[sdiy] speaking of tantalums...

Tom Wiltshire tom at electricdruid.net
Mon Nov 26 13:53:43 CET 2018


My objection wasn’t that changing the pants is “hot rodding”, just that if I want any changes making, I’d rather make them myself, so I’d always choose an instrument that’s closer to original. As you say, that’s more to do with the "variances in quality of repairs /tech work” (love the phrase - very diplomatic!) 

Tom

> On 26 Nov 2018, at 11:50, Tom Bugs <admin at bugbrand.co.uk> wrote:
> 
> I'm not quite so sure - mainly in reaction to the view that replacing power line tants could be seen as hot-rodding.
> I don't think it is - I think it is sensible precautionary mesaures given the larger problems that can occur when tants do fail.
> 
> Though, of course, if it is currently working I do think you're right to suggest leaving it for the new owner.
> & this is all ignoring the possible variances in quality of repairs/tech-work.
> 
> Tom
> 
> On 26/11/2018 11:33, Tom Wiltshire wrote:
>> +1 agree with this. I’d pick the instrument that had been messed about with *least* too.
>> 
>> If the next owner thinks it is something that they would like to have done, then they can do it or find someone who can. Unless you think there’s a significant bonus on the price if you put “recently serviced and tantalums replaced” in the advert, I wouldn’t bother. Somehow I don’t think it’ll make enough difference to cover the time.
>> 
>> 
>>> On 26 Nov 2018, at 03:47, rsdio at audiobanshee.com wrote:
>>> 
>>> I’ll put it another way, which has nothing to do with my experience repairing these old synths, arcade machines, computers, and other electronics…
>>> 
>>> If I were looking at two Prophet 5 Rev 3.3 units, and had to pick one to buy: I’d pick the one that hadn’t had someone in there prematurely replacing caps. Since you’re wanting to sell this thing, I say leave the choice to the next owner. It’s like a vintage car - there’s a much larger market for the original, stock models compared to the street hot rods that have been souped up.
>>> 
>>> If you were going to keep this P5r3.3, I’d say that the choice is yours. Otherwise...
>>> 
>>> Brian
>>> 
>>> 
>>> On Nov 25, 2018, at 7:33 PM, Adam Inglis <21pointy at tpg.com.au> wrote:
>>>> Brian, I do take your point, however, I’m careful and my Hakko desoldering gun works quickly.
>>>> 
>>>> 
>>>> On 11/25/2018 4:12 PM, gm wrote:
>>>>> While I agree that unnecessary work should be avoided, in the case of P5s (and P10s, and ARPs and Oberheims from the eighties) the tantalum bypass caps are the most common failure points.
>>>>> 
>>>>> I've got over 500 P5s in my repair database, and a good half of them came in with one or more tantalums shorted out.  Replacing them with high-temp modern electrolytics is part of my routine service.
>>>>> The P5 (whatever rev) has tantalum power bypass caps on the power supply, front panel, CPU and voice boards, all of which should be replaced to ensure longer life of the instrument.
>>>>> ~GMM
>>>>> 
>>>>> 
>>>>> On 11/25/2018 3:50 PM, rsdio at audiobanshee.com wrote:
>>>>>> As someone who would consider purchasing a P5 r3.3, I say No.
>>>>>> 
>>>>>> There’s no need to replace capacitors that have not failed. The copper traces on these PCBs can be fragile, and any desoldering heat could cause damage. It’s best to avoid unnecessary surgery.
>>>>>> 
>>>>>> If you restrict yourself to the power supply PCB only, then perhaps, but I still don’t see it as an advantage. The more work that is done on these ancient beasts, the more fragile they become.
>>>>>> 
>>>>>> Brian Willoughby
>>>>>> 
>>>>>> 
>>>>>> On Nov 25, 2018, at 2:39 PM, Adam Inglis <21pointy at tpg.com.au> wrote:
>>>>>>> I’m getting a Prophet 5 rev 3.3. (no midi) ready for sale. I’m wondering if I should be replacing the tantalums in it. They seem to be considered a ticking time bomb. One site I came across suggested replacing the decoupling tants with low ESR electrolytics, I assume you just use identical farad values:
>>>>>>> 
>>>>>>> Anyone experienced with these machines care to comment?
>>>>>>> 
>>>>>>> Adam
>>>>>>> 
>>> 
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