKS
author_rank: Super Contributor
timestamp: December 22, 2018, 02:47:03 pm
content: in other words... the so called E/W signal (or cushion or east west correction)is faulty messy with some low freq noise.Question is where that noise is entering the chain

author: Fred27
author_rank: Unknown
timestamp: December 22, 2018, 04:44:22 pm
content: It seems this is not a problem that is likely to be rectified in the future. I was watching The Expanse and all their high tech devices seem to have screens that do exactly this. Why? In what way does that make things seem futuristic?Sorry - a bit off topic!

author: Rasz
author_rank: Super Contributor
timestamp: December 22, 2018, 05:42:02 pm
content: Quote from: Fred27 on December 22, 2018, 04:44:22 pmits probably just their retro futuristic design aesthetic, like Alien/Fallout CP/M terminals

author: sideburn
author_rank: Regular Contributor
timestamp: July 25, 2022, 08:37:45 am
content: Hey y’all, I’m back and revisiting this again. Same monitor. But the symptoms are now a little different. I never fixed it and it was put away for a coiled years. Now the horizontal is shifting on a slow vertical sweeping. I ruled out the a/c outlet / ground loop and the composite video input. Opened it up and caps physically look ok as well as solder connections and traces. No schematic and I can’t tell where to look on the board or what to try next. Can you look at my YouTube video and see if you have any suggestions?Video here—>https://youtu.be/Qfw7dzLMNPo

author: PKTKS
author_rank: Super Contributor
timestamp: July 25, 2022, 10:33:06 am
content: by the age of such components ....My first guess is really a bad cap unable to filter the signal....This is old stuff expect a lot of vintage components faultyToday - unless you are vintage collector - repairman hardly invest time on this stuffno parts no support no schemas (they are all on printed services..)(those service manuals at time costing a fortune... today they skyrocket..)and no value for the money.Unlesss it is yours and collectors stuff.. ( i have some vintage pet gizmos myself..)Expect no money or support anywhere...Paul

author: sideburn
author_rank: Regular Contributor
timestamp: July 25, 2022, 08:29:00 pm
content: Totally collector, hobby, repair. I fix old computers etc.. this is hooked to a repaired apple ][ and C64.I assume its a cap but I'd rather not have to replace them all to find out. Would like to isolate down to a certain area. Just not sure which area. Maybe its A/C noise so the issue is in the power supply zone...

author: Rasz
author_rank: Super Contributor
timestamp: July 26, 2022, 02:29:43 am
content: You can try blowing cold/hot with a hair drier and watching for change in distortion

author: Bud
author_rank: Super Contributor
timestamp: July 26, 2022, 05:32:39 am
content: It is just screaming power supply capacitors problem.They may look ok but you cant tell just by the look unless they leaked. They may have dried, not leaked.

author: Ian.M
author_rank: Super Contributor
timestamp: July 26, 2022, 07:27:26 am
content: Yes. The slow rolling offset is caused by the beat frequency between your nom. 60Hz mains supply, which wanders by approx +/-0.05 Hz due to demand on your regional electricity supply grid and the SX64's crystal generated frame sync, again nom. 60Hz. Something is taking the monitor's horizontal scan circuit out of spec for part of each mains cycle, and a dried out main reservoir capacitor in the power supply (causing excessive 2x line frequency ripple on its outputs) is a prime suspect.Its a pity you didn't shoot the video with the whole screen in shot, and preferably with a grid pattern displayed. If we saw two bands of distortion moving up or down, with each coming onto the screen before the other leaves the opposite edge, it would indicate 120Hz ripple, which is diagnostic of a non PFC PSU with a bad reservoir cap. OTOH if it had a single band, that would indicate either 60Hz ripple possibly due to a bad diode in the mains rectification section of the PSU, or due to a ground loop causing a threshold shift in the line sync circuit. I think we can rule out a bad degaussing circuit due to the good color purity and the sharp transitions between straight scan edges and where its distorted.

author: sideburn
author_rank: Regular Contributor
timestamp: July 26, 2022, 07:21:43 pm
content: Quote from: Rasz on July 26, 2022, 02:29:43 amgood idea, on the main PCB right?

