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| Thread ID: 30343 | 2003-02-16 22:32:00 | Monitors (again) | B.M. (505) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 121788 | 2003-02-18 07:35:00 | Craig I mean that there is probably an electronic component failure, which could be as simple as a diode or as challenging as an IC. The start point is to measure the bias on the CRT, that is, the cathode, grid and A1 voltages. If the pix is normal colour but whited out, you are looking at a fault that affects all three cathode which again points to a biasing fault. An R, G or B channel fault would produce an excess of one primary or one complementary colour, depending on whether the gun is driven on or off. Excessive brightness is cause by the following voltage variations from the norm: Cathodes low, grids high, A1s high. problem is unless you have a good background in video circuits you will need a circuit to know what voltages are normal and which are wrong. Of course it could be a failure in the brightness control circuit as well (which would drive the cathodes low unless the circuit is a bit archaic, in which case it could drive the grid positive. If you are really lucky it could be an open circuit on the CRT base on the grid connection, which would allow the grid voltage to float. However, this would normally cause the grid voltage to rise gradually so you would have a picture that was more or less normal at switch on but would increase in brightness very quickly. I'm sorry but without any more knowledge of the model or circuit type I can only speak in generalities and some of what I say may not even be applicable to your circumstances. You are going to have to apply some of that electronics training I'm afraid. Cheers Billy 8-{) |
Billy T (70) | ||
| 121789 | 2003-02-18 10:21:00 | Cheers for the hints anyway Billy T, I will have to have a play with the monitor for a while in the coming days. Hopefully I can find something wrong... Unfortunately the monitor is a no-name brand so I have not been able to find any documentation on it... What you mentioned about the open circuit on the crt base is what is occuring (from memory), I am pretty sure it is OK for a few seconds and quickly whites out, but I will have a good test of it, and maybe I will have something more specific to ask... Thanks, Craig. |
craig_b (2740) | ||
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