Studer a810 problem

Hi baxa?

Let us know where you are located and your full name so that we know how to address you.

As for your problem A810, there are several things that could cause the noise isssue. Based on your report, I am assuming the machine produces no noise with it powered on and tape not moving. You are hearing the noise as soon as the tape starts to move accros the repro head and it is being amplified through its Line Output connectors in the back for both channels.

It is always a good idea to clean the heads and entire tape path along with demagetizing the heads and all metal contact points. Magnetized head will give you white noise like sound (not to mention recording the noise onto your tape being played).

Then, I would suggest you take the back cover off to measure the supply voltages paying attention to +/- 15VDC for audio supplies. The procedure is well documented in the manual (assuming again... you have access to the manual.)

One of the most likely suspect areas especially if the A810 had been in storage for a long time is the +/- 15VDC supply filter caps in the tape head preamp - located under the head cover. I have seen one or both filter caps not working as well as sometimes damaging the NE5532 opamp causing all kinds of strange noises.

Of course you can swap the Repro Amp cards and Line Output cards from one channel to the other to futher isolate the issue - if you can differentiate two channels from the level of noise or have spare cards.

Let us know what you find with the head condition and the tape head preamp first.

Thanks,

Ki

I bet something is magnetized

baxa said:

Heads and head block has been demagnitzed and cleaned.
Nois produce only mooving tape across sync or repro head and only megnetised section of tape however when the tape stops preamplipifier dont produce any sound or noise
.

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Are you saying if you push the Sync button instead of the Repro button from your VU meters (for both channels) you get the same noise like when the machine is in the Repro mode? If this is true, you have eliminated the tape head preamp as the cause of the noise since the Sync signal starts from Record head but gets switched at the front end of the Repro Amp card - by passing the tape head preamp. Thus your problem is probably with the Repro Amp card and/or Line Amp card.

However, I very seldom see noise issues on both channels at the same time if the problem stems from one of the audio cards...so let's see what you come up with the common power supply. It seems you have an access to an oscilloscope, so do use it instead of the voltmeter and look for HF noises.

Having +2VU at 16Khz would be within HF EQ adjustment range and sounds normal.

Ki

baxa said:

Problem solved!!!
Steve has right , recorder was megnetized and I make terrible mistake.
When recorder arrived first think what I was dooing I put my Tape Project tape to listening.When I hear that loud noise I put to play emty tape and noise again.
Just after that I demahnitized the recorder and put again same tapes to listening and when I hear again the noise (recorded on tape by first listening) make I wrong concluzion that magnetizm is not a problem.
When I today listen same empty tape when noise an second part of tape (not listened yesterday ) suddenly disappear -----eureka
Good news: I learn that new recorder must I first be demagnetized
Baad news: 2 ruined master tape

I would like to thank one moor time to Ki and Steve to help and aford
Marijan

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Thanks

I base the comment out of a similar problem with my Studer A810.

Interesting that every media type has its Achilles Heels, but experience gained over time means that ultimately everyone knows, or learns early in the piece, the correct procedures to go through with that storage mechanism to get the best out of it. Tape is now in that mature stage, vinyl is largely sorted out but perhaps has a bit further to go, and digital is way, way behind the 8 ball. There is still a lot further to go in terms in real understanding of what makes CD work properly, but when that happens it will be considered ludicrous that tape was once regarded as superior to CD ...

Frank

baxa said:

BDW If enybady have shema A810 record Head to connector in head block I by grateful.

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You can download all the manuals (including the service one in japanese) for the A810 from the ftp Studer site:

ftp://ftp.studer.ch/Public/Products/Recording_Analog/A810/Manuals/

I think all the connectors are documented - the english service manual has 465 pages!