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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: kirk_m on January 02, 2018, 02:49:00 PM
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I have a 1960 monitor that still works, but, it's seemingly getting glitchy. It makes a popping/whining noise on powering on and video mode switches. Not terribly loud, but, noticeable enough to make me think there is a problem. What typically goes bad on these? I can bring it to a TV repairman for a once over, but, I'd like to get an idea on what I might be facing before bringing it over there.
Thanks!
Kirk
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the whine is totally normal, this is the flyback singing when sync frequencies move.
nothing serious at all :)
the real known issue on this monitor is that sometime you can hear a real big "pop" and the picture disappear during this "pop". then all back to normal.
this is an insulation problem, a capacitor discharge directly on the chassis.
i don't remember exactly where the leak is, but once the chassis is taped, it's fine.
they are not all affected by the way.
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I have a 1960 monitor that still works, but, it's seemingly getting glitchy. It makes a popping/whining noise on powering on and video mode switches. Not terribly loud, but, noticeable enough to make me think there is a problem. What typically goes bad on these? I can bring it to a TV repairman for a once over, but, I'd like to get an idea on what I might be facing before bringing it over there.
Thanks!
Kirk
the flyback and high power fets usually develop bad solder joints,if you run it long enough this way it will die. I suggest u have someone resolder any suspect joints on the board.recap it while you are in it. I had one 1960 from a guy who ran it so long the fet burned up and turned to powder and burned a 1/2" hole in the pcb. i did manage to repair it though.
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I have a 1960 monitor that still works, but, it's seemingly getting glitchy. It makes a popping/whining noise on powering on and video mode switches. Not terribly loud, but, noticeable enough to make me think there is a problem. What typically goes bad on these? I can bring it to a TV repairman for a once over, but, I'd like to get an idea on what I might be facing before bringing it over there.
Thanks!
Kirk
Sometimes a flyback will develop a crack in the caseing and you will get high voltage discharge to ground. Sometimes can be fixed with silicone. Another possibility is excessive dirt around the anode (the wire that goes from the flyback up to the side of the picture tube), in this case a good cleaning is in order. I had one that would "snap" at random times so I set up a video camera (with the back of the monitor) to record the event. Then a slow motion playback showed me the exact location of the problem.
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i repeat myself, but flyback whining shortly at power on, and on modes switching are normal on the 1960.
this happend because synchro frequencies are moving during this time.
i have one who did that too, it's not a fault.
and poping sound may be the leakage i talked about. you can ask a repairman to check for that.
but if it's not a big "pop" wich happen randomly, it's probably just crt static discharge when high voltage come and go, and it's not an issue, it's normal.
by the way, without listening... it's hard to tell.
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https://flic.kr/p/23mz5c5 (https://flic.kr/p/23mz5c5)
(http://flic.kr/p/23mz5c5)
OK, a few days after posting this, the monitor stopped working. Even the power LED doesn't illuminate. I had it on, and, suddenly, a bunch of random colors and such appeared on the screen and then it all faded away. After letting it sit the last few weeks, unplugged, I opened up the case to have a look. I didn't see any obvious expansion in any of the capacitors, and the only suspect area on the PCB was under the tube. It looked to be burned, and, there was some corrosion on the part. The white cylindrical component above has the burns around it.
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https://flic.kr/p/23mz5c5 (https://flic.kr/p/23mz5c5)
(http://flic.kr/p/23mz5c5)
OK, a few days after posting this, the monitor stopped working. Even the power LED doesn't illuminate. I had it on, and, suddenly, a bunch of random colors and such appeared on the screen and then it all faded away. After letting it sit the last few weeks, unplugged, I opened up the case to have a look. I didn't see any obvious expansion in any of the capacitors, and the only suspect area on the PCB was under the tube. It looked to be burned, and, there was some corrosion on the part. The white cylindrical component above has the burns around it.
Sad but it happens. I have a monitor graveyard for the Amiga and I kinda lose a couple every year it seems. I have a 1084 that has just started whistling and another that is giving out a very strange noise. I first had the issue on a Philips, but in those days I knew a guy that could repair them. If you can get it repaired I would cus my Philips that was repaired is still going fine.
Just as an aside I had this Samung flat screen monitor develop the same problem and did get it repaired. I haven't had a monitor last more than a few months after the whistling starts. So depressing. They generally just stop working and go black and lifeless.
I do have one Commodore monitor that refuses to give in. It is like fleurescent red and blue on screen and you cannot read it until I give it a big whack on the side and then she comes back to life. I use it with a C64. Been like it for years.... no whistling though.
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Sad but it happens. I have a monitor graveyard for the Amiga and I kinda lose a couple every year it seems. I have a 1084 that has just started whistling and another that is giving out a very strange noise. I first had the issue on a Philips, but in those days I knew a guy that could repair them. If you can get it repaired I would cus my Philips that was repaired is still going fine.
Just as an aside I had this Samung flat screen monitor develop the same problem and did get it repaired. I haven't had a monitor last more than a few months after the whistling starts. So depressing. They generally just stop working and go black and lifeless.
I do have one Commodore monitor that refuses to give in. It is like fleurescent red and blue on screen and you cannot read it until I give it a big whack on the side and then she comes back to life. I use it with a C64. Been like it for years.... no whistling though.
sadly 50% of these monitors could be saved if people would quit using them when they first show symptoms and fix them.
Bad solder joints happen so often on them,and when you beat on them often its enough to make contact,but the joints carrying high current get hot due to the resistance and run until they arc and burn.
Bad solder on the flyback causes arcing and just does damage the longer you run it.
the last 1960 i was given the guy ran it until the FET fried itself and burned legs off and burned a hole in the pcb.
