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

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Success Stories

Notices

Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

Closed Thread
 
Thread Tools
Old 13th Jun 2020, 5:57 pm   #1
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Thurlby Thandar TS3022 repair and modified to tracking PSU

I bought a Thurlby Thandar TS3022 Dual 30V 2A supply on ebay as spares or repair. Described fault was "Was working but now blows fuse when powered up"
I was confident of being able to repair this as the two supplies are entirely separate in the case and I found the manual on line.
If you need the manual for these supplies search for "S Series" DC power supplies.

On receipt it was in good condition but has evidence of having been dropped onto its front lower RHS at some time.

The obvious fault was a short circuit diode on the bridge rectifier on the LH supply, I changed all four diodes just in case.
This restored working condition but the RH supply had some missing segments on both displays.

I diagnosed that it was the actual displays that were faulty and the DVM chips were OK. The best way to test is with a dual trace scope, channel A on the back plane pin and then probe the segments with channel B. If the waveforms are in phase the segment should be off and if out of phase then on.

To be honest I thought it was game over at this stage and had thought about using complete DVM modules as used in the Sussex valve tester but had a look on e-bay.
To my amazement I managed to find the exact displays I needed NOS, I had to buy 10 but they worked out at £1 each.

While they were pin compatible and the same size the legs were shorter than on the power supply so I had to cut the legs on the old diplays close to the display itself and solder the new one to the remaining legs. I measured the height to make sure it ended up the same.
Anyway it worked so on to calibration.

While studying the schematic I noticed that one version of the s series had the ability to throw a switch and have the supplies track so I decided to make the modification to mine.

The LH supply is designated as "slave" and is the minus supply while the RH supply is designated the "Master" and becomes the positive supply.

The switch connects the + terminal of the slave to the negative of the master and the coarse pot of the slave no longer sets the reference for the supply, instead this is taken from the + terminal of the master via a resistor and pot. The pot calibrates the tracking voltage. The schematic in the manual shows this clearly
Again I am happy to report that it works!

I am keeping a further 2 displays for spares and will offer the other 6 on the forum at cost.


Peter
Attached Thumbnails
Click image for larger version

Name:	IMG_20200611_132001.jpg
Views:	217
Size:	57.2 KB
ID:	208408   Click image for larger version

Name:	IMG_20200613_134946.jpg
Views:	243
Size:	95.7 KB
ID:	208409   Click image for larger version

Name:	IMG_20200613_135125.jpg
Views:	222
Size:	100.5 KB
ID:	208410   Click image for larger version

Name:	IMG_20200613_170030.jpg
Views:	297
Size:	79.0 KB
ID:	208411  
Electronpusher0 is offline  
Old 13th Jun 2020, 7:00 pm   #2
greg_simons
Octode
 
greg_simons's Avatar
 
Join Date: Jul 2004
Location: Evesham, Worcestershire, UK.
Posts: 1,415
Default Re: Thurlby Thandar TS3022 repair and modified to tracking PSU

Excellent repair and a nice piece of kit, looks a dead ringer for the farnell kit i used at work.
Greg.
__________________
Picture, sound?, DOOR.
greg_simons is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 5:02 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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.