SWR 220

[paul_5]

Anybody else had this problem with their 220? The power light doesn't come on, but the Power amp clip light is on all the time and nay sound comes out. I've tried plugging the bass into the FX return and Power amp in, but still no sound.

Any ideas?

[MarkBassChat]

I don't know why you have no sound with the power amp but the power amp clip light suggest that one low voltage rails (either +15, or -15V) is missing. Can you measure the voltage on Zener diodes (after large, white resistors) in the power supply? I'm only guessing but I would start with this measurement.

Mark

Edited February 28, 2013 by MarkBassChat

[BassBod]

No idea...get it to a good tech - mine have commented on how well they are put together (meaning they are very fixable!) I might even have a circuit plan somewhere - PM me if you think it would help?

[icastle]

There is a fault similar to yours described [url="http://music-electronics-forum.com/t30669/"]here[/url].

Unfortunately, the diagnosis (and subsequent solution) is going to be a bit hit and miss unless you have the appropriate equipment.

[icastle]

[quote name='BassBod' timestamp='1362090104' post='1995773']
No idea...get it to a good tech - mine have commented on how well they are put together (meaning they are very fixable!) [/quote]

They're dead right - nearly all of the components are easily available 'off the shelf' stuff that most decent amp techs will have to hand.

[paul_5]

Got replacement parts for most of the pre section in me 'bits box'... I'll make the coffee and get me meter out

[paul_5]

spent an hour tonight checking components and nothing seems broken - the game is afoot!

[icastle]

[quote name='paul_5' timestamp='1362178080' post='1996959']
spent an hour tonight checking components and nothing seems broken - the game is afoot!
[/quote]

[paul_5]

will check the voltage rails tomorrow. CBA right now.

[paul_5]

Well, thanks for the replies and schematics chaps, you're an awful lot faster than SWR themselves who haven't responded to my email from the end of February yet. Is this normal?

[BassBod]

SWR used to be pretty good at helping (even when Fender owned) but there are interweb rumours that they might not be long for this (corporate) world...see talk bass.

[paul_5]

Had a mail back from 'Bob' complete with schematics for the pre and power stages. Last night I replaced two fritzed diodes and it's 'business as usual'. Happy days.