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Author Topic: Studer B67 - help!  (Read 3372 times)

Offline eduardlapas

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Studer B67 - help!
« on: March 25, 2016, 03:10:19 AM »
Hello All,

I'm new on this forum, so please let me introduce myself first.
My name is Eduard, I'm 37 years old, I'm from Romania and Music and Hi-Fi Audio Gear is my hobby ::)

My first tape recorder was a Revox B77 MKII and now I replaced it with a Studer B67 MKII (7.5IPS/15IPS/30IPS) which I just bought two months ago. I just love this machine .. is much better sonding than Revox B77 MKII!

This Studer seems to be in good working order, so I started to make some normal "optimization" in order to get the best from it:
- I replaced the pitch roller and conter rubber ring with new ones bought from eBay
- I bought a good professional milivoltmere/decibel metter/frequency meter (METRIX)   
- I bought a pocket signal generator from Velleman (which seems to be very accurate on audio frequency band - checked with the METRIX tester described above
- I have an old Tektronix osciloscope (2 x 50 MHz) which is still on normal parameters
- I bought Calibration Tapes from a trusted eBayer from Germany, IEC/CCIR standard - for 7.5 IPS and 15 IPS (for 30 IPS I didn't find a calibration tape yet) 
- I followed all the calibration steps specified in the Studer Manual for B67 MKII and now all the parameters are perfect for Playback and Rec, for IEC/CCIR standard for 7.5 IPS and 15 IPS.

In this moment my Studer a wonderful sounding machine!

But, there is a problem which I could not trace yet and I'm kindly asiking you to help me, based on your experience:

From time to time, an internal BUZZ sound is starting (like a transformer BUZZ), which sometimes is very loud. When this buzz is very loud I can also hear this buzz in the speakers if I pull the volume knob of the amplifier to a higher level (11 o'Clock). Sometimes, If I turn OFF the recorder and I turn it ON again the BUZZ disapears, sometimes not. Sometimes the buzz does not apear at all during 1-2 weeks of almost daily  (1-2-3 hours) operation.

What can couse this BUZZ sound, which sems to come from the transformer?

Thank you in advance!


Offline docb

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Re: Studer B67 - help!
« Reply #1 on: March 25, 2016, 09:09:47 AM »
My first thought is that you may have some power supply capacitors that are leaking and need to be replaced.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline eduardlapas

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Re: Studer B67 - help!
« Reply #2 on: March 29, 2016, 08:01:54 AM »
Thank you for your quick reply!

I will do check especially on the hig main capacitors. You are right ... if the big capacitors are leaking, then the internal power consumption shlould increase and this can cause the power transformer to saturate and to BUZZ. But if this is the cause and the  internal power consuption increases, then one of the fuses shluld blown, am I right?

Is it possible that a DC component than comeon the 230V AC power line, from time to time, to cause the transformer saturation?