Can I repair a Linn Hifi amplifier ?

[@garycollins8253]

I used to work in an industrial controls repair center. When this happened we used a brass eyelet and crimped it down . Then we soldered around the outside to the trace and left the center open. Vola a new through hole to fit the cap . just solder the cap in and you're done.

[@nicodenhaak3961]

Thats a good repair.

[@paulb4661]

Crimping a through via would be the standard MO in my book, the only issue I can see is, that industrial quality, electrolytic copper ones, usually come in a pack of 1000.

[@RobWhittlestone]

I would suggest a ferrule of apropriate diameter to fix the plate through.. You can get a selection of sizes for a few Euro. You can trim its length before or after.

[@Si1983h]

That amp has been reworked at least once before during its life, it and a couple of other products which use the same amp board were the subject of a recall to replace those two caps with higher voltage spec parts (a reliability mod because they were too close to the limit at the top of the mains voltage tolerance range)… there’s a sticker on the base which does indicate it was done… however I’d be absolutely amazed if anyone at Linn was responsible for that abomination, they are meticulous about quality control and workmanship and if it had been damaged there, they would have fitted a new PCB… so I’d say someone has been in there since! PS, it’s pretty difficult to actually do that damage on Linn products, the PCBs are very high quality, I’ve reworked many (usually after 20 years or so of service) and never damaged one.

[@sdgelectronics]

I think you were supposed to remove the aluminium bar associated with that one pcb, rather than the transistors. It would have avoided the broken temperature cut out. Did you consider drilling a small hole and soldering the wire bridge on both sides? I'm not sure you would have flowed solder to the top side now you have no plating

[@nigelsretroworkshop]

Actually I did try to remove the bar but I couldn't slide the board back far enough - the caps fouled on the casing. Leaves me wondering how they got there in the first place, I assume the original caps were shorter. I was careful with the soldering & was happy the solder had flowed through.

[@TomSherwood-z5l]

I fixed a LInn tuner once and Linn was helpful with supplying tech data for it so I could figure out what was the problem. I suppose it may depend on whether or not the unit is still in production or obsolete. If a production unit they may insist you deal with their people.

[@bazzaar1869]

I wouldn't be happy about the wire connection on the top side of the board under the capacitor. You cant see it to know if it is soldered. Perhaps you should have soldered it first, then fitted the cap. Large capacitors relying on only the solder connections for mechanical stability is asking for broken through-plated connections.

[@nicodenhaak3961]

Hi, Difficult to see where things go, and how they work without a schematic. Just one question: the cooling strip where the outputs are mounted on, seems easy to remove. Just two inbus screws. Then you could have left the outputs attached on there, and remove that as a whole. I know, in a new to you amp isn't always easy to see how things things come apart. Creative thinking about the through hole repair, but you definatly should have soldered the topside first, and then fitting the cap. Now you have now way of knowing if the solder has flowed enough on the topside. It might have done so, but no way of knowing for sure. Strange faillure of the board by the way. Thanks for sharing. Cheers from the Netherlands.

[@M0UAW_IO83]

Nice, I've done this a few times with ILP MOSFET amp decks, they used to be really popular with mobile DJs and the caps flexed on the boards, breaking tracks and the legs of the caps.

[@nigelsretroworkshop]

I assumed it was maybe the result of a drop but after I filmed this video I found some old forum posts referring to a recall on this amp, specifically for these capacitors. They were changed for a higher voltage, lower capacitance - and the ones I found in the amp were the replacements so now I'm pretty certain the damage was the result of a bodged job!

[@ianhaylock7409]

@@nigelsretroworkshop If that's the case, then how come the through plating was still on the caps leg? I think the original replacement damaged the through hole plating, and a bit of bashing in the amps lifetime caused the through plating to completely break as they didn't silicone the caps to the board.

[@andymouse]

Nice !

[@RobWhittlestone]

Very enjoyable video Nigel. Could you perhaps include a list of your equipment (preferably with links) in the video description? I'm looking to get some test equipment for several activities and it would help to know what's out there and works. All the best, Rob in Switzerland

[@nigelsretroworkshop]

Hi Rob. Actually I intend to make some videos about test equipment and some really basic from scratch how-tos but maybe not soon enough for you. A lot of what I have is old so you won't be able to buy the same. I'll put some basic info in the description.

[@RobWhittlestone]

@@nigelsretroworkshop Great, thanks Nigel! I bought a Chinese clone of a Mark Levinson John Curl design but the soldering quality is apparently very variable and my first one developed pops, crackles and bangs after only 3 weeks. I sent it back and should receive a replacement soon but am not holding my breath (about the soldering). In a forum someone had the same problem and resoldered all the dodgy connections and dry joints. He's now very happy with it, so I may have to do the same. I think he upgraded some capacitors also, which I may not. But having basic test equipment would be a boon. All the best, Rob in Switzerland

[@joemalone7385]

Ive just jad the exacrly the same issue on a Linn LK140. Those small copper sleeves came out with the the capacitor connectors. I couldnt understand it, I have a very good desoldering iron.

[@gadgetmind]

I've fixed so many things were they hoped the top pad would do the work for a large component, didn't have much copper on the bottom, and it all went wrong. And those caps weren't supported with "goop" so vibration could have cracked them off.

[@zdzisiek1979]

Witam. Duży transformator w tym wzmacniaczu. Spytam czy ten oscyloskop to firma GOULD? Pozdrawiam

[@paulb4661]

Not that this amf tester is without its foibles, but it's worth to note that for a 6.8mF, at 50 or 63VDC, the esr should be about 10 or 20 of miliohms at most. Half an ohm is way to high, I think and indicates wear. Sanken (subdivision of Sanyo) C3519 & A1386 outputs aren't fets, they're bipolar transistors.

[@nigelsretroworkshop]

I stand corrected, thanks

[@paulb4661]

@@nigelsretroworkshop Im just learning myself, so by no means an expert, if I may rec'd sth, then please take a look at through vias, but make sure they're copper, not Chinese brass, which is prone to rupture. You can get away without a press, if you're careful and ensure PCB is supported, by using two punches to gently force it open once in place. You may need to drill a clean hole to accommodate the via, but it's worth it. Once you get the hang of it, they'll look factory installed.

[@matthewtaylor7355]

Another overpriced overhyped under performer