author: sideburn
author_rank: Regular Contributor
timestamp: July 26, 2022, 07:22:58 pm
content: Quote from: Bud on July 26, 2022, 05:32:39 amwould that be that big cap on the main board? trying to find out WHICH caps they are...

author: sideburn
author_rank: Regular Contributor
timestamp: July 26, 2022, 07:25:33 pm
content: Quote from: Ian.M on July 26, 2022, 07:27:26 amThere is one spot in the video of the whole screen also i have shots of the PCB do you know where on the PCB I should be working based on the screenshot ? I will look it over some more for bridge rectifier/power circuit area

author: Bud
author_rank: Super Contributor
timestamp: July 26, 2022, 08:23:59 pm
content: Quote from: sideburn on July 26, 2022, 07:22:58 pmElectrolythic capacitors dry out faster from heat. Look at capacitors located in close proximity (1-10mm) to a heat source, e.g. high power resistors, heatsinks.

author: james_s
author_rank: Super Contributor
timestamp: July 26, 2022, 11:26:41 pm
content: Why don't you get an ESR meter and test them? I bought one back in the late 90s when it was almost $200, a lot of money back then but I was repairing quite a few CRT monitors and it was an indispensable tool. Now you can get them a lot cheaper, or build one yourself.

author: sideburn
author_rank: Regular Contributor
timestamp: July 28, 2022, 08:04:43 pm
content: Quote from: james_s on July 26, 2022, 11:26:41 pmPretty sure I have one. The problem is there's tons of caps on this board and I would have to remove them anyway to test them so at that point, might as well replace them anyway since they are so old.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: July 28, 2022, 11:39:39 pm
content: That has to do with the camera scan rate and the TV/monitors it takes specialequipment to make that go away.Not the same as the power supply capacitors failing.Jeff

author: sideburn
author_rank: Regular Contributor
timestamp: August 16, 2022, 02:54:54 am
content: Hey All, I checked the caps on the board with an ESR meter and visual inspection again. I see no bulging and the ESR is showing them as ok.Here is a full screen view video of the issue:https://youtu.be/_liYw2lJrPcThe horizontal line thats moving up the screen is not visible in real world so that must be a syncing issue with the camera. but you can see the shifting section on both the left and right edges of the screen. its like a 5" tall section is shifted to the right by a few "pixels"...still trying to resolve this mystery.

author: floobydust
author_rank: Super Contributor
timestamp: August 16, 2022, 03:54:54 am
content: It looks like AC hum bars, you have mains frequency ripple. What 's the monitor's model number?Hum bars are usually in the monitor's power supply on say a 130VDC rail if it's using mains rectified. Or your computer has hum in the video output and the monitor is fine.Either way, it's likely a filter capacitor has failed low value.The de-gaussing circuit not shutting off looks different, the entire screen wobbles.

author: sideburn
author_rank: Regular Contributor
timestamp: August 16, 2022, 12:59:29 pm
content: Quote from: floobydust on August 16, 2022, 03:54:54 amIt’s a Sony PVM—380. It’s definately the monitor and not the computer or my a/c outlet. I’ve ruled that out and connected multiple composite inputs from other devices in multiple locations.I’ve attached a couple photos of the main board. Maybe you can see which caps I might want to have another look at and maybe swap out? I was wondering if it may be the big brown ceramic cap below the fuse and above the power cable on the bottom left. No idea what type it is or what its value is though...

author: sideburn
author_rank: Regular Contributor
timestamp: August 16, 2022, 03:01:30 pm
content: Looks like that cap is inline with the a/c main, the fuse and what looks like an inductor..?..I have a cap in my parts bin form another monitor repair that looks similar.Maybe I could piggy back that onto the board or swap it out if you think that may be the culprit?

