Masteradio T851 advice - UK Vintage Radio Repair and Restoration Discussion Forum

kingbeau · 5th Apr 2023, 9:37 pm

So I’m a TV engineer (still working!) with around 30 years experience, so I’m familiar with CRT TVs that were around in the early 1990’s onwards. Ferguson TX10, Philips G11 etc. but honestly have pretty much zero knowledge of TVs that are not solid state. Valves are a mystery to me.

Anyway I picked up an unmolested Masteradio T851 a couple of years back, and so far it’s just been a prop, or a conversation piece in pride of place in my shop. I’d love to get it running though and wonder what would be involved. I understand I’d need to recap it, and check individual resistors. What type of caps do you replace the paper caps with though? What else is involved?
I have modern test gear, and I know my way around a scope, but what else would I need? Is a variac and isolation transformer necessary? I don’t have any way of testing valves either. Any help/advice/encouragement would be greatly appreciated 😊

slidertogrid · 6th Apr 2023, 9:50 am

Hi There is a thread here which may show what you are up against.
https://www.vintage-radio.net/forum/...ad.php?t=93927
Rich.

kingbeau · 6th Apr 2023, 5:15 pm

Thanks Rich. After reading through that thread, I think I'd be better suited to making it into a cat bed lol. I consider myself as fairly knowledgeable with the electronics in modern TVs, but a fair amount of the thread was way over my head

slidertogrid · 6th Apr 2023, 5:47 pm

I must admit I found it fairly daunting the first time I restored a 1950's TV. Mine was a TV22. After a lifetime of doing repairs where you would trace the fault and replace just the faulty parts(s) the thought of replacing every capacitor and checking every resistor, pot etc seemed a lot to do.
There is plenty of help, encouragement and advice available on this forum though. If you tackle it in smaller stages it is less daunting. I.F are 'just two radios', frame 'just an amplifier', work your way through stage by stage.
The problem might be the tube if it's a Mazda. They weren't the best. If you test it and it shows as poor that may put you off going any further but a tube that tests low often gives a respectable picture in reality. If it is poor it may improve with use and there is a non-destructive way to improve a poor tube without boosting it which may finish it off completely!
What is the condition of the LOPT? assuming it is pitch covered it may need drying out if the set has been stored.
How about some pictures of the set and chassis?

FERNSEH · 6th Apr 2023, 6:27 pm

Hi Kingbeau,
is your Masteradio T851 the model with radio?
For goodness sake please don't join the hipster cat bed brigade, these sets are far too rare to finish up in that manner. Remember the set is seventy years old now. I'm sure I can help you through the restoration of this set.

DFWB.

FERNSEH · 8th Apr 2023, 11:25 am

My Masteradio T851 hasn't been switched on for ages. This picture was taken yesterday evening. The image on the screen looks bright but in reality the CRT isn't all that good. The 12 channel tuner is still a hopeless unit and I might well take on JohnHKS suggestion and replace it with one taken from an early Pye VT4, those sets which have 16 and 19.5Mc/s IFs.

DFWB.

5th Apr 2023, 9:37 pm	#1
kingbeau Tetrode Join Date: Oct 2018 Location: Dundee, Scotland, UK. Posts: 58	Masteradio T851 advice So I’m a TV engineer (still working!) with around 30 years experience, so I’m familiar with CRT TVs that were around in the early 1990’s onwards. Ferguson TX10, Philips G11 etc. but honestly have pretty much zero knowledge of TVs that are not solid state. Valves are a mystery to me. Anyway I picked up an unmolested Masteradio T851 a couple of years back, and so far it’s just been a prop, or a conversation piece in pride of place in my shop. I’d love to get it running though and wonder what would be involved. I understand I’d need to recap it, and check individual resistors. What type of caps do you replace the paper caps with though? What else is involved? I have modern test gear, and I know my way around a scope, but what else would I need? Is a variac and isolation transformer necessary? I don’t have any way of testing valves either. Any help/advice/encouragement would be greatly appreciated 😊

6th Apr 2023, 9:50 am	#2
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: Masteradio T851 advice Hi There is a thread here which may show what you are up against. https://www.vintage-radio.net/forum/...ad.php?t=93927 Rich.

6th Apr 2023, 5:15 pm	#3
kingbeau Tetrode Join Date: Oct 2018 Location: Dundee, Scotland, UK. Posts: 58	Re: Masteradio T851 advice Thanks Rich. After reading through that thread, I think I'd be better suited to making it into a cat bed lol. I consider myself as fairly knowledgeable with the electronics in modern TVs, but a fair amount of the thread was way over my head

6th Apr 2023, 5:47 pm	#4
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: Masteradio T851 advice I must admit I found it fairly daunting the first time I restored a 1950's TV. Mine was a TV22. After a lifetime of doing repairs where you would trace the fault and replace just the faulty parts(s) the thought of replacing every capacitor and checking every resistor, pot etc seemed a lot to do. There is plenty of help, encouragement and advice available on this forum though. If you tackle it in smaller stages it is less daunting. I.F are 'just two radios', frame 'just an amplifier', work your way through stage by stage. The problem might be the tube if it's a Mazda. They weren't the best. If you test it and it shows as poor that may put you off going any further but a tube that tests low often gives a respectable picture in reality. If it is poor it may improve with use and there is a non-destructive way to improve a poor tube without boosting it which may finish it off completely! What is the condition of the LOPT? assuming it is pitch covered it may need drying out if the set has been stored. How about some pictures of the set and chassis?

6th Apr 2023, 6:27 pm	#5
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Masteradio T851 advice Hi Kingbeau, is your Masteradio T851 the model with radio? For goodness sake please don't join the hipster cat bed brigade, these sets are far too rare to finish up in that manner. Remember the set is seventy years old now. I'm sure I can help you through the restoration of this set. DFWB.

8th Apr 2023, 11:25 am	#6
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Masteradio T851 advice My Masteradio T851 hasn't been switched on for ages. This picture was taken yesterday evening. The image on the screen looks bright but in reality the CRT isn't all that good. The 12 channel tuner is still a hopeless unit and I might well take on JohnHKS suggestion and replace it with one taken from an early Pye VT4, those sets which have 16 and 19.5Mc/s IFs. DFWB. Attached Thumbnails