Hi all,

I was given a small 12" late 1960's/70's AWA Deep Image B&W portable television set, and thinking it was going to be solid state, was suprised to find out that it is a valve set. 13 valves that is, excluding the CRT.

I'm uploading a video on Youtube which clearly shows the ongoing issues, but I'll describe them here too. The vertical deflection isn't covering the bottom of the screen. After all the CRT reading I've done, I'm thinking this could possibly be a valve issue. When I had the case open, I could here the anode connection making a crackling sound, but now that it's back in the case, I can no longer hear it.

The other issue is with the speaker. It makes a loud static crackling when I touch the power/volume control knob, even when the volume is on zero. Could this also be a valve issue?

I don't know much about this set, because the model number has rubbed off. There are the markings on the chassis: 46-02 FA0030.

There are thirteen valves, but the writing on one has rubbed off (a big valve, similar in shape and appearance to a 6AU4), so I'll only list the twelve known ones:

6CM5
IX2B
12AU7A
6EJ7
6EH7
6KV8
6CB6A
6CS8
6EW6
6BM8
6HG8
6GK5

All the valves are AWV Super Radiotrons (so is the CRT), so I don't believe that they've been replaced (except for the IX2B, which I just replaced). There's a sticker on the bottom of the set. for a television repair service, and it says that they recommend Philips Miniwatt valves for their televisions. This is what leads me to believe that none have been replaced.

All help is greatly appreciated, and it'd be awesome to know the model number. When the video uploads, I'll post a link for it. I'll also see if Brad can post some photos for me and I've drawn a quick image of the valve locations on the circuitry.

Hi Chris.
Is one of the TV's as shown on this link the same as yours?

http://trove.nla.gov.au/ndp/del/printArticlePdf/48080635/3?print=n.

I have a full manufacturers service manual for a P1. The valve line-up is the same as yours. Though according to the circuit, the Damper is a 6AX4GT, not a 6AU4GT.

Let me know if you want it, and if so, I'll scan you a copy.

Cheers.

Hi Monochrome,

It is the same as the one the pretty lady is holding, the one on the bottom right of the page. The 11" (thought it was 12) P1. It's the same design but nice blue colour instead. I'd be interested in getting a copy of the service manual please. Does the service manual have a circuit diagram with tube type numbers?

Also for anyone in general, I'll be needing a new power/volume control knob. The one on this (three pins on the potentiometer, four on the power switch) has broken.

The vertical sweep of the image has also collapsed to a line across the screen, so I'm investigating that. Would the 6AX4GT have anything to do with that?

Anyways, I'll start a seperate thread for the volume knob and any valves I'll be needing.

I also think that the speaker crackling issue was something to do with the porentiometer, maybe dirty contacts? Anyways, I'll be getting it replaced now.

I'm still waiting for the video to upload (I'm never doing a video in 640p again!), so I'll post the link for that and I'll send some photos for Brad to post.

Cheers,

Chris

"The vertical deflection isn't covering the bottom of the screen. After all the CRT reading I've done, I'm thinking this could possibly be a valve issue"

Often in sets this old it's the capacitors getting leaky. Just like valve radios, all the wax paper caps should be replaced.

Hi Chris.

The P1 service manual has everything. There are 8 pages + circuit diagram. As a bonus I will also send you the 4 page service manual for the TB1 turret-tuner that is in the P1. These scans will take a little time to prepare. You will have them by tomorrow at the latest. Is your email address the same as in your profile?

Cheers.

Photos posted.

I lived in Rusden Street in Armidale for a short time as a kid, right next door to New State Motors. Long time ago that was now.

Hi Monochrome, thanks for that! Whenever you have the time is okay. My email address hasn't changed.

I've have the video for the telly posted:
http://www.youtube.com/watch?v=meW95UscB40.

Brads also posted the photos for me. Thanks Brad!

Cheers,

Chris

A few tips:-

Always use a small flat blade screwdriver to remove octal valves. Sometimes the bases work loose and if a wire breaks inside the base it is a nightmare to fix. Not impossible but very difficult.

The scratchy volume control is a dirty track inside the potentiometer. It'll need a blast with contact cleaner and should be right after that.

If the anode clip is not connected correctly it can spark under the rubber boot or even spark from the HT lead to the back of the screen. It's worth sorting this out though make sure the caps on the board are correctly discharged before doing this.

Not sure what is causing the blank portion of the picutre at the bottom but it could be many things, misaligned yoke, dried condenser, dry joint, loss of voltage on a supply rail, etc.

Brad, the image is now just a thinish line across the screen like in the photo. There is next to no vertical deflection. I'll be replacing the electrolytic caps as my next step in the project, so I'll hope this works.

Monochome also has a copy of the service manual, so this should help in sorting this out. Could the valves also be a contributing factor with the vertical deflection issues?

Chris

Chris.
AWA P1 manual sent.

Thank you for that Monochrome! I'll have a good look in the morning. It's far to late, and I should've been in bed and asleep a while ago. The joys of caffeine before bed...

Chris

That's a nice clean little P1 on the inside. For a valve TV these tend to be fairly rugged and manage to stay working on the original parts despite being around 40 years old.

Make sure you turn the brightness down while you have the vertical deflection fault. Running the TV like this will burn a line in the CRT phosphor because the beam is concentrated. Turning the brightness down so the line is visible but not really bright will prevent this.

The crackly sound is due to a dirty volume control. Unless it has physically broken it should respond to some contact cleaner. Replacement parts are not going to be easy to find.

The EHT connection to the CRT on your TV has been done wrong which is why it may be crackling. The red insulating cap should be snug against the glass and sit UNDER the plastic CRT bracket.

The vertical collapse can be any number of things but only involve the parts around the vertical oscillator and output stages. You are getting a line across the screen so you know the power supply and horizontal deflection / EHT sections are working. The fault could be as simple as a broken wire to the defection yoke or a bad connection on the 6BM8 valve socket. Most of the capacitors in these TV's are polyester types so are normally quite reliable. There are a few wax types used and these will need to be replaced as they were probably the cause of your original fault and may be also the vertical collapse. C319 is a known problem capacitor on these TV's. It would be the first part I would check, then the best way to proceed is to look at the circuit and think logically!

Replacing parts in the hope of fixing the TV will cost you in time and money but not necessarily fix the TV.

Thanks TV Collector.

I had the brightness turned up just the the photo. I've seen other sets with burnt phosphor, and it's not nice!

Are you sure about C319? It's a 6800pF 100v polyester capacitor. There are a few electrolytic caps that need replacement though.

Brad, do you remember L. W. Burgess repair shop from Armidale?

Chris

Hi Chris.

I've sent you the TB series tuner manual.
C319 is rated at 1800 volts, not 100. Those 2 other white UCC paper caps look like they are about to have kittens.
They are C414, 0.047uf/600v & C415, 0.047uf/1000v.

Cheers.

Hmm, I'll have to get around to getting this restored! I have so many other bloomin' sets to fix! I have some concerns that it may be a hefty job, as some of the components seem to have been changed with units of incorrect value (such as C319, which is rated for 100v instead of 1800v! It's a wonder it didn't blow... ). Still, it'll be a nice set once restored!

Chris