author: sideburn
author_rank: Regular Contributor
timestamp: August 16, 2022, 03:04:56 pm
content: photos:front/backpub backspare cap (this was for an arcade machine monitor chassis i never ended up using. Maybe it will work as a replacement?:

author: Ian.M
author_rank: Super Contributor
timestamp: August 16, 2022, 03:23:31 pm
content: Nope. That's a line filter cap across the line after the fuse. If it was bad it would blow the fuse, and could never cause your symptoms, even if you dyked it out completely!The odds are in excess of 99.9% that the fault is a badELECTROLYTICcap in the PSU section.However there doesn't appear to be a switching transformer in the PSU, and from the PCB layout of that section, and the lack of an isolation gap anywhere except round the Video/Audio In section, its almost certainly got a live chassis, so extreme caution is required when working on it. Unless formally qualified to do so, please don't attempt to make any measurements or otherwise handle it with the mains supply connected.I cant find any references to a "Sony PVM—380" monitor - please post a photo of the model and serial no. label so we can search for the exact model number and try to find you a schematic.

author: andy2000
author_rank: Frequent Contributor
timestamp: August 17, 2022, 05:16:38 am
content: The only part of the monitor that could introduce power line ripple is the power supply. I'd start by replacing the caps near the 20W 200 ohm resistor. They work hard, and are exposed to heat from the resistor and voltage regulator on the big heat sink.That monitor is based on a common for the era Sony 13" TV chassis without the tuner and IF components. It uses a hot chassis with opto-isolators on the video input.

author: sideburn
author_rank: Regular Contributor
timestamp: August 18, 2022, 03:27:30 pm
content: Quote from: Ian.M on August 16, 2022, 03:23:31 pmAhh ok, thanks for clearing that up, and thanks for the caution, I've worked on many monitors and familiar with the KV's they put out so i try to be safe. Yeah I was unable to find schematics or any info...I have attached photos of the back with the model and serial number:SER. NO. 5004449MODEL NO. PVM - 1380MFG Date: MAY, 1987

author: sideburn
author_rank: Regular Contributor
timestamp: August 18, 2022, 03:30:57 pm
content: Quote from: andy2000 on August 17, 2022, 05:16:38 amI keep thinking it might be that big cap right above the 20W resistor. ESR says its good but maybe I should remove it, test again and replace it anyway.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 18, 2022, 07:31:46 pm
content: The power supply has a bridge rectifier so all its electrolytics are seeing twice the mains frequency. Your disturbance is at mains frequency, not twice it. First suspect would be an open circuit diode in the bridge rectifier.

author: floobydust
author_rank: Super Contributor
timestamp: August 18, 2022, 08:31:50 pm
content: I don't find a service manual or schematic for the Sony PVM-1380. You have to find the chassis number SCC-___, as you can see the same board 1-614-793-22 may have also been used as a TV set. I checked and BVM-1310 broadcast 19" rack-mount is a different bird.I've seen the hum bars as a problem with the 120VDC or maybe 130VDC rail, whatever comes out of IC601 - if you can give us that part number. The main filter cap being low value, OP you say the ESR is good but that is not capacitance value. C603 330uF and the little cap next to it would be suspect. Be very careful any stray charge there will bite.I've also seen the hum from the NTC/degauss causing low input voltage to IC601.edit: maybe look herehttps://archive.org/details/sonymonitorsfor monitors in the same family.

author: sideburn
author_rank: Regular Contributor
timestamp: August 19, 2022, 12:51:41 am
content: ok i will have to pull the board back out and then I can get you the IC601 PN.I don't even see the bridge rectifier looking at the photos I took...

author: wasedadoc
author_rank: Super Contributor
timestamp: August 19, 2022, 12:53:30 am
content: Quote from: sideburn on August 19, 2022, 12:51:41 amIt is the black square with the + and - written on it. Just to the left of the 20 Watt resistor.

author: sideburn
author_rank: Regular Contributor
timestamp: August 19, 2022, 06:29:16 am
content: Ahhh right ok I will test it and see what the resistances are.

