Bush SRG110 - UK Vintage Radio Repair and Restoration Discussion Forum

robreddog · 25th Oct 2023, 1:29 pm

Hi, having failed to impress the wife with a marconi radiogram i bought another, a bush (never give up ).
It looks unmolested.
skipping the pre checks that were done i got to a point where the gram section works but the radio bit not.
I am not a radio expert by a long (long) way but looking at the scheme seems to me that the problem could be around v3 ef89 as this according to valve museum it is the if amplifier.
there are no volts on the anode but 236 volts into L18 so my previous working life makes me think the coil is open cct and could be part of the problem.
Please guys now step in and affirm or correct me, if i am correct how do i go about fixing this coil ?? i have no idea.

robreddog · 25th Oct 2023, 1:50 pm

sorry forgot the schematic

vinrads · 25th Oct 2023, 2:16 pm

Hi Have you taken readings at the actual coil terminals , if so it looks like your diagnosis is correct the coil must be o/c ,I would remove it marking which way round it goes ,remove the can and see if there is any wires adrift inside , Mick.

robreddog · 25th Oct 2023, 3:04 pm

Hi, yes voltage readings are on the schematic
My question now is does ift5 plug into a base or soldered on to pcb,also what is the connecting bit between top of ift4 and ift5 ?
Thanks for the reply.
Rob.

ms660 · 25th Oct 2023, 3:41 pm

Quote:

Originally Posted by robreddog

My question now is does ift5 plug into a base or soldered on to pcb,also what is the connecting bit between top of ift4 and ift5 ?

Most likely soldered.

The bit in the schematic that connects between the top of IFT 4 and IFT 5 is the tuned primary of the 2nd AM IF transformer.

Lawrence.

PJL · 25th Oct 2023, 3:59 pm

It appears to be the 10.7MHz IFT that is open circuit I would first resolder the board around the IFT pins to see if its a dry joint. You should be able to short across L18 to see if AM is working but ultimately you will need to remove the IFT and open it up.

robreddog · 25th Oct 2023, 4:00 pm

hi, here we can see the fine wire detached, where does it connect, is it where i have marked, tricky i think.

dazzlevision · 25th Oct 2023, 4:47 pm

I should have a set of IFTs removed from a working Bush SRG110, should you need one.

I can have a look to see exactly where the loose wire should go.

Unusually, this radiogram chassis is actually a Murphy design, but with a Bush VHF RF unit - in the grey die cast metal box. Probably still made in Murphy's Welwyn Garden City or Scarborough factory, rather than the Bush factory in Plymouth.

The SRG110 was produced a year or two after Rank bought Murphy (in June 1962) and merged it with their Bush subsidiary.

robreddog · 25th Oct 2023, 4:56 pm

hi, thanks so much,if at least if i can see where the wire should go i can try to fix if not your offer would be greatly received.
Rob.

robreddog · 26th Oct 2023, 4:41 pm

hi, so i have managed to tease out some of the coil where i thought the wire should go and happy days i have music on FM and speach on LW and MW and although capacitors seem to be ok think i will change the usual suspects step by step and see how it goes, the output valve bases will need attention for a start.
So at the moment don't need an IFT, but keep it handy as it's early days.
Rob.

dazzlevision · 26th Oct 2023, 4:59 pm

Quote:

Originally Posted by robreddog

So at the moment don't need an ift but keep it handy it's early days.
Rob.

Glad you've fixed it.

Should you need other special parts, I may well have them.

robreddog · 21st Nov 2023, 8:32 am

hi, there is a glimmer of hope that when finished this may be accepted in the house, with that in mind i got hold of an AT6 to replace the AT5 so as to be able to use a MM cartridge,testing the AT6 (with a old 70's cartridge unfortunately dead)i found that it will track at +3 grams i have looked through post's on the subject and found a few recommendations but can anyone share how they fixed them in the headshell did you make yourself or find a suitable adapter.
The AT5 works well and apart from the mat and is in decent condition fitted with a ronette 105.
Rob.

25th Oct 2023, 1:29 pm	#1
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Bush SRG110 Hi, having failed to impress the wife with a marconi radiogram i bought another, a bush (never give up ). It looks unmolested. skipping the pre checks that were done i got to a point where the gram section works but the radio bit not. I am not a radio expert by a long (long) way but looking at the scheme seems to me that the problem could be around v3 ef89 as this according to valve museum it is the if amplifier. there are no volts on the anode but 236 volts into L18 so my previous working life makes me think the coil is open cct and could be part of the problem. Please guys now step in and affirm or correct me, if i am correct how do i go about fixing this coil ?? i have no idea. Attached Thumbnails

25th Oct 2023, 1:50 pm	#2
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Re: Bush SRG110 sorry forgot the schematic Attached Thumbnails

25th Oct 2023, 2:16 pm	#3
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,655	Re: Bush SRG110 Hi Have you taken readings at the actual coil terminals , if so it looks like your diagnosis is correct the coil must be o/c ,I would remove it marking which way round it goes ,remove the can and see if there is any wires adrift inside , Mick.

25th Oct 2023, 3:04 pm	#4
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Re: Bush SRG110 Hi, yes voltage readings are on the schematic My question now is does ift5 plug into a base or soldered on to pcb,also what is the connecting bit between top of ift4 and ift5 ? Thanks for the reply. Rob.

25th Oct 2023, 3:59 pm	#6
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,937	Re: Bush SRG110 It appears to be the 10.7MHz IFT that is open circuit I would first resolder the board around the IFT pins to see if its a dry joint. You should be able to short across L18 to see if AM is working but ultimately you will need to remove the IFT and open it up.

25th Oct 2023, 4:00 pm	#7
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Re: Bush SRG110 hi, here we can see the fine wire detached, where does it connect, is it where i have marked, tricky i think. Attached Thumbnails

25th Oct 2023, 4:47 pm	#8
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,490	Re: Bush SRG110 I should have a set of IFTs removed from a working Bush SRG110, should you need one. I can have a look to see exactly where the loose wire should go. Unusually, this radiogram chassis is actually a Murphy design, but with a Bush VHF RF unit - in the grey die cast metal box. Probably still made in Murphy's Welwyn Garden City or Scarborough factory, rather than the Bush factory in Plymouth. The SRG110 was produced a year or two after Rank bought Murphy (in June 1962) and merged it with their Bush subsidiary.

25th Oct 2023, 4:56 pm	#9
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Re: Bush SRG110 hi, thanks so much,if at least if i can see where the wire should go i can try to fix if not your offer would be greatly received. Rob.

26th Oct 2023, 4:41 pm	#10
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Re: Bush SRG110 hi, so i have managed to tease out some of the coil where i thought the wire should go and happy days i have music on FM and speach on LW and MW and although capacitors seem to be ok think i will change the usual suspects step by step and see how it goes, the output valve bases will need attention for a start. So at the moment don't need an IFT, but keep it handy as it's early days. Rob.

21st Nov 2023, 8:32 am	#12
robreddog Pentode Join Date: Apr 2020 Location: Derby, Derbyshire, UK. Posts: 187	Re: Bush SRG110 hi, there is a glimmer of hope that when finished this may be accepted in the house, with that in mind i got hold of an AT6 to replace the AT5 so as to be able to use a MM cartridge,testing the AT6 (with a old 70's cartridge unfortunately dead)i found that it will track at +3 grams i have looked through post's on the subject and found a few recommendations but can anyone share how they fixed them in the headshell did you make yourself or find a suitable adapter. The AT5 works well and apart from the mat and is in decent condition fitted with a ronette 105. Rob.