Help with 1st tube amp - Lafayette LA-55

[hcruz]

So I finally got a tube amp.
Fired it up and hooked my phone to the aux input and sound came out. While idle the amp has a noticeable "hiss" sound and after about 5 minutes playing the "hiss" was louder, noticeable even while playing music.

Opened it up and found a leaking cap and many components that looked brownish (maybe overheated components?) so haven't fired it up since.

As always I tried to get ahead of myself and started reading all over the place trying to learn how to service this unit. Then I replaced the power cord, a leaky power supply cap and another cap that I'm not really sure what it does, then decided to stop before messing something up.

What should I do next?
Here are some pics of the amp.

 

[pete1729]

I can't find a schematic, but ask 'tbavis', he might have a Sams folder for it. There are few capacitors so plan on replacing all of them, look up restuffing can caps here on AK using the 'search AK with google' feature. The can capacitors can be replaced with parts from Mouser electronic supply. For the large under chassis capacitors consider using some 716 'Orage Drops' by Sprague. Remember you can use higher voltage caps if exact vaue replacement parts are unavailable. Also, to match capacitance values getting within 10% is probably OK, however if you want to match exact values capacitors and be wired in parallel and their capacitance adds arithmetically.

 

[Tom Bavis]

You rang? Some advice - the gray Japanese capacitors can be tested as follows:

Drop them into a trash can. If they make a noise when the hit the bottom, they were bad.

Email for a scan of the Sams folder- tbavis(at)rochester(dot)rr(dot)com

 

[Pioneer Vir]

I have two in-service LA-55s that I have running as "mono blocks" with a Lafayette LT-78 tuner to some Frazier Concertos in a spare room. You can get replacement cans from Dave at www.justradios.com for the 44/40 - 400 and 20/20 - 350 cans if you want to go that route at pretty reasonable prices IMO. These are pretty easy to work on with a lot of room underneath the chassis. The two I have actually sound pretty decent for what they are. Of course, I think the Frazier's help that out! I have a copy of the Sam's (503-11) also if you need it. Good luck! Fun little amp to play around with.

Don

 

[hcruz]

You rang? Some advice - the gray Japanese capacitors can be tested as follows:

Drop them into a trash can. If they make a noise when the hit the bottom, they were bad.

Email for a scan of the Sams folder- tbavis(at)rochester(dot)rr(dot)com

Thanks Pete and mr TBavis!
I guess I should get busy looking up parts in digikey.

Somewhere in a thread I read about some places to get the canned multi caps but cant find it. Will it be Ok if i replace them with regular electrolitics splitting them between the top and the bottom of the chassis?

Here are some more pictures of the tubes.

 

[hcruz]

I have two in-service LA-55s that I have running as "mono blocks" with a Lafayette LT-78 tuner to some Frazier Concertos in a spare room. You can get replacement cans from Dave at www.justradios.com for the 44/40 - 400 and 20/20 - 350 cans if you want to go that route at pretty reasonable prices IMO. These are pretty easy to work on with a lot of room underneath the chassis. The two I have actually sound pretty decent for what they are. Of course, I think the Frazier's help that out! I have a copy of the Sam's (503-11) also if you need it. Good luck! Fun little amp to play around with.

Don

Ahaa! you got ahead of me by a few clicks, I'll check out the cans in justradios.com
Thanks!

 

[ricohman]

Check out hayseed hamfest for multi section cans.

 

[pete1729]

If there are new can caps with the same values, definately get them. Restuffing is simple enough to do yourself, but nothing beats swaping out old parts for identical new ones.