Bush TV22 Mk1 - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Ian - G4JQT · 5th Mar 2016, 1:11 pm

Have you twiddled with the width linearity control yet? It's accessible from the back of the set and should have a core.

Ian

EF80TVVALVE · 5th Mar 2016, 1:34 pm

Hi, just replaced the PZ30 with a known good one and I still have the problem. I keep having a play with the width linearity control with no improvements unfortunately.
Regards

mark pirate · 5th Mar 2016, 4:02 pm

Have you fiddled with TC1 to achieve maximum EHT yet?
This will have an impact on the width.

Mark

EF80TVVALVE · 8th Mar 2016, 9:50 am

Hi Mark,
Yes, I have had a go at adjusting TC1 with no improvement too. Since changing the mica capacitor connected to the width control it has made it slightly better but it is still there and does cause quite bad crushing of the picture. I have also reset all of the controls as instructed by the service sheet with no improvement.
Regards

mark pirate · 8th Mar 2016, 10:23 am

Have you checked the EHT, it should be around 6.5kv. Also check the HT voltage.
What effect does turning up the brightness have on picture size and focus?

Mark

EF80TVVALVE · 23rd Mar 2016, 12:03 pm

Hi, a little more fault finding found the ECL80 close to the mains dropper wasn't performing properly. I still need to check some resistances but it is coming along well. Here are some photos, the cabinet was worn and watermarked but some time in the bath and plenty of buffing with wax polish and it has come uo beautifully.
Regards

Ian - G4JQT · 23rd Mar 2016, 12:12 pm

I see you have the tearing at the top. These sets often (but not always) suffer this, no matter how the controls are adjusted or what capacitors or resistors are replaced.

My rebuilt TV24 suffers it at the start of watching but reduces after an hour or so - heat related presumably.

I've seen this mentioned before, but don't recall a definitive cause being identified - unless I missed it.

Anyway, you seem to have a good tube. And the cabinets do polish up nicely.

Ian

KeithsTV · 23rd Mar 2016, 12:24 pm

The tearing at the top may be due to the presence of equalising pulses during the field sync period. The original 405 line spec, which the TV22 would have been designed for, didn't have equalising pulses. If you're using an Aurora one of the options is to enable/disable these pulses.

Keith

Ian - G4JQT · 23rd Mar 2016, 12:27 pm

Thanks Keith.

Yes, I've certainly heard of that and tried it, but switching them on and off only reduced it a little...

Ian

Courtney Louise · 28th Mar 2016, 8:11 am

Have you tried it without the Band III Converter?

5th Mar 2016, 1:11 pm	#41
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,323	Re: Bush TV22 Mk1 Have you twiddled with the width linearity control yet? It's accessible from the back of the set and should have a core. Ian

5th Mar 2016, 1:34 pm	#42
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Bush TV22 Mk1 Hi, just replaced the PZ30 with a known good one and I still have the problem. I keep having a play with the width linearity control with no improvements unfortunately. Regards

5th Mar 2016, 4:02 pm	#43
mark pirate Dekatron Join Date: Mar 2008 Location: Worthing, West Sussex, UK Posts: 5,185	Re: Bush TV22 Mk1 Have you fiddled with TC1 to achieve maximum EHT yet? This will have an impact on the width. Mark

8th Mar 2016, 9:50 am	#44
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Bush TV22 Mk1 Hi Mark, Yes, I have had a go at adjusting TC1 with no improvement too. Since changing the mica capacitor connected to the width control it has made it slightly better but it is still there and does cause quite bad crushing of the picture. I have also reset all of the controls as instructed by the service sheet with no improvement. Regards

8th Mar 2016, 10:23 am	#45
mark pirate Dekatron Join Date: Mar 2008 Location: Worthing, West Sussex, UK Posts: 5,185	Re: Bush TV22 Mk1 Have you checked the EHT, it should be around 6.5kv. Also check the HT voltage. What effect does turning up the brightness have on picture size and focus? Mark

23rd Mar 2016, 12:03 pm	#46
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Bush TV22 Mk1 Hi, a little more fault finding found the ECL80 close to the mains dropper wasn't performing properly. I still need to check some resistances but it is coming along well. Here are some photos, the cabinet was worn and watermarked but some time in the bath and plenty of buffing with wax polish and it has come uo beautifully. Regards Attached Thumbnails

23rd Mar 2016, 12:12 pm	#47
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,323	Re: Bush TV22 Mk1 I see you have the tearing at the top. These sets often (but not always) suffer this, no matter how the controls are adjusted or what capacitors or resistors are replaced. My rebuilt TV24 suffers it at the start of watching but reduces after an hour or so - heat related presumably. I've seen this mentioned before, but don't recall a definitive cause being identified - unless I missed it. Anyway, you seem to have a good tube. And the cabinets do polish up nicely. Ian

23rd Mar 2016, 12:24 pm	#48
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,573	Re: Bush TV22 Mk1 The tearing at the top may be due to the presence of equalising pulses during the field sync period. The original 405 line spec, which the TV22 would have been designed for, didn't have equalising pulses. If you're using an Aurora one of the options is to enable/disable these pulses. Keith

23rd Mar 2016, 12:27 pm	#49
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,323	Re: Bush TV22 Mk1 Thanks Keith. Yes, I've certainly heard of that and tried it, but switching them on and off only reduced it a little... Ian

28th Mar 2016, 8:11 am	#50
Courtney Louise Octode Join Date: Sep 2005 Location: Welshpool, Powys, Wales Posts: 1,327	Re: Bush TV22 Mk1 Have you tried it without the Band III Converter? __________________ *33, 45, 78, around and around they go...*