vintage radios - Page 1
Forum section: electronics / repair

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 07, 2014, 07:30:28 am
content: At the moment me and my dad are trying to fix a Westminster cta5350 radio but were having some trouble. We have put new capacitors in it and some of the wiring has been redone. It works brilliantly on gramophone input but the radio bit doesn't do anything.

author: Whales
author_rank: Super Contributor
timestamp: November 07, 2014, 07:47:55 am
content: Different people would debug this in different ways. I'm not amazingly experienced in it, but this is an approach I can think of.(1) Make sure the tuning knob is actually strung onto what looks like a variable capacitor, and such cap turns when you turn the knob. You might be stuck on part of a reception range that's silent/being treated as silent. Long shot, but the strings have been known to rot and break.(2) Presumably the 'input selection' (for choosing between gramaphone, radio, etc) is a rotary knob that chooses which signal to send to the amplifier. This knob 's contants might be be flaky/need cleaning -- if you have an oscilloscope, hook it up to the tab/post/etc on the back which looks like it comes from the electronics that are radio related and see if the signal is getting that far. If not, try and trace it backwards a little bit and see if it's just the last few components at fault.I'm assuming you're not extremely familiar with radio electronics -- apologies if I'm overshooting-radio section of the circuit boardswill have at least one tuning capacitor (google images for examples of various sizes) and a coil.-amplifier sectionis the final circuit stage where the small signals are amplified into levels for the speakers. Generally composed of a couple of tubes, depending on the type.- Tube amps generally run above safe voltage levels. Don't probe around if you don't feel you have enough space to safely do so -- partially disassemble the case if you need to and don't rush things. Take it easy and respect the power eighty or more volts can deliverAdditionally: you do not seem to have set your country in your profile. If you state your city/state you mind find members that can lend a hand.

author: Mark Hennessy
author_rank: Frequent Contributor
timestamp: November 07, 2014, 01:41:44 pm
content: That is a UK set. There are several UK forums that specialise in vintage radios.Of all the ones I know,http://www.vintage-radio.net/forum/has the most activity and you are most likely to find the best help there. Also, the owner has written a lot of articles about how radios work, so if you need to brush up on the basics before asking for help (highly recommended), then try starting here:http://www.vintage-radio.com/repair-restore-information/index.html

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 08, 2014, 08:14:45 am
content: I'm slightly better than my dad with radios but this one has confused both of us

author: Mark Hennessy
author_rank: Frequent Contributor
timestamp: November 08, 2014, 10:00:39 am
content: Honestly, if you want people to help you, you are going to have to give us something to go onYou haven't told us what you've done so far todiagnosethe radio section.You haven't told usspecificallyabout your (or your dad's) experience with electronics or radios.You haven't replied directly to the two posts you've had so far.For all we know, you might be a total novice or a seasoned expert. For all we know, you might not know the very basics of electrical safety, and you might end up putting yourself in danger when working on this set (does it have a live chassis? Do you have an isolating transformer? What other test gear do you have?).If you were expecting someone to pop up and say "hi - you just need to change C8 and you'll be right!", then you're going to be disappointed. Sets fail for a variety of reasons, and while there are certain "stock faults" with certain sets, you're less likely to find people who know them all on a general electronics forum (hence my recommendation to try a specific UK radio forum). But in practice, you are likely to need to do some logical step by step fault diagnosis. If you want us to be able to help, then start by posting the schematic and telling us what you've checked so far. And tell us about yourself so that we can understand your skill level.

author: Simon123
author_rank: Regular Contributor
timestamp: November 08, 2014, 11:22:34 am
content: You should go on youtube and watch some repair videos.Shango066 has good vids.

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 10, 2014, 06:20:50 pm
content: OK my dad works on electronics for the RAF and I am one of those people who will have a go at making or repairing any old finish I don't have an isolating transformer but I do have two multimeter's a soldering iron some helping hands a test speaker a test radio a huge collection of tools and many cleaning chemicals. So far on this project we have replaced the tuning cord all of the wax caps have been sealed for some from a reliable source and it has new scale lamps. Our next move is to order some new valves. I have 73vintage radios some of which need repairing more than this so is a mains isolating transformer and an oscilloscope necessary ?

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 10, 2014, 06:23:42 pm
content: I have also checked some voltage levels and it appears to check out

author: Raff
author_rank: Regular Contributor
timestamp: November 11, 2014, 02:28:07 am
content: There is a goldmine of very useful tips and information herehttp://www.thebakeliteradio.com/page102/page102.htmlRegards,Raff

author: bills
author_rank: Frequent Contributor
timestamp: November 11, 2014, 03:57:58 am
content: Can you post a schematic?if it has grid caps touch the grid cap on the oscillator tube if you get reception that means the oscillator is not doing it's thing.than check the coils. you need to do a full recap and check for out of tolerance resistors first before plugging it in.

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 11, 2014, 07:09:40 am
content: I've just looked at it and remembered that the oscillator tube had white mould inside it and did not light up

author: anachrocomputer
author_rank: Regular Contributor
timestamp: November 11, 2014, 09:05:03 am
content: That's not white mould, it's a getter flash that's been exposed to oxygen. The getter is a patch of highly reactive metal that's evaporated onto the inside of the glass. The idea is that it will react with any stray gas molecules inside the valve, and keep the vacuum hard. Yours, if it's white, has entirely oxidised due to a gross leak in the valve. That valve is dud, and needs replacement.

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 13, 2014, 07:27:30 am
content: Ah so I need to get a new oScillator valve for it