Hi Can anyone help? I have a TT Unisys in for repair and the main ht smoothing caps need replacing. Can anyone tell me the spec for these?
Thanks
David
Thanks
David
No, otherwise I wouldn't be asking the question! The two large psu caps are unmarked and just say 'Made especially for Tube Technology'
If possible, measure the DC voltage across each cap and choose a voltage rating 20% or more higher.
A stereo amp would use a minimum of 10,000uF per cap, and many use much more.
If the caps are defective, measure the open circuit AC voltage on the transformer secondary
to help estimate the voltage rating needed.
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Sorry about that, then look for 20uF and up. The HV could be 400V and up.
Are the two big caps in series, or is one terminal of each grounded? Is there a choke present?
Is the rectifier tube or ss?
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I know you are trying to be helpful but my question was: does anyone know the rating of these particular TT caps not what typical valve amps use. As a pro repairer I'm well aware of the latter thanks.
Sh** happens, now for the first time a cap like this is gone in a Tube Technology Unisis amp.
The gentleman asking for it by the way was not serious: " I don't think it's the main caps either
but wanted the info in case before starting. The symptom is that it starts distorting after some
time in use, the distortion being like an echoey tearing noise." .. "I should add I've narrowed
down the problem to the left channel power amp" ... "The problem is the fault is intermittent."
So a completely different problem. After some correspondence he gave up. I suspect he had
a cable or contact problem or something like this. A waste of time for me.
The diagram scans are too bad to be published here. Send me PM if you need them.
The gentleman asking for it by the way was not serious: " I don't think it's the main caps either
but wanted the info in case before starting. The symptom is that it starts distorting after some
time in use, the distortion being like an echoey tearing noise." .. "I should add I've narrowed
down the problem to the left channel power amp" ... "The problem is the fault is intermittent."
So a completely different problem. After some correspondence he gave up. I suspect he had
a cable or contact problem or something like this. A waste of time for me.
The diagram scans are too bad to be published here. Send me PM if you need them.
The above is the starbegest message I have yet seen on DIY Audio. It is quite often the case that one doesn't get an answer to a simple request: my question was straightforward and in response AS Audio claimed that he could dig out a schematic. In the event, he could not produce one. Despite it being obvious from our correspondence that I am in the trade, he suggested I send a Scope screenshot to him!?!? He also claimed to have been servicing Tube Technology products for a number of years. When I asked him if he had any experience of the type of fault I was experiencing the reply was 'don't bother with the caps they never fail....." on a twenty year old amp!
In fact, the fault was a smoothing cap in the pre stage, which was breaking down intermittently and causing the problem. So, caps most definitely fail in twenty year old amps and it's helpful if people actually read messages and respond appropriately rather than vent their predispoitions. And why As Audio feels the need to air private messages frankly beats me!
Well, no real need to answer this, true ? But ..
"Starbegest" is a word I can not find in any dictionary, so I leave it as it is.
The "straightforward" and "simple request", for a cap spec, was answered
already by me in post 8, bypassing some earlier speculation.
In subsequent pm exchange I said that I could not find a schematic of this
particular model (although it was not necessary to have one for this simple
request any more) and suggested that the main caps may not be the problem.
"Can dig out the diagram" does not mean that I am obliged to send one, OK?
Anybody heard of old paper files? What about asking your neighbour Tube
Technology - Coldershaw Road - Ealing in London?
After that it came out that the problem was indeed different. This would be
useful to write in the thread.
This is what I understand DIYA forum is about if you notice a problem:
describe it exactly as it is and you can expect a useful answer. As I have shown
simple Google picture search tells you the answer to the query in post 1. This
may lead me to the assumption that you are NO "pro repairer" (post 7).
If the problem turns out to be different: sorry, why not ask again. All I could say
was that I could not trace this from a distance and so it would be useful to send
me (and the forum) a scope screen shot.
Everybody can do this, even with "an old school scope" (sorry, private mail ..)
and then, in the forum, everybody can see and learn from it. You own a camera
(in the telephone)?
This is what this forum is also about: help others while solving your particular
problem by describing it the best you can. Your thread will be found, you have
been warned (this one is from MJ, also from London).
Displaying what you claim to hear on a scope screen is the first step in repairing
it if you are a "pro repairer".
Yes, it is true that I did the service of this brand for the german distributor from the
beginning. I will not tell you about my opinion about it and of particular experience
or the status of the company today and in general.
But it is true also that I never encountered ANY cap failure in 20+ years of service
which is in itself remarkable - and it is also remarkable that the first and even "main
smoothing cap" failure was seen today, one month after post 1 of this thread, having
these particular caps in question.
