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Tech Chat Retro electro workshop.

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Cathovisor
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@slidertogrid I'm still very suspicious of this "replace all the caps" mentality (am I channelling Chas Miller here?). I have only had to do this once, on an HP P4-based small form factor PC where every cap around the processor was venting - yet strangely, I have an identical machine where this hasn't occurred.

The last few bits of transistorised kit I've had my hands in, it's been semiconductors and resistors at fault - not capacitors.

 
Posted : 17/08/2023 11:53 am
slidertogrid
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I fully agree Mike I don't recap unless it is necessary which as you say in more modern equipment is rarely needed. That said I repaired a small Japanese radio for a friend a year or so ago in which every Electrolytic was open! It was a swine to get to them as well as some were under the tuning cap pully and others very near the drive cord. Tin foil protected that though while I steamed in with the Weller!  I have many sets still quite happy with some or all of the original capacitors. I just understood that in the case of these computers featured it was the done thing ? The fact that Rob got them both working without shows that the capacitors are at least good enough at the moment. He was after all doing repairs rather than reconditioning them.  

 
Posted : 17/08/2023 12:06 pm
Cathovisor
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Posted by: @slidertogrid

I just understood that in the case of these computers featured it was the done thing ? The fact that Rob got them both working without shows that the capacitors are at least good enough at the moment. He was after all doing repairs rather than reconditioning them.  

The story of fake electrolytics and the problems they caused even with respectable manufacturers - for some time I had a couple of re-capped Pentium 3 motherboards in service courtesy of a control system at work which had replaced them - has led a lot of people via the badcaps website to believe that only blanket replacement of electrolytics will do and it has spread beyond computers, look at the number of people who believe that it's the ONLY course of action in vintage hi-fi - I believe Naim get mentioned a lot.

I once had a very expensive Sony CD/radio/cassette cross my path, with a report of crackling. Others had already looked at it and in the end, it was a failing printed circuit 'via' that caused it!

I must ask my friend Caroline if she does this when restoring her 8-bit machines.

 
Posted : 17/08/2023 1:12 pm
Doz
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@sideband That was Chris Carey, he relayed the story to me when I worked for him in the early 00's.... apparently he visited every TV repair shop on the south coast and bought every BY127 he could to make those strings up. The failure allegedly being caused by opening a cabinet door whilst the thing was on full chat, and the interlock ungraciously axing the power.

 
Posted : 18/08/2023 10:16 am
sideband
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Ha ha well at least they were all the same diodes! Back in the 60's I visualised a hastily made up string of diodes in an untidy rough circle in series-parallel, wobbling about with a couple of wires for support and a piece of string tied up in the corner for extra support so that they didn't touch anything else. A fan blowing on them also tied up in the corner. A hastily scribbled note in big red letters ...Do NOT increase transmitter power......!

 
Posted : 19/08/2023 7:26 am
Cathovisor
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I must admit I raised an eyebrow at the price of that Weltron in last week's episode - and was that a Hedghog converter supplied with that Ferguson TV?

As for tape cassettes, I would add the early Garrard cartridge system as used on the Murphy TR1.

 
Posted : 28/08/2023 9:55 pm
slidertogrid
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Yes I was also surprised that they sold it and lost £50 after the work had been done. Either they paid too much in the first place or sold too cheaply, (He says, stating the bleedin' obvious!) But at least it proves the programme is not faking it as they could have easily adjusted the sale price to suit them....

Yes it was a Hedghog he made a good job of the telly, Maybe lucky that the LOPT was OK and didn't need drying out? Or maybe there was more work done than shown? I suppose they have to keep it reasonably brief and not get bogged down with too much detail.  

Tonight - Pinball machine... Can't wait! 

 
Posted : 29/08/2023 7:52 am
Boater Sam
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Posted by: @slidertogrid

Yes I was also surprised that they sold it and lost £50 after the work had been done. Either they paid too much in the first place or sold too cheaply, (He says, stating the bleedin' obvious!) But at least it proves the programme is not faking it as they could have easily adjusted the sale price to suit them....

Yes it was a Hedghog he made a good job of the telly, Maybe lucky that the LOPT was OK and didn't need drying out? Or maybe there was more work done than shown? I suppose they have to keep it reasonably brief and not get bogged down with too much detail.  

Tonight - Pinball machine... Can't wait! 

Paid far too much IMHO.

I will watch tonight with fond memories of being a teenager assembling Bally pinball tables in the UK from USA kits. All those lilliput lamps!

The prices that these fetch today is eye watering.

 

Boater Sam

 
Posted : 29/08/2023 10:42 am
Cathovisor
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Posted by: @slidertogrid

Yes it was a Hedghog he made a good job of the telly, Maybe lucky that the LOPT was OK and didn't need drying out? Or maybe there was more work done than shown?

Knowing Rob, a *lot* more work will have gone on behind the scenes with that TV - am I right in thinking it has a lamp to illuminate the channel selector? I'm afraid I spotted the handiwork of our 'friends' Anobium Punctatum as soon as he was introduced to the set though.

I must do something with the bits I have accumulated for a Hedghog, although the availability of parts for them greatly concerns me.

 
Posted : 29/08/2023 10:51 am
slidertogrid
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Yes I think the tuner control did illuminate. Not very common practice I think. That was one of the things I liked about the first KB deep scene I got as a lad, the tuner dials lit up! Very 'Space 1999' ! 

