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Old 16th December 2011, 06:34 PM   #31
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I don't think it's the valves you have to worry about : it's that little power supply circuit board with the relay on it where things go wrong.
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Old 16th December 2011, 08:53 PM   #32
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The newest version.... the 828A does not have the relays on the power supply board...
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Old 21st December 2011, 10:55 AM   #33
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well, my amp i doing it again...


this time the left gu29 red plated on the inside half of the tube. no bad smell or anything. it has run for a few 100 hour since it did it last time, but once again at low volume and for no apparent reason it has done it again,

there is obviously something wrong with it and i don't have the expertise to fix it i can look at a schematic and what out what is what but i don't like my chances of finding a fault unless there is a visably damaged component like last time.

has anyone else had the power tubes red plate and what was the cause?

thanks!
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Old 21st December 2011, 10:54 PM   #34
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Mine is probably approaching 50 hours of operation now. I lost one 6N1 tube but thats it and replaced them both with Russian tubes. I pulled the Chineese FU-29 tubes in leiu of a pair of RCA JAN 829B tubes that I got on Ebay. I let them burn in for a couple of days and then set the bias to .5 volts grid to ground as instructed. The result is a much smoother sounding amplifier and it has moved me 10 rows closer to the performance. All in all my FU-29 just keeps on ticking and sounding great.

If you keep having problems loosing tubes or with red plates get your self some real tubes.... like GE, RCA or Sylvania. Cetron still makes brand new 829B's. Be sure they are properly biased as it makes a huge difference on sound... Note: I ordered and got a matched quad of GU-29 tubes from Russia. All 4 of them are bad!!

Mark
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Old 28th June 2014, 11:08 PM   #35
AJT is offline AJT  Philippines
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Quote:
Note: I ordered and got a matched quad of GU-29 tubes from Russia. All 4 of them are bad!!

i hope you did not trash those tubes....
a friend gave me two of these russians that did not work
when first inserted into the socket.
so what i did was to sand the pins with a 400 grit paper
and then with 1000 grit, cleaned with a toothbrush
and lo and behold, the tubes worked....
i chanced upon this method when i got a bunch of 6C33 with the same issues...
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Old 29th June 2014, 12:17 AM   #36
Zekk is offline Zekk  Singapore
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Quote:
Originally Posted by poynton View Post
Are the Audioromy amps available in Singapore and if so, where ?

I looked for some last year when I was in Singapore and could not find them.


Andy


..
Adelphi Shopping Centre.
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Old 4th April 2016, 02:17 AM   #37
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Piero7 .. Mybe you should do schrmatics in nice form (pdf ..) for all DIY newbies.
I do like 12AX7 ...but prefere 5751.
I will make video on you tube between those tubes.
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Old 20th April 2016, 10:04 AM   #38
AJT is offline AJT  Philippines
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Quote:
Originally Posted by tdmax View Post
Hi Guys,

I am from Singapore and I really need help and advice on my fried audioromy Fu29 amp. The amp just got fried on its own last week.
And upon opening up the bottom plate, I saw 2 pieces of badly burned resistors.

Due to the resistors burned condition, I can't figure out the resistors value to get them replace. I really appreciate if some kind souls, having the same amp could open up the bottom casing and advice on the resistors color code and value, could help me out on this mess.

All help is greatly appreciated.
Hi, that amp can be problematic.....so what did i do with it?

1. i lowered the G2 voltage to just slightly lower than 200volts..
2. discarded the fixed biasing and used cathode biasing instead....
3. i used a cathode resistor of 250 ohms 5 watts bypassed with 220ufd/100 volt ecap..
4. replaced plate caps with ceramic types....
5. i added 2.2k carbon comp grid stoppers on the output tubes...

after that the amp amp behaved very well....the owner was happy....
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Old 20th April 2016, 08:37 PM   #39
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Quote:
Originally Posted by AJT View Post
Hi, that amp can be problematic.....so what did i do with it?

1. i lowered the G2 voltage to just slightly lower than 200volts..
2. discarded the fixed biasing and used cathode biasing instead....
3. i used a cathode resistor of 250 ohms 5 watts bypassed with 220ufd/100 volt ecap..
4. replaced plate caps with ceramic types....
5. i added 2.2k carbon comp grid stoppers on the output tubes...

after that the amp amp behaved very well....the owner was happy....
Hi AJT, I saw 270ohm 5 Watts resistor from your pic. Please advise. Thank you.
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Old 20th April 2016, 10:20 PM   #40
AJT is offline AJT  Philippines
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yes, 270 ohms is right....
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