Monitor recapping and low ESR

[JezC]

Will grab a piccie or two at the weekend if I can & upload it (it's my daughter's birthday so it might not happen until the weekend after unless we wear her out earlier in the day).

Then I can see if it looks anything like yours - thanks for the offer!

Sure thing! The 1084 that's coming in tomorrow might have yet another design. Will post pictures if that's the case.

If there is enough resemblance, I can provide a recap list for two different versions I did (D2 and P1).

Sounds like a plan to me...and when I've sorted that colour monitor I can try and fix a faulty SM124...used to work & then just stopped powering up...so hopefully it's just a simple fault

[sandord]

[quote=JezC post_id=12642 time=1540855288 user_id=83]
Sounds like a plan to me...and when I've sorted that colour monitor I can try and fix a faulty SM124...used to work & then just stopped powering up...so hopefully it's just a simple fault
[/quote]

Please find the attached instructions for fixing a dead SM124. As a bonus, your SM124 will be more resilient to tuning. I blew one up when I was a kid by enlarging the picture using internal adjustments. That clearly pushed it over the edge.

[JezC]

Thank you for that. I will read through that and see if I can manage it.
Got to say how great it is with all the advice being shared by everyone.

[sandord]

So, I got the next 1084S in. This one's supposedly broken, the previous owner says it just quit working.

If you look at the pictures, you can probably tell the previous owner has a second hobby, next to retro computing
Let's say, I can very clearly smell it.

So I ordered a couple of bottles of IPA, planning to give a good wash on the inside. Let's see how well that goes...

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[chiark]

Eww, that's nasty. I think a little nastier than the 1081 that I've just acquired that was shown as powering up, but now does nothing other than blow fuses with extreme efficiency.

I also have a 1084ST that had a panicking power supply: removed the LOPT (flyback) and that stopped the PSU shutting down. Replaced the LOPT and HOT and get... power on, but nothing. No picture. Need to start testing that.

Good luck!

[sandord]

Some caps "back in the day" were the size of coke cans, replacements like 5% of the size...

bi-polar caps though ? Wonder why... I probably would have just stuck a polyester in it instead

Today I came cross this post on Atari-Forum https://www.atari-forum.com/viewtopic.p ... cbb18bb237 and it got me worried.

Since the start of this post here, I replaced something like three bipolar caps in similar CRTs with those really small ones and now I feel I have to replace them again with... polyester bi-polar caps? I didn't really pay attention to the polyester remark at the time and thought the small ones would be okay.

Any more hints on the safest way to proceed here?

By the way, I remember you mentioning once that a bi-polar cap is basically nothing more than two regular caps stuck together. Maybe that could be a path in case getting the right part proves to be hard.

[exxos]

I don't think I ever mentioned bipolar caps.. If you had those and replaced with electrolytics then that's not good...

Bipolar caps were just reversable electolylitics , more space saving as polyesters were larger back in the day, and more expensive.

So if you had a bipolar cap like 10uf 50v or whatever, I would replace with a ceramic or polyester cap or whatever.

[derkom]

When I serviced my SC1435, I ran into the same situation of Mouser et al selling only really tiny bipolars with the voltage and capacitance specs of the one bipolar in the SC1435. I recall finding a post in a forum somewhere advising against using these, although I do not recall the specific explanation as to why!

The only place I was able to find a proper replacement was Console5 in the US, but they had quite low stock at the time, and are now sadly out of stock. I think if I were doing the same job today, I would probably just stick a beefy ceramic in there.

As I mentioned over in the AW thread, I recapped my SM124 with all ceramics. Not the cheapest operation of course, but I feel good about that project, and it's been running with a full size picture for a couple of years with no sign of any difficulty. (But certainly it's not getting a whole lot of hours, so time will tell if this really works "forever".)

[sandord]

Thanks guys!

I've done a quick search at a parts store and found 4.7 µF 50V 10% ceramic caps measuring only 1.6 x 3.2 x 1.6 mm (I know, SMT). I find it hard to believe that these even smaller caps will do. But sure, specs are specs, right?

They only sell the SMT types, but I don't mind using those if they're safe to use.

[derkom]

I've done a quick search at a parts store and found 4.7 µF 50V 10% ceramic caps measuring only 1.6 x 3.2 x 1.6 mm (I know, SMT). I find it hard to believe that these even smaller caps will do. But sure, specs are specs, right?

I would not expect that to be able to handle anywhere near the required current, but maybe @exxos should take this one.