Ampex atr102 calibration

[damianschwartz]

Yes, completely recapped all the electronics, got rid of all the tants. I can't remember if there's tants in the signal path, I would keep those, but anything power related you're better to off those and replace with a similar value electrolytic.

Exploding tants is not a nice thing.

http://www.groupdiy.com/index.php?topic=16989.msg197772#msg197772

Also, check your bias frequency, mine was horribly off. I had to replace the ceramic cap(s) off the bias generator to get it back to the proper frequency again.

Mark

Hey Mark, was going through this thread, since i'm recapping and fixing my ATR, would you care to comment how you checked Bias frequency?

 

[rmburrow]

You must have a manual for that machine before making any adjustments.  I assume you have the input and output terminated correctly for setting levels.  It's been many years since I worked on a ATR102.  Considering the age of the machine, changing the tantalum and electrolytic caps was a good move (as long as high quality replacements were used).  I recall the ATR series were the last stand alone audio recorders produced by Ampex.  Hope you have a good alignment tape.

 

[fazer]

how you checked Bias frequency?

Haven’t seen BiasRocks here for a long time.  There are test points on the machine’s cards.  You need extender cards which usually are stored in the transport for those cards.  There is a special extender card for adjusting th VU calibration.  Usually not sold with the machine.    The manual which is available on the web somewhere gives instruction on how to calibrate the machine.  An Oscope is a necessary piece of gear and can be used to check frequencies of the bias oscillator as well as a frequency counter.  Also the time period of the wave is 1/freq so can be derived from even an older scope.    There are a variety of spring scales that are used to measure tension and also a tentelometer to look at tension while playing the tape in a normal running state.  The manual has all this info as well as theory of operation of the circuits.  Way beyond the manuals you see today.  Hope this helps.    If I remember right the bias was 432khz.  A scope time base would be 1/432khz.  You want to look at the waveform and make sure it’s pure sine wave and symmetrical.