GEC 2028 distorted sound :o( - UK Vintage Radio Repair and Restoration Discussion Forum

Dr-Watts · 29th Nov 2007, 9:56 pm

Hi all,

The GEC is still holding its own, but it's always had poor sound.

It's not weak or quiet, just distorted on anything more than speech-based.
Even loud speech based recordings (DVD or VHS) sound pretty dreadful no matter what the volume, if the off-air audio level is low, it sounds OK.
I'm certain it's not the speaker because as mentioned in the above line, it sounds fine at any setting with low level recordings.
It's so bad with LOUD recordings etc. that you can't understand speech !

Any ideas oh mighty TV Gurus?

Dr. Dave

Focus Diode · 29th Nov 2007, 10:33 pm

Suspects are R127 (120ohm), C112 (50uF) & R125 (18K screen feed resistor). Of course try a new PCL86 audio output valve, but not until the above components are checked as if defective a new valve might apparently restore normal service, but will have a short life.

If the above fails to cure the problem the sound output transformer could be defective, although this is unlikely.

The 2028 sound is generally good, although not brilliant.

Brian

Dr-Watts · 29th May 2008, 7:57 pm

At last, the sound fault on my GEC 2028 has been found !
I finally got a chance to spend a couple of hours on it Tuesday evening.
Basically the sound sounded overloaded, like feeding a CD player into a Phono stage of an amplifier.
It was always fairly nasty, but over the last couple of months it just got worse and worse.
Thanks to Brian and Steve P who suggested R's 127 & 125, both had changed value dramatically, but while I was poking around in the audio stage I checked all of the nasty dark brown R's and found that:
R129 - 4.7M,
R130 - 2.2M &
R126 - 10K were all miles out of spec and R128 - 220K was O/C.

It was also mentioned that I should change C112, but my set doesn't have this fitted !
The sound is now faultless - thank gawd !

Here's a couple of pictures that Faith took showing how non-user-friendly the 2028 is for those who have not been unfortunate enough to have had to work on one

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Kind Regards

Dr. Dave

Mikey405 · 30th May 2008, 8:24 am

Well done Dave - That's excellent.

29th Nov 2007, 9:56 pm	#1
Dr-Watts Heptode Join Date: Dec 2006 Location: Milton Keynes, Buckinghamshire, UK. Posts: 696	GEC 2028 distorted sound :o( Hi all, The GEC is still holding its own, but it's always had poor sound. It's not weak or quiet, just distorted on anything more than speech-based. Even loud speech based recordings (DVD or VHS) sound pretty dreadful no matter what the volume, if the off-air audio level is low, it sounds OK. I'm certain it's not the speaker because as mentioned in the above line, it sounds fine at any setting with low level recordings. It's so bad with LOUD recordings etc. that you can't understand speech ! Any ideas oh mighty TV Gurus? Dr. Dave __________________ Do you have the scope to be a TV repair man Last edited by Mike Phelan; 12th Jan 2010 at 4:17 pm. Reason: S&P corrected

29th Nov 2007, 10:33 pm	#2
Focus Diode Octode Join Date: Jan 2006 Location: Borough of Gateshead, UK. Posts: 1,420	Re: GEC 2028 distorted sound :o( Suspects are R127 (120ohm), C112 (50uF) & R125 (18K screen feed resistor). Of course try a new PCL86 audio output valve, but not until the above components are checked as if defective a new valve might apparently restore normal service, but will have a short life. If the above fails to cure the problem the sound output transformer could be defective, although this is unlikely. The 2028 sound is generally good, although not brilliant. Brian

29th May 2008, 7:57 pm	#3
Dr-Watts Heptode Join Date: Dec 2006 Location: Milton Keynes, Buckinghamshire, UK. Posts: 696	GEC 2028 Aweful sound problem solved ! At last, the sound fault on my GEC 2028 has been found ! I finally got a chance to spend a couple of hours on it Tuesday evening. Basically the sound sounded overloaded, like feeding a CD player into a Phono stage of an amplifier. It was always fairly nasty, but over the last couple of months it just got worse and worse. Thanks to Brian and Steve P who suggested R's 127 & 125, both had changed value dramatically, but while I was poking around in the audio stage I checked all of the nasty dark brown R's and found that: R129 - 4.7M, R130 - 2.2M & R126 - 10K were all miles out of spec and R128 - 220K was O/C. It was also mentioned that I should change C112, but my set doesn't have this fitted ! The sound is now faultless - thank gawd ! Here's a couple of pictures that Faith took showing how non-user-friendly the 2028 is for those who have not been unfortunate enough to have had to work on one Kind Regards Dr. Dave __________________ Do you have the scope to be a TV repair man

30th May 2008, 8:24 am	#4
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	Re: GEC 2028 Aweful sound problem solved ! Well done Dave - That's excellent. __________________ G7TRF