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-   -   Kt88 Pin alignement problem=did a mistake (http://www.diyaudio.com/forums/tubes-valves/227665-kt88-pin-alignement-problem-did-mistake.html)

banaca 13th January 2013 01:15 AM

Kt88 Pin alignement problem=did a mistake= HELP NEEDED
 
Someone sold me a Amp ( Quicksilver V4) with a set of JJ kt88 . Some of the central pins of the tube are missing ... ( the plastic guide in the middle) I instaled the the tubes, but I think a mis- aligne a tube... Now my amp don't bias. I've broken my wonderfull amp... Can someone tell me the problem ( a capacitor? , a resistor is damaged? )

scott17 13th January 2013 01:48 AM

Identify the correct orientation for the tube, re-install it, and see if it works.

Quote:

Originally Posted by banaca (Post 3323192)
Someone sold me a Amp ( Quicksilver V4) with a set of JJ kt88 . Some of the central pins of the tube are missing ... ( the plastic guide in the middle) I instaled the the tubes, but I think a mis- aligne a tube... Now my amp don't bias. I've broken my wonderfull amp... Can someone tell me the problem ( a capacitor? , a resistor is damaged? )


Loren42 13th January 2013 01:50 AM

Quote:

Originally Posted by banaca (Post 3323192)
Someone sold me a Amp ( Quicksilver V4) with a set of JJ kt88 . Some of the central pins of the tube are missing ... ( the plastic guide in the middle) I instaled the the tubes, but I think a mis- aligne a tube... Now my amp don't bias. I've broken my wonderfull amp... Can someone tell me the problem ( a capacitor? , a resistor is damaged? )

I would suspect the tube. Can you swap the KT88s with another amp (assuming you have two mono blocks)?

If the problem follows the tubes than you know what you need to do.

banaca 13th January 2013 02:01 AM

I did change the tubes ( I had a extra quad) The amp will not bias anymore. It only goes to 20ma ( it is supposed to go up to 45-50ma) I did check my slow blow fuses, the inputs tubes... still a problem... My other mono is ok btw.

scott17 13th January 2013 03:18 AM

A schematic is required.

banaca 13th January 2013 09:40 AM

I've emailed Mike Sanders , the guy who build it, ( about another amp) I told me , there is no shematics for is amps ( including mine) the V4

Vinylsavor 13th January 2013 09:43 AM

Hi!

Best is to consult the person who built the amps. He should know best what the problem might be and he would also be the best person to repair it

Thomas

Parafeed813 13th January 2013 10:24 AM

Without a scematic it will be mostly guesswork.
So let's see if we can guess in the right direction...
Do you know how the KT88 was oriented? One, two,... pins (counter)clockwise? Perhaps we can deduct what might have happened.
With the powercord and the KT88's removed, can you measure the resistance of pins 1 & 8 (the ones next to the locator notch) to ground? Comparing that to the resistance in the good amp will tell you if there is a problem with the kathode resistors (assuming there are kathode risistors).

banaca 13th January 2013 02:00 PM

Quote:

Originally Posted by Parafeed813 (Post 3323603)
Without a scematic it will be mostly guesswork.
So let's see if we can guess in the right direction...
Do you know how the KT88 was oriented? One, two,... pins (counter)clockwise? Perhaps we can deduct what might have happened.
With the powercord and the KT88's removed, can you measure the resistance of pins 1 & 8 (the ones next to the locator notch) to ground? Comparing that to the resistance in the good amp will tell you if there is a problem with the kathode resistors (assuming there are kathode risistors).


Great info ' thanks! It was almost a the right aligment. But I can not say counter or clockwise.... I will have the amp check by a tech. But I will tell him want you just said about the kathode risistor . Thanks!

jrenkin 13th January 2013 02:06 PM

My guess, since you CAN bias to 20mA, is that the bias pot is the problem, or one of the other resistors in the bias circuit. Maybe check those.


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