Bush DAC90A Strange Fault - UK Vintage Radio Repair and Restoration Discussion Forum

bobhowe · 15th May 2021, 2:51 pm

Got a Bush DAC90A off a forum member about 8 years ago changed all the dodgy waxies few resistors and got a auto transformer of Ed Dinning ( done a great job ) . The radio works ok but it had 2 faults 1 is background hum & another fault i would crackle and go silent tap the radio and it would play again so yesterday i read about removing the connection on pin 4 on the UL41 valve so i removed the connection & no mains hum i had the chassis out of the cabinet & upside down & it was playing great for over a hour . So i put the chassis back in the cabinet & guess what ? after 10 mins it went silent had checked for dry joints and valve pin connections the only thing i had done apart from removing pin 4 connection was to remove the UL41 valve to count the pins so went to check that the valve was in ifs socket properly then i found the fault a piece of metal inside the valve shorting round the pins turned the set upside down the set played with out giong silent

Herald1360 · 16th May 2021, 10:16 am

Find a set using a UL41 mounted sideways or upside down (maybe a record player?), do a swap and you could be your own uncle

Could the debris be persuaded to sit on the top mica, out of the way?

stevehertz · 16th May 2021, 2:08 pm

Well found. Just put a replacement in, that's what I'd do.

15th May 2021, 2:51 pm	#1
bobhowe Heptode Join Date: Jun 2005 Location: Sunderland, Tyne and Wear, UK. Posts: 661	Bush DAC90A Strange Fault Got a Bush DAC90A off a forum member about 8 years ago changed all the dodgy waxies few resistors and got a auto transformer of Ed Dinning ( done a great job ) . The radio works ok but it had 2 faults 1 is background hum & another fault i would crackle and go silent tap the radio and it would play again so yesterday i read about removing the connection on pin 4 on the UL41 valve so i removed the connection & no mains hum i had the chassis out of the cabinet & upside down & it was playing great for over a hour . So i put the chassis back in the cabinet & guess what ? after 10 mins it went silent had checked for dry joints and valve pin connections the only thing i had done apart from removing pin 4 connection was to remove the UL41 valve to count the pins so went to check that the valve was in ifs socket properly then i found the fault a piece of metal inside the valve shorting round the pins turned the set upside down the set played with out giong silent

16th May 2021, 10:16 am	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Bush DAC90A Strange Fault Find a set using a UL41 mounted sideways or upside down (maybe a record player?), do a swap and you could be your own uncle Could the debris be persuaded to sit on the top mica, out of the way? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

16th May 2021, 2:08 pm	#3
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,831	Re: Bush DAC90A Strange Fault Well found. Just put a replacement in, that's what I'd do. __________________ A digital radio is the latest thing, but a vintage wireless is forever..