Peaking coil
 

I'd have to say no. That, I'm afraid, would give you a negative video. That would increase your delay time in viedo signal. :nono:

I have a junk 630 chassis sitting in my garage, if you can tell me which part it is (a picture showing location would be great!) I can see if it has one.

Would a difference of 7uH make that big of a difference? I found that digikey has one from JW Miller which is 100uH with 3.6 ohms of DC resistance. You sure that won't work?

Eric H

Here is a link to the picture. The coil circled in green is the one I need. It makes me wish I was more careful. A new 100uH axial leaded inductor with 3.6 ohms of dc resistance won't work?

Thanks.

Jonathan

OK, I have one, I'll have to get a soldering iron out to the garage to remove it, I don't want to clip the leads.

I don't know if the extra 7uH would matter or not but you can have the original thing if you want it, just P.M. me your address and I'll try to send it out Monday.

Eric

Man, that's a nice clean chassis! Mine is a rustbucket, I should post a pic just for laughs.

Eric H

Before I make you go through all that work, I want to figure out if a 100uH 3.6ohms dc resistance inductor will do the trick. I don't see why not, but Bill says otherwise.

Bill,

The video would be negative with the increase of 7uH? Most inductors back then had a 20% tolerance or greater, didn't they? DC does pass through it, and I guess it saturates at the video peak? I'm not really sure how it works.

Thanks.

Jonathan

Johathan,
Your L190, a 93uH peaking coil in the plate circuit of the 1st video amplifier is part of a series-shunt compensating filter netowrk used to optomize the bandwith perfromance of the amplifier. A 100uH inductor should be OK. I may cause a bit of a change in the resopnes of the amplifier, but you likely could not see the diferance.

John,

Thanks. I just remembered I had my Air King A1000 chassis. I took the replacement coil from there. When I work on it I'll use a 100uH coil.

Eric H,

Thanks for the offer, but my trusty Air King A1000 chassis came to the rescue. I even found quite a lot of mistakes with it using my 630TS chassis.

I'll keep you guys updated and will provide pictures.

Jonathan

Well, I go to plug it in, the lights dim, the plug vibrates, and the breaker is on the brink of popping. I've got a short somewhere. The primary winding on the power transformer has a DC resistance of .6 ohms on my meter, so it's ok. The problem, I believe, lies in the crappy rewiring job of the electrolytics. The short must be there. Either it's connected the wrong way or connected to the wrong point. Once my head clears I'll go back to it.

Jonathan

The power switch seems to operate backwards. When I turn it off, the switch is closed according to my meter, and I get .02 ohms, basically a short. When I turn it on, the switch is open according to my meter. I know this sounds like I'm doing somethong wrong. I got it once ot twice to show an open when the switch actually was open and when it was closed it read 40 ohms. I'll give it a spray with some contact cleaner, maybe that might help things.

Secondly, the excessive current draw. The primary winding reads .6 ohms on my meter, which is the DC resistance it should be according to the service data. When I plugged it into a surge protector, the plug vibrated and the lights dimmed. There is a short somewhere on the secondary side of the transformer. I think I wired the electrolytics wrong, infact I'm almost sure of it. What I'm curious about is why didn't it draw that much current as to pop the breaker? I'm not sure if the surge protector limited the current or it was the limitation of the transformer. It was odd and something I never experienced before, so that's why I'm asking about it.

Thanks.

Jonathan

Sounds like you have a special application control for a hi-fi system tone control or such.

Limitation of the transformer. But don't let it go like that for more than a few seconds, or the transformer will burn out. Remember all that Underwriter's Labs cares about is that such a fault inside the set doesn't cause a fire that burns your house down. I would highly recomend that you install on the primary side of the transformer an in-line fuse holder and a fuse of about twice the rated load current (wattage/powerline volts) so you don't ruin the transformer if you still have trouble correcting the problem.

The problem is in the B+ section. I removed the rectifiers and plugged it in and the tubes lit up. Something in the B+ is causing a short somehow. I don't think it's an electrolytic in the wrong way, but it could be. I'm being very cautious about the power transformer, as getting it rewound could probably cost up to $500 or more. But I know the short is in the B+, so just got to troubleshoot from there.

Jonathan

Check the electrolytics carefully, the can isn't always chassis ground, especially true if they are mounted in a fiber insulator.

Usually a cap wired backwards will blow the 5U4 or the Cap itself but it normally doesn't cause such a noticable overload.

After going through the capacitors again I can see no visible problems. With both rectifiers out, there is no excessive draw in current, but of course, there is no B+ either. The only caps connected to chassis ground around the transformer was a 20uF used for filtering B+ on the audio, and 80uF. The one on the bracket and the one closest to the outside of the chassis were all on insulators. All of their commons were connected to -100V. All of the negative ends are connected to the transformer lead with is the center tap of the B+ winding. The smaller 1000uF/250uF commons are connected to +275.

I'm going to recheck the electrolytics again and do a resistance check on the rectifiers and see if that fixes anything.

Thanks again.

Jonathan