Hartley CT436 problems - UK Vintage Radio Repair and Restoration Discussion Forum

Alan Stepney · 26th May 2008, 10:13 am

A few days ago I tried my CT436, only to find that it isnt working.

Symptoms:
1. Trace faint, out of focus and blooms at the slightest provocation.
2. Brightness control of Y1 doesnt work. (Y2 is OK).
3. Flyback suppression appears to be inoperative.
("Appears" as it is hard to tell with such a faint trace.)

A vary quick check revealed that the -1500 volt EHT line is actually -1100.
The -1640 line is obviously low as well, and all the other supplies appear to be OK.

The -1100 can be varied between roughly -1000 and -1100, by adjustment of the appropriate pot.

The voltages around V17 (eht control valve) dont appear unreasonable, and the valve itself is OK.

These are not the easiest sets to work on, and the circuit is fairly complex (needlessly so around the eht area), so before I start diving in to it, is there anyone with experience of these sets, who knows of common faults?

It just might, he said hopefully, be something common and simple to fix!

26th May 2008, 10:13 am	#1
Alan Stepney Rest in Peace Join Date: Feb 2008 Location: Dorset, UK. Posts: 947	Hartley CT436 problems A few days ago I tried my CT436, only to find that it isnt working. Symptoms: 1. Trace faint, out of focus and blooms at the slightest provocation. 2. Brightness control of Y1 doesnt work. (Y2 is OK). 3. Flyback suppression appears to be inoperative. ("Appears" as it is hard to tell with such a faint trace.) A vary quick check revealed that the -1500 volt EHT line is actually -1100. The -1640 line is obviously low as well, and all the other supplies appear to be OK. The -1100 can be varied between roughly -1000 and -1100, by adjustment of the appropriate pot. The voltages around V17 (eht control valve) dont appear unreasonable, and the valve itself is OK. These are not the easiest sets to work on, and the circuit is fairly complex (needlessly so around the eht area), so before I start diving in to it, is there anyone with experience of these sets, who knows of common faults? It just might, he said hopefully, be something common and simple to fix!