author: sideburn
author_rank: Regular Contributor
timestamp: September 02, 2022, 10:14:42 pm
content: OK guys I am back with some more results.First, I pulled both the large c602 and small c603 and they tested ok from what I can tell ESR in range...cap checker showed ocorrect uf values... The two ceramic looking caps next to c603 and both reading open circuit with my ohm meter, not sure if thats normal.The large ceramic resistor checks good as well.But the bridge rectifier looks suspicious to me, when I check the 4 pins with my DMM in diode check mode, I am getting .5 or so one way between the pins and 1.8v the other way EXCEPT for the two pins that the mains is connected to fi i check THOSE two pins i get 1.8ohm + to - and 1.8ohms - to +.... only those two pins. all the rest give me .4 or .5 ohms one way and 1.8 the other.** I think I may have been testing it wrong. Maybe those results are expected. Not sure if I should be getting 1.3v when i test pos to pos and neg to neg on the output side though... Should that be Open? starting to the maybe the bridge rectifier is actually ok.. hmm... if so maybe its those blue caps ceramic caps (c407 and c409)?can I bodge a diode between those pins to see if it fixes it?IC601 is a an STR 30135 (7317)

author: wasedadoc
author_rank: Super Contributor
timestamp: September 03, 2022, 08:13:17 am
content: Every bridge rectifier has four diodes and four pins. Two pins are the AC input, one pin is the +ve output and one pin is the -ve output.Draw the schematic of the four diodes and the four pins on a piece of paper. It should be obvious to you how to check each individual diode.

author: sideburn
author_rank: Regular Contributor
timestamp: September 05, 2022, 11:47:47 am
content: Yeah. I know what they are I jumped the gun on it when I tested. It seems ok to me the only thing is when I test the reverse polarity a am getting 1.5v and not and open circuit. But I’m testing in circuit so maybe that’s normal.I don’t know. So far everything is checking out ok.

author: wasedadoc
author_rank: Super Contributor
timestamp: September 05, 2022, 02:47:39 pm
content: Quote from: sideburn on September 05, 2022, 11:47:47 amYou should be testing each of the four diodes individually, forward and reverse. Eight tests in total.

author: sideburn
author_rank: Regular Contributor
timestamp: September 05, 2022, 05:42:22 pm
content: Yes. I have. And I get .5v one way and 1.5 to 1.8v the other way on each diode.

author: wasedadoc
author_rank: Super Contributor
timestamp: September 05, 2022, 05:55:09 pm
content: Take the bridge off the board and test it again to be sure.

author: sideburn
author_rank: Regular Contributor
timestamp: September 07, 2022, 05:43:30 pm
content: Quote from: wasedadoc on September 05, 2022, 05:55:09 pmBridge checks out good out of circuit, so based on that and low ESR on the caps, nothing looks suspicious.I guess I’ll replace them anyway and see what happens.

author: floobydust
author_rank: Super Contributor
timestamp: September 08, 2022, 03:59:19 am
content: Hum bars I've seen caused by:1. the main filter capacitor low in value2. degauss PTC thermistor bad (high ohmic value) starving the input voltage to IC601.3. B+ voltage regulator IC601 STR 30135 which has a spec. 135VDC +/-0.8V output with 150-175VDC input. You could check the main B+ rail is in spec.

author: sideburn
author_rank: Regular Contributor
timestamp: September 08, 2022, 06:35:48 pm
content: Yea I can check b+ Once I find where to probe.Was also wondering if I can somehow narrow it down with an o’scope by looking at the a/c waveform in different areas.

author: sideburn
author_rank: Regular Contributor
timestamp: September 08, 2022, 06:41:35 pm
content: Not sure if this is any clues but way back when this monitor started acting up it was more jittering than smoothly warping.Here’s the first video clip:https://youtu.be/_FlFdDvYHpAAnd here is it’s now again to compare:https://youtu.be/_liYw2lJrPc

author: wasedadoc
author_rank: Super Contributor
timestamp: September 08, 2022, 06:59:23 pm
content: Quote from: sideburn on September 08, 2022, 06:35:48 pmDo NOT try to use an oscilloscope unless:1. It is running from batteries or, highly preferably, you have an adequately rated isolation transformer powering the TV.2. You fully understand how to avoid electrocuting yourself.That TV's power supply has no mains isolation and no matter which way you connect the AC supply the chassis is never at neutral (or whatever it is termed in your part of the world).Suggest you watch the EEV blog video

author: sideburn
author_rank: Regular Contributor
timestamp: September 16, 2022, 10:03:56 pm
content: Well I replaced the bridge rectifier, the large 330uf 200v cap, the 33uf and the 10uf and no change. If anything it may be worse.All components I changed out are marked in yellow in the attachment.

