Adcom 5800 Power Amplifier

Tradesman1

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Back in the 80s I wielded a soldering iron more than I ever wanted to and studied this type of thing and never enjoyed it, got away as quick as possible (was in the Air Force) and brought in some guys off the flight line avionics shop - it's beyond me
 

audiomano

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Thank you for your reply.

My request is for the complete power supply section which is not showed in the schematic sent.

Regards,

Audiómano
 

audiomano

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audiomano

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Just for your information, I requested twice the schematics to Adcom without success, fortunately I found the complete Service Manual at HiFi Engine for free.

To you, as a Power Supply expert, I will be very glad to ask some questions on ps matters of course if you don`t have any inconvenience on it.

Again thank you for your reply
 

audiomano

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I undestand, but the kind of questions that any audiomaniac makes to himself are more or less as follow:

1.-Is said that the rated voltage of a replacement capacitor should be as close as the original to be replaced, otherwise if you install one with a rated voltage larger than the original chances are that the new capacitor does not last too much due to the electrolyte won`t be enough saturated, shortening its service life. Is this correct?.

2.-I need to replace a 2 pair of 470uF-50v Nichicon Bi-Polar caps. which feed the + - voltage of an LM 391 N-100, IC used as pre-drivers in a Amber series 70 amp. being its real working voltage + - 16 v. I have at hand an almost boutique 1.000uF-100v Non Polar electrolityc caps 2 pair, do you think that in consideration of the above matter does is a good idea to make such replacement?.

3.-Taken into consideration the rectifier bridge capacity, does is possible to increase the capacitance of the main capacitors bank in order to obtain a better bass control. Remember that BAT has an option for their models called BAT Pack which increase the capacitors bank 5 times or so with regard to their standard models, they say that this capacitance increment improve bass response in a surprising order of magnitude. What do you think about it?.

Regards
 

Tradesman1

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Back in the 80s I wielded a soldering iron more than I ever wanted to and studied this type of thing and never enjoyed it, got away as quick as possible (was in the Air Force) and brought in some guys off the flight line avionics shop - it's beyond me
 

audiomano

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Thank you Trademan
 

keithrosenfeld

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Audiomano-

I saw in another section that you were looking for me (I co-founded Amber Electronics, which made the Series 70). Feel free to call me at work (434-220-0489) and I'll try to help.

- Keith Rosenfeld

 

audiomano

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Keith::

I an very happy for your reply. Thank you.
I own a pair of Series 70 amps which work wonderfully after all these years, only was neccessary some time ago to replace the aged 470 uF capacitors, which was done with audio grade non polar electrolytic ones of the same original values.

In another hand I have seen in internet a Series 70´s Schematic Diagram which shows 2 pair of 1.000 uF caps instead of one 470 uF pair. Here in this new schematic which it seems is a factory mod, one pair feed the LM391 N 100 and the other one, the driver transistors.

1.-Does this mod improve the already excelent performance of the amp?
2.-Can I incorporate it into my units?.
3.- Can I replace at least the 470 uF pair with a 1.000 uF new pair without problems like a surge on the LM391?.
4.- Does is neccessary to change the diodes too for this new capacitance?.
5.-The way I am using my pair is: removing the (+) (-) fuses in one channel on both amps to allow the entire power supply feed only one channel at time. The results are: a very natural sound of my Dahlquist DQ-10s particularly on strings chamber music. The series 70 were built like a tank. I love their musicality really.

Regards,
 
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