Atari SC1224 (JVC-V2) Stereo Conversion

[+mytek]

IIRC from my ST days, the JVC did indeed have the best looking picture but didn't handle 50Hz software as well as the others (picture got a little weird at the top).

 

Yea I saw that weirdness at first, but all it required was a little tweak of the V-Height and V-Hold controls to get rid of it. Looks really nice being driven by Sophia at PAL frequencies now. However I can't speak for how it would look when driven from an ST computer instead, and these adjustments might not make any difference in that case.

 

- Michael

[+mytek]

Project Completed

 

I decided to go bigger with the speakers, and also to cut holes into the sides (the only place they would fit). So although this was a tough decision, but in the end it turned out to be the right one because the stereo separation is superb, and the sound quality is quite incredible. The dynamic range covers the audio spectrum amazingly well, having crisp highs and good bass while not being too boomy.

 

 

 

 

 

 

 

 

This is a very rare 'STEREO' SC1224 . Ready to plug straight into my 1088XEL with modified Sophia board installed .

 

BTW, the speakers I am using are magnetically shielded. Ordinary speakers that close to the CRT would be a problem, skewing the electron beam.

 

- Michael

[+Stephen]

Excellent! I've considered doing something similar to my 1084S, but that's used as my spare since I've got the smaller Sony PVM. I have to get a decent set of PC speakers to use with it, as 1 - it's mono, and 2 - the sound is terrible.

[+mytek]

Excellent! I've considered doing something similar to my 1084S, but that's used as my spare since I've got the smaller Sony PVM. I have to get a decent set of PC speakers to use with it, as 1 - it's mono, and 2 - the sound is terrible.

 

Unfortunately the quality of the sound was never a priority with most of the CRT monitors, or even a lot of the TV's back in the day (not unless you bought one of those wood cabinet behemoths). However In the beginning of the HDTV era a lot of the sets had some pretty decent speakers built-in, and of course it was stereo or in some cases surround sound with wireless rear satellites. I remember a Hitachi DLP TV I got around 2004 that had something like 12 individual speakers in it, which produced some pretty awesome sound. Later this got replaced with a Visio 50" Plasma around 2009, which had about a 5-6" space below the screen for a built-in sound bar. and it came with a wireless sub-woofer as well as rear speakers. That too had great sound (and still does). Then I picked up a 65" JVC. On this one the sound wasn't very good because the screen had gotten thinner, and they no longer left any room for decent speakers. Now it seems like all of the HDTV's require you to buy a sound bar. Progress

 

Does the 1084S have stereo audio?

 

- Michael

[+Stephen]

 

Does the 1084S have stereo audio?

 

- Michael

Yeah - the S denotes the stereo version of the monitors. I noticed the other night, it has a 3.5mm jack next to the left speaker for headphones, so I don't think I'll modify the internal speakers on that monitor.

[+mytek]

Yeah - the S denotes the stereo version of the monitors. I noticed the other night, it has a 3.5mm jack next to the left speaker for headphones, so I don't think I'll modify the internal speakers on that monitor.

 

If the built-in stereo amplifier is good, changing out the speakers for better ones would probably make a big difference. Headphone jack should work regardless, if that's what you were concerned with.

 

After doing a bit of research, it appears that the original speakers are 3" round 16 ohm devices. If that is the case, and assuming you have some depth in the original locations, you might try something like these which probably have bigger magnets and a bit more excursion than the stock speakers ($15 w/free shipping)...

 

eBay Link: 2 Pack of 2" Round Frame Mini Speakers - 2W, 16 Ohm

 

- Michael

[+Stephen]

 

If the built-in stereo amplifier is good, changing out the speakers for better ones would probably make a big difference. Headphone jack should work regardless, if that's what you were concerned with.

 

After doing a bit of research, it appears that the original speakers are 3" round 16 ohm devices. If that is the case, and assuming you have some depth in the original locations, you might try something like these which probably have bigger magnets and a bit more excursion than the stock speakers ($15 w/free shipping)...

 

eBay Link: 2 Pack of 2" Round Frame Mini Speakers - 2W, 16 Ohm

 

- Michael

I'd think I would need to get magnetically shielded speakers for that cabinet - the speakers are pretty far back in the case and up high, next to the neck of the CRT. The monitor does need repair, I am having some issues with instability in the high voltage power supply. When I take it apart to investigate that, I'll consider upgrading the speakers.