author: floobydust
author_rank: Super Contributor
timestamp: September 16, 2022, 10:15:25 pm
content: Quote from: sideburn on September 08, 2022, 06:35:48 pmWhat do you measure for B+? I think it's 135VDC.

author: sideburn
author_rank: Regular Contributor
timestamp: September 17, 2022, 12:02:39 am
content: How do I locate B+ ?

author: sideburn
author_rank: Regular Contributor
timestamp: September 17, 2022, 12:35:24 am
content: This spot has a “B” could that be it?See attachment:

author: floobydust
author_rank: Super Contributor
timestamp: September 17, 2022, 04:56:57 am
content: Without a schematic or service manual, a repair can be very difficult. You really need an isolation transformer for safety when making measurements.Also, it's a 'hot chassis' monitor yet somewhere the video input is isolated??? This doesn't make sense, is there continuity from the video input jacks to the chassis common? That's from the bridge rectifier (-) to the inputs. I can't see an isolator module. Hopefully your computers aren't getting a lift...The output of IC601 STR30135the +135VDC regulator goes to C519 33uF 160V, also needs C603 10uF to be OK, (both of which you say you've replaced).You could carefully measure DCV at C519/nearby jumper, to the chassis common. If your multimeter is AC-coupled you can also measure ACV to see how much ripple is present.I notice there is provision for a tuner? so this same chassis may have been a TV set, and sometimes used for bigger CRT's. So a service manual for a TV (vs monitor) or bigger set (say 15-17") can match a board sometimes.I dislike the too much flux on the flyback transformer pads, I would clean with IPA/q-tip and scrape a bit and then let it really dry off. Some pins have 800V, 180V outputs which like to arc. Make sure the board dries out thoroughly.edit: I did see another isolated small power supply for the video board I think. T401 and C416, with regulator Q416 C422, C423. Check those caps.Check R449 looks broken? It must be a high value part for safety I think. By connector A-6, it's between the isolated video and hot chassis common.The other 9VDC power regulator for the (hot) video is C241, C408, C410 with Q241.

author: sideburn
author_rank: Regular Contributor
timestamp: September 17, 2022, 06:44:35 am
content: Thanks I will check these next. I did check the voltage on the large white ceramic resistor and it is 135v on one side and 85v on the other.

author: wasedadoc
author_rank: Super Contributor
timestamp: September 17, 2022, 11:33:43 am
content: Quote from: floobydust on September 17, 2022, 04:56:57 amIn Reply #44, Andy2000 wrote:"That monitor is based on a common for the era Sony 13" TV chassis without the tuner and IF components. It uses a hot chassis with opto-isolators on the video input."

author: m k
author_rank: Super Contributor
timestamp: September 17, 2022, 12:52:37 pm
content: Quote from: sideburn on September 08, 2022, 06:41:35 pmFrom first video I'd say it's a cracked solder.Second video can't be compared.It's more like a locking, grounding or power issue.Do a new video with same screen as in the first one, or at least something with black background.Anybody tried finding a hiding crack with a laser pointer, how was it?

author: floobydust
author_rank: Super Contributor
timestamp: September 17, 2022, 07:38:21 pm
content: Quote from: sideburn on September 17, 2022, 06:44:35 amI see a problem with those voltages on the big power resistor R606 200Ω 20W. One leg connects to the output of the bridge rectifier. I would expect at least 160VDC there.Other leg goes to the STR30135 IC601 voltage regulator output, I would expect 135VDC there.This makes me believe the circuit is starved and running at low B+ voltage, or more likely the readings are wrong.There's not many parts that can cause this problem - open diode on the bridge rectifier D601, low value for main filter capacitor C602 330uF, high value for R602 is 2.2Ω and likely not to fail high value as a wirewound part, L601 also not likely to fail high ohms, on/off switch etc. and OP you've replaced those parts. The degauss coil and PTC is independent across the line, not in series as some sets do.So it doesn't make sense which means the voltage readings are wrong or new parts are duds. OP do you measure voltage to earth-ground or the hot chassis common? Use the chassis (-) common which is the black wire on the backside as your reference point.

