Commodore CRT monitors. Re-working and re-capping and troubleshooting.

[seastalker]

Today I was brave and after viewing tons of safety videos and obtaining 'overkill' protection (funny word for working on CRTs), I recapped my entire Commodore 1702 monitor. It sat for over a year but I still had gloves and boots, discharged, etc.

I have more to do, but before I plug in for smoke tests, I hope to share pics and discuss some potential weak points.  When I got the 1702 in a lot sale, it 'worked' but I heard some scary periodic power arcing and turned it off. There was a small burning smell and I waited about a year, thinking something fried.  In that time, I learned the basic mechanics of a CRT, and opened my 1702 today. After recapping, my paper plate of old caps had leaking liquid but it is hard to determine which one(s) were the culprits. I hope all caps being replaced will fix any previous problems. I air sprayed the mainboard and all daughter boards and then washed all with Electronics cleaner. I will likely isoprop any white residue the cleaner left and hope to get this back up and running.  *Interestingly,  Commodore made an error on the silkscreen on some 1702s at capacitor C101 (like mine) as documented by Console5:

https://console5.com/store/commodore-1702-cap-kit.html and their wiki: https://console5.com/wiki/Commodore_1702 where I printed my checklist and maps from.

 

All PCBs look like the business end is only on the bottom.

 

Questions:

Should I replace anything other than the caps?  Voltage regulators?  What caused the arcing before? bad caps? The power switch is solid. Should I RGB mod?  Replace the power cord to one with a ground? I will do a multi-meter continuity test on all fuses.

 

Also, I may have cracked or lifted three traces/pads so advice on my repair plans is appreciated:

 

Mainboard Problems:

C201 (10uF 16v)- Negative pad lifting

C204 (3.3uF 50v) - Bipolar (BP) lifting on one leg

C603 (10uF 50v) - lifting pad

 

Power Board:

C905 (100uF 25v) - NOTE the red patch wire is for visual reference and can be desoldered easily.  Also, I will not plug it back in the wall until I am certain all is well (and it is sealed up!)

 

In some of these intended fixes, the plan is to use a wire if the path between points may contact unintended places. Otherwise, for a straight shot, I like the remaining clipped capacitor legs. Note I have yet to clip the legs on the spots in question so I have visual aid when finishing. Also, how precise should I consider gauge size when I use such short wire runs? My guess is the power board may matter more in this thinking.

 

I do hope this project will fix the arcing issues (please don't be a tube problem itself), and restore this 1702 to day one original glory!

 

 

Edited February 3, 2020 by seastalker
typo

[seastalker]

I am looking into RGB modding it too, and only see three ICs on the mainboard - 

 

4H1 HA11247

https://elcodis.com/parts/5775883/HA11247.html

 

4H2 HA11244 (TV Sync Processor)

https://html.alldatasheet.com/html-pdf/91358/HITACHI/HA11244/246/1/HA11244.html

 

4D2 HA11401 (TV Video Amplifier)

https://datasheet4u.com/datasheet-parts/HA11401-datasheet.php?id=543988

 

Looks like the first one has the r,g,b signals

[seastalker]

UPDATE: SUCCESS!  I went over my 4 problem spots and opted to scrape down to the copper traces and get a sturdy connection and joint. To advanced solderers, it may be elementary, but to me, I had to consider it all and thought jumper wires should be used to patch a broken trace, not for SUPPORT to hold something in place. 

 

I hope sharing this will help others (I am not responsible for your safety - watch videos like Retro Tech's channel and Perifractic's Retro Recipes for a start on CRT safety). Then I checked the two fuses on the mainboard for continuity and all systems go.  I cleaned the flyback and all cables with IPA, and even added fresh solder to all flyback joints for good measure. The power switch is something normally to replace, but my original is still going strong and I didn't want to wait.  I connected everything back except the rear cover to see if I would still get electrical arcing (then a replacement flyback would be my next fix) but several minutes and all was well. I'm guessing I had bad capacitors causing the arcing.   I tested it with a C64 Plug N Play (it's a real C64- ask Jeri), and then with an Atari Flashback 2. All was beautiful and the sound really struck me as amazing for mono! Pitfall's vine swing sounded epic as did the C64's famous opening line in Impossible Mission... let's hope this re-capping of my 1702 helps make it "Staaaaayyyy Foh-evvvahhh!"

 

I'm sharing pics in hopes it helps others, because the nearest CRT repair to me is very far and I have to pay a lot for the now niche ability I taught myself to do. Note the scrape marks in pic 2.  If anyone has a good method to prevent this (I'm sure the red paint is not just cosmetic) with ZERO sacrifice to personal safety in the process while discharging, please chime in!!

 

I decided not to RGB mod it because I have other Commodore monitors I'm doing that already have RGBi and I avoid cutting into original plastic when I can. I will enjoy its S-video quality and convenient front composite jacks. No more scary electrical arc/popping sounds and bad smells.  Is a recapping/cleaning of this 1702 monitor on 2020-02-03 the equivalent of going back in time to view it during it's original manufacture date of October 1984?

 

P.s. I would be happy to know what causes the condition in my flux picture.

