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Old 24th August 2002, 09:58 PM   #21
fcel is offline fcel  United States
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Location: LA County
In case you have not heard, ZEN version 4 write up will be out next week and I think I read that it'll be compatible with Aleph 3 (power output wise?). Pass labs is selling the boards.
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Old 27th August 2002, 12:37 PM   #22
2Bak is offline 2Bak  Denmark
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rtirion,
are you sure that 220 H stands for 220pF and not 22pF ?
For example:


Code = 2 significant digits of the cap value + number of zeros to follow:

10pF = 100
100pF = 101
1000pF = 102
22,000pF = 223
330,000pF = 334

thus 220 would be 22pF
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Old 27th August 2002, 02:29 PM   #23
2Bak is offline 2Bak  Denmark
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...also this this information indicates that they must be 22pF
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Old 27th August 2002, 07:56 PM   #24
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The coding one ceramic disc capcitors is according to your first link
2 digits for base value times a multiplier 10 power digit. Hope this makes sense.
i.e. 473 means 47 times 10 to the power of 3 so 47000pF = 47nF

This is not usually done on styroflex capacitors. At least I have never seen that. Most stryro's from Europe I know are from siemens. They did not use that type of coding on stryro's.

So I am pretty sure 220H means 220pF.
Also the location of the cap at the input make a 220pF look more in place.
Pity you do not have a schematic to verify.

Regards
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Old 28th August 2002, 12:01 PM   #25
2Bak is offline 2Bak  Denmark
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thanks

I'm waiting for my silver micas, meanwhile I have changed the top styro to a ceramic, but not the two other styros... maybe they are damaged too, cause I hear some hum in my speakers, not very loud humming, but still too much.

would there be some connection here between styros and humming, or should I start to look for other damaged parts (resistors ?)...?

normally hum is caused by missing ground, or ?
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Old 28th August 2002, 07:56 PM   #26
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I do not think the hum is due to the damaged styro's.
I would try to locate the hum as follow.
Use the RCA shorting plugs previously discussed as input for your
amp.
If the hum is still there, check all grounding connections.
btw I hope the hum is apperent with your original setup. And
not getting in with the new BOSOZ.
Did you check the entire PCB for bad solder connections?
Check the input resistors for correct value.

If the hum is gone (with RCA short) then I would take a good look
at the interconnects, and everything in front of the amp.
Even do a check with only one channel connected. This is to see
if there is no ground loop when you connect both channels

Hope this helps

Regards
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Old 28th August 2002, 09:02 PM   #27
2Bak is offline 2Bak  Denmark
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Thanks for instructions, rtirion

No, also hum using another source than BosoZ.
No, I didn't do the soldering check yet...

Hum is equal in both channels. Also hum with shortened RCA's.
I will check for resistors values, like you describe. And the solderings...

Finally I did the DC check with shortened RCAs:
@Left channel speaker 2,25 v
@Right channel speaker 814 mv
This doesn't look to good does it?

Should I start to look for a replacement for this amp.....
Zen 4 or Aleph 3?
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Old 28th August 2002, 09:44 PM   #28
2Bak is offline 2Bak  Denmark
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btw: listening to my new BoSoZ plugged into this Norwegian amp doesn't make me too happy to dump it. But I guess I would change my my mind if I listened to a Zen or Aleph amp.... :dizzy:
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Old 28th August 2002, 10:06 PM   #29
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I am afraid that does not look really good.
Finding the source of this will not be real easy without a
schematic.
If I would be you the first thing I would do is tedious reverse
engineering. i.e. using a multimeter, pencil and piece off paper
to draw up the total schema, incl. voltage readings on critical
points. This is not an easy task. But if my heart was with this
amp, I would probably enjoy it
From there on I would start the fault finding.

I know I am not making this any easier for you. So a ZEN V2 or V4
could be a very good option.

regards
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Old 28th August 2002, 10:40 PM   #30
2Bak is offline 2Bak  Denmark
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thanks, I will do my best

A few final questions:

- what would normally cause DC offset?
This amplifier is from mid 80's and I can't be 100% certain that the hum and DC offset was caused by my BoSoz mistake....but I'm almost certain that the hum is new.

- why would I build a Zen 2 or Zen 4 instead of Aleph? It is easier to build isn't it? My BoSoZ is unbalanced only.

- could I use the toroid from the Audio 60 for a Zen? 500VA, 2*22 volts or something...

regards
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