Astro City Monitor Issue

I'm having a issue with the monitor or video board. I don't know if this is happening because I moved the astro acouple of times to clean it. I had this loud syncing noise coming from the monitor so I went to the back to check it and the video board was coming loose from the monitor connector so I reset it and everything was all good for like 2 weeks or so. Today I was messing around with my astro, I did not move it, and the hissing noise started again and then when I went in back of the monitor, the video board was loose again and had to push it back in. Is this common, could this be caused from moving the astro back and forth. Or is the monitor connector or video connectors starting to get worn or loose. I really don't no what the correct terminology is but I think you guys know what I'm talking about.

Could this be happening because I removed that aluminum shield in the back?

are you talking about the neck card or main chassis ?

The neck card. Thats the pcb that attaches to the neck of the monitor right? I get this hissing noise. It comes and go's. I cleaned out the neck and the neck card yesterday and It seemed to go away. I did hear really faint hiss for like 20 seconds and after 2 hours of leaving the cab on I did not hear anything, but then again this is a random thing. I've only had the cab for maybe a month.

I've did some research and narrowed it down to acouple of things. Correct me if I'm wrong.

1. The Flyback. I've heard acouple of people say it was coming from there flyback, but I don't know how hard it is to find or replace something like this. And I don't know for sure if this is the problem. And I don't know what the flyback looks like.

2. Cleaning. I've dusted off the neck card with one of those electronic can dusters, but maybe I need to do a more thorough job

3. Resetting the Neck Card. There is maybe a possibility that the neck card was not set properly, so I reset it.

4. Voltage. This has to be set @ 120 right? How would I verify this on my power supply? I've never messed around with a power supply.

Its hard finding a trouble that is not constant. Sometimes the hissing is so loud that I could be in my room and hear it. Kind of sounds like when your on a Airplane and reach a certain altitude and your hear that high pitch noise in your ears. Its pretty dam annoying, but the image on the monitor looks fine.

well its most likely to be ht whistle from the anode cap,any dampness or dust build up around that will cause hissing
the neck card is another possibility if it is loose,they should never get loose-check the crt socket looks ok and consider using some silicon glue to hold it in place-always make sure the neck card is fully pushed in place

Will do some further cleaning and testing

The flyback is the big black block connected to the chassis board that supplies all the power. It will make a very high pitched noise, which is common with aging monitors. You can only really replace that with another one from the same chassis type, which you most likely won't find unless you buy an entire new chassis. To me it just sounds like something is loose if it isn't constant.

poodude said:

The flyback is the big black block connected to the chassis board that supplies all the power. It will make a very high pitched noise, which is common with aging monitors. You can only really replace that with another one from the same chassis type, which you most likely won't find unless you buy an entire new chassis. To me it just sounds like something is loose if it isn't constant.

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It doesn't supply ALL the power, it supplies the EHT.

A high pitched noise isn't common with aging monitors, its common with 15khz monitors (new or old).

Spare flybacks are quite easy to get hold of for just about any chassis.

OP: Discharge, Remove the anode cap, and then clean the back of your tube with some methylated spirits and a rag. Dry with a towel and then replace the cap.