Predicta Holiday No Picture or Sound

[greggburnett]

I am currently restoring a Predicta Holiday, and am having trouble resolving an issue with "no picture, no sound". I have a faint raster, and an audio hum (hum decreases at full CW on the volume control).
I have reviewed a similar thread on Videokarma, but that has not helped (yet).
Here is what I have done so far:
- Tested all tubes
- Re-capped all electrolytics
- Re-capped the chassis
- Replaced the rectifier diodes and caps
- Replaced R77 with individual resistors (13 ohm, 18 ohm, 8 ohm)
- Replaced R76 with two SL12's
- Replaced R78 "fusistor" with a 5.6 ohm 10W resistor and a 1A fuse
- Re-capped the main board, replaced all networks and the 12CA5 (someone has replaced the socket)
- Corrected a cold solder joint in the tuner filament connector pin
- Removed a solder bridge from the 2nd IF (shorting C14 and R15) , replaced some resistors, and replaced the 5AM8
- Verified resistance values in the fly-back and L23 (okay)
- Replaced resistors R66, R67, R70, and R71 in the Width/Boost circuit
- Checked R5 (Width) and R68; measure okay

Using Sam's as a reference, here are my voltages:
- Cathode of M1: 275V vs. 290V
- 280V Source: 262V
- 260V A Source: 257V
- 260V B Tuner B+: 239V
- 260V C Source: 238V
- 140V Source: 144V
- 435V Boost: 391V at pin 1 of the CRT ( R5 full CCW; 350V centered); voltage seems to decay slowly

I would certainly appreciate some insight...

[Electronic M]

Do you have any test equipment that you can use to inject video and or IF signals (also a power isolation transformer to keep the hot chassis from frying your test equipment)?

The voltages mostly look within reasonable tolerance (in tube equipment a 20-30% B+ and general voltage reading tolerance is not unreasonable).

[greggburnett]

Thank you for responding.

I have a B&K Isolation Transformer, and a B&K Model 1077 Television Analyst. I have injected an RF signal at the antenna terminals (nothing). I have input an IF signal at the 3rd IF amp (very faint, fuzzy test pattern outline, no sound). I repeated this at the 2nd and 1st IF amps, with the same results.

I thought maybe the low 435V Boost might be part of the dim raster issue, but I can't seem to correct it.

[greggburnett]

I just re-ran the 3rd IF test, and have an audio tone. I adjusted the Horizontal Range, Height, and Vertical Lin controls, and have an image! A bit distorted though (pulled down from the top,etc). I have attached an image (sorry for the glare). I re-ran the RF test, and still no sound or picture. Maybe the tuner. I will re-run the 2nd and 1st IF tests.

[greggburnett]

Re-ran the 2nd and 1st IF tests. Still get an image and tone. The picture is still pulled down from the top. The vertical centering magnet doesn't seem to help.

[Tom9589]

Have you or the previous owner tested the CRT?

[bandersen]

Vertical linearit is off. Do the vert linearity and height controls have an effect? One or both made be concentric controls on the side you need a screw driver to get at.

[greggburnett]

Thank you for helping with this.

I have not yet put the CRT on my B&K 465 tester/restorer. The previous owner said the CRT has an open grid 2. I wanted to test it with the restored chassis first. I will test the CRT.

The vertical linearity and height controls do have an effect. I have worked to balance those, as well as the vertical hold. When I adjust the linearity, the vertical rolls, so I have to go back and forth. I have been able to improve the vertical linearity and width a bit, and now it is over-scanning a bit vertically.

Some new clues:
- When I turn the Horizontal Hold CCW, the screen goes dark.
- I was able to get an RF signal through the tuner. This was by accident, as I had the tuner on Ch 3, and switched the B&K 1077 channel to 2. Maybe tuner alignment.

[Tom9589]

Before you go off trying to align the tuner, check the fine tuning mechanism closely. Many fine tuning adjustments can get you a complete channel off, particularly if their mechanical mechanism for connection with the fine tuning knob is off.

[old_coot88]

If that's a wafer type tuner, be sure all the wafer rotors are turning solidly with the shaft with no slop or play. Sometimes a a rotor will even be stripped at the hub and not turning at all.

[greggburnett]

Thank you.

I'll take a closer look at the tuner, and fine tuning.

CRT emissions test "bad", although I have an image.

[greggburnett]

The tuner rotors are all working properly. The fine tuning mechanism seems to be in order as well. Can't find any cold solder joints. Tubes test okay. Kind of stumped.

[bandersen]

Check that the coax from the tuner to the IF board is making good contact

[greggburnett]

Thank you all for your suggestions!

I removed and cleaned the tuner, including the fine tuning capacitor plate. Checked for cold solder joints, etc. None found. Re-installed the tuner, making sure I had good contact from the coax connector to the IF board. Put an RF signal from my B&K 1077 through the tuner, and have sound and an image! Put a signal from my DVD player through the tuner (on channel 3), and have a decent picture and sound! The picture is faint, probably due to my CRT being very weak.

Still making some tweaks. The sound still is low, and has a significant buzz. The buzz pot doesn't help much. Sometimes the picture rolls and jitters when scenes change.

Is anyone willing to part with a 21FDP4 or 21DAP4 CRT?

I also need a fine tuning knob.

Again, thank you for your help!

[greggburnett]

Forgot to mention that I also replaced the 5X8 in the tuner. The old tube read "good", but the replacement has a higher output. May have made a difference.