SWR SM-400

Texan · #1 12-15-2010, 09:09 AM

Can any of the SWR Gurus out there help me date a SWR SM-400 head? I'm positive it was prior to 1993. The odd thing is that the silk screening is cream as opposed to the common red. I'm thinking that it was one of the original runs. Thanks in advance.

mdogs · #2 12-15-2010, 07:17 PM

Usually the date is marked on top of the transformer.

Low Class · #3 12-15-2010, 08:25 PM

Yes, you have one of the very first production units. Late '80's.

T-Bird · #4 12-15-2010, 11:09 PM

Hi.

Quote:

Originally Posted by mdogs

Usually the date is marked on top of the transformer.

^This.

You should also have sharpie dates on the PCBs if my memory serves me right.

Regards
Sam

Texan · #5 12-17-2010, 10:07 AM

Thanks for the info, I did not think about looking a the boards. I got the head and Goliath III cab for $450. Major score either way!

T-Bird · #6 12-17-2010, 09:40 PM

Hi.

Also, something I forgot that should be included on every ST220 family threads.

Do get the MosFets re-biased. The bias tends to drift and there's a chance that the MosFets will fry if that's overlooked. The tell-tale signs of the bias being incorrect is (relatively) low power and (again relatively) high chassis temperature. I say relatively, since the SM400 is often accused of having less power than advertized (not true IME), and heating up like a frying pan.

If there's no exess heat, You are probably safe, but the procedure is a simple task to a tech so it won't break the bank.

Regards
Sam