Revox PR99 MKII Calibration

almandog

New Member
I have a Revox PR99 that I am trying to calibrate. The deck was completely recapped and transistors replaced also. I am following the manual to the calibration and I am on the step to adjust the Reproduce Level output. The deck can record and playback. But the playback is very low. I can also hear the 1khz tone from the test tape through my headphone.

So: What I am trying to do is to adjust the Repro Level according to the service manual and I am supposed to turn the Repro Trimmers until I get the operating level +4dB (1.23v) and I should see that reading on the millivoltmeter also. Neither the millivoltmeter or the VU meter move when I turn the trimmers. The VU meters are working: when I am in the record mode and record some music, the VU meters work. But on playback they barely move. I think I will have a look at the Repo Amp PCB. Any idea what could be going on?
 
Greetings from RojoLand!

Where is the front-panel LEVEL pot (item 18 on page 5 of the service manual) set? Are you referring to section 6.4.10 "Adjustment of reproduce level from test tape"? Please describe your test tape.

Given the recap and transistor replacement, I would double-check that those parts are correctly replaced, especially if you did that work yourself.

Take care,

J. E. Knox "The Victor Freak"
 
Update:
Something strange has happened in the PR99 to cause:
C1 and C2 on the Output Amp and C12 and C13 on the Reproduce Amp to fail. I checked them with the ESR meter and Compnent tester on the oscilloscope. No other components failed after checking all of the other PCBs. I must remind you that the PR99 was recapped and all transistors replaced. Has anyone experienced this before?20180201_162505.jpg 20180201_162259.jpg
 
Greetings from RojoLand!

The "OL" (over-limit) indication on your meter doesn't really tell me anything. I can't tell how that meter is set up. It is perfectly normal for a DMM to indicate "OL" in Ohms mode when measuring a capacitor; it will give a reading when first connected but that reading should rise until the "OL" appears. Do you have an actual capacitance meter, and if so, what does it show for the parts in question? I am not familiar with your 'scope and its "component tester." It looks like a great scope though. However, I can't read the screen text regarding "Component Test" in your photo. (Bear with me — I'm 62 and have bad eyes. Just retired after nearly 30 years as bench tech at our local public-access TV station.)

If those capacitors have in fact failed and they are recent replacements, they may simply be bad parts or they may have been installed backwards, which would invite early failure. Polarity is very important with electrolytics.

Take care,

J. E. Knox "The Victor Freak"
 
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