my first 2009 find - 1988 Magnadyne

[Kiwick]

picked up this set from the curb a few days ago, it's a 24" 1988 stereo Magnadyne.

This may look like an ordinary late 80s set, but it's a special set for several reasons...

This is the last Magnadyne set fitted with their own 70s-like 100% Italian handmade chassis, everything in this set is Italian, the CRT, semiconductors, speakers, capacitors and so on... starting in 1990 they began to use a Samsung chassis and a Toshiba CRT in this same cabinet until they went out of business in the late 90s

Also, this set has one heck of a sound, the warmth and powerful deep bass is simply unbelievable

This particular set was scrapped due to a faulty digital control module, it flips channels and turns the volume up and down by itself, i bet it's an easy fix

[zenithfan1]

Neat, those speakers do look pretty beefy. Let us know if you get 'er fixed. Don't ya just love stuff 100% made in your home country. I wish things were still like that.

[Kiwick]

fixed! there was a bad (swollen and leaking acid) capacitor in the power supply, allowing SMPS ripple to reach the control module.

the CRT is still very strong but sometimes the picture slowly turns greenish, stays this way for hours then it usually comes back to normal tint sooner or later, and the picture on this set is positively unbelievable when it's working right!

Not a dry joint and prodding/wiggling the CRT board and chassis doesn't fix the problem.

The CRT board is different from the rest of the chassis, apparently an OEM outsourced part, and uses weird SMD resistors, they're round and are color coded like a conventional resistor but are surface mounted, maybe one of them is about to go.

The speakers are coaxial units with ceramic tweeters and long throw oval woofers with foam surrounds, driven by an 8+8 watt transistor amplifier

[Kiwick]

damn! i was watching this set when i heard a snap, followed by a VERY bright green raster for a few seconds then some protection circuit kicked in and killed the HV.

now if i turn on the set from cold, i can see a purple picture while the CRT warms up but then it goes bright green again and the HV promptly trips off

RGB output transistors are good, tell me i don't have a busted CRT

[compucat]

Sounds like a heater to cathode short in the picture tube. If you have access to a CRT tester you might be able to clear the short. I wouldn't count it out just yet.

[Kiwick]

fixed!

a spark gap on the CRT board (it looked like a small capacitor) somehow got dead short, i replaced it and the TV is now working fine! the picture is really gorgeous and no longer turns greenish (this must have been due to the failing spark gap)

anyway, here's a pic of the chassis... there's real old time quality in there, all ICs are on sockets and the PCB tracks are silk screened on the component side for ease of servicing

[Kiwick]

Damn! i took the speakers out of the set to blow 20 years worth of dust from behind the metal grilles and noticed the foam surrounds on the oval woofers are perished, they're still there but they have a few radial cracks and some kind of mildew growing onto them, i think they're getting brittle and they will probably disintegrate if i keep on using the set.

The speakers are two way coaxial units and they put out one heck of a sound, i doubt a replacement will sound as good.

Is there some way to repair and preserve the original surrounds, like brushing some kind of glue onto them? or any place on the Internet where i can buy replacement oval foam surrounds? they're absolutely unobtanium around here.

[ChrisW6ATV]

New speaker foam:

www.newfoam.com

I repaired my 1985 EPI T/E-100 speakers several years ago, and the process worked fine.