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Old 13th October 2007, 06:33 PM   #1
rajacat is online now rajacat  United States
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Default Heathkit W-5M

I was recently given W-5M monoblocks that are in good condition although I haven't attempted to fire them up yet. I'm looking for suggestions on how to refurbish and/or mod them and whether it would be advisable to go with a new cap board or try to leave them as stock as possible. I'm not too experienced with DIY so the path of least resistance would probably be best for me.

Thanks,

Roy
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Old 13th October 2007, 07:49 PM   #2
Trout is offline Trout  United States
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You should just sell them to me for $75.00us each,, They are cans of worms


All kidding aside,
If you got lucky and got the ones with the peerless output transformers, Restore them. Though not the Best Mono's on the planet, They sound great!!

I think I still have an original assembly manual around here someplace. The Schematics are easy to locate on the web.
Trout
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Old 13th October 2007, 07:57 PM   #3
rajacat is online now rajacat  United States
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Quote:
Originally posted by Trout
You should just sell them to me for $75.00us each,, They are cans of worms


All kidding aside,
If you got lucky and got the ones with the peerless output transformers, Restore them. Though not the Best Mono's on the planet, They sound great!!

I think I still have an original assembly manual around here someplace. The Schematics are easy to locate on the web.
Trout
They are the ones with the 16309 Peerless output trannys. I'm having trouble finding a replacement for the big Royalite caps so I was considering this http://quadesl.com/refurb/refurb_heathW5M.html

Do you know anything about these replacement boards?

--Roy
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Old 13th October 2007, 08:26 PM   #4
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Quote:
Do you know anything about these replacement boards?
Sheldon Stokes' cap. PCBs enjoy a GOOD reputation. BTW, you can replace the twistlok caps. with clamp mounted parts. Buy "potato masher" 5R4s and limit the total capacitance in the 1st filter position to 20 muF.

Good KT66s are not that easy to come by. SED (=C=) 6L6GCs are the (IMO) logical choice.
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Old 13th October 2007, 11:50 PM   #5
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If you want some Chinese KT66s selected and matched for a W5, BOI AudioWorks probably can do it (and will say honestly if they cannot). I have purchased a few sets from them for my Craftsmen 500a's, and usually get only negligible plate glow in the dark at 450V / 60mA.

BTW, running these at <115V on a variac will be a good idea, to keep the plate and filament voltages reasonable. I'm sure the power transformer is rated for 115V, so 125V will push everything past tolerance.
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Old 14th October 2007, 02:18 AM   #6
Trout is offline Trout  United States
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Be ready to change those big black coupling caps also. 3 of 4 units I have gotten had leakage issues.

Not expensive to change and well worth the insurance of reliability.

Trout
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Old 14th October 2007, 03:24 AM   #7
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Quote:
Originally posted by Eli Duttman


Sheldon Stokes' cap. PCBs enjoy a GOOD reputation. BTW, you can replace the twistlok caps. with clamp mounted parts. Buy "potato masher" 5R4s and limit the total capacitance in the 1st filter position to 20 muF.

Good KT66s are not that easy to come by. SED (=C=) 6L6GCs are the (IMO) logical choice.

That Sheldon guy is a real quack...

MY circuit board isn't anything magical, it's just a way to neatly hold modern parts under the chassis. The only advantage my board has is that it's easier to change things later than RTV'ing the same parts to the chassis floor. You can easily use perf-board and build something similar or even etch the boards yourself (but please not for commercial use) based on the artwork on my web site.

I really enjoy the W5M's. They work really well driving the panels of my hybrid electrostats. I'm currently using chinese KT66's which are a lot better than I thought they would be. They also don't seem to cause flames to shoot out of the amp like the old chinese KT88's used to.


Sheldon
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Old 15th October 2007, 07:51 PM   #8
rajacat is online now rajacat  United States
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Thanks for all the responses. I'm now in the process choosing and buying tubes so that I can fire them up albeit using a simple homemade variac consisting of a 50W lightbulb in line with the power cord.

--Roy
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