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Forum Index : Electronics : Stock Std Warpinverter
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| Warpspeed Guru  Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Its probably a physically a fairly large resistor, not for the power rating, but the voltage rating. If it is a 2M2, in the direct EHT supply to the tube, try and find a one watt carbon resistor. The usual very small metal film resistors will not be up to the job. Cheers, Tony. |
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renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Thanks mate. https://www.jaycar.com.au/2-2m-ohm-1-watt-carbon-film-resistors-pack-of-2/p/RR2854 OMG Ringwood even have them in stock. Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yup  Cheers, Tony. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
One further thought Mark. That resistor looks pretty fried, it did not die a peaceful death. Check C430 6.8nF 5Kv is not shorted. If it is, a replacement resistor will probably also fry prety quickly, so grab a second spare resistor just in case. Both components run at around 4,700 volts so its pretty serious stuff. If you need another C430 we can look into that. Cheers, Tony. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Cap is OK, I replaced the resistor, it worked for 20 seconds and went pop again. Not worth mucking around with. Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Mark, completely remove the C430 cap and try again. That cap may be breaking down at the very high voltage, and that may not show up on a multimeter. Cheers, Tony. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
OK that got it working again, but the trace doesn't extend to the full width of the screen anymore. So, either rooted or it needs those caps to work properly. There is actually two in parallel in this one, it's different to the schematic from the other model. Bit hard to find those caps........   Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
You are almost there Mark I will chase up some 5Kv caps, and that should fix it. Cheers, Tony. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Bloody hell, been searching for 30 min, can't find them  If you have some in your parts bins that would be great. Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Will this work? Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Nice find Mark, yes that will be perfect. I have been looking too on the internet and the capacitors are common up to about 3Kv, then they jump to 20Kv which would be too physically large. Same problem in my own parts bin, lots of 1Kv and 3Kv and some 20Kv and 30Kv but nothing really suitable in the middle. Without that capacitor fitted, expect to see some weird geometry and brightness/focus problems. That is to be expected. The extra high voltage to the picture tube will be all over the place. That big capacitor is there to hold the dc voltage pretty constant. The actual value is not critical, more is better if you cannot get the exact original value. Should be a pretty cheap fix, and the old girl may possibly be good for another 25 years. Cheers, Tony. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Bloody hell, thought I would have to ask the KGB for them, very hard to find Mouser delivery is $24 unless you order $60, so got another capacitor the same as the others (for DC rail). They are a whisker cheaper too. HERE BTW there are 3 of the 5kv caps in the close vicinity so got 3 to replace them all. Mouser also have another good option for the DC rail caps HERE 100,000uf, works out to just over $1 per uf and the esr is a lot lower than the 51,000uf Cheers Caveman Mark Off grid eastern Melb |
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mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
could this be easier? ebay bwd 826 cro |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Thanks mate, I did see that, often ebay stuff goes for waaaaay above what it's worth. I bid on some that got to $200..... for a 25 year old CRO?  If $11 in caps doesn't fix it I'll get a digital unit. I'll probably still get one anyway, but wait till the warm weather comes and business picks up a bit. Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
That ended bidding at $137 I'd rather put money into a lower end new digital unit. All I'm ever really going to use is to check the wave and drivers signals, you don't need a flash one for that. LOL when my caps come and if it works fine I'll bloody sell that and put it toward a digital unit. Just can't understand them going for that much, mine was $75 from gumtree, even that is a lot to pay for a gamble. These old girls couldn't have much more life in them. You could buy one and potentially only get a week out of it, mine didn't last a year. Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Well those caps came, it didn't fix it though. Bin job for the old  Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Oh well, worth a try at least. Cheers, Tony. |
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LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Why do they die? By life do you mean that of the tube or something else? |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Why do they die? By life do you mean that of the tube or something else? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
They grow old... Small electrolytics dry out and become leaky. Dry joints that worked for years start to act up. Potentiometers become noisy or worn out. Switches wear out and become intermittent, as do some plug in connectors. Rust and corrosion can appear on the circuit boards and metalwork. Knobs and controls break or get lost. That is the very old analog equipment typically thirty years old plus. For something a bit more recent, various types of ROM use stored charges on capacitors which after twenty or so years start to randomly drop bits. Some of the chips such as programmable gate arrays and special analog hybrid chips, and such, may be propriety and no longer made or available. For something current. Surface mount multilayer boards without component designators or a schematic are simply unrepairable. Once its out of warranty that is the end of it, because the Chinese only produce finished products, never spare parts. If its in warranty and it stops working, the local agent will just give you another new one after the service tech confirms that its dead and not just a fuse or something silly. The old stuff was built to be repairable, the latest electronics are all designed to be difficult to copy and completely disposable when it fails. I have just spent over an hour replacing a battery in my digital calipers, it had to come completely apart with many really small screws and many fiddly parts that were quite difficult to put back together. I was supposed to go out and buy another $35.00 new set of calipers and throw these away, just because the battery went flat. That is how it is these days. Cheers, Tony. |
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