Ok. Let’s try this again…RCA 9TC240 Alignment

[Kevin Kuehn]

It sounds like a intermittent solder joint. Requires opening things up and applying pressure to various areas with a length of wood dowel in attempt to isolate it to a smaller area. Eventually you can hone in on it, but often takes a lot of time.

[Chris K]

Originally Posted by Kevin Kuehn

It sounds like a intermittent solder joint. Requires opening things up and applying pressure to various areas with a length of wood dowel in attempt to isolate it to a smaller area. Eventually you can hone in on it, but often takes a lot of time.

Yes that’s what I think. More than likely in the main board and not one of the modules. The main board is more susceptible given it’s a horizontal board and will flex. I’ll be working on it tonight

[Penthode]

It uses cards on connectors. It is made by HP and should be nearly bullet proof.

I would simply open the box and reset the connectors and cards and VOILA it will work again.

[Chris K]

Originally Posted by Penthode

It uses cards on connectors. It is made by HP and should be nearly bullet proof.

I would simply open the box and reset the connectors and cards and VOILA it will work again.

I did and cleaned the connectors again and made sure everything was seated firmly. I reassembled it after pulling off the 30 lbs of equipment on it and it's working fine. Time will tell but as long as it's operating, I'll get back on it tonight.

[Penthode]

Don't try to listen to the tone. It is AM. The sound discriminator is for FM.

Is the VTVM set to AC? Is the bias pot set correctly? Is the video IF, video detector and video amplifier working properly? Is the VTVM attached properly? You need to systematically go through things.

When setting up to adjust the traps, slightly mis tune the generator. Look for a deflection on the VTVM that goes up and down when the generator output level is adjust up and down. And the deflection must increase as you increase the RF level. I suspect you are going to have to increase the RF level to see a deflection. Again do not adjust things until you see the needle deflect with signal.

Also make sure you are not overloading. Overloading is as bad as no signal: it will distort your results.

Once you see the needle deflecting with signal, then fine tune to the trap frequency. Adjust the RF level until you see just enough to adjust the trap for a dip.

[Chris K]

Originally Posted by Penthode

Don't try to listen to the tone. It is AM. The sound discriminator is for FM.

Is the VTVM set to AC? Is the bias pot set correctly? Is the video IF, video detector and video amplifier working properly? Is the VTVM attached properly? You need to systematically go through things.

When setting up to adjust the traps, slightly mis tune the generator. Look for a deflection on the VTVM that goes up and down when the generator output level is adjust up and down. And the deflection must increase as you increase the RF level. I suspect you are going to have to increase the RF level to see a deflection. Again do not adjust things until you see the needle deflect with signal.

Also make sure you are not overloading. Overloading is as bad as no signal: it will distort your results.

Once you see the needle deflecting with signal, then fine tune to the trap frequency. Adjust the RF level until you see just enough to adjust the trap for a dip.

Ok I will forget about the tone. I’ll answer your questions one by one…The VTVM is set to AC and the range is set to 5V as you said.
The 250K pot is in place and the voltage at R135/136 was adjusted to -4.5V DC
When I have fed a video signal through the antenna from my pattern generator I get an image. The multiburst pattern is ok but the high resolution bands are not sharp. Anyway I’m assuming this means the video IF circuit is working?
The AC probe of the VTVM is connected to pin 1 of V106. The needle on the VTVM does deflect sharply to being pegged if I raise the frequency on the 8601. I get lost with what you say after that. Should I slightly mistune the generator and then do something after that? I got confused because you started talking about signal gain and levels and not changes based on mistuning.

[Penthode]

Originally Posted by Chris K

Ok I will forget about the tone. I’ll answer your questions one by one…The VTVM is set to AC and the range is set to 5V as you said.
The 250K pot is in place and the voltage at R135/136 was adjusted to -4.5V DC
When I have fed a video signal through the antenna from my pattern generator I get an image. The multiburst pattern is ok but the high resolution bands are not sharp. Anyway I’m assuming this means the video IF circuit is working?
The AC probe of the VTVM is connected to pin 1 of V106. The needle on the VTVM does deflect sharply to being pegged if I raise the frequency on the 8601. I get lost with what you say after that. Should I slightly mistune the generator and then do something after that? I got confused because you started talking about signal gain and levels and not changes based on mistuning.

If you swing the generator away from 21.25MHz and both sides the amplitude increases, then the trap is working. Remember there are two 21.25MHz traps.

You may have to raise the RF signal at the trap frequency sufficiently until you see the nedle deflect. I am only suggesting you slightly swing the generator away from 21.25MHz to test for the trap presence because the trap will cause a big dip. It seems that you are not applying sufficient RF at 21.25MHz to make the adjustment.

[Chris K]

I’ve gone pretty high on the RF signal. I mean several people have posted going to 500mV is a HUGE rf signal. I’ve gone as high as 300mV and can’t get any deflection at T-103. Should I just move on to another trap at another frequency? No deflection adjusting T105 either at 21.25mc. That’s the sound trap correct?
What do you think of my idea of going back to square one with one of the other KCS28 chassis I have and resurrecting it on mostly original components?

[Penthode]

Originally Posted by Chris K

I’ve gone pretty high on the RF signal. I mean several people have posted going to 500mV is a HUGE rf signal. I’ve gone as high as 300mV and can’t get any deflection at T-103. Should I just move on to another trap at another frequency? No deflection adjusting T105 either at 21.25mc. That’s the sound trap correct?
What do you think of my idea of going back to square one with one of the other KCS28 chassis I have and resurrecting it on mostly original components?

Can you get a signal thru at 22MHz? If so then the trap is attenuating. Because you offset the stagger tuned stages, likely there is less gain around 21.25MHz.

Tell us if you get anything at 22, 23 or 24MHz. If so, you are not getting sufficient signal thru at 21.25MHz. raise the signal and reduce the bias from -4.5v. adjust the pot until you get a signal.

How are you injecting the RF out from the HP8601a?