Amiga A1080 Monitor Schematic

I doubt a schematic will do you much good, what's the problem with the monitor? These have been around long enough someone will probably have an idea of what to look for.

Google some of the part-numbers (particularly the FBTX transformer), and see if you get any hits that way.

Actually I replied mentioning a guy who had one for sale in the USA.

A common problem was dry joints all through around the area concerning the FBT and horizontal stage. Go over the whole board resoldering everything.

Otherwise check out the Monitor Repair FAQ.

Dave

Hi Rick, try this web site

See, for example,

Moreover, if you live in Europe (or can get an European PAL tv set from some specialist store, or order one abroad), they usually have RGB, CVBS and Y/C inputs via the Scart socket, can decode NTSC colors, and will sync to both 525/60 and 625/50 signals.

No vertical deflection, thin line across the center of the display. I've replaced the electrolytic capacitors throughout the unit and the vertical deflection driver transistors. There's no signal coming out of the TA7644 IC to the base of the vertical driver transistors, but the signals on other pins of the IC have active signals running. It may be the TA7644 is bad or some inputs to it. I need a schematic to troubleshoot it further.

an

Or just replace the IC and see what happens. Signal going into it but no signal coming out is a reasonable indication that it's bad.

From a tech's website... it might be something you haven't thought of:

try contacting this guy.. you may also find what you need at his web page.

twbrown

On Tue, 07 Jun 2005 18:51:08 -0500, Rick Jones put finger to keyboard and composed:

FWIW, this datasheet has the pinouts for the TA7644:

- Franc Zabkar

Already have that. That's how I was able to scope some of the signals. Unfortunately it shows nothing other than the pinouts - no internal workings diagram, no sample circuits showing interfacing to other components, etc.

Spoke with Ray 6 months ago. He originally had the schematic for another CBM monitor labeled as similar to the A1080. When I tried to troubleshoot mine with that schematic I found out different. I told Ray and that's when he changed the information on his site.

On a long shot... have you tried contacting Toshiba itself?

Rick, Just in case my last message didn't get through... I have a 1080, so if you run out of ideas, I'll crack mine open and work with you to troubleshoot yours.

Ray

I did 6 months ago when I first tried troubleshooting this. I asked for information on the TA7644 chip but the person I talked to at the time couldn't help me. I actually thought today of giving it a try again, but it's been 20 years since this monitor was manufactured so getting data on an obsolete chip like that seems very unlikely.

That might be one way to go about it. While I have 30+ years experience in electronics none of it is with video circuits. I know there's no base drive out of the TA7644 chip to the base of the vertical deflection transistor pair. I have no idea what input conditions, if any, are necessary on that IC for an output to be present at that pin. Someone earlier posted a link for an NTE replacement IC which has the IC pins labeled.

Note that this monitor has a service switch in the center of the bottom board towards the left side. That switch should be in the NORMAL position. If in SERVICE, the vertical sweep will collapse to a single horizontal line (used for CRT setup adjustments.

Well, the switch couldn't throw itself. The display slowly collapsed to a thin line across the center over a period of 2-3 months. Changing the caps and vertical deflection transistors didn't correct that. I suppose that switch *might* be dirty. I can spray some contact cleaner in/on it to make sure.

That

sweep

adjustments.

You`ll probably kick yourself if it turns out to be the problem.