author: sideburn
author_rank: Regular Contributor
timestamp: September 18, 2022, 02:43:21 am
content: Hmm maybe i mis-measured. I will make a new video shortly if the current condition. I’ll put a game on it with a black background and mount the camera on a tripod so it will be more accurate.

author: floobydust
author_rank: Super Contributor
timestamp: September 18, 2022, 03:34:42 am
content: Please check isolation resistance from the video input jack shell to the hot chassis(-) at that black wire on the underside.The monitor has a "death resistor" that I can see, connected between the hot chassis(-) and the (isolated) video power - as it looks damaged. R449 by connector A6, I'm guessing it's 4.7MEGΩ carbon comp. Might be similar to R601 (near L602 and the bridge rectifier). I would say it's a safety critical resistor R449.

author: sideburn
author_rank: Regular Contributor
timestamp: September 18, 2022, 05:56:16 pm
content: OK new test results, new video and photos.First off, I tested the voltages incorrectly across the ceramic 200ohm resistor (R606). I was measuring from chassis and and a/c neutral.This time I pulled the board out completely, dropped the flyback anode into a glass container and powered the board up. I then measured D/C voltage from the - pin on the bridge rectifier to the resistor and measured 155vdc on left side and 136vdc on right side.R449 is measuring 4.8M ohm (in circuit)R601 is .9M ohm (in circuit)c416,c423, and other nearby capos are all low ESRNew video:https://youtu.be/umTy5FhXovM

author: wasedadoc
author_rank: Super Contributor
timestamp: September 18, 2022, 08:43:48 pm
content: The video and audio circuitry between the input sockets and the optocouplers must have a separate power supply. Check the components in that.

author: m k
author_rank: Super Contributor
timestamp: September 19, 2022, 12:12:09 pm
content: Times are 5.5s, 13.8s and 22.1s.Shapes are also clearly sine.So horizontal deflection is feeling an extra wave.It also seems to have a high point every 8 seconds.Can you demonstrate different picture formats?

author: wasedadoc
author_rank: Super Contributor
timestamp: September 19, 2022, 05:48:27 pm
content: Those regular times are merely a consequence of the slightly different frequencies of the AC mains supply and the vertical scan rate of the video source.

author: sideburn
author_rank: Regular Contributor
timestamp: September 19, 2022, 11:57:06 pm
content: I’m not sure what you mean. Do you mean check the components on the separate video input board where the composite inputs are?

author: sideburn
author_rank: Regular Contributor
timestamp: September 19, 2022, 11:58:31 pm
content: Quote from: m k on September 19, 2022, 12:12:09 pmWhat kind of picture formats?

author: wasedadoc
author_rank: Super Contributor
timestamp: September 20, 2022, 08:31:02 am
content: Check the components of the separate, isolated power supply for the circuitry that is between the input sockets and the optocouplers.

author: m k
author_rank: Super Contributor
timestamp: September 20, 2022, 03:19:09 pm
content: Quote from: sideburn on September 19, 2022, 11:58:31 pmDifferent horizontal and/or vertical refresh rates.Exotics would be nice but CGA can also be one and normal interlaced video with static picture another.Idea is to have interference differences, or not.That way you may get some new info of the situation.Jitter is clearly gone but my guess is that it is still there somewhere.

author: sideburn
author_rank: Regular Contributor
timestamp: September 28, 2022, 11:08:19 pm
content: Quote from: wasedadoc on September 20, 2022, 08:31:02 amThere is no separate power supply.. am I confused?

author: sideburn
author_rank: Regular Contributor
timestamp: September 28, 2022, 11:09:22 pm
content: Quote from: m k on September 20, 2022, 03:19:09 pmBut the only input is composite.

author: sideburn
author_rank: Regular Contributor
timestamp: September 28, 2022, 11:10:27 pm
content: Quote from: wasedadoc on September 18, 2022, 08:43:48 pmHmm on that main board? I see a transformer in there.

author: floobydust
author_rank: Super Contributor
timestamp: September 28, 2022, 11:33:09 pm
content: Quote from: floobydust on September 17, 2022, 04:56:57 amIt's hard to know just where the AC hum is getting into the monitor.Assuming the hum is getting in at the video isolator, there are two small power sections to check:The isolated input jack side "T401 and C416, with regulator Q416 C422, C423" and then the hot-chassis side "9VDC power regulator for the (hot) video is C241, C408, C410 with Q241."Next I would see where the vertical deflection is powered from, see if a bad cap is there.

