DAY4201
Active Member
Back on the restoration of my Seven after a bit over a year off for various reasons. When I quit working on it earlier, I had just finished the tone board. I had tested it and it was working well, no issues. I had rechecked that the “output balance” and “current alignment” were within the limits according to the service manual.
When I got back to it, I plugged it into the DBT. Turned it on, the relay did not open. I rechecked the alignments which were fine. I recapped the board testing all the caps which were good. I also tested diodes D905 & D906 both F-14A and transistors, TR901 & TR902 both 2SC634A. All tested good and returned them to the board.
I replaced the relay after with MY4-02. Upon testing on DBT I found that the relay opened immediately at power on and I heard a popping sound through both speakers even with the sound completely off. Same popping when turned off. I don’t remember having this problem earlier otherwise I would have noted it and asked for assistance as I am now.
Rechecked alignments which had not changed and were within spec. Below, is my first recap of the Protection Block (F-1140). All caps were grey Elna’s. I assume originals.
C901, 47/6.3V BP, changed to 47/16V Nichicon MUSE BP
C902, 1/50V changed to Kemet 1/63V film
C903, 220/6.3V changed to 220/25V Nichicon UPM
C904, 100/50V changed to 100/63V Nichicon UPW
C905, 1/50V changed to 1/63V Kemet film
After searching AK posts on the subject of Sansui relay related issues. I found several that suggested increasing cap uF and increasing the value of R905. None of these were specific to the SEVEN.
After some trial and “error” I found I could increase the relay delay time enough to either minimize the popping on both turn on and off. Or increase it enough to almost completely eliminate any popping which is what I assume is best.
Changes made to almost completely eliminate relay related popping:
R905 82K increased to 100K (Vishay Metal film 1W).
C901, 47/6.3V BP, changed to 100/35V Rubycon BP
C904, 100/50V changed to 330/63V Nichicon UKL
All others stay as noted above.
To completely eliminate popping:
C904, 100/50V changed to 470/63V Nichicon UKL
All others stay as noted above.
So, the question is. Is there any harm in the changes I have made to increase the relay delay time?
Sorry for the long post but I wanted to try to cover the obvious questions and provide enough detail.
As always thanks for any comments.
When I got back to it, I plugged it into the DBT. Turned it on, the relay did not open. I rechecked the alignments which were fine. I recapped the board testing all the caps which were good. I also tested diodes D905 & D906 both F-14A and transistors, TR901 & TR902 both 2SC634A. All tested good and returned them to the board.
I replaced the relay after with MY4-02. Upon testing on DBT I found that the relay opened immediately at power on and I heard a popping sound through both speakers even with the sound completely off. Same popping when turned off. I don’t remember having this problem earlier otherwise I would have noted it and asked for assistance as I am now.
Rechecked alignments which had not changed and were within spec. Below, is my first recap of the Protection Block (F-1140). All caps were grey Elna’s. I assume originals.
C901, 47/6.3V BP, changed to 47/16V Nichicon MUSE BP
C902, 1/50V changed to Kemet 1/63V film
C903, 220/6.3V changed to 220/25V Nichicon UPM
C904, 100/50V changed to 100/63V Nichicon UPW
C905, 1/50V changed to 1/63V Kemet film
After searching AK posts on the subject of Sansui relay related issues. I found several that suggested increasing cap uF and increasing the value of R905. None of these were specific to the SEVEN.
After some trial and “error” I found I could increase the relay delay time enough to either minimize the popping on both turn on and off. Or increase it enough to almost completely eliminate any popping which is what I assume is best.
Changes made to almost completely eliminate relay related popping:
R905 82K increased to 100K (Vishay Metal film 1W).
C901, 47/6.3V BP, changed to 100/35V Rubycon BP
C904, 100/50V changed to 330/63V Nichicon UKL
All others stay as noted above.
To completely eliminate popping:
C904, 100/50V changed to 470/63V Nichicon UKL
All others stay as noted above.
So, the question is. Is there any harm in the changes I have made to increase the relay delay time?
Sorry for the long post but I wanted to try to cover the obvious questions and provide enough detail.
As always thanks for any comments.