[Bigsound]

I would like some help regarding my tube amp. - it is amp for hifi stereo
Well,what happened.During I was listening the amp,the black out occurred
- when the electricity came,I connected again my stereo tube amp but I noticed that the music picture is not the same - the bass was not so mighty like before and the whole music picture went a little bit back.In the same time I noticed that the power transformer is getting warmer  then before - the amp has 70 w in push pull amplification
on ultralinear position and 36 in triode mode.Do You have any idea what that might be??.I think the only thing that could happened that some capacitors got shock.In fact I was told that the 2 power electrolitic capacitors might get over voltage as ther rated voltage is 500 volt and they get 438 volt normaly...where can I buy new ones?...I would like to buy new ones but with higher rated voltage - 600 volt or so....this are 2 capacitors  330 mf/500 v   each

[rollo]

 The Parts Connection or contact the Cayin to obtain same caps. the damage most likely was caused by the surge when the power was turned back on. Bummer.
   Next time a black out occurs , God forbid, UNPLUG your gear until power returns. Good luck.


charles

[Niteshade]

The caps are working within their rated voltage- so that's fine. Capacitors usually do not go quietly. There is usually hissing and smoke, maybe a loud bang and electrolyte all over the place. If the amp is quiet, the main filter caps are most likely good.

Did you check the bias voltages? Did you consistently check the power transformer's heat output up to this point (in past days, weeks, months)? Could it be when you checked the heat dissipation that it was on longer than during a previous checks?

JJ/Tesla makes good 500v filter caps. Did you check the caps for bloating, cracked seals, over heating?

Wanted to add something: You can take two, say 450v 400uf capacitors and put them in series. The result would be a 800v capacitor with a 200uf rating. Series capacitors have to be the same specifications. Always divide the capacitance by how ever many caps are being placed in series and add their voltage ratings together. i.e.: 200v, 800uf+200v, 800uf+200v, 800uf = 600v @ 267uf

[Bigsound]

The caps are working within their rated voltage- so that's fine. Capacitors usually do not go quietly. There is usually hissing and smoke, maybe a loud bang and electrolyte all over the place. If the amp is quiet, the main filter caps are most likely good.

Did you check the bias voltages? Did you consistently check the power transformer's heat output up to this point (in past days, weeks, months)? Could it be when you checked the heat dissipation that it was on longer than during a previous checks?

JJ/Tesla makes good 500v filter caps. Did you check the caps for bloating, cracked seals, over heating?

Wanted to add something: You can take two, say 450v 400uf capacitors and put them in series. The result would be a 800v capacitor with a 200uf rating. Series capacitors have to be the same specifications. Always divide the capacitance by how ever many caps are being placed in series and add their voltage ratings together. i.e.: 200v, 800uf+200v, 800uf+200v, 800uf = 600v @ 267uf

in fact the amp was in service but all measurments show that all voltages are ok.I was told that the caps can go softly demage like they show normal capacity when not runing.Now I have amps schematic diagram.I could send you on your email address so You could see how it is built.

[Niteshade]

You're welcome to send a PM to me. I believe, however, that if all the voltages are good, the caps look normal and the amp is not humming, or tubes glowing red- it might be a bias adjustment. If not that- you could have soft tubes.

[Bigsound]

The Parts Connection or contact the Cayin to obtain same caps. the damage most likely was caused by the surge when the power was turned back on. Bummer.
   Next time a black out occurs , God forbid, UNPLUG your gear until power returns. Good luck.


charles

well...I turned off the amp so when electricity was back I turned it on...so this moment is not critical.I am very woried as the service check went negative but I hear this sound differents VERY clearly.It's jut that the bass atack is not so deep and strong.I miss the buss harmonics - the main buss is there but do not have any more this terific deepnes and atack

[Bigsound]

You're welcome to send a PM to me. I believe, however, that if all the voltages are good, the caps look normal and the amp is not humming, or tubes glowing red- it might be a bias adjustment. If not that- you could have soft tubes.

well...this is totaly new amp...and this sound differents hapened in a second...after turning on the amp..this "new" sound was suddenly there.So it must be that something small went wrong what can be not measured but my ear does hear that.The bias was adjusted in service to its optimum value.As this is to be heard on both channels I am still thinking that it must have to do something with power supply...and there only this few electrolitic capacitors are possible problem.I think the only way is to change all electrolitic capacitors - 8 of them...and then hope.Please can You give me your email address as here I have no idea how to put it in attachments

[Niteshade]

I sent a message to your mail box. When you go back to the main page it will show you have one message in the upper left-hand corner. (Unless you have more unread messages, of course.)

I agree it sounds like a power supply issue if it effects both channels.

By any chance: did you do anything with the speakers? If one was disconnected and wired backwards ( + to - instead of + to +) that would cancel some of your bass response.

[Bigsound]

I sent a message to your mail box. When you go back to the main page it will show you have one message in the upper left-hand corner. (Unless you have more unread messages, of course.)

I agree it sounds like a power supply issue if it effects both channels.

By any chance: did you do anything with the speakers? If one was disconnected and wired backwards ( + to - instead of + to +) that would cancel some of your bass response.

No.the speakers are ok..I checked them , polarity as well...I feel it is in power supply ...and there in this power supply only this large capacitors are sensitive ones...resistors are few and they are ok...so this caps I will change..I will send you schemnatic diagram

[Niteshade]

I just looked at your schematic. Did you check to make sure the amp is on the ultra linear setting? That would provide better bass/more power than triode mode. I will look at it further and will get back to you later today.

[Bigsound]

I just looked at your schematic. Did you check to make sure the amp is on the ultra linear setting? That would provide better bass/more power than triode mode. I will look at it further and will get back to you later today.

Yes I know that..but again..it is again not what was before..a litle bit better but before it was terific bass in that mode...in other words..it shows always the same lower bass atack...one more thing..the high frequencies are a little bit more clear what was not before but it came again from this lost in bass range