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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 16th May 2020, 4:28 pm   #161
deepspacedaz
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Default Re: Fixing a GEC BT 302 Television

Ill switch it on
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Old 16th May 2020, 4:30 pm   #162
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Default Re: Fixing a GEC BT 302 Television

Well hopefully Daz. 3 pictures for you. The Z329 is the first picture. Notice it's circular internal cylinder with round holes.
The second one is the B729. Note the much smaller internal assembly. The 6/30L2 that you have in yours is a direct replacement.

The third picture is two versions of the EF80. There are different versions of this valve but all have the much finer perforations in the internal screen cylinder.
You have a Z152 and I think you mention you have a 6BX6.
These valves are equivalents of the EF80 and will replace the Z329 in your GEC.

The Z329 has a Mazda equivalent known as the 30F5 with identical internals. The only reason I mention this is because you may have one and wonder what it is.

I say again, double check your work and make sure all is correct. John.
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Old 16th May 2020, 4:33 pm   #163
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Default Re: Fixing a GEC BT 302 Television

no whine now, no white spot when I switch off like before
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Old 16th May 2020, 4:34 pm   #164
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Default Re: Fixing a GEC BT 302 Television

Check your valve positions.....particularly on the TIMEBASE board. J.

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Old 16th May 2020, 4:41 pm   #165
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Default Re: Fixing a GEC BT 302 Television

Here my work
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Old 16th May 2020, 4:51 pm   #166
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Default Re: Fixing a GEC BT 302 Television

Daz. You have a 6BX6 [EF80] in the position that the B729 [6/30L2 should be. Can you also post a better picture of the bottom three valves. J.
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Old 16th May 2020, 4:56 pm   #167
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Default Re: Fixing a GEC BT 302 Television

The bottom valve nearest the line output box V14, should be a Z329 or one of it's equivalents.

The valve above it V17 is the much smaller D77.

The valve above that one, V18 should be another Z329.

The valve above that one V16 is the B729

and finally the top valve, the tall one is a N379 GEC or equivalents Mazda 30P18 or Mullard PL84.

Check also the positions of the two large octal valves at the bottom and make sure the top cap connectors aren't crossed. J.
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Old 16th May 2020, 5:16 pm   #168
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Default Re: Fixing a GEC BT 302 Television

here we go
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Old 16th May 2020, 5:23 pm   #169
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Default Re: Fixing a GEC BT 302 Television

Ok If that bottom valve is a Z329 or one of it's equivalents and you have checked the two large valves for position, give it another try. We want to get back to the 'whine' and switch off spot. J.
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Old 16th May 2020, 5:37 pm   #170
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Default Re: Fixing a GEC BT 302 Television

O got a line across the screen and a whine
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Old 16th May 2020, 5:42 pm   #171
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Default Re: Fixing a GEC BT 302 Television

Great!First things first. Are you now sure you have the B729 valve in position second from top, underneath the tall valve at the very top?
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Old 16th May 2020, 5:45 pm   #172
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Default Re: Fixing a GEC BT 330 Television

I have this and the Whine sound
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Old 16th May 2020, 5:55 pm   #173
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Default Re: Fixing a GEC BT 302 Television

If you now sure you have the valves correctly located you will need to make a voltage test with your meter.
At the top of the panel there are two small plugs with a red and orange pair of leads soldered to the pin connectors. These leads go to the frame output transformer.

With your test meter on the 600volt DC range and with the black lead connected to chassis, first check that you have around 200v on both red and orange wires. Do not attempt anything further. J.
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Old 16th May 2020, 5:57 pm   #174
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Default Re: Fixing a GEC BT 302 Television

It's a start. Is the B729 in it's correct socket below the taller valve above it.
The white line by the way is called a frame collapse.
P.S. You can't work on it properly inside the case. Pull the knobs off, unplug the speaker leads, release the two self tapping screws that hold the chassis in and pull it out. It will be much easier to work on.
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Old 16th May 2020, 5:58 pm   #175
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Default Re: Fixing a GEC BT 302 Television

The b729 is the second valve down its correct now
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Old 16th May 2020, 6:08 pm   #176
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Default Re: Fixing a GEC BT 302 Television

172 V RED

134 v ORANGE

Drops a little
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Old 16th May 2020, 6:18 pm   #177
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Default Re: Fixing a GEC BT 302 Television

Sounds OK for first test.
It's quite unusual to have a total collapse on a BT302. Before we go any further have you replaced any components on the timebase panel previously?

If not I would first check to see if you have a disconnected component on the solder side of the board. Check particularly around the height preset and make sure the preset is intact and not damaged.

If everything looks OK I want you to change over a couple of valves. Swop over the tall valve [frame output] with the sound output valve. [same size] the sound output valve is mounted at the bottom of the I.F. board and is a bit difficult to get wiggle out.The frame output valve is the top one above the B729.
Swop them over and try again.

Does the brightness control work? Can you brighten and darken the line? If you rotate the tuner unit, does the line flutter and do you get crackles on the speaker?
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Old 16th May 2020, 6:19 pm   #178
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Default Re: Fixing a GEC BT 302 Television

Its also missing a grounding spring.
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Old 16th May 2020, 6:20 pm   #179
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Default Re: Fixing a GEC BT 302 Television

Ok ill carry the test out brightness works. no audible sound
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Old 16th May 2020, 6:24 pm   #180
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Default Re: Fixing a GEC BT 302 Television

So v9 in place of V5 CORRECT
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