Bush TR130 208 B/S dead - UK Vintage Radio Repair and Restoration Discussion Forum

telstar · 31st Jul 2019, 3:51 pm

Hi. I have managed to restore the l.w band on my Bush TR130 radio, although the m.w still requires a bit of attention (whistles while tuning on certain parts of the dial.
Would like to restore the 208 B/S as this is dead. The oscillator coil measures alright (no o/c windings). The resistors seem slightly out of tolerance in that section, but does not seem that bad to stop it oscillating. Any ideas?
Cheers
Mike

David G4EBT · 31st Jul 2019, 7:31 pm

Continuity of the Lux push button switch contacts? ('SC').

Alignment in the 208 switch position per the Bush datasheet (L8, 9 10 and C3)?

crackle · 31st Jul 2019, 8:58 pm

Have you checked the RF decoupling electrolytic. C27 on the Trader sheet.

Mike

telstar · 1st Aug 2019, 2:21 pm

Hi.
Many thanks for both replies.
I have had a look at the 208 B/S switch, but can not see it out of alignment. Will try the other components like C27.
Cheers
Mike

Sideband · 1st Aug 2019, 6:54 pm

I.F decoupling as mentioned above will cause whistling when tuned. Also if the RF alignment is out this can cause whistling on certain frequencies due to the aerial tuned circuit not being able to 'reject' unwanted frequencies....so called 'second channel' interference.

Sideband · 1st Aug 2019, 6:57 pm

Quote:

Originally Posted by telstar

Hi.
Many thanks for both replies.
I have had a look at the 208 B/S switch, but can not see it out of alignment. Will try the other components like C27.
Cheers
Mike

David was referring to the RF alignment....not the physical alignment or the position of the switch.

telstar · 5th Aug 2019, 3:50 pm

Hi. I managed to track down the B/S fault. It turned out to be the wire that connected the switch to capacitors C11 & C12 junction on the circuit board. I gently prodded the wire and it came back to life (although rather briefly). It is probably fractured inside. I have not got any wire that size, but I will look in my box of spares.
cheers
Mike

crackle · 5th Aug 2019, 4:03 pm

It is unusual for an insulated wire to break inside the insulation, unless it is used as a flexible cord, it is more likely for any wire to break at the soldered connection.
This sounds like you may have found a dirty connection inside the switch and when you prodded the wire it moved the switch connection.
Mike

31st Jul 2019, 3:51 pm	#1
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,592	Bush TR130 208 B/S dead Hi. I have managed to restore the l.w band on my Bush TR130 radio, although the m.w still requires a bit of attention (whistles while tuning on certain parts of the dial. Would like to restore the 208 B/S as this is dead. The oscillator coil measures alright (no o/c windings). The resistors seem slightly out of tolerance in that section, but does not seem that bad to stop it oscillating. Any ideas? Cheers Mike

31st Jul 2019, 7:31 pm	#2
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: Bush TR130 208 B/S dead Continuity of the Lux push button switch contacts? ('SC'). Alignment in the 208 switch position per the Bush datasheet (L8, 9 10 and C3)? __________________ David. BVWS Member. G-QRP Club member 1339.

31st Jul 2019, 8:58 pm	#3
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Bush TR130 208 B/S dead Have you checked the RF decoupling electrolytic. C27 on the Trader sheet. Mike

1st Aug 2019, 2:21 pm	#4
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,592	Re: Bush TR130 208 B/S dead Hi. Many thanks for both replies. I have had a look at the 208 B/S switch, but can not see it out of alignment. Will try the other components like C27. Cheers Mike

1st Aug 2019, 6:54 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: Bush TR130 208 B/S dead I.F decoupling as mentioned above will cause whistling when tuned. Also if the RF alignment is out this can cause whistling on certain frequencies due to the aerial tuned circuit not being able to 'reject' unwanted frequencies....so called 'second channel' interference. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

5th Aug 2019, 3:50 pm	#7
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,592	Re: Bush TR130 208 B/S dead Hi. I managed to track down the B/S fault. It turned out to be the wire that connected the switch to capacitors C11 & C12 junction on the circuit board. I gently prodded the wire and it came back to life (although rather briefly). It is probably fractured inside. I have not got any wire that size, but I will look in my box of spares. cheers Mike

5th Aug 2019, 4:03 pm	#8
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Bush TR130 208 B/S dead It is unusual for an insulated wire to break inside the insulation, unless it is used as a flexible cord, it is more likely for any wire to break at the soldered connection. This sounds like you may have found a dirty connection inside the switch and when you prodded the wire it moved the switch connection. Mike