I used would have loved an old pinball machine years ago when they were being flogged off for peanuts but room was the problem. I used to repair the video gaming machines for a local company (and still have nightmares!) they had pretty much disposed of all their old machines by then but I did manage to get a Rock-Ola jukebox that was destined for the scrap man. He would take them away and burn them to recover the metal and wire. Mine is still rocking away nearly 40 years after I saved it, it does occasionally throw a wobbly, but that is all part of the fun!  

 
Posted : 29/08/2023 1:49 pm
Cathovisor
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Posted by: @slidertogrid

Yes I think the tuner control did illuminate. Not very common practice I think. That was one of the things I liked about the first KB deep scene I got as a lad, the tuner dials lit up! Very 'Space 1999' ! 

Yes, I remember that! I also had a Sobell T174C many, many years ago which illuminated the user controls at the side: I also had an Ekco with VHF radio that lit the clear ring at the centre of the channel selector when switched to radio.

 
Posted : 29/08/2023 2:17 pm
Boater Sam
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Glass lamp with metalwork and metal BC lamp holders.

He rewired it with no earth! Horrible!

Boater Sam

 
Posted : 29/08/2023 9:03 pm
Cathovisor
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@boater-sam Nothing wrong with what he did there, Sam - I mean, show me where the earth is on an Anglepoise!

The problem is, if he had earthed it he'd have changed the class of the item and therein lurks a whole world of hurt. It has 'grandfather rights'. I had great sport with the "compulsive earthers" over on UKVRRR with an old electric fire...

I'm sure, if asked, @sideband could tell us more.

As for Rob's radios: the transistor in the Regency looks very similar to the point-contact OC50 we had in the UK - and if I'm right, I think I recognised who he was bidding against for the Pye and it's no surprise he lost out.

 
Posted : 30/08/2023 9:22 pm
sideband
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Yes absolutely correct however ridiculous it may sound. The fact that it was for someone else as well..... The lamp wasn't designed with an earth so rewiring it without an earth is correct since now it's been returned to the owner in it's original state so it only has to meet the safety standards at the time of manufacture. In other words YOU haven't changed anything. If it had been rewired with an earth, it would have changed the class of the item and should have been subjected to re-testing as a class I item. If it had been returned to the customer rewired with an earth and something had gone wrong it could be argued that the lamp had been incorrectly wired....yes I know but that would be the situation....try arguing it in a court of law (it has happened). You can do what you like with your own equipment if you are the only user and it's likely that earthing the metalwork wouldn't cause any problems but you can't take the chance with someone else's equipment. 

As cathovisor says, there are a lot of 'compulsive earthers' out there. Please lets not get in to any arguments over this. I deal with safety testing every day and the law is what it is.

For the record, I've never earthed a chassis that wasn't designed to be earthed. 

 
Posted : 31/08/2023 7:51 am
Boater Sam
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Posted by: @cathovisor

@boater-sam Nothing wrong with what he did there, Sam - I mean, show me where the earth is on an Anglepoise!

The problem is, if he had earthed it he'd have changed the class of the item and therein lurks a whole world of hurt. It has 'grandfather rights'. I had great sport with the "compulsive earthers" over on UKVRRR with an old electric fire...

I'm sure, if asked, @sideband could tell us more.

As for Rob's radios: the transistor in the Regency looks very similar to the point-contact OC50 we had in the UK - and if I'm right, I think I recognised who he was bidding against for the Pye and it's no surprise he lost out.

My anglepoise has an earth, from new.3 core twisted flex, earth connected to the first knuckle.

 

Boater Sam

 
Posted : 31/08/2023 8:03 am
sideband
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That's fine. However it means that only the first knuckle is reliably earthed. The second and any subsequent knuckle is not....by virtue of the fact that the knuckles pivot and therefore move and so cannot make reliable earth connection with the rest of the metalwork. 

 
Posted : 31/08/2023 8:17 am
Cathovisor
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I remember when EaW testing was introduced at work, some people got utterly obsessed with earthing exposed metalwork and frankly, it verged on the ridiculous.

 
Posted : 31/08/2023 9:14 am
Lloyd
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That’s good to know, I have an anglepoise that I recently got and that needs a rewire, it’s currently got 3 different bits of old cable cobbled together by various means, no earth at all. It’s difficult rewiring these with modern cable, so 2 core will make it easier.

I have several modern lamps and they aren’t earthed, and they are metal construction!

Regards,

 Lloyd 

 
Posted : 31/08/2023 9:20 am
slidertogrid
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Without wanting to go too far off topic introducing an earth does provide a reliable return path where there previously wasn't one so could increase the risk of shock.

I had a Fidelity record player which had belonged to my mate's girlfriend from new. It had the usual twin flex mains lead, one side going to the amp chassis. The problem was that the link on the BSR UA8 on the tag strip that goes from the screen of the pickup to the centre screw of the tag strip hadn't been cut during manufacture. (This is usually done on these to isolate the deck). This meant that the deck was connected to the chassis and guess what ? The chassis was live, this meant for all of it's life the record player had had a live deck! I presume the only reason my mate's girlfriend hadn't had a shock was because she was isolated from return. Wooden floorboards - no central heating radiator to lean on etc... I wonder if this record player was the only one that slipped the net?

The small suitcase Fidelitys are the same with no isolation capacitors so depending on how the plug is wired the black cartridge lead could be at mains potential. If you put your finger under the arm when changing records the only thing between you and live mains is the rubber sleeve on the cartridge connections. Earth the turntable on one of those and you make shock hazard worse! There are those who earth the speaker mesh on DAC90As as well... Why?

 
Posted : 31/08/2023 10:55 am
Pye Man
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I have two metal anglepoise lamps of recent vintage from a certain Swedish owned store. Twin flex only.

Nick

 
Posted : 01/09/2023 4:36 pm
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