Granada M20 HR1 - (RBM A774) - UK Vintage Radio Repair and Restoration Discussion Forum

Radioman05 · 17th Apr 2007, 10:20 am

I have a Granada television set which is not working properly. I just bought a new valve for it (PY88) - all the filaments in all the valves are lit and in the CRT. The speaker makes a clicking sound constantly once the valves have warmed up; does the set pick up on VHF or UHF?

Thanks Tom

Hybrid tellies · 18th Apr 2007, 5:59 pm

If it's the Hybrid single standard (625) mono RBM chassis it's the A774. If you have heaters and HT, chances are it's a line output fault as the LT supply for the tuner and IF stages is derived from the line output stage.

Can you put a picture of the set up for us, or give us a description of the appearance of the set, like how many tuner buttons and the location of the brightness, contrast controls etc?
From this we should be able to recognise what set you have here.

The trouble with Granada is that they use to badge all their TVs. They mostly used mono sets from BRC, GEC, Decca or Rank.

jay_oldstuff · 15th May 2007, 5:08 pm

Ok, I am now the custodian of this set
I have given the set the once-over and it is indeed an RBM A774 chassis.

First fault found was an o/c fusible resistor in the line output area. With this re-soldered I applied power. Valves came up but as the line output valves warmed up and the line whistle could be heard the lopt started flashing over and letting out the magic smoke

First off - anyone got the service data for this set, also has anyone got a spare lopt?

I do have a lopt that I may be able to get working with this set, but it is not the correct one and would mean a lot of messing about to fit.

Jay

jay_oldstuff · 16th May 2007, 5:00 pm

Ok, I've fixed it

I decided I would take the lopt out to see where it was flashing over.
Upon removal I noticed that the bit of paxolin that makes up the connection board was carbonised around where it is used as an anchor point for the wires going to the valve top caps.

I removed this carbonised bit of paxolin and made the connections directly, covering them after with heatshrink sleeving; after this I put the lopt back in and gave the set a go.

First, the sound came up, which was a good start, followed by a slightly squashed picture. A quick tweak of the height control sorted that out and I now have a very good picture.

The set has now been running for over two hours with no problems so far.

Jay

Tazman1966 · 16th May 2007, 10:58 pm

An excellent result, Jay. Well done. These had one of the better pictures of the time so I seem to remember - well I was only a lad!

Tas

17th Apr 2007, 10:20 am	#1
Radioman05 Retired Dormant Member Join Date: Oct 2005 Location: Stockport, Greater Manchester, UK. Posts: 6	Granada M20 HR1 - (RBM A774) I have a Granada television set which is not working properly. I just bought a new valve for it (PY88) - all the filaments in all the valves are lit and in the CRT. The speaker makes a clicking sound constantly once the valves have warmed up; does the set pick up on VHF or UHF? Thanks Tom Last edited by Mike Phelan; 18th Mar 2008 at 9:18 am. Reason: S&P

18th Apr 2007, 5:59 pm	#2
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	Re: Granada M20 HR1 If it's the Hybrid single standard (625) mono RBM chassis it's the A774. If you have heaters and HT, chances are it's a line output fault as the LT supply for the tuner and IF stages is derived from the line output stage. Can you put a picture of the set up for us, or give us a description of the appearance of the set, like how many tuner buttons and the location of the brightness, contrast controls etc? From this we should be able to recognise what set you have here. The trouble with Granada is that they use to badge all their TVs. They mostly used mono sets from BRC, GEC, Decca or Rank. __________________ Simon BVWS member

15th May 2007, 5:08 pm	#3
jay_oldstuff Octode Join Date: Jan 2005 Location: Hyde, Greater Manchester, UK. Posts: 1,074	Re: Granada M20 HR1 Ok, I am now the custodian of this set I have given the set the once-over and it is indeed an RBM A774 chassis. First fault found was an o/c fusible resistor in the line output area. With this re-soldered I applied power. Valves came up but as the line output valves warmed up and the line whistle could be heard the lopt started flashing over and letting out the magic smoke First off - anyone got the service data for this set, also has anyone got a spare lopt? I do have a lopt that I may be able to get working with this set, but it is not the correct one and would mean a lot of messing about to fit. Jay __________________ The light at the end of the tunnel is probably the headlight of an oncoming train Last edited by Mike Phelan; 18th Mar 2008 at 9:22 am. Reason: Readability

16th May 2007, 5:00 pm	#4
jay_oldstuff Octode Join Date: Jan 2005 Location: Hyde, Greater Manchester, UK. Posts: 1,074	Re: Granada M20 HR1 Ok, I've fixed it I decided I would take the lopt out to see where it was flashing over. Upon removal I noticed that the bit of paxolin that makes up the connection board was carbonised around where it is used as an anchor point for the wires going to the valve top caps. I removed this carbonised bit of paxolin and made the connections directly, covering them after with heatshrink sleeving; after this I put the lopt back in and gave the set a go. First, the sound came up, which was a good start, followed by a slightly squashed picture. A quick tweak of the height control sorted that out and I now have a very good picture. The set has now been running for over two hours with no problems so far. Jay Attached Thumbnails __________________ The light at the end of the tunnel is probably the headlight of an oncoming train

16th May 2007, 10:58 pm	#5
Tazman1966 Nonode Join Date: May 2006 Location: St Albans, Herts, UK. Posts: 2,193	Re: Granada M20 HR1 An excellent result, Jay. Well done. These had one of the better pictures of the time so I seem to remember - well I was only a lad! Tas