1084 high pitched noise

[Liqourice]

My 1084 works, or at least it did the last time I tried it.


Problem is it has a very high pitched noise when it's on. I can barely hear it but I'm getting close to 60 and have tinnitus so my hearing isn't what it used to be. My ex did hear it clearly though and said it almost made her feel nauseous.


I know little or nothing about old CRTs so just want to ask if anyone has an idea what's causing this. Caps getting bad or something else?

[dlfrsilver]

Originally Posted by Liqourice

My 1084 works, or at least it did the last time I tried it.


Problem is it has a very high pitched noise when it's on. I can barely hear it but I'm getting close to 60 and have tinnitus so my hearing isn't what it used to be. My ex did hear it clearly though and said it almost made her feel nauseous.


I know little or nothing about old CRTs so just want to ask if anyone has an idea what's causing this. Caps getting bad or something else?

THT need to be replaced, and a recap would also be good....

[Liqourice]

Originally Posted by dlfrsilver

THT need to be replaced, and a recap would also be good....

As I said I know pretty much nothing about CRTs so what's the THT?

[dlfrsilver]

Originally Posted by Liqourice

As I said I know pretty much nothing about CRTs so what's the THT?

You should find then someone able to work on your monitor.

It's dangerous, and in no way you should handle this if you're not used to repair CRT monitors. A qualified person is needed.

[giantclam]

Originally Posted by Liqourice

I know little or nothing about old CRTs so just want to ask if anyone has an idea what's causing this. Caps getting bad or something else?

Typically both at this age of life. When caps go out of spec, this can impact the loading and frequencies of coils and high-tension transformer. The transformers themselves can also fail for other reasons, age/time in duty being one. (breakdown of internal insulation and resin layers).


You should not continue using the unit ~ such may incur further damage/failure. As stated these units can store enough electrical charge to kill a person in one zap. If you're not trained in the danger, "No User Serviceable Parts Inside" applies.



A competent repair strategy that would be undertaken here, would be check/replace capacitors, then recheck test voltages & alignment. If the high tension transformer is the culprit (it continues 'ringing'), a replacement needs to be sourced and fitting, and the unit adjusted/checked again. Failure of these transformers is unfortunately common.

[Liqourice]

Originally Posted by dlfrsilver

You should find then someone able to work on your monitor.

It's dangerous, and in no way you should handle this if you're not used to repair CRT monitors. A qualified person is needed.

Never said I was gonna do anything myself, just want to know.

[Liqourice]

So, found someone who knew a bit more and it's apparently the flyback transformer that's giving up. Down side is that for my model it seems more or less impossible to find a replacement these days. I guess I need to start looking around for another monitor instead.

[dlfrsilver]

You can find one.

Ho ! : https://www.ebay.fr/itm/323881872931

The 1084 use an HR7506.

[Liqourice]

Originally Posted by dlfrsilver

You can find one. Ho ! : https://www.ebay.fr/itm/323881872931The 1084 use an HR7506.

As far as I've concluded my 1084 uses a HR6489, according to the database I've found. But I'll open it up tomorrow to check for sure.

[dlfrsilver]

Originally Posted by Liqourice

As far as I've concluded my 1084 uses a HR6489, according to the database I've found. But I'll open it up tomorrow to check for sure.

What is the exact model of your 1084 ? 1084-D, 1084-P ?

[Liqourice]

Originally Posted by dlfrsilver

What is the exact model of your 1084 ? 1084-D, 1084-P ?

Plain 1084.

[Liqourice]

Opened it up and took an image of the transformer.

[idrougge]

All solder joints should be reflowed before replacing parts at random. Especially on something as heavy as the line transformer.

[Liqourice]

Originally Posted by idrougge

All solder joints should be reflowed before replacing parts at random. Especially on something as heavy as the line transformer.

Now that you mention this it makes a lot of sense. It was after I moved to where I live now a few years ago that I noticed this. Before it didn't have this issue. The ride may have been a bit bumpy.

This I can pretty much do myself so I'll have a go at this and see if that helps.

I doubt there's any residual charge left anywhere since it hasn't been connected to anything for about 4 years?

[mykrowyre]

The whine is likely not due to a cracked solder joint, it's the windings breaking loose from the ferrite core. A bad solder joint will cause the monitor to work occasionally, or not at all. Usually banging on it can identify a cracked solder joint.

I just replaced the flyback in my 1084S. Not difficult if you have repair experience but certainly not easy or safe enough to do without some experience. Often you need to drill a new hole since the pins may be slightly different between new and old flyback.

[Liqourice]

Originally Posted by mykrowyre

The whine is likely not due to a cracked solder joint, it's the windings breaking loose from the ferrite core. A bad solder joint will cause the monitor to work occasionally, or not at all. Usually banging on it can identify a cracked solder joint.

I just replaced the flyback in my 1084S. Not difficult if you have repair experience but certainly not easy or safe enough to do without some experience. Often you need to drill a new hole since the pins may be slightly different between new and old flyback.

Currently it works sometimes and sometimes not so there probably is a bad solder somewhere. However, I think it's the flyback as well and that's another story since there are no replacements to be found for the version I have.


I've put it aside and gonna let it rest over summer so I can open it up and properly go over the board. If I can find the bad solder(s) and fix that it may at least work for a while until I find other alternatives. I have a 1084S that works perfectly as well connected to my 500, the non-S 1084 I planned to use for my C64 if I can get it working.

[giantclam]

It could be an intermittent short inside the flyback itself

[Liqourice]

Originally Posted by giantclam

It could be an intermittent short inside the flyback itself

Perhaps. Ideally I would like to find a replacement flyback but I haven't had any luck so far.

[mykrowyre]

Originally Posted by Liqourice

Currently it works sometimes and sometimes not so there probably is a bad solder somewhere.

In this case, I would check the solder joints under the flyback (easy) to fix the intermittent issue as mentioned earlier but this may be unrelated to the whine.

You might try also replacing the horizontal output transistor, easy and cheap. It can also cause a whine if it's failing. It's usually on the side of the PCB next to the flyback transformer attached to a large heat sink.

[Liqourice]

Originally Posted by mykrowyre

In this case, I would check the solder joints under the flyback (easy) to fix the intermittent issue as mentioned earlier but this may be unrelated to the whine.

You might try also replacing the horizontal output transistor, easy and cheap. It can also cause a whine if it's failing. It's usually on the side of the PCB next to the flyback transformer attached to a large heat sink.

We'll see what I find when I get into it. Gave it a quick look when I had it open before but didn't see any obvious broken solder joints. Doesn't mean there aren't any though.