WAGDAG
Active member
I have been working on this chassis for some time now and could really use some help.
I read everything that I could find regarding repairing this model and I just can't seem to figure out what is going on. I bought it dead and have no history. It is clean and in excellent condition.
- I recapped it (minus filter which checked out fine on my ESR tester), thorough reflow, tested HOT, VR, and replaced insulators. Powered it up and was still dead. B+ was at 78.2v at SP20.
- Replaced TDA2593 and it fired up. Took a while to warm up and the flyback was making quite a bit of noise but I kept running it to see how it would look warmed up. The image was fairly dim and the brightness POT's original position was cranked up near full, but it could be used as is. Focus and colors looked good with the Craftymech's awesome TPG hooked up. I pushed Centipede signal to it and it sync'ed fine but the image had a slow, constant, mild wave to it. Sorta a slow "hula"....or being under water. Focus got a bit worse as time went on so I shut it down and ordered a new flyback.
- CRT tested good on all guns with Sencore CR70
- Installed new flyback and gave the POTS a good De-Oxit workout. Fired it up and the image was very dim. Also, the image is almost doubled / split vertically, and is way to narrow. When I turned up Screen POT past a certain point, I heard snapping and the image would disappear. I saw arcing in the neckboard socket (around pin 5).
- Replaced neckboard socket and now it can take the full voltage without arcing
- Messed around for a couple hours and decided to put the old flyback back in to see if image would return to prior state. It did not. I am super careful when soldering and working on these as to not bridge or damage traces. I did not manhandle the thing or have any issue removing the old fly so I am at a loss as to wth happened.
- I put the new flyback back in and tested the brightness POT out of circuit...was 8.6K and should be 10K. Not perfect but should be good enough to work until next parts order.
Image was the same. Checked B+ and found it to be only 78.4v with G2 at min. Adjusted B+ POT and it does absolutely nothing through full swing. Tested it out of circuit and it tested fine.
-Started checking diodes and resistors nearby. R23, R18, D5, tested good out of circuit.
- Got frustrated and decided to walk away before I got pissed and made things worse.
I apologize for writing a book, but I wanted to get details listed and show that I'm willing to work for it and listen to advice...just need a push over the hump.
MKL, Ken, Ohmerone, and others have posted repair tips in the past on this model and I am grateful for that.
So, where do I go from here to get B+ up to 115v? I don't remember if I took a B+ reading for the short time that I ran it while wavy. I'm not even sure how it is working as well as it is with such low voltage.
Any help would be greatly appreciated if someone can point me in the right direction.
http://www.arcade-museum.com/manuals-monitors/Hantarex MTC900E Service Manual.pdf
I read everything that I could find regarding repairing this model and I just can't seem to figure out what is going on. I bought it dead and have no history. It is clean and in excellent condition.
- I recapped it (minus filter which checked out fine on my ESR tester), thorough reflow, tested HOT, VR, and replaced insulators. Powered it up and was still dead. B+ was at 78.2v at SP20.
- Replaced TDA2593 and it fired up. Took a while to warm up and the flyback was making quite a bit of noise but I kept running it to see how it would look warmed up. The image was fairly dim and the brightness POT's original position was cranked up near full, but it could be used as is. Focus and colors looked good with the Craftymech's awesome TPG hooked up. I pushed Centipede signal to it and it sync'ed fine but the image had a slow, constant, mild wave to it. Sorta a slow "hula"....or being under water. Focus got a bit worse as time went on so I shut it down and ordered a new flyback.
- CRT tested good on all guns with Sencore CR70
- Installed new flyback and gave the POTS a good De-Oxit workout. Fired it up and the image was very dim. Also, the image is almost doubled / split vertically, and is way to narrow. When I turned up Screen POT past a certain point, I heard snapping and the image would disappear. I saw arcing in the neckboard socket (around pin 5).
- Replaced neckboard socket and now it can take the full voltage without arcing
- Messed around for a couple hours and decided to put the old flyback back in to see if image would return to prior state. It did not. I am super careful when soldering and working on these as to not bridge or damage traces. I did not manhandle the thing or have any issue removing the old fly so I am at a loss as to wth happened.
- I put the new flyback back in and tested the brightness POT out of circuit...was 8.6K and should be 10K. Not perfect but should be good enough to work until next parts order.
Image was the same. Checked B+ and found it to be only 78.4v with G2 at min. Adjusted B+ POT and it does absolutely nothing through full swing. Tested it out of circuit and it tested fine.
-Started checking diodes and resistors nearby. R23, R18, D5, tested good out of circuit.
- Got frustrated and decided to walk away before I got pissed and made things worse.
I apologize for writing a book, but I wanted to get details listed and show that I'm willing to work for it and listen to advice...just need a push over the hump.
MKL, Ken, Ohmerone, and others have posted repair tips in the past on this model and I am grateful for that.
So, where do I go from here to get B+ up to 115v? I don't remember if I took a B+ reading for the short time that I ran it while wavy. I'm not even sure how it is working as well as it is with such low voltage.
Any help would be greatly appreciated if someone can point me in the right direction.
http://www.arcade-museum.com/manuals-monitors/Hantarex MTC900E Service Manual.pdf
