bilbomacuser
Active member
I have 2 of the IIc monochrome monitors (UK 240V versions, made by Samsung) that I have just got out of storage. Both worked perfectly when I first turned them on. One of them made a horrible smell and stopped working after a couple of minutes, the other worked fine for about 10 minutes before tripping the power off.
I found a Sams book that has the schematic, and I dismantled one of the monitors. I spent a considerable amount of time going through all of the electrolytic capacitors, comparing specs with the schematic and nearly all of them matched. The schematic often didn’t specify voltage, so I noted that down from the existing capacitors, and measured their sizes too so that I didn’t order replacements that would be too big. I’ve ordered the 24 capacitors from Mouser and am waiting for them to arrive (I also ordered some spare fuses). Whilst there is some information about capacitor replacements, it is often incomplete, so if I can successfully replace all of the electrolytic capacitors and get the monitor working reliably the I plan to report back with a full list of specifications (capacitance, voltage, size, model number). IMPORTANT: I did follow correct discharge procedure to protect against high voltage from the anode.
I have 2 questions:
C515 is a 4 uF 25V capacitor and is quite large (aaprox 15 mm dia and 35 mm long) - mouser don’t seem to sell a suitable replacement, and the Sams manual lists this as being a part not widely available. I have ordered Nichicon [SIZE=10pt]URZ1E4R7MDD which was the nearest I could find (4.7 uF 25V) but I found an article about capacitance affecting horizontal linearity, so I’m wondering whether for this particular capacitor it is important to get it exactly right, it also makes me wonder whether there is a reason why it’s so large, perhaps it’s critical that this capacitor is more stable / precise than others? I read that multiple capacitors in parallel could work as equivalent, so I may look into this, such as having a couple of 2uF. [/SIZE]
[SIZE=10pt]i’m also wondering if there is likely to be anything else that could have aged / failed that I should consider other than the electrolytic capacitors ? My plan was to replace the electrolytic capacitors and then go from there. [/SIZE]
I found a Sams book that has the schematic, and I dismantled one of the monitors. I spent a considerable amount of time going through all of the electrolytic capacitors, comparing specs with the schematic and nearly all of them matched. The schematic often didn’t specify voltage, so I noted that down from the existing capacitors, and measured their sizes too so that I didn’t order replacements that would be too big. I’ve ordered the 24 capacitors from Mouser and am waiting for them to arrive (I also ordered some spare fuses). Whilst there is some information about capacitor replacements, it is often incomplete, so if I can successfully replace all of the electrolytic capacitors and get the monitor working reliably the I plan to report back with a full list of specifications (capacitance, voltage, size, model number). IMPORTANT: I did follow correct discharge procedure to protect against high voltage from the anode.
I have 2 questions:
C515 is a 4 uF 25V capacitor and is quite large (aaprox 15 mm dia and 35 mm long) - mouser don’t seem to sell a suitable replacement, and the Sams manual lists this as being a part not widely available. I have ordered Nichicon [SIZE=10pt]URZ1E4R7MDD which was the nearest I could find (4.7 uF 25V) but I found an article about capacitance affecting horizontal linearity, so I’m wondering whether for this particular capacitor it is important to get it exactly right, it also makes me wonder whether there is a reason why it’s so large, perhaps it’s critical that this capacitor is more stable / precise than others? I read that multiple capacitors in parallel could work as equivalent, so I may look into this, such as having a couple of 2uF. [/SIZE]
[SIZE=10pt]i’m also wondering if there is likely to be anything else that could have aged / failed that I should consider other than the electrolytic capacitors ? My plan was to replace the electrolytic capacitors and then go from there. [/SIZE]
