1992 RCA Console SET

[Console User]

Question to try to help a friend out. They have I believe a 1992 RCA Console with CTC 177AM2. They have real good color from the picture yet but when they use the set the Picture wants to pull from Left to Right. Any ideas what the issue could be? A Bad cap in the vertical circuit on the Main board or something else? Any ideas or help would be appreciated. I think it's a 27 Inch Set is what they told me.

[Electronic M]

Left to right would indicate horizontal issues not vertical.

Beyond that I'll let the solid state guys chime in.

[JohnCT]

Originally Posted by Console User

Question to try to help a friend out. They have I believe a 1992 RCA Console with CTC 177AM2. They have real good color from the picture yet but when they use the set the Picture wants to pull from Left to Right. Any ideas what the issue could be? A Bad cap in the vertical circuit on the Main board or something else? Any ideas or help would be appreciated. I think it's a 27 Inch Set is what they told me.

One of the unique things about the 177 was that it was totally software aligned, including the tuner. Other than the Focus and G2 pots on the flyback, everything else was done through the service menu.

What that means is that there is literally no symptom that could not be caused by a corrupted eeprom (where the alignment data is stored).

No sound? eeprom. Picture distorted? eeprom. Picture shrinking, stretched, pulling? eeprom.

The most common reason the eeprom gets corrupted is because of the bad ground structure in the tuner. RCA goofed a bit with this design in that the tuner ground shield and internal ground points are in series with the cold side ground of the power supply and the far side of the chassis. Any ground issues causes small spikes in the micro area where the eeprom lives and corrupts it.

The second reason the eeproms get corrupted is bad solder on the two large heatsink ground tabs where the low voltage regulator is and the where the horiz output transistor is. Solder both tabs thoroughly.

Any service of the 17X series begins with a tuner ground repair. If you don't intend to use the tuner, you can hard wire the cold side of the power supply bypass cap grounds to the microprocessor.

Once the grounds are done and the two heatsink ground tabs are soldered, service the chassis like any other.

Getting back to your symptom - you could be describing a bit corruption in the horiz phase or horiz osc adjustment.

After the tuner grounds are serviced (or bypassed), the procedure is to go into the service menu and adjust the horiz phase or oscillator adjustment(s) to see if the problem is there. Make note of all adjustment values before moving them. Careful with the horiz osc - if you adjust too high, it will go into shutdown and you'll have to add some capacitance in the horiz sweep to force the HV down so you can readjust.

If you can post a pic of the symptom that would help.

John

[Alex KL-1]

I don't know this model but, if it is similar to most TV using all-in-one video processor, is also good to check if it have bad soldering on H feedback capacitors, the small ceramic ones in the HOT collector (if it uses this), at least to be sure.

[zeno]

The chassis that put one son through 6 yrs of collage, TNX Thompson !!
He would tag along & do them along with other common problem sets.
Anyhows if this set has a PIN circuit one of the HV caps would open, maybe
this one is just starting. JohnCT may remember which one. IIRC RCA
supplied a different style.

73 Zeno
LFOD !

[JohnCT]

Originally Posted by zeno

The chassis that put one son through 6 yrs of collage, TNX Thompson !!
He would tag along & do them along with other common problem sets.
Anyhows if this set has a PIN circuit one of the HV caps would open, maybe
this one is just starting. JohnCT may remember which one. IIRC RCA
supplied a different style.

73 Zeno
LFOD !

Not off the top of my pointy little head..

I didn't think pin because OP said the pic was moving left to right, so I was thinking either horiz phase or horizontal centering. Any bowing (which he might have but didn't mention) would indicate pincussion caps which were indeed known to fail.

Pics certainly would be a big help.

John

[Console User]

[zeno]

In any case first all parameters should be WRITTEN down then the solder job.
I would not recommend just anyone do it unless expirienced with SMD.
& have a nice iron. Under the shield things are VERY close, its
a miracle I only splashed one out of hundreds done !

73 Zeno

[Console User]

Think I got pictures taken of the Console Set with the issue . They are in my Album . I do not know how to get the pictures onto the thread.

[Console User]

IMG_0647.jpeg

IMG_0646.jpeg


Anyone know for sure what the issue is by looking at the photos?

[JohnCT]

Originally Posted by Console User

Anyone know for sure what the issue is by looking at the photos?

Yes, your horiz osc adjustment is off. This is done through the service menu and means the data in the eeprom is most likely corrupt (I have seen this literally a thousand times or more).

Go back to post #3 above and see how to address the cause of the eeprom corruption, otherwise any adjustments you make will be in vain. Corruption of the eeprom can cause any symtom up to a dead TV. If the TV is dead, you will need to remove the eeprom and reprogram it on a programmer or replace the eeprom if you can find one.

I no longer recall the exact way of getting to the osc adjustment but I seem to think that you hold down the menu, hit the power (release) and vol + (release vol + and power and you should see two sets of numbers on the screen. You will raise either the vol or channel until one set reads 76, then you can advance to the horiz osc and adjust that. Maybe someone else remembers the exact position and sequence to get into the serv menu. If not, I have that info somewhere.

But to be clear, these chassis will corrupt the eeprom if the ground structure around the tuner isn't repaired or bypassed and both heatsink ground tabs aren't resoldered. This must be done before *any* work on these chassis takes place.

John

[JohnCT]

Originally Posted by zeno

In any case first all parameters should be WRITTEN down then the solder job.
I would not recommend just anyone do it unless expirienced with SMD.
& have a nice iron. Under the shield things are VERY close, its
a miracle I only splashed one out of hundreds done !

73 Zeno

LOL, I splashed a lot more than one...

You make a good point - the best option for amateurs is probably to bypass the tuner shielding entirely and ground the T-Chip and micro cage areas directly to the cold side of the power supply because, as you say, it's tight in that tuner.

John