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Yet another Heath W5M rebuild

ab0ez

ab0ez

AB0EZ
Started another project, a pair of Heath W5Ms for a friend of mine in Arizona. After a quick look underneath, it's pretty obvious what needs to be done: A total gutting and new build from the ground up. The chassis, cages and bottoms are going to the powder coating shop on Monday.

Hey, I have an idea! Let's see if we can count all of the things wrong with these amps and use them as an example of what NOT to do to a tube amp!
 

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They look like just a mess with everything haphazardly laid out, that would drive me crazy but, I can be a little OCD :P :D

I've seen a couple of these on here, what are there specs like? I really like my Heathkit (even though it's not finished yet)
 
Fire hazard, shock hazard, you name it! No, you're not OCD. There's a right way and a wrong way to build and wire amplifiers. If you shoot me a PM with your email, I'll send you a copy of the manual for these amps. Specs only tell part of the story, but the numbers are pretty good for the W5M.
 
It's funny to see this thread as I just finished the 2nd of a pair yesterday. btw, your original restore thread was very helpful.

I have them in "test mode" with a pair of Pilot 172 speakers. The combo sounds really good.

Based on your previous w5m thread, your friend's pair is in good hands. :thmbsp:

w5m1_zps9bd9bfa3.jpg

w5m2_zps53724897.jpg
 
ab0ez said:
Started another project, a pair of Heath W5Ms for a friend of mine in Arizona. After a quick look underneath, it's pretty obvious what needs to be done: A total gutting and new build from the ground up.
Click to expand...
That is one pretty scary pair of W-5M amplifiers. :no: Those pictures are more suitable for Halloween than early November.
 
cc43fan said:
It's funny to see this thread as I just finished the 2nd of a pair yesterday. btw, your original restore thread was very helpful.

I have them in "test mode" with a pair of Pilot 172 speakers. The combo sounds really good.

Based on your previous w5m thread, your friend's pair is in good hands. :thmbsp:

w5m1_zps9bd9bfa3.jpg

w5m2_zps53724897.jpg
Click to expand...

Nice work and thanks for the kind words. I'll be doing a little bit more work on these W5Ms to the driver section and the phase splitter section, mostly to bias them in the most linear portion of their operating curves. Stay tuned.
 
Sorry about the cruddy picture, but here is where this W5M rebuild is officially starting: The pile waiting to go to the powder coat shop!
 

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A few quick powder coat questions.

1. I trust you CAN take them in the condition shown, i.e. you do not have to remove rust, old paint, etc?
2. I trust THEY remove the old paint, rust etc. as part of the process?
3. What kind of $$ are we looking at?

Anxious to see what they look like post-powder.
 
rustnrot said:
A few quick powder coat questions.

1. I trust you CAN take them in the condition shown, i.e. you do not have to remove rust, old paint, etc?
2. I trust THEY remove the old paint, rust etc. as part of the process?
3. What kind of $$ are we looking at?

Anxious to see what they look like post-powder.
Click to expand...

The shop I use does all the metal prep work. That way they know for sure it has been done right and the customer gets an excellent product. I took in a really ratty pair of Altec 511B horns that looked horrible, pitted, and trashed. They bead blasted the pair and coated them in hammertone Altec green. They came out excellent and cost about $80, IIRC.

I'll post the estimate when I get it.
 
Whoa nelly, that's not bad at all. Wicked cheap compared to re-chroming IF you can even find a place that will do it anymore...
 
Yeah, no kidding! Most of us in the area where I live now have to take chrome jobs up to Canada, unfortunately. There used to be a great chrome shop just a couple of miles from where I live, but the EPA forced them out of business years ago.
 
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A gathering of parts while the chassis is out at the powder coat shop. I like to overbuild tube amps so that once they leave my place I don't have to worry about them coming back.

For example, shown in the picture is the original 100 ohm 4 watt resistor from the power supply section. These are undersized and I have seen more than a few W5Ms with burned resistors and heat scorching on the underside of the chassis. The replacement 100 ohm resistor is a 1% wire-wound 25 watt. Not much price difference, really, if you shop around. Anytime you can get components running cooler in a tube amp, it's money well spent, IMHO.
 

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Here's the first filter section. Since the original can caps are just for appearance, the first filter section (before the choke) is a 4uF 600VDC oil filled cap with a 1M bleeder and a .01Uf 1kv bypass cap.

Why a 4uF cap? Two reasons: 1) Heath ran the daylights out of the output tubes and today's higher line voltages are a sure-fire recipe for shortened output tube life. The 4uF input cap to the choke will knock a few volts off of the B+ and get it down to about where it should be. 2) The power transformers on the W5Ms have a reputation of being somewhat fragile on the high voltage windings. Couple that with the quick warm-up characteristic of the 5R4 rectifier trying to feed a large capacitor load at start up, and you get the idea.

Of course, surgistors will also be added in series with the AC input on the primary side of the power transformer.
 

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Good idea on the 4 uf input cap. You are creating, at least the way I like to think of it, somewhere between a cap input and choke input power supply. Chap input?

In other words, there is a continuum between pure choke input i.e. 0 uf cap if you will, and a "true" cap input, i.e. using upwards of 20 uf or so....
 
rustnrot said:
Good idea on the 4 uf input cap. You are creating, at least the way I like to think of it, somewhere between a cap input and choke input power supply. Chap input?

In other words, there is a continuum between pure choke input i.e. 0 uf cap if you will, and a "true" cap input, i.e. using upwards of 20 uf or so....
Click to expand...

Yeah, you could call it that or you could call it "tuning" the Pi filter section for the output wanted.
 
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