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Heathkit W5M rebuilds

suzerain said:
Yes,
a whole hearted thanks for the detailed chronicle,
a quality rebuild indeed.

And I think a new rectifier (and perhaps output) socket - as you recommend - may help stabilize my wandering balance voltage in one of my W5. Going to try it.

Both mine W5m show continuity from outer RCA style signal input coupler to anywhere on the chassis.................. interesting.:scratch2:
Click to expand...

Check your insulating hardware on both sides of the