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sadly 50% of these monitors could be saved if people would quit using them when they first show symptoms and fix them.
Bad solder joints happen so often on them,and when you beat on them often its enough to make contact,but the joints carrying high current get hot due to the resistance and run until they arc and burn.
Bad solder on the flyback causes arcing and just does damage the longer you run it.
the last 1960 i was given the guy ran it until the FET fried itself and burned legs off and burned a hole in the pcb.
Is this unfixable? I can take it all apart and look, but, need to know what I am looking at first. What is the white cylindrical component that has the burns around it?
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I have a 1084 monitor that would work for about 10 min. cold but once warmed up it went dead. I took it apart ( high tension lead VERY scary) but used a wooden brood handle with a nail with wire to metal frame and discharged voltage several times results was bad solder joints work like a charm now :)
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https://gona.mactar.hu/Commodore/monitor/Commodore_monitors_by_model_number.html
This site has schematic of 1960 monitor if you are going to work on the monitor.
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Sorry to resurrect this thread, but I think it is time to try and repair this monitor. For the last few years, I've been more into arcade cabinets than Amiga. I've repaired quite a few arcade monitors during this time. This monitor is different, though, since it has its own SMPS versus relying upon an isolation transformer built into a cabinet.
Several times in this thread, @mechy mentioned the FET being an issue in the ones he's repaired. @mechy , are you referring to Q403 (a 2SC4123 located on the heatsink/shield immediately next to the flyback transformer)? Is this transistor the HOT? I've pulled this transistor and tested it via a diode test on my multimeter, and it is shorted. What I've learned from arcade monitors is that if the HOT is shorted, there's a problem somewhere else that is causing it. Where to look next? I plan on first recapping things, but, if it's the flyback that's out, is that an unobtainable part?
Thanks!
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Bump... no monitor gurus here?
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I was hoping someone who has worked on this particular model would have answered, but I used to work on CRT TV's and other monitors so......The transistor next to the flyback is probably the HOT. Often a shorted HOT means the Flyback is bad. It's also possible to have an issue in the horizontal drive circuit. From 25 year old memories, I had TX82 RCA TV's that would blow the HOT because the drive signal at the Base of the HOT was 1 Volt peak to peak instead of 5V (was bad diodes). TV would work for a few minutes but the HOT would get so hot it would fail. Sorry I'm not more familiar with this model, but if it's like most monitors, I would be suspicious of the flyback.
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Is this unfixable? I can take it all apart and look, but, need to know what I am looking at first. What is the white cylindrical component that has the burns around it?
I fixed said monitor,and it was a nightmare. If you aren't familiar with these monitors please don't mess around in them. There lethal high voltages. Most cases they can be repaired but finding someone to take it on these days is tough. If you find someone,bring them the schematics.
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Sorry to resurrect this thread, but I think it is time to try and repair this monitor. For the last few years, I've been more into arcade cabinets than Amiga. I've repaired quite a few arcade monitors during this time. This monitor is different, though, since it has its own SMPS versus relying upon an isolation transformer built into a cabinet.
Several times in this thread, @mechy mentioned the FET being an issue in the ones he's repaired. @mechy , are you referring to Q403 (a 2SC4123 located on the heatsink/shield immediately next to the flyback transformer)? Is this transistor the HOT? I've pulled this transistor and tested it via a diode test on my multimeter, and it is shorted. What I've learned from arcade monitors is that if the HOT is shorted, there's a problem somewhere else that is causing it. Where to look next? I plan on first recapping things, but, if it's the flyback that's out, is that an unobtainable part?
Thanks!
Sorry,i am not a expert by any means on this monitor.. this was 15-20 years ago,i recall i replaced the transistor with a cross..irf640? 680? 840? i dont recall. I can't tell you if it was Q403 but i seem to recall is was somewhat in the middle of the board?.Seem to remember some bad diodes i replaced and caps. Sorry i can't be of more help! i see a flyback here,page claims to be updated but looks..eh? https://www.technotronic-dimensions.com/Products2c.html
It lists some flyback numbers that could be searched elsewhere maybe.
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I've got a new flyback on order as well as a replacement HOT (ordered it a few days ago from that particular supplier). I've checked all the diodes on the board, and none are bad. I'm very familiar with monitor voltages, I've repaired 20-30 arcade monitors in the last few years. I still have to make a cap list and perform a recap. I'll update the thread as I move forward with the repairs, and I hopefully have a lead on an original copy of schematics, versus all the poor quality scans of them on the web.
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Good luck,it will be interesting to see what you find! I hope you get it fixed.
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Swapped out the FBT and the HOT today...no change. The power LED blinks quickly, and, I have no B+ voltage at TP4. What else should I be looking at?
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I am recapping the monitor...so I compiled a list of all 54 caps as I removed them from the main chassis and the neck board. Maybe this might help someone else resurrect one of these monitors. The list is attached to the post.
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Recapping didn't fix the problem, neither did replacing the HOT or flyback. Likely, these parts were all still good, unfortunately. I should have known that the issue was with the SMPS, because even with the old components, the power led would flash on and off rapidly, and a very, very faint ticking could be heard if I were to work on it in an extremely quiet room. I began checking the DC lines and eventually found that D805 was shorted. Replacing it with an identical fast recovery diode of required rating brought it back to life. HV immediately appeared, and I adjusted the B+ trim pot, now have a solid 86V B+. Just a few tweaks to focus and screen controls were all that were needed. The monitor lives again after nearly 6 years of being dead.
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@ kirk_m
Congratulations - Good Work! Your thread will no doubt help others on into the future as well.
Happy Year Year!