Quasar WP3422QW only stays on for a couple seconds

[blue lander]

Hi everyone,

I picked up a Quasar WP3422QW at a thrift store recently. It's a late 70's color TV. When I turn it on, I hear static out of the speaker for about two seconds and then no sound. I don't see anything on the screen, not even a glow with the lights out. I can feel static on the surface of the screen though.

If I turn the TV off and back on again I don't hear static. But if I wait about a minute before I turn it on again, I do.

I assume step one here is to replace all the electrolytic capacitors, but is there anything else I should check out?

[zeno]

Sounds like HVSD ( high voltage shut down) . If you have a variac
try running the set at @95 VAC. IIRC this chassis had a repair kit
for the power supply. Too long ago to remember the details. A recap
not in order, fix the HVSD first then there are a few caps to change.
A wholesale recap usually ends in sorrow
Anyhows they were good sets & odds are it will come out fine.

73 Zeno
LFOD !

[blue lander]

Thanks! I don't have a variac, could I use a light bulb in series with the power cable for the same effect?

I looked up the part number on the bottom of the chassis, it's a TS-969 apparently.
https://www.worldradiohistory.com/Ar...TD-1980-06.pdf

A schematic for the board is on page 58

[zeno]

Originally Posted by blue lander

Thanks! I don't have a variac, could I use a light bulb in series with the power cable for the same effect?

I looked up the part number on the bottom of the chassis, it's a TS-969 apparently.
https://www.worldradiohistory.com/Ar...TD-1980-06.pdf

A schematic for the board is on page 58

Shure dim bulb it. You should also pull the back & find the horz out transistor.
Then fire it up for a few seconds. Un power & feel the transistor & see if it gets hot. If so dont go further. If cool do again for 10 sec, 30 sec etc. That will get you started.

Zeno

[vol.2]

Originally Posted by zeno

IIRC this chassis had a repair kit
for the power supply.

Sounds like maybe OP should pull and check the components in the PSU. I know in some cases, you're not supposed to directly measure B+, but this set schematic doesn't seem to warrant that, so could start off by checking that is okay?

[blue lander]

I went ahead and ordered a variac. At 90VAC the TV appears to work fine. Is the next step to measure the temperature of horiz out transistor?

[vol.2]

Originally Posted by blue lander

I went ahead and ordered a variac. At 90VAC the TV appears to work fine. Is the next step to measure the temperature of horiz out transistor?

I'm not sure what Zeno meant, but I would pay attention to the components in the power supply. Check the values of the components in that whole area and make sure there isn't anything obvious like a blown or shorted resistor.

If you really want to get help though, it's best to make it easy for people to see the schematic. For example, someone could quickly look at this and maybe offer a suggestion.

[damen]

I would first check or replace those two 33mf electrolytics, C809 and C812. Measure the b+ at the F2 fuse and see if the 130 volt adjustment does anything at all. If it doesn't and the electrolytics are good, suspect R811 the 47K resistor connected to the control, or the transistors.

[zeno]

Originally Posted by blue lander

I went ahead and ordered a variac. At 90VAC the TV appears to work fine. Is the next step to measure the temperature of horiz out transistor?

Good tips so far. Next step is check the 130 V line. Put meter on that
and slowly turn up variac. The 130 V must not go over 130 V. If it does
you have a regulator prob. If it shuts down on 130 V its a HVSD problem, not shown on the schematic, probably a bad zener diode.

Zeno

[blue lander]

Thanks everyone. I'll measure the 130v but first I think I need to give the chassis a serious cleaning.

[vol.2]

Originally Posted by blue lander

Thanks everyone. I'll measure the 130v but first I think I need to give the chassis a serious cleaning.

That's pretty filthy. Be careful though. I would just use compressed air, or a soft paintbrush and a vacuum cleaner

you'll probably want to clean all those pots with fader cleaner. Caig Faderlube works good, but I guess there are other kinds

[blue lander]

Fader cleaner is a good idea. I have some deoxit that should do the trick.

I also noticed what appears to be a stain on the bottom of the case towards the back. Maybe somebody spilled something in there

[vol.2]

Originally Posted by blue lander

Fader cleaner is a good idea. I have some deoxit that should do the trick.

I also noticed what appears to be a stain on the bottom of the case towards the back. Maybe somebody spilled something in there

Be aware that there are different kinds of Deoxit. The red kind is mainly for metal to metal contact and corrosion. The green kind is for carbon traces.

The green deoxit is less harsh with the solvent and designed to not dissolve delicate carbon traces (which can sometimes happen). It also contains a conductive lubricant that clings to the traces and keeps it gooey and smooth over time, lengthening it's useful life.

Before I knew this, I ruined a couple of rare-ish walkman pots that had tiny carbon traces known for being fragile and vulnerable to harsh contact cleaners.

[blue lander]

I was not aware of that! I think I have deoxit gold.

[vol.2]

Originally Posted by blue lander

I was not aware of that! I think I have deoxit gold.

I've never used the gold stuff before. Not sure about that. It says it's okay on plastics, which is different than the red stuff. Probably fine?