author: sideburn
author_rank: Regular Contributor
timestamp: September 29, 2022, 01:39:49 am
content: Ok. I’ll check that next when I jump back into it. So far I cannot find a bad cap ESR. And I’ve checked most of them.

author: floobydust
author_rank: Super Contributor
timestamp: September 29, 2022, 04:20:02 am
content: Relying exclusively on ESR as a pass/fail for electrolytic capacitors, I don't think it works because the ESR table you are using, they are all over the place.Just keep in mind that notion might not be working here and low values for capacitance are passing OK. The small parts like 10uF and 47uF have widely varying ESR numbers.example: I have 47uF 16V Nichicon VZ (blue) 16 years old 3Ω ESR. Is that a pass? I measured capacitance at 28uF or -40%. 10uF measured ESR 2.1-3Ω

author: wasedadoc
author_rank: Super Contributor
timestamp: September 29, 2022, 07:52:21 am
content: It isn't a bad cap anywhere related to vertical deflection. The disturbance to the horizontal deflection is not at vertical deflection frequency. That is why it moves vertically.

author: m k
author_rank: Super Contributor
timestamp: September 29, 2022, 11:36:47 am
content: Quote from: sideburn on September 28, 2022, 11:09:22 pmYou can still have different formats.What kind of possible sources you may have?Apple II and C64 are mentioned.Have you tried grounding(to known earth) the input connector's frame when picture is on?Don't connect it, just tap the connector with the wire.Is the hum same with DVD menu?

author: sideburn
author_rank: Regular Contributor
timestamp: September 29, 2022, 01:35:24 pm
content: The last video I did with the blue game game menu picture was one of those cheap handheld Nintendo knockoff multi game consoles you can get on Amazon for $20 bucks. I’ve tried apple ][, Atari 130 xe, Atari 800xl, commodore sx-64, NES emulator console. Multiple A/C outlets from different locations. All the same result. I could have tried dvd but I think I just gave my last one away. I’m not positive about grounding test but I confirmed that the video input is connected to the ground pin on the power cord.

author: sideburn
author_rank: Regular Contributor
timestamp: September 29, 2022, 01:40:52 pm
content: Also the handheld game unit used in the most recent video I posted is running on battery power and has its own composite video output.

author: m k
author_rank: Super Contributor
timestamp: September 29, 2022, 04:22:48 pm
content: Quote from: sideburn on September 29, 2022, 01:35:24 pmBoth Atari models may have PAL capabilities.NES emulator can have what ever.QuoteAnd you're certain that at least one had a proper grounding?QuoteWhy?QuoteTo the wall end?

author: wasedadoc
author_rank: Super Contributor
timestamp: September 29, 2022, 04:34:58 pm
content: @floobydust.You've made references to component numbers which makes me think you have a schematic. Can you post it or a link to where it can be downloaded?

author: floobydust
author_rank: Super Contributor
timestamp: September 29, 2022, 05:49:08 pm
content: Quote from: wasedadoc on September 29, 2022, 04:34:58 pmI would not be an asshat and withhold a schematic/service manual from the thread. I could not find one and am just looking at the PC board photos OP posted to list components to test. I have been in TV's/monitors enough to know the building blocks and in the day no schematic or service manual was available so you'd have to dig. Each section is marked on the bottom silkscreen.I know hum bars as they are called are usually due to heterodyning between mains and the vertical deflection frequency, causing ripple on the rail (+135VDC) for the horizontal deflection. The horiz. defl is modulated by this which is the tearing/bump that is seen rolling.OP's replaced the usual suspects filter caps but I wonder if the cap testing is actually working with just the ESR meter or in-circuit readings are misleading. With an isolation transformer and scope you can quickly find the fault but have to instead guess here.At this point I think it's either some other capacitors that failed low value, or IC601 STR30135 +135VDC Vreg is weak and has mains ripple coming out, we used to sell a lot of them back in the day. OP could measure ACV on that rail.Right now the repair doesn't make sense, the 3-4 prime suspect caps have been changed but hum is still getting in somewhere. The isolator board might have a problem due to the high common-mode voltage between hot-chassis and the video input jack.