If a fault that you did not describe in the forum "was a smoothing cap in the pre stage,
which was breaking down intermittently" it would probably be useful to know for others.
So a least we have learned something, thank you for this - no harm intended. And, by
the way, my exact statement was "I never encountered failed main caps" before.
Until today.
"Starbegest" is a word I can not find in any dictionary, so I leave it as it is.
The "straightforward" and "simple request", for a cap spec, was answered
already by me in post 8, bypassing some earlier speculation.
In subsequent pm exchange I said that I could not find a schematic of this
particular model (although it was not necessary to have one for this simple
request any more) and suggested that the main caps may not be the problem.
"Can dig out the diagram" does not mean that I am obliged to send one, OK?
Anybody heard of old paper files? What about asking your neighbour Tube
Technology - Coldershaw Road - Ealing in London?
After that it came out that the problem was indeed different. This would be
useful to write in the thread.
This is what I understand DIYA forum is about if you notice a problem:
describe it exactly as it is and you can expect a useful answer. As I have shown
simple Google picture search tells you the answer to the query in post 1. This
may lead me to the assumption that you are NO "pro repairer" (post 7).
If the problem turns out to be different: sorry, why not ask again. All I could say
was that I could not trace this from a distance and so it would be useful to send
me (and the forum) a scope screen shot.
Everybody can do this, even with "an old school scope" (sorry, private mail ..)
and then, in the forum, everybody can see and learn from it. You own a camera
(in the telephone)?
This is what this forum is also about: help others while solving your particular
problem by describing it the best you can. Your thread will be found, you have
been warned (this one is from MJ, also from London).
Displaying what you claim to hear on a scope screen is the first step in repairing
it if you are a "pro repairer".
Yes, it is true that I did the service of this brand for the german distributor from the
beginning. I will not tell you about my opinion about it and of particular experience
or the status of the company today and in general.
But it is true also that I never encountered ANY cap failure in 20+ years of service
which is in itself remarkable - and it is also remarkable that the first and even "main
smoothing cap" failure was seen today, one month after post 1 of this thread, having
these particular caps in question.
If a fault that you did not describe in the forum "was a smoothing cap in the pre stage,
which was breaking down intermittently" it would probably be useful to know for others.
So a least we have learned something, thank you for this - no harm intended. And, by
the way, my exact statement was "I never encountered failed main caps" before.
Until today.
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Oh dear, this kindergarten exchange must be a little tedious for others. I will respond to a few of the points you make but thereafter will make no further comments.
1. You have absolutely no right to disclose private e mails. To do so in the selective way you have simply does you no favours as well as well as being a breach of etiquette.
2. Your comment about ‘asking my neighbor ‘Tube Technology’ shows you have no knowledge of the company at all. They ceased trading quite a few years ago and the Proprietor now works in California.
Among the other non sequiturs in our private e mail exchange were the following:
I tell you the scope trace is normal and you ask me to send you a photo of the trace………
You state categorically ‘I strongly advise NOT to change any caps. These caps are not 20 years old but a few hundred working hours or even less.’
Anyone with any repair knowledge of Tube Technology would know that the amps use great ironwork but use cheap passive components and the capacitors would have a working life of a few thousand hours max. But as you don’t know anything about the history of the amp that just amounts to speculation and of course the culprit was one of the main smoothing caps in the pre section.
So please, don’t misquote private e mail exchanges, and understand why I dropped our exchange in view of your non sequitur replies.
I will say no more on this subject.
1. You have absolutely no right to disclose private e mails. To do so in the selective way you have simply does you no favours as well as well as being a breach of etiquette.
2. Your comment about ‘asking my neighbor ‘Tube Technology’ shows you have no knowledge of the company at all. They ceased trading quite a few years ago and the Proprietor now works in California.
Among the other non sequiturs in our private e mail exchange were the following:
I tell you the scope trace is normal and you ask me to send you a photo of the trace………
You state categorically ‘I strongly advise NOT to change any caps. These caps are not 20 years old but a few hundred working hours or even less.’
Anyone with any repair knowledge of Tube Technology would know that the amps use great ironwork but use cheap passive components and the capacitors would have a working life of a few thousand hours max. But as you don’t know anything about the history of the amp that just amounts to speculation and of course the culprit was one of the main smoothing caps in the pre section.
So please, don’t misquote private e mail exchanges, and understand why I dropped our exchange in view of your non sequitur replies.
I will say no more on this subject.