Dead Sony KV-1200U

[freakaftr8]

Nope no short to ground at all, I know the heat sync mounted B+ trans you are talking about it's at the top of the chassis to the right. Ill PM you. Thanks!

[freakaftr8]

BTW the fuse blowing is not the 1.6A on the HV pinout on the cage, it's the main puppy off the CB powercord area.

[freakaftr8]

Well looking more nto this set I have found 2 3 way diodes that are on the board with the h osc transistor these diodes supply the power to the degausing field and light on the tuner and the transformer that supples 6.3v to the CRT filiments. And that circuit works. I think the diode d603 and 602 are the ones I'm thinking of. R 603 got hot and lost the enamal. But still tests good. This resistor comes from B of the osc. I bypassed the power switch thinking that was a bad connection. I'm not getting B+ going to the transformer. I believe these wires are white/violet line and green/ violet line. Rectifier diode is fine. I did however find one thing odd. From the collector of the h osc is a 103k inductor. Tested open so I replaced it. Still nothing.

[freakaftr8]

HEy does anyone know a good substitute for the two line rectifier diodes for this KV-1200U? they are 3 pole diodes. TRhe part number on one is 4 0 H and the other id 4 R 0 G. I dont know what these mean, and the schmematic doesn't give any details as to what the specs are.. In the schematic they are D602 and D603. Both shot.
Thanks

[kx250rider]

Those are just two ordinary B+ rectifiers in one package. All you need is to get four B+ diodes, and wire them in a bridge as the schematic shows. I don't remember the ECG (NTE) number, but you can use something like an NTE 500, if I'm not mistaken. Hopefully someone else will pop up an exact detail on a good choice. Maybe 1-amp or so.

Charles

[freakaftr8]

Coool, thanx Charles

[freakaftr8]

Well, tonight I replaced the bad rectifier diodes, and came across a low resintance reading Q601 REG drive transistor off the B to E. Not shorted but close enough to call it open. So I pulled Q505 (Horiz drive) to measure differences since that is also a 2SC867. That one's funky as well. So it looks like I need to order 2 of these puppies and they are like 25 bucks each!
So either the rect diode shorted and took out Q601 OR Q605 took out the B+ rect. This set has got me running in circles.

[Findm-Keepm]

DON'T replace the 2SC867 with another 2SC867 - Sony put out a green sheet (kinda like RCA's Goldenrod's) on the 2SC867 and how starting in 1981 they only supplied the 2SC867A. That sorta makes all of the "new" 2SC867's out there to be not what they seem. Get a Sony 2SC867A and know you aren't facing more problems. Sony part number for the 2SC867A was a 2-765-.... number and the old 2SC867 was a 2-729...... number. I used to know them by heart, along with the 2SC1034 and SG613 / SG629 part numbers, and the 470BEB22 dud price....oh what days they were!

Cheers,

[Findm-Keepm]

Another gotcha - look out for the 4.7uF cap! C513 on most Sony KV-12XX sets. It'll go high ESR on ya adn cause a dead set, but won't blow the fuse.. 160V cap, IIRC, and we always put in a 250V one - same size physically and held up just fine.

Cheers,

[Stanislaw]

Dear friends,

I hope nothing is wrong in my posting to this old topic. I have found here some important information and I would like to get some clarifications if possible.

My current project is restoration/rehabilitation of an old Sony reel-to-reel tape recorder that features some 2SC867 transistors in the motor(s) servo circuits.

I need to replace them but here I came across this posting:

Originally Posted by Findm-Keepm

DON'T replace the 2SC867 with another 2SC867 - Sony put out a green sheet (kinda like RCA's Goldenrod's) on the 2SC867 and how starting in 1981 they only supplied the 2SC867A. That sorta makes all of the "new" 2SC867's out there to be not what they seem. Get a Sony 2SC867A and know you aren't facing more problems.

Can anyone clarify what is wrong with the original 2SC867, what is meant by "green sheet" and what problems I may face if I put 2SC867 instead of 2SC867A.

Thank you!

[ChrisW6ATV]

Stanislaw-

Welcome to Videokarma.

While I cannot help you with your exact question, it is quite possible that parts that were critical in a TV horizontal circuit may be less so in a tape recorder. Others may have better information. The specific model of TV set in this discussion is one known (to me, at least) to be picky about some of its transistors even though I may have never seen that in any other TV or other device.

[freakaftr8]

Oh well I bit the bullet and purchased 2 2SC867A's. You were right Brian, yes the transistor and cap were changed some time back as it is already a 250v 4.7mfd and the trans was already a sony replacement 2SC867A. Lets see if this works..