Jolida 502A lost output...?

REALFLEO · 11th September 2011, 03:43 PM

Hi all,

I have a Jolida 502A tube amp equiped with 6550. I was listening some music and it just stop working. In fact I ear just a little on the right channel. I check the bias and my tubes are all around 50mv.

I never changed the tubes. Are they dead, what do you think? Do you have a way to tell if it is power tube or signal one?

Suggestions for new tubes?

Thanks,
Simon

REALFLEO · 14th September 2011, 01:46 AM

I cannot believe nobody can help with this... Please I am new to tube amp...

ronaldw441 · 14th September 2011, 04:23 AM

OK, I'll try to help.

Let's review. The filaments in all tubes light up & you're able to get 50mv at the bias check points?

Have you tried the other inputs? Your 502a has 4 sets of inputs. Try them all & report back.

REALFLEO · 15th September 2011, 04:25 PM

Hi,

First thanks for the help!

By inputs do you mean CD/tuner, etc? They are all not functional and yes the filaments are light up and 50mv to each bias connector.

Simon

kevinkr · 15th September 2011, 04:29 PM

Not much to go on here. I'm going to assume that you have no technical skills at this point, and recommend you find someone local to you who would be willing to mentor you and also at this point in time fix your amp..

Since both channels are out it seems likely that some common component likely in the power supply has failed.. (I would guess a power resistor in the supply filter circuitry..) It could be a number of other things as well.

REALFLEO · 15th September 2011, 06:57 PM

I know it can be tons of things but my question was more is it a typical symptoms of burned tubes? I never changed them ...

Thanks
Simon

vinylkid58 · 15th September 2011, 07:06 PM

Quote:

Originally Posted by REALFLEO

I know it can be tons of things but my question was more is it a typical symptoms of burned tubes? I never changed them ...

Even with old output tubes, the odds of having both channels fail simultaneously is pretty rare. How long have you been running the tubes?

jeff

REALFLEO · 15th September 2011, 07:26 PM

I am running them for 3 years maybe...

vinylkid58 · 15th September 2011, 07:31 PM

That's not a long time unless the amp is on 24-7. Is the amp also approx. 3 years old also?

jeff

REALFLEO · 16th September 2011, 03:07 AM

No I bought the amp used. It is 10 years old I think.

11th September 2011, 03:43 PM	#1
REALFLEO diyAudio Member Join Date: Nov 2006	Jolida 502A lost output...? Hi all, I have a Jolida 502A tube amp equiped with 6550. I was listening some music and it just stop working. In fact I ear just a little on the right channel. I check the bias and my tubes are all around 50mv. I never changed the tubes. Are they dead, what do you think? Do you have a way to tell if it is power tube or signal one? Suggestions for new tubes? Thanks, Simon

15th September 2011, 04:29 PM	#5
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Not much to go on here. I'm going to assume that you have no technical skills at this point, and recommend you find someone local to you who would be willing to mentor you and also at this point in time fix your amp.. Since both channels are out it seems likely that some common component likely in the power supply has failed.. (I would guess a power resistor in the supply filter circuitry..) It could be a number of other things as well. __________________ www.kta-hifi.net

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14th September 2011, 01:46 AM	#2
REALFLEO diyAudio Member Join Date: Nov 2006	I cannot believe nobody can help with this... Please I am new to tube amp...

14th September 2011, 04:23 AM	#3
ronaldw441 diyAudio Member Join Date: Aug 2008	OK, I'll try to help. Let's review. The filaments in all tubes light up & you're able to get 50mv at the bias check points? Have you tried the other inputs? Your 502a has 4 sets of inputs. Try them all & report back.

15th September 2011, 04:25 PM	#4
REALFLEO diyAudio Member Join Date: Nov 2006	Hi, First thanks for the help! By inputs do you mean CD/tuner, etc? They are all not functional and yes the filaments are light up and 50mv to each bias connector. Simon

15th September 2011, 06:57 PM	#6
REALFLEO diyAudio Member Join Date: Nov 2006	I know it can be tons of things but my question was more is it a typical symptoms of burned tubes? I never changed them ... Thanks Simon

15th September 2011, 07:26 PM	#8
REALFLEO diyAudio Member Join Date: Nov 2006	I am running them for 3 years maybe...

15th September 2011, 07:31 PM	#9
vinylkid58 diyAudio Member Join Date: May 2005 Location: Victoria, B.C.	That's not a long time unless the amp is on 24-7. Is the amp also approx. 3 years old also? jeff

16th September 2011, 03:07 AM	#10
REALFLEO diyAudio Member Join Date: Nov 2006	No I bought the amp used. It is 10 years old I think.

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