Burnt Woodside STA35 valve amp... Help!

e-mos · 29th May 2007, 01:15 PM

hey,
I have got a sta35 valve amp with one burnt sokket for el84 and one exploded chip. I want to fixs this amp and are desperat too find out what type of chip that should been there. are there anyone out there that know the name of this chip?? or have a schematics or a parts list or somthing?

I would be greatful for any help..

anatech · 29th May 2007, 01:25 PM

Hi e-mos,
Your are talking about a Dynaco?

Can you post a picture of the damaged part?

-Chris

70s music · 29th May 2007, 02:06 PM

While on the tube subject i found this = http://www.chambonino.com/construct/const3.html http://www.chambonino.com/construct/const10.html

Svein_B · 29th May 2007, 03:13 PM

I believe (with the assistance of Google) that Woodside Electronics was formed after Arthur Radford retired in 1989.

The Woodside STA-35 is based on the Radford STA25 circuit but incorporated improved power transformer, power supply components and general component quality.

The Radford STA25 and STA25R diagrams can be found here: http://www.ampslab.com/vintage1.htm

Other info on of STA25 (without any chips):
http://www.walther-mathieu.de/PROJEC...luckyfind.html
http://www.audio-muziek.nl/audio/aud...radfordsta.htm

Hope this may help.
(they are however EL34 / 6550, and not EL84)

Svein.

anatech · 29th May 2007, 03:27 PM

Hi Svein,
Thanks! I just learned something here. Never heard of Woodside before.

-Chris

e-mos · 30th May 2007, 09:42 PM

hi svein
thnx for the info..
this helped me alot..

i have already fixed the burnt out part..
and now i am waiting for som parts inclusive some new tubs/valves..

the problems in my ampmost likly started in the power supply. i found a defective tantalium condenser to the power (78l05) to the exploded part.

yes as you said the schematics of the radford sta-25r amp are very much the same with a few mods.
it looks like sta35 have sepert power supplys for its channel
In the power in the sta-25 there are a lm393 dual comparator op amp how ever in the sta-35 amp there are a bigger ic and this one are most likly a lm339 or simeler (correct me if i'm wrong) and are a quad comparator op amp.
also i noticed that in my amp there are different tubes then what the sta25 uses. my amp there are used ecc81 as input and a ecc82 as driver and el84 as output. ecc81 and 82 are dual triodes and from the schematics of the sta25 there are used an ecc88 as input (dual triode) and 6ua8 as driver (seems too be a pentode and a triode?) also kt88 or 6550 as output. anybody that knows why???

any way as said i have fixed one channel of the sta35 and it is working....

it is working with one 12at7(ecc81), one ecc82 and two el84.. (if this is wrong plz let me know)

pictures are coming soon..

e-mos · 30th May 2007, 09:42 PM

my bad... there are no el84.... they are el34....

alexander1972 · 7th February 2008, 02:17 PM

Hello, do you still have this amp?
I'm interested.
Regards,
Alex.

e-mos · 3rd March 2008, 11:48 AM

hello alex,

yes I still got the amp, have been very busy the last couple of months. So I haven't been able to post any pictures, yet.

but i will take some pictures of the amp and post them later to day.

alexander1972 · 3rd March 2008, 12:03 PM

Hello, I'm interested in buying.
Can we discuss?
Please let me know.
Many Thanks, Alex

29th May 2007, 01:15 PM	#1
e-mos diyAudio Member Join Date: Jun 2004 Location: gvarv	burnt Woodside STA35 valve amp... help hey, I have got a sta35 valve amp with one burnt sokket for el84 and one exploded chip. I want to fixs this amp and are desperat too find out what type of chip that should been there. are there anyone out there that know the name of this chip?? or have a schematics or a parts list or somthing? I would be greatful for any help..

29th May 2007, 01:25 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi e-mos, Your are talking about a Dynaco? Can you post a picture of the damaged part? -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

29th May 2007, 03:27 PM	#5
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Svein, Thanks! I just learned something here. Never heard of Woodside before. -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

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29th May 2007, 03:13 PM	#4
Svein_B diyAudio Member Join Date: Oct 2005	I believe (with the assistance of Google) that Woodside Electronics was formed after Arthur Radford retired in 1989. The Woodside STA-35 is based on the Radford STA25 circuit but incorporated improved power transformer, power supply components and general component quality. The Radford STA25 and STA25R diagrams can be found here: http://www.ampslab.com/vintage1.htm Other info on of STA25 (without any chips): http://www.walther-mathieu.de/PROJEC...luckyfind.html http://www.audio-muziek.nl/audio/aud...radfordsta.htm Hope this may help. (they are however EL34 / 6550, and not EL84) Svein.

30th May 2007, 09:42 PM	#6
e-mos diyAudio Member Join Date: Jun 2004 Location: gvarv	hi svein thnx for the info.. this helped me alot.. i have already fixed the burnt out part.. and now i am waiting for som parts inclusive some new tubs/valves.. the problems in my ampmost likly started in the power supply. i found a defective tantalium condenser to the power (78l05) to the exploded part. yes as you said the schematics of the radford sta-25r amp are very much the same with a few mods. it looks like sta35 have sepert power supplys for its channel In the power in the sta-25 there are a lm393 dual comparator op amp how ever in the sta-35 amp there are a bigger ic and this one are most likly a lm339 or simeler (correct me if i'm wrong) and are a quad comparator op amp. also i noticed that in my amp there are different tubes then what the sta25 uses. my amp there are used ecc81 as input and a ecc82 as driver and el84 as output. ecc81 and 82 are dual triodes and from the schematics of the sta25 there are used an ecc88 as input (dual triode) and 6ua8 as driver (seems too be a pentode and a triode?) also kt88 or 6550 as output. anybody that knows why??? any way as said i have fixed one channel of the sta35 and it is working.... it is working with one 12at7(ecc81), one ecc82 and two el84.. (if this is wrong plz let me know) pictures are coming soon..

7th February 2008, 02:17 PM	#8
alexander1972 diyAudio Member Join Date: Feb 2008	Hello, do you still have this amp? I'm interested. Regards, Alex.

3rd March 2008, 11:48 AM	#9
e-mos diyAudio Member Join Date: Jun 2004 Location: gvarv	hello alex, yes I still got the amp, have been very busy the last couple of months. So I haven't been able to post any pictures, yet. but i will take some pictures of the amp and post them later to day.

3rd March 2008, 12:03 PM	#10
alexander1972 diyAudio Member Join Date: Feb 2008	Hello, I'm interested in buying. Can we discuss? Please let me know. Many Thanks, Alex

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