Excellent picture in 31khz bright and low contrast picture in 15khz

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LarsVegas
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Excellent picture in 31khz bright and low contrast picture in 15khz

Post by LarsVegas »

I have a MS2931 Tube with a 2930 Chassis. If I want to make it compatible I have to change the heater resistor value, right? First, where do I find this resistor and which value should I expect and which new value do I need?
Last edited by LarsVegas on January 29th, 2022, 11:20 pm, edited 1 time in total.
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nem
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Re: Heater resistor MS 2931 tube

Post by nem »

Have you tried it yet? It might not need anything changed. If it's overly bright / washed out, then you'll have to replace the resistor.
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Re: Heater resistor MS 2931 tube

Post by LarsVegas »

Yes, it has been in use and is working ok, but the picture looks flat and to bright. I can't picture it. Did brightness and color adjustments already.
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nem
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Re: Heater resistor MS 2931 tube

Post by nem »

The heater resistor is R732. It's on the chassis. It's a 1W flameproof one, should be pretty easy to spot.

What resistance is yours?

Also, what tube do you have?

viewtopic.php?p=523900#p523900
LarsVegas
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Re: Heater resistor MS 2931 tube

Post by LarsVegas »

I have to look. Maybe next week. I have 2931 tube with 2930 Chassis. In this case, the picture was dimm, in my case it's bright. But my setup is the other way around. So makes sense.
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Re: Heater resistor MS 2931 tube

Post by LarsVegas »

Working again on this combo. It's a Toshiba A68LBT696X Tube. This should be compatible with the 1 Ohm resistor of the MS 2930 Chassis. On a MS 2931 chassis, I find the heater resistor R732, but where is this resistor located on a MS 2930 chassis?
LarsVegas
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Re: Heater resistor MS 2931 tube

Post by LarsVegas »

Played a little with screen, cut-offs, contrast and brightness again. Thought I had a nearly good picture, by reducing sub contrast and screen. Now when I start the monitor after a while, I get grid in the black and it stays like this. Can resolve it with brightness or screen, but don't know how long. Someone an idea, what can cause this problem?
LarsVegas
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by LarsVegas »

I hooked up a 31khz picture and it's stable and rich in both, contrast and colors. Only 15khz is a awful picture. Low contrast and totally washed out. Compared to other monitors the space between the scan lines seems much more. Is there an option to adjust the space between the horizontal lines or is it something else failing?
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by nem »

LarsVegas wrote: January 29th, 2022, 11:24 pmCompared to other monitors the space between the scan lines seems much more.

That's normal on trisyncs. Are you comparing to other trisyncs or dual res monitors?
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by LarsVegas »

I have another 2931 tube, but the 2000 Toshiba model and with 2931 chassis. No problems with this one.
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by mikejmoffitt »

Is it possible that your termination is wrong? Are you sending 15khz through the VGA-style HDB15 input?
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by LarsVegas »

Nope, everything is correct. Wired over Jamma with the dips in correct position. I don't use any adapter.
Or can it have something to do with the B+ voltage?
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by mikejmoffitt »

On the MS-293x there is no separate B+ voltage between different modes. The HV is separate from the "low voltage" sections (deflection, signaling) so it is not necessary.

The space between the lines is the monitor working correctly. That just means the focus on your tube is good!

It is best to set your cutoff levels and calibrate your white point only after the monitor has warmed up.

In addition, is it safe to assume your chassis has already had its capacitors replaced?
LarsVegas
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Re: Excellent picture in 31khz bright and low contrast picture in 15khz

Post by LarsVegas »

Yes, complete cap kit, colors adjusted and focus adjusted.
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