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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 2nd Jan 2019, 7:33 pm   #1
stevehertz
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Default Faulty Tandberg hifi

Having repaired/restored quite a few receivers, tuners and cassette decks by Tandberg, I've known for some time that they are very prone to poor/dry solder joints on the PCBs. This was never more plain to see than in the case of a TR 2060L receiver of mine. I bought it about three years ago and it basically worked. I did a bit of titivating, cleaning pots and switches, that sort of thing and it was fine. After a few months of occasional use it started to 'play up'. At the time, I couldn't be bothered to begin sorting it out, it seemed like there was quite a bit wrong with it. Ok, fast forwards to now, and I thought I should sort it out. My plan was to first of all go over all of the PCBs and re-solder any joint that looked poor or even vaguely dodgy. I did that, and there were MANY of them. I also released every connector and cleaned (contact cleaner sprayed) and replaced them, moving them up and down to bed them in. I sprayed every pot and switch. After that, I thought it would at least give me a good starting point to begin fault finding. Except I didn't have to, it worked perfectly.

Yes, Tandberg hifi units are VERY prone to dry/poor PCB solder joints and also poor electrical mating of the many connectors too. So if my tip isn't already blindingly clear, if you get a faulty Tandberg hifi unit, forget 'fault finding' it at first, just do your stuff with all those solder joints and connectors and the chances are you will have cured most, if not all of the problems it may have.

In retrospect it's a shame that Tandberg stuff is like this, as in many ways they are great designs both electronically and mechanically. Some companies just didn't get their flow soldering right, and now more than ever, it shows.
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Old 3rd Jan 2019, 2:53 am   #2
ben
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Default Re: Faulty Tandberg hifi

Interesting. can't say I've had much trouble with dry joints on TB kit but definitely with connectors, also lockfit transistors and relays in some tape equipment.
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Old 3rd Jan 2019, 8:37 am   #3
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Default Re: Faulty Tandberg hifi

It isn't just Tandberg. Icom amateur radio equipment had a period when their flow-solder process was very iffy. It was about 1990 before they improved. We could make a good guess at the date of commissioning a new fluxing stage.

David
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Old 3rd Jan 2019, 12:40 pm   #4
stevehertz
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Default Re: Faulty Tandberg hifi

Indeed David. I reckon all companies will have had trouble with their flow soldering at some time or other, fleetingly or otherwise, it just seems that Tandberg had more than their fair share of problems. When I worked at Thorn Automation we had a production manager who used to spend a lot of his time titivating and teasing the flow solder machine to produce nice shiny joints. And of course sometimes you would get a batch of poorly tinned resistors and that wouldn't help.

I mean, I have found certain hifi units from other companies to have poor PCB connections, but then again I have found other units from those same companies to have very good joints. My own conclusion is, even if it was only for a few days, most companies must, at some time or another have produced bad solder joints as a result of the flow soldering machine not working properly; poor temperature control, flux problems, etc etc. From all the evidence I have seen (lots), it just seems that Tandberg had more than their fair share of 'bad days' - months or years I reckon!
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Old 3rd Jan 2019, 6:38 pm   #5
John Caswell
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Default Re: Faulty Tandberg hifi

Interesting comments.
I have had a Tandberg TD20A, and a Tandberg TCD310 MkI for approx 45Yrs and they have both been fine - performed faultlessly.
As I repair a lot of varied stuff as a hobby/income supplement, I recently bought a TR2045 as a workshop general dogsbody, and once cleaned up it worked excellently on the shelf.
Suddenly after about 8 weeks all hell broke loose, nearly blew the L/S cones out with noise.
Traced to an earthing strip on the audio preamp PCB, broken/dry joints. This had not been touched by me or anyone else by the looks of it, so why it should fail after 50ish years I don't know.
I still don't understand electronics Perhaps I am doomed, as in my servicing days I would go out with say 10 jobs and all would be swines eg a dry joint inside the burst gate amplifier transformer, whereas my colleague Jim would whistle through 10 in the morning. Hey Ho Lucky me!
I had an Icom set and spent an inordinate amount of time soldering up dry joints to finally get it functional

John

Last edited by John Caswell; 3rd Jan 2019 at 6:41 pm. Reason: Additions
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Old 3rd Jan 2019, 8:57 pm   #6
turretslug
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Default Re: Faulty Tandberg hifi

A whole day and Philips consumer gear hasn't been mentioned!

I've read that one cause of poor flow soldered joints was the steadily accumulative presence of dissolved copper in the bath, resulting in a raised melting point slushy bath with poor adhesion and tendency to dry-jointing. It's understandable that bean-counters would want to keep process going as long as possible with a given charge of solder, but surely there would be provision for salvage return and refinement of what must have been a valuable quantity of alloy?
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Old 1st Feb 2019, 3:10 pm   #7
Leon Crampin
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Default Re: Faulty Tandberg hifi

One of my jobs in the automotive electronics industry (when we had one) was to assess and specify standards for component solderability, ensure that all stock was used within a specified time, and to obtain a weekly solder analysis of the flow soldering stations.

I have been appalled by the low standards in other sectors of the industry. The Japanese, as usual, nearly always got it right.

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