UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Reply
 
Thread Tools
Old 11th Jul 2019, 8:39 pm   #1
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Ultra 761. Actually a T671.

I have required an Ultra 761 radio which looks in great condition cosmetically.
There are all the usual leaky caps and a couple of scorched wire wound resisters.
Do any members with more experience than me know this machine. Is it a good set?. Were they popular? I cannot find any information about it on the internet.
Where can I acquire a schematic.
Any advice would be appreciated.
RobertF is offline   Reply With Quote
Old 11th Jul 2019, 9:00 pm   #2
cathoderay57
Hexode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 468
Default Re: Ultra 761

Hi Robert, are you sure you don't mean Ultra U7961? If not then a picture would be good. Cheers, Jerry
cathoderay57 is offline   Reply With Quote
Old 11th Jul 2019, 9:05 pm   #3
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 6,851
Default Re: Ultra 761

Yes, Photos, valve line up, wavebands etc if it’s not the U7961
__________________
Frank
Nuvistor is online now   Reply With Quote
Old 11th Jul 2019, 9:31 pm   #4
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Re: Ultra 761

The markings on the label on the rear of the radio show T 761.
Most of the valve markings are illegible..
I will take some pictures of the chassis and the cabinet and post them tomorrow.
Thanks for the advise guys.
Robert
RobertF is offline   Reply With Quote
Old 11th Jul 2019, 9:52 pm   #5
ajgriff
Heptode
 
ajgriff's Avatar
 
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 569
Default Re: Ultra 761

Something described as an Ultra T761 Receiver appears in the results of the Sept 2017 BVWS auction. Interesting to see the photos when available.

Alan
ajgriff is online now   Reply With Quote
Old 12th Jul 2019, 9:10 am   #6
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Re: Ultra 761

Apologies Lads,
When I took pictures of the radio and enlarged them, I realized it is a T671 and not a T761.
I have attached some pictures.
I don't have any information on this set.
Any advise would be greatly appreciated.
Regards

Robert
Attached Thumbnails
Click image for larger version

Name:	IMG_4171 (002).JPG
Views:	84
Size:	124.7 KB
ID:	186512   Click image for larger version

Name:	IMG_4172 (002).JPG
Views:	76
Size:	120.8 KB
ID:	186513   Click image for larger version

Name:	IMG_4173 (002).JPG
Views:	80
Size:	129.0 KB
ID:	186514   Click image for larger version

Name:	IMG_4174 (002).JPG
Views:	71
Size:	112.2 KB
ID:	186515  
RobertF is offline   Reply With Quote
Old 12th Jul 2019, 9:27 am   #7
cathoderay57
Hexode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 468
Default Re: Ultra 761. Actually a T671.

Hi Robert, there are images and valve line-up on the RadioMuseum website here: https://www.radiomuseum.org/r/ultra_t671t_67.html but no service data. However, I found another website that says the T671 is similar to the Ultra Leader 51, for which Trader service sheet 1017 applies. If you click the Vintage Radio Service Data link at the top right of this Forum page, and put Leader 51 into the search box you'll find it. Good luck! Jerry
cathoderay57 is offline   Reply With Quote
Old 12th Jul 2019, 9:28 am   #8
Mike. Watterson
Heptode
 
Join Date: Dec 2014
Location: Limerick, Ireland.
Posts: 721
Default Re: Ultra 761. Actually a T671.

https://www.radiomuseum.org/r/ultra_t671t_67.html
Look up the equivalents to the Mazda valves.
Any set with a similar lineup won't be much different.

I don't think it's in Trader sheets or R&TVS, though there may be a similar model. Check the index of service sheets here.

It's likely the first thing is to replace any paper dielectric capacitors (waxies, Hunts, Metalmite) before power is applied.
Mike. Watterson is online now   Reply With Quote
Old 12th Jul 2019, 11:19 am   #9
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Re: Ultra 761. Actually a T671.

I have downloaded the service information for the Leader 51 which looks like the same set.
I will start by changing the usual caps over the next few days before powering it up.
Thanks for pointing me in the right direction.
I will let you know how I get on. I may need further help down the road.
Regards

Robert
RobertF is offline   Reply With Quote
Old 16th Jul 2019, 9:22 pm   #10
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Re: Ultra 761. Actually a T671.

I know there are acceptable tolerances on resistors. Can anyone tell me what is acceptable.
I have some readings which I think are ok. Ie. 1.2k reading 1.3k and 100 ohm reading 114 ohm.
I have one I am not sure about ie. 18k reading 21.5k
Then one I think is unacceptable. ie. 68k reading 106k
Is there a % of the value you should use as a guide.
Any help would new appreciated.

Regards

Robert
RobertF is offline   Reply With Quote
Old 16th Jul 2019, 9:32 pm   #11
crackle
Nonode
 
crackle's Avatar
 
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 2,943
Default Re: Ultra 761. Actually a T671.

I would say that 10% is the normal tollerance for vintage radios.

Mike
__________________
BVWS Member
The KB Museum

My collection in the Radio Museum
crackle is offline   Reply With Quote
Old 16th Jul 2019, 9:40 pm   #12
Mike. Watterson
Heptode
 
Join Date: Dec 2014
Location: Limerick, Ireland.
Posts: 721
Default Re: Ultra 761. Actually a T671.

20% often fitted and valve circuits can tolerate even 50%, except for cathode resistors or battery set HT- bias resistor, which indeed 10% is better.

The 68K reading 106K may or not matter depending where it is. If it's the Local Oscillator HT feed, then indeed it's too high. It doesn't much matter for a grid resistor.

Older resistors
No band = 20%
Silver = 10%
Gold = 5%

Newer resistors
green = 5%
red = 2%
brown = 1% (there is usually an extra value band, so Red, Yellow, Black, Orange, Brown = 270K 1%)
Mike. Watterson is online now   Reply With Quote
Old Yesterday, 9:24 am   #13
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Re: Ultra 761. Actually a T671.

Hi Mike,
The 68k resistor is the osc. anode feed.
I think I will go ahead and replace it.

regards

Robert
RobertF is offline   Reply With Quote
Old Yesterday, 9:37 am   #14
Mike. Watterson
Heptode
 
Join Date: Dec 2014
Location: Limerick, Ireland.
Posts: 721
Default Re: Ultra 761. Actually a T671.

I thought it might. A notorious place for high resistors. Often results in reception stopping at one end of a band, or if mains low (or batteries low).
If you have only 1/4W resistors you can put a pair of 33K in series. That's only 3% out and modern resistors are 2% or 1%. Twist the middle connection and cut short. Cut out existing one close to body and use pointy pliers to make hooks for new resistor wires. Unless the existing tags easy to solder.

An actual value of to 55K to 82K will likely be fine. It may even "work" at 106K, but that is 56% out and the oscillator might not start at any lower Q part of band, or band if the radio turned on.
Mike. Watterson is online now   Reply With Quote
Old Yesterday, 6:46 pm   #15
RobertF
Triode
 
Join Date: May 2019
Location: Cavan, Republic of Ireland.
Posts: 10
Default Re: Ultra 761. Actually a T671.

Thanks for the advise Mike. I will swap it out and if i come across any others over 20% out I will replace them also..

Regards

Robert
RobertF is offline   Reply With Quote
Old Yesterday, 7:01 pm   #16
Mike. Watterson
Heptode
 
Join Date: Dec 2014
Location: Limerick, Ireland.
Posts: 721
Default Re: Ultra 761. Actually a T671.

I'd not worry even at 30% unless a cathode to ground (0V) / chassis.
Mike. Watterson is online now   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 6:30 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.