P.P.S.  I plan to do two more and different Commodore monitors and update here on the adventures!!

 

[+wongojack]

Great work

 

also . . .

 

Disgusting flux picture!

[SoundGammon]

On my 1702, I put a s-video jack in the back and wired it to the luminance & chroma inputs!

 

So I can use it with any s-video source!

[+DrVenkman]

4 minutes ago, SoundGammon said:

On my 1702, I put a s-video jack in the back and wired it to the luminance & chroma inputs!

 

So I can use it with any s-video source!

For those who don't want to do that kind of surgery to the monitor, there's also these two items:

 

S-video FEMALE-FEMALE connector + S-video to Chroma/Luma cable

 

Using those, you can accomplish the same end result without risk to your monitor.

 

[SoundGammon]

Wasn't hard to do!

 

Plenty of room to mount, just had to drill a hole for it to fit in and a couple of mounting screws.

[seastalker]

21 hours ago, wongojack said:

Great work

 

also . . .

 

Disgusting flux picture!

 

Thanks on the former and agreed on the latter.   I didn't use that flux on the monitor, rest assured. I used my liquid pen flux. That disgusting looking flux is a mystery. It just sat sealed in a drawer in a cool dry place.  I appreciate SoundGammon's work getting a clean S-Video port, but I only mod the outer shell of anything if I have no other way. That's just me. I already have a S-video to chroma/luma 'y' splitter cable and run that to an S-video switch box for my 800xl and C64 with two spare switch ports (still organizing consoles).  I do like being able to plug an Atari Flashback 2 in to the front composite jack or C-64 DTV. I moved my S-Video PC Engine to my big CRT tv so have to consider my S-video only consoles. I have a TI-99 laying around- I'll see what I have the desk space for.

 

Stay tuned for future Commodore 1902 and 1084S recap pics

[Zitruskeks]

The Red Paint is probably red alkyd paint to prevent arcing due to humid air condensing in that area on the flass etc. Next time, round over the corners of your screw driver that you use for discharging. Or use a High Voltage probe with usually can flex a bit. And/or just repaint with Red Alkyd.

 

Same goes for the Aquadag, the graphite based conductive paint. I damaged it on my Vectrex when I had the tube in the shower (as this paint is water based), panicked a bit and then found that this can be bought in spray or paintbrush applied form nearly anywhere. Opted for a spray (used Kontakt Chemie GRAPHIT 33 76009-AA) and there isnt even a seam left to see, also it works perfectly.

 

I also recapped my 1084 (Philips, Mono, EU PAL) with a slightly adapted cap list based on the 1084-S list from Console5 (only the main filter caps are different due to 220V vs 110V and the audio board of the mono one is different, obviously, and mine is the one with no sharpness control at the front, so 2 caps arent installed in that area, too.. I can upload some pics later. Still waiting for the low ESR bipolar cap though, so i didn't perform the smoke test yet

[wildstar87]

On 2/3/2020 at 6:39 AM, seastalker said:

I am looking into RGB modding it too, and only see three ICs on the mainboard - 

 

4H1 HA11247

https://elcodis.com/parts/5775883/HA11247.html

 

4H2 HA11244 (TV Sync Processor)

https://html.alldatasheet.com/html-pdf/91358/HITACHI/HA11244/246/1/HA11244.html

 

4D2 HA11401 (TV Video Amplifier)

https://datasheet4u.com/datasheet-parts/HA11401-datasheet.php?id=543988

 

Looks like the first one has the r,g,b signals

I'm doing repair to my 1702, would be interested in modding it for RGB, do you have a good idea how to do this, or could point me to any links?  I did search on RGB mods for 1702, but came up short, it seems that people say that it can't be done, or isn't worth trying.

[jsoper]

On 2/3/2020 at 4:01 PM, DrVenkman said:

S-video FEMALE-FEMALE connector + S-video to Chroma/Luma cable

 

Using those, you can accomplish the same end result without risk to your monitor.

 

You put the same link twice.  Here is the second one: Adapter cable

 

I wish I'd known about this back in the day.  There's no real good place to put an s-video jack on a 1702.  

Edited October 16, 2021 by jsoper

[thegamezmaster]

Wow! Great work. Keep it going.

[seastalker]

On 10/1/2021 at 6:08 PM, wildstar87 said:

I'm doing repair to my 1702, would be interested in modding it for RGB, do you have a good idea how to do this, or could point me to any links?  I did search on RGB mods for 1702, but came up short, it seems that people say that it can't be done, or isn't worth trying.

Sorry friend- I haven't done any RGB or Component mods yet. I did get a cable/adapter to change Chroma and Luma to an S-Video input. I may mess around with my Commodore RGBi 80 column port on my C128 monitor.

[jsoper]

On 10/16/2021 at 3:05 PM, jsoper said:

You put the same link twice.  Here is the second one: Adapter cable

 

I wish I'd known about this back in the day.  There's no real good place to put an s-video jack on a 1702.  

I just noticed there's a 5-foot version.  If that can reach from your 1702 to your s-video switch box, you don't need a female-to-female or anything else.

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