[+mytek]

I'd think I would need to get magnetically shielded speakers for that cabinet - the speakers are pretty far back in the case and up high, next to the neck of the CRT. The monitor does need repair, I am having some issues with instability in the high voltage power supply. When I take it apart to investigate that, I'll consider upgrading the speakers.

 

Here's an option I've used in the past: Ultraperm 80 Metal Shielding Sheet

 

Worked great for magnetically shielding a dual 10" sub-woofer cabinet I placed just below a 19" CRT in the past, although in that case I had to use a 2 sheet thickness due to the large magnets on the speakers. This material is also called Mu Metal. I would have considered using this in my SC1224, if I hadn't found the shielded speakers that I did (eBay Link). And even though those are 3" diameter, the voice coils are 4 ohms which might be a bit risky to use with your situation.

 

- Michael

[+mytek]

UPDATE: Added Spacers for Speaker Mounting

 

As AA member MrFish so kindly pointed out, the ridge around the speaker frame was causing the plastic case to indent. He also suggested that washers might provide the needed spacers to prevent this from happening. These speakers were originally meant to mount from the outside, so that the ridge would presumably hold some kind of snap in grille, and probably also add some resistance to bending. However I wanted to minimize the visual impact that these speakers make, so opted for an inside mount instead.

 

Here's the fix...

 

 

 

 

Thanks MrFish

 

- Michael

[+mytek]

Speaker Location

 

 

This worked for me using those particular speakers. Hole diameter is 3 inches, and I used the speaker as a template for the mounting holes.

 

- Michael

[Mathy]

Hello Michael

 

But now there is a gap between the housing and the speaker. Meaning sound waves from the front of the speaker and sound waves from the back will mix via the gap, where they (partly) cancel each other out. Closing the gap with foam will probably improve the sound.

 

Sincerely

 

Mathy

[+mytek]

Hello Michael

 

But now there is a gap between the housing and the speaker. Meaning sound waves from the front of the speaker and sound waves from the back will mix via the gap, where they (partly) cancel each other out. Closing the gap with foam will probably improve the sound.

 

Sincerely

 

Mathy

 

That is a visual illusion. In reality the ridge (or lip) of the metal flange still makes contact and slightly digs into the plastic from the inside. The washers I used were just a tad bit thinner than the height of that ridge. On the backside of that flange is a very pliable gasket material which the nut squishes into, sealing off leakage through that avenue. There might still be some micro gaps here and there, but they would be too small to affect the sound by cancellation as you suggested. This of course would affect the bass more than anything, which seems to be just fine in my listening tests.

 

- Michael

[+mytek]

Reducing the Horizontal Width

 

The one thing that really bugged me, was that a bit of the on-screen content was being cut-off due to the horizontal width being too wide. So not finding an adjustment for that on the back panel, I consulted Google and low and behold came up with the answer. There is a Horizontal Coil with an allen adjustment slug inside that can be used to vary the width. In the case of the SC1224 (JVC Version), rotating left (CCW) will reduce the horizontal width that the picture takes up. This coil is located on the monitor's PCB on the side where the red HV lead connects to the back of the CRT.

 

WARNING: DO NOT MAKE THIS ADJUSTMENT WITH THE POWER TURNED ON - DON'T LEAVE THE ALLEN WRENCH IN THE COIL AFTER DOING SO - AND BE SURE TO LEAVE ONE HAND IN YOUR POCKET, KEEPING WELL AWAY FROM THAT RED HV LEAD.

 

I was able to rotate the slug on mine about 2-1/2 turns before meeting resistance. This was enough for my purposes, but it would have been nice to take it a bit farther just to give some breathing room. Some units may allow for this, but be careful not to apply very much force since the slug is made out of a very brittle ferrite material.

 

 

- Michael

[Roydea6]

How does one identify a JVC monitor Schematic.

 

SC1224_Schematic.pdf

sc1224.zip

 

I also recently found the Manual..

 

In gif picture format..

[+mytek]

sc1224.zip

 

I also recently found the Manual..

 

In gif picture format..

Thank you, that is most appreciated

 

Edit: Unfortunately that is not the JVC version I was seeking . What you have is the one for the GoldStar version. I've attached the service manual I found for the GoldStar that is in a slightly better pdf format, as well as the user manual for the JVC. But where is that elusive JVC Service Manual?

 

Atari GoldStar SC1224 RGB Monitor Service Manual.pdf

 

Atari JVC SC1224 (V2) RGB User Monitor Manual.pdf

 

Merry Christmas

 

- Michael