Six Weeks of Troubleshooting...I think I found it!

[Chris K]

Originally Posted by bandersen

Well at least try reducing the sweep width to 0.5Mhz to verify your generator is working properly.

It worked at 0.5MHz.

Better news is the voltage regulator chip arrived and is installed. The 8601 is working. Five volts DC on this DC circuit now. Fingers crossed it stays stable.

[Kevin Kuehn]

Congratulations on finding the bad regulator and hopefully it solves your issue. The HP 8601 along with the HP 8600 Digital Marker combination are most likely the best relatively modern thing going for TV alignment. If you feel challenged while troubleshooting those two, you'll be horrified of the 8664's internal complexity, as well as the 8662. They are not at all user friendly service wise.

[Kevin Kuehn]

It would appear the HP 1820-0196 is a Ua723 regulator in a TO99 package. A fairly common part from that time period.

[Penthode]

Originally Posted by Kevin Kuehn

Congratulations on finding the bad regulator and hopefully it solves your issue. The HP 8601 along with the HP 8600 Digital Marker combination are most likely the best relatively modern thing going for TV alignment. If you feel challenged while troubleshooting those two, you'll be horrified of the 8664's internal complexity, as well as the 8662. They are not at all user friendly service wise.

Yes the overall challenge is what I am afraid of. There is also a factor of trust with the equipment as the complexity removes you from the actual task.

The main pros of the 8600a/8601a are multiple accurate markers, marker adding does not interfere with the displayed frequency response and simple sweep and frequency and amplitude controls.

[Chris K]

Originally Posted by Kevin Kuehn

It would appear the HP 1820-0196 is a Ua723 regulator in a TO99 package. A fairly common part from that time period.

Yes further research showed that. You can still get them with the right form factor for a bit more than I paid..DigiKey and Mouser among others.

[Chris K]

Originally Posted by Penthode

Yes the overall challenge is what I am afraid of. There is also a factor of trust with the equipment as the complexity removes you from the actual task.

The main pros of the 8600a/8601a are multiple accurate markers, marker adding does not interfere with the displayed frequency response and simple sweep and frequency and amplitude controls.

Lesson learned! It's been working great so far and I was able to produce nice traces on the scope for the discriminator and sound response traces for the RCA.
Next is getting to these traps...again. I found and serviced the exact RCA VoltOhmyst VTVM from this era recommended for the alignment. I had some custom probes made up by an eBayer who is well known for quality reproductions of old test equipment probes and leads. What could go wrong...right???!!!

[Penthode]

You need first to make sure before adjusting the traps is ensure the IF adjustments are roughly correct. I would suggest first assessing the state of the VIF stages as I believe you may have inadvertently adjusted two stages to the same frequency which may indyuce oscillation.

When adjusting the traps, you may have to increase the input signal and/or reduce the bias to get a clear indication on the VTVM. With this alignment you have to check, recheck and check again that you have not adjusted something to an odd spurious peak or null. You have to moderate the IF amplifier gain and input signal to it to ensure the amplifier is linearly amplifying. That is not too high and not too low. The signal output level of the amplifier at the 2nd detector is important to constantly monitor and reference.

I have continued on about this because earlier (aside from the equipment deficiencies) this issue I believe caused you no end of grief earlier. The RCA Alignment instructions are only a guide. You must understand what you are doing and stop if you have any question.

Again, before adjusting the traps, you must ensure the IF amplifier is roughly correct and that no oscillation ensues when you reduce the control bias.