author: sideburn
author_rank: Regular Contributor
timestamp: September 30, 2022, 03:44:55 pm
content: Quote from: m k on September 29, 2022, 04:22:48 pmI dont have anything that can do PAL.

author: sideburn
author_rank: Regular Contributor
timestamp: September 30, 2022, 04:39:18 pm
content: Quote from: floobydust on September 28, 2022, 11:33:09 pmESR on all these caps and diode check on transistors check out ok. I was wondering about IC601... I could order one and swap it out.

author: sideburn
author_rank: Regular Contributor
timestamp: September 30, 2022, 04:50:58 pm
content: i will swap out:c422c2421C416C241C408C410I happen to have all of these values already in my box o' caps.

author: sideburn
author_rank: Regular Contributor
timestamp: September 30, 2022, 05:12:42 pm
content: Yikes! I think I found it. C423 - 470uf 16V. I pulled it out and saw leakage on the bottom of the cap and on the PCB and out of circuit ESR is ridiculously low. like at 0.016 ohms.Its also an ELNA cap and ive had them go bad before. I think they have a track record of being crappy.

author: sideburn
author_rank: Regular Contributor
timestamp: September 30, 2022, 05:37:18 pm
content: NOPE: UHG..swapped out c422,c423,c241,c408,c410, and c416 and no change!

author: sideburn
author_rank: Regular Contributor
timestamp: September 30, 2022, 06:09:51 pm
content: I happen to have an STR30130 here from another repair. Would that work as a replacement to the STR30135? I assume not since the output is 5v less.

author: m k
author_rank: Super Contributor
timestamp: October 01, 2022, 06:21:03 pm
content: It's 4% down, manual has bigger differences, your call.QuoteBoth Atari schematics have internal PAL something.No idea what it really is or what kind of sync differences it can give.Monitor has NTSC colors so possible PAL picture is most likely without colors.PAL H-sync is close enough but V-sync is a bit low, -8Hz is accepted, if I understood the manual.Monitor manual has also that its resolution is 250 TV lines.Educated guess is that one TV line here is two scanlines high.My guess is that your demo pictures are non-interlaced first field stuff only.Seems also that I'm actually unaware how CGA picture is actually generated, from manual I got an impression that it's 200 lines interlaced.Do you have any true NTSC video sources of 525 interlaced scanlines?Can you lend an alternative power source, like inverter or so?Monitor manual states that 50Hz is accepted.

author: floobydust
author_rank: Super Contributor
timestamp: October 01, 2022, 08:11:19 pm
content: OP look at that video isolator (jack) board, maybe post pics of it.I would not change from a 135VDC to 130VDC regulator, it will scuttle the set's calibration and lead to a goose chase.

author: sideburn
author_rank: Regular Contributor
timestamp: October 02, 2022, 10:36:23 am
content: Quote from: m k on October 01, 2022, 06:21:03 pmI can’t think of any other power supply options off hand or an easy way to get a PAL signal.One thing to note is this monitor has been fine as my go to composite video monitor for all of these vintage computers for years and then started the jittering and now the horizontal rippling later on.

author: sideburn
author_rank: Regular Contributor
timestamp: October 02, 2022, 10:38:52 am
content: Quote from: floobydust on October 01, 2022, 08:11:19 pmI’ll take some pics of the video board today and post.Any other caps you suggest I replace?Lots of them are those ELNA brand that have a bad rep.

author: sideburn
author_rank: Regular Contributor
timestamp: November 23, 2022, 03:58:14 am
content: Quote from: floobydust on October 01, 2022, 08:11:19 pmCracked her back open today and replaced the STR30135 with a new one I received in the mail. waving is still there. Also just an FYI the a/v input board has two composite a/v inputs A and B and both are behaving the same way. So far I’ve replaced several caps, the bridge rectifier and the str30135. 🤷‍♂️The problem does seem to be subtler now or better after it warms up. At least it seems that way right now. Maybe a fluke though… this ones a tough one.