N.O.S. Launched: Kn...
 
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N.O.S. Launched: Knowledge Base

 
crustytv
(@crustytv)
Vrat Founder Admin

No! not "New Old Stock" but "New Old Service".

Today, in addition to all the "free-to-view" service data, chassis stock faults and "servicing the sets" I have launched a new manufacturers "real-world" stock faults knowledge database service called "Knowledge Base" or K-Base for short.

This new service does not require membership of the forum nor VIP access, it can be accessed via the homepage.

The database is fully searchable via its own engine,or you can just manually browse the categories.

Over the coming weeks, months and likely year, I will be adding more and more content into the database. Hopefully it will end up containing a vast array of "real-world" faults, covering a multitude of manufactures, across many decades, all with their associated solutions.

One problem though, I have no end of material to populate television, both B&W and colour, however the same cannot be said for Radio. As ever there is a severe lack of radio stock faults for the UK sets. I have but a small number of papers I can call upon to populate the radio section of the KBase Db. I do have a massive American manual which provides stock faults for their brands from the 30's thru to the early 50's, there seems little point in spending time loading these when what we really need is UK manufacturers. 

If anyone has access to UK radio repair stock faults or hints and tips and is prepared to OCR them for me, then that would be great. There is an option for folk to submit tips for inclusion, a link to do this is provided on the KBase homepage. On the other hand we have so few Radio folk participating on the forum these days perhaps it might be effort unnecessarily expended.

 

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Topic starter Posted : 27/08/2019 10:35 am
Terry
(@terrykc)
Famed V-Ratter Rest in Peace

Could it be that stock faults in radios were relatively rare, Chris? The only one that springs to my mind is the contact cooled selenium HT rectifier used in a wide range of Bush radios but, on the other hand, I don't recall it being used by anybody else. 

I think there was so much similarity in the circuitry of all radios that, barring specific component faults like this, just about any fault could occur in any set from any manufacturer. TV design philosophy, on the other hand, varied considerably so that many faults were unique to specific sets.

Are you considering extending this to anything else - tape recorders, say? Take the Grundig TK20, for example. Open circuit w/w resistor in the feed to the record/playback relay. A common fault but unique to this model. Crackling on record caused by a leaky Wima cap allowing the capacitor microphone's polarising voltage through to the grid of the input stage. I'm sure that there was another common fault caused by one of these Wima caps but can't for the life remember what it was now!

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Posted : 27/08/2019 11:08 am
crustytv
(@crustytv)
Vrat Founder Admin
Posted by: @terrykc

Could it be that stock faults in radios were relatively rare, Chris?

Hi Terry, I must admit I hadn't but did start to think it odd.

"Somewhere" I have a large amount of "Electrical and Radio Trading" extracts, these were full of "real-world" UK radio faults and included the solution to fix. Unfortunately  sods law dictates I cannot find them, no doubt I stored them in a safe place even from me. ? 

Posted by: @terrykc

Are you considering extending this to anything else - tape recorders, say? Take the Grundig TK20, for example

I don't see why not ?

What I may do, due to the lack of radio material, is turn the third category from "Radio" into a generic "Other" category which can be a catch-all.

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Topic starter Posted : 27/08/2019 11:34 am
Nuvistor
(@nuvistor)
Famed V-Ratter Registered

Stock faults on UK 1950/60’s radios were pretty mediocre, capacitors, mainly paper or electrolytic, occasionally resistors or valves, dirty controls all very straightforward.

The transistors radios were in the main very reliable until the AF115 series came along, they were a stock fault themselves.

Mains operated transistor radios using the Ac128/AC176 range were another stock fault, usually with burned out emitter resistors.

These were in general very simple radios so were easy to fix, internal access to some was perhaps more of a problem.

After 50-60 years the same items will give problems plus others due to age.

A 1960 Ekco radio I fixed about 5 years ago, there is a thread on the site. I checked the resistors and changed a couple out of spec, replaced the 3 or 4 electrolytic caps and the half a dozen Hunts capacitors, turned it on and that was it fixed and still working.

 

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Posted : 27/08/2019 12:14 pm
Terry
(@terrykc)
Famed V-Ratter Rest in Peace
Posted by: @nuvistor

Stock faults on UK 1950/60’s radios were pretty mediocre, capacitors, mainly paper or electrolytic, occasionally resistors or valves, dirty controls all very straightforward.

What you are describing are the everyday run-of-the-mill faults that could, and did, affect everything that you handled. To me, stock faults are repetitive faults that only affected individual models or ranges of models, the type of fault that you could go to right away - provided you were familiar with that particular set and its tricks - because you knew from the customer's description what was wrong before you even took the back off in many cases.

E.g.: 21Ω w/w resistors in the HT mains voltage setting of the Bush TV75, 85 and 95 series. Replace with the higher rated 5W RS type and always replace both! The CZ19 thermistor problem in the Bush TV125 series (reverse the positions of the new CZ19 and the adjacent 10Ω w/w to prevent a recurrence).

The unique faults I previously mentioned on the TK20. Only Grundig used a capacitor microphone - the input capacitor (if one even existed) on any other make of machine could have gone fully short circuit and nobody would have been any the wiser.

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Posted : 27/08/2019 4:49 pm
Nuvistor
(@nuvistor)
Famed V-Ratter Registered

Hi Terry,

That was what I was trying to say, obviously not very well, it’s just I don’t recall those radios having the type of stock faults TV’s had.

 

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Posted : 27/08/2019 5:46 pm
Terry
(@terrykc)
Famed V-Ratter Rest in Peace

Hi Frank,

What I was querying is that you stated - four times! -  that  everyday run-of-the-mill faults were 'stock faults' but they are not what understand is meant by the expression. No doubt others will have there own ideas about it.

I doubt it is clearly defined anywhere. I tried a Google search and ended up with lots of railway rolling stock faults! Removing 'rolling' brought up a mix of farming and geological fault replies. I've seen lots of electrolytics erupt but that's not the same thing. At that point, I gave up!

Where we differ is that you seem to class any common fault as a stock fault whereas to me they are two different types entirely (although they are, of course, all faults.)

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Posted : 28/08/2019 10:48 am
Nuvistor
(@nuvistor)
Famed V-Ratter Registered

I like the google search returning farming, railways etc. Made me smile on the wet dismal morning.

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Posted : 28/08/2019 12:51 pm
Terry
(@terrykc)
Famed V-Ratter Rest in Peace

Chris, just looked at /bush-tv105/ and found this reference to a resistor "coloured orange, orange, orange (331(52)"

Obviously 331 is a typo for 333 which I assume should be followed by (33k) but I can't see how this could end up as 52! 

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Posted : 28/08/2019 5:42 pm
crustytv
(@crustytv)
Vrat Founder Admin

Cheers Terry, the joys of spurious OCR errors. Now amended. 

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Topic starter Posted : 28/08/2019 6:08 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

Whilst sending a piece of kit I've sold on eBay, I've found several Bush "service notes" for various TV and radio receivers that detailed stock faults. They'll be scanned in due course.

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Posted : 28/08/2019 6:34 pm