Oh no, Looks like my H/K CD-401 getting sick

[xchg.ca]

With green sickness.

I was at first surprise with weird recording levels, then I was not able to bias any tape...
And now I know why....
Well sooner or later this will happen to any old gear.
Looks like I have to stash up some caps.
So far I discovered that many of the shown capacitors are going leaking.
The other ones whcih are labeles as Rubicon and TK are fine. I think there also few Nippon Chemi-Con there as well. But those blue ones are
10uFx16V and 1uFx50V are main suspects.
Looks like I have to replace them all !
Any specific recommendation what to get or I just picked appropriate value Rubicons or Nippon Chemi-Cons from the Mouser ?

 

[xchg.ca]

Ordered bunch of capacitors from DigiKey.ca
Hoping to get them soon as I very impatient to fix the deck

 

[xchg.ca]

Looks like changing leaked capacitors did not really helped.
Bias and record level is still low
Checking the level at test points.
Wondering what this suppose to mean, see screenshot:



775mV -25dB

I do understand 775mV signal level. But 775mV -25dB is weird.
Is that 775mV attenuated down by -25dB ?

 

[xchg.ca]

Update on "775mV-25Bd"
This thous be interpreted as 25db lover the 775mV
Which is super weird to me, why just not to say voltage of 44mV ?
I have used this calculator
http://www.sengpielaudio.com/calculator-amplification.htm

 

[xchg.ca]

Recapped, partially, my HK CD 401
And of course capture all on video:

 

[xchg.ca]

Finally I got proper calibration cassettes and tuned up this guy inside-out
Here is my FR response on Sony HF of unknown age

 

[Sam08861]

Hi xchg.ca,

I'm about to start the calibration of one of these decks and awaiting parts for the various blank tapes and jigs needed for the dolby encoder/decoder steps.

Curious how you did the FR measurements and the source for the 20hz-30khz sweeps? I was thinking to use REW, since I'm familiar with that.

Also, were you able to find a 20khz tone tape for setting the playback eq setting or were you able to use a signal gen for that part?

Thanks!

Sam

btw, thanks for posting the 775mV-25db calculation results. You saved me a lot of aggravation, lol.

 

[xchg.ca]

Hi xchg.ca,

I'm about to start the calibration of one of these decks and awaiting parts for the various blank tapes and jigs needed for the dolby encoder/decoder steps.

Curious how you did the FR measurements and the source for the 20hz-30khz sweeps? I was thinking to use REW, since I'm familiar with that.

Also, were you able to find a 20khz tone tape for setting the playback eq setting or were you able to use a signal gen for that part?

Thanks!

Sam

btw, thanks for posting the 775mV-25db calculation results. You saved me a lot of aggravation, lol.

I have standalone Frequency Generator and Digilent Analog Discovery device that can do FR sweeps in Network Analyzer mode.
I personally despise all stuff that is Soundcard based and it will not provide clear picture, in my opinion, because you have to be very careful with rec/pb levels to make sure what you see is actually true. Calibrate voltages etc.