Packard Bell 17VT1 Audio

[old_tv_nut]

The lines at the top are the Copyguard protection from your video source. They prevent videotaping the signal. Old TVs without power vertical retrace blanking will show them. This is the bane of vintage TV restorers. If you are using a separate player and modulator, you can find a device to purchase that you insert in the video feed to remove them (or a schematic to build your own). A professional video proc amp (generally more expensive) that reinserts clean sync and blanking also does the job.

[Winky Dink]

Thanks for that explanation. It also explains why I didn't previously have this problem--until now I had been using a combination VCR/DVD player with a direct connection to the TV antenna. I might go back to that, but a name or description of a copyguard defeater so that I can look for one?

[old_tv_nut]

It's been a long time since I acquired one, so maybe I was optimistic about availability of a built unit. Search around to see what you can find.

[Winky Dink]

Correction to my previous quick reply: The combination VCR/DVD player also produces the copyguard lines. I'll look around for a device.

[Electronic M]

The copy guard system was called macrovision. Look for a macrovision remover.

Macrovision wouldn't just mess with retrace it would often also mess with AGC which would change contrast/brightness of the video and on some tube sets mess with the audio as you're experiencing...If the AGC misadjusts the gain till the IF goes into clipping it can create buzz at the audio detector.

[Notimetolooz]

I bought one of these products a long time ago. It looks to be the grey one.
I think that was before they had so many products. They must have increased the prices. Maybe twice as expensive now. Looks like the Red versions are discontinued. I seem to remember I got it through Amazon.
http://www.xdimax.com/common/default.html

There must be similar things cheaper now.

[Winky Dink]

As it turns out, the Macrovision/copy guard lines are not a problem for me. The DVDs I intend to use are all cheap collections of 1950s television. So far I haven't found any of them to have any type of copy prevention.

However, Dimax (or XDimax) makes the "GREX" which is available from the XDimax website (www.xdimax.com) for $98 (plus shipping, I guess) or from Amazon for $98.99 free shipping for prime.

Regarding a possible leaky C37 coupling--C37 is a new .020 film cap, and I couldn't see any defects with V9 - 6AS5 Audio Out or V8 - 6T8 AF Amp. The filter caps are all new electrolytics.

So, while watching Roy Rogers, I couldn't hear any buzz, but low frequency audio is distorted and seems louder than it should be at any volume and increasing the volume distorts a higher range of frequencies. Normal dialog at mid-volume sounds normal.

Any suggestions as to what I should look at next?

Thanks,
The Eternal Novice

[jr_tech]

Have you tried probing the audio stages with your signal tracer? You might be able to locate the stage where the distortion starts.

jr

[Winky Dink]

Thanks. Makes sense to me. I'll try that, but it'll take some time because I have to pull the CRT for unfettered access to the circuitry.