Atari SC1224 & SM124 not really working - Did I get done?

[ST-ranger]

Just today picked up an SC1224 & SM124 for prices slightly lower than market, to go with the 1040 & STE.

 

Turning them on, feels like I fell for the "just need a recap" line. Was unable to test them at the guy's house.

 

SM124 - Screen rolls vertically, slowing down until it stops with the screen bottom halfway in the middle and horizontal white lines.

SC1224 - no power light. High-pitched buzz that oscillates in frequency, unaffected by contrast etc. knobs.

 

Have I got lemons?

[TGB1718]

The 124 sounds like it just needs adjusting, this may help.

 

Not sure about the 1224, here's another doc.

SM124_Service_Manual_MT-9.pdf SC1224_Service_Manual_CA-3.pdf

[MasterMotorola]

5 hours ago, ST-ranger said:

Just today picked up an SC1224 & SM124 for prices slightly lower than market, to go with the 1040 & STE.

 

Turning them on, feels like I fell for the "just need a recap" line. Was unable to test them at the guy's house.

I would have showed up to the guy's house with my ST and power cord.  Nothing gets a price reduction faster than showing the seller their items don't work as advertised right in front of them.  Granted, some sellers are not outright liars about their items -- most are just uninformed or inexperienced.

 

Let's hope that with the service documents and help of the forums that you can get them working.  Those are two great monitors and any collector would love to have them.  How is the physical condition of the monitors?

[ST-ranger]

7 hours ago, TGB1718 said:

The 124 sounds like it just needs adjusting, this may help.

 

Not sure about the 1224, here's another doc.

SM124_Service_Manual_MT-9.pdf 7.28 MB · 3 downloads SC1224_Service_Manual_CA-3.pdf 10.83 MB · 7 downloads

 

Thanks, these are helpful. I'm becoming comfortable with discharging and recapping CRTs now, however these manuals are practically hieroglyphic. Have read little scare bits-n-pieces about creating x-rays with poorly aligned tubes, so confidence is low that I'll be repairing them myself.

 

2 hours ago, MasterMotorola said:

I would have showed up to the guy's house with my ST and power cord.  Nothing gets a price reduction faster than showing the seller their items don't work as advertised right in front of them.  Granted, some sellers are not outright liars about their items -- most are just uninformed or inexperienced.

 

Let's hope that with the service documents and help of the forums that you can get them working.  Those are two great monitors and any collector would love to have them.  How is the physical condition of the monitors?

This probably would have been the sensible move. Unfortunately I got ahead of myself there, had previously picked up quite a fair few 80s computer items from him that were perfectly repairable for great prices. I "trusted" that they were an easy repair. He definitely wasn't inexperienced with electronics (house covered in gaming consoles from the '90s), however not sure about CRTs. Lesson sorely learnt for a few hundred $AUD.

 

Hoping you're right. Would also like to hold onto them and enjoy Lemmings etc. in colour.

 

The condition is good to very good, sadly. No scratching, blemishing, or yellowing. The screens look immaculate.

 

 

 

 

Thanks for your help

 

[Zogging Hell]

On the SM124 I would check the fault related to people adjusting the screen size over spec first (outrageously so it fills the screen!). This is a common cause of failure.

Try here for an explanation and fix https://mikrosk.github.io/doitarchive/doitf030/0808.htm

[mattsoft]

1 hour ago, Zogging Hell said:

On the SM124 I would check the fault related to people adjusting the screen size over spec first (outrageously so it fills the screen!). This is a common cause of failure.

Try here for an explanation and fix https://mikrosk.github.io/doitarchive/doitf030/0808.htm

This info is gold! Bookmarking now... Thanks!

[oky2000]

Power light on the SC1224 could be a good sign, as the problem is probably in the main PSU area on the board and there aren't as many things to go wrong. H

 

On the mono monitor, once it has warmed up (say a few minutes) can you then adjust the v position and v hold potentiometers to get the pic showing correctly. I have a VCS that will not show in colour until it has warmed up for a few minutes. 

 

I used to buy stuff all the time from an ebay reseller, who lived very close to me so I saved hundreds in postage costs but CRTs and disk drives are open to interpretation. It is possible re-capping will fix all the problems and the seller was just busy/lazy. I don't know exactly how they were described/shown in photos to you so I will leave it at that.

 

This is one of the reasons why I stopped collecting now, I have bought loads of things over the last 3 decades that worked fine when tested and never worked again which is just money down the toilet. Last few things I bought were really rare and couldn't be tested, like the Atari PC1 with no monitor. I probably did work from my experience of the sort of beeps and whirring PCs make but when was the last time you saw an EGA monitor for sale!

[ST-ranger]

 

On 10/3/2021 at 8:44 AM, Zogging Hell said:

On the SM124 I would check the fault related to people adjusting the screen size over spec first (outrageously so it fills the screen!). This is a common cause of failure.

Try here for an explanation and fix https://mikrosk.github.io/doitarchive/doitf030/0808.htm

Thanks, this is great information. The "parallel two caps for the correct value" part was a little confusing. I'll take the display apart and see if I can find this section.

On 10/3/2021 at 6:36 PM, oky2000 said:

Power light on the SC1224 could be a good sign, as the problem is probably in the main PSU area on the board and there aren't as many things to go wrong. H

 

On the mono monitor, once it has warmed up (say a few minutes) can you then adjust the v position and v hold potentiometers to get the pic showing correctly. I have a VCS that will not show in colour until it has warmed up for a few minutes. 

 

I used to buy stuff all the time from an ebay reseller, who lived very close to me so I saved hundreds in postage costs but CRTs and disk drives are open to interpretation. It is possible re-capping will fix all the problems and the seller was just busy/lazy. I don't know exactly how they were described/shown in photos to you so I will leave it at that.

 

This is one of the reasons why I stopped collecting now, I have bought loads of things over the last 3 decades that worked fine when tested and never worked again which is just money down the toilet. Last few things I bought were really rare and couldn't be tested, like the Atari PC1 with no monitor. I probably

did work from my experience of the sort of beeps and whirring PCs make but when was the last time you saw an EGA monitor for sale!

Hoping you're right, I will definitely attempt a recap. Understand the feeling completely not being able to test things... sometimes it's not really practical or acceptable in a social sense. Sadly, it reduces my enthusiasm from buying from "that guy who always acquires cool stuff for nothing!".

 

Unfortunately, there is no power light on the SC1224... just an oscillating electric-style buzz. I will take them both apart, discharge them (hopefully can find the ground lug) and see what they look like inside.

[TGB1718]

12 hours ago, ST-ranger said:

Unfortunately, there is no power light on the SC1224.

Having looked at the circuit, there appears to be 2 models, either way the power LED is on the +12V rail,

so I would look at the full wave rectifier diodes and the 12V regulator.

 

Worth having a look at any high wattage resistors too, over the years they may have burnt out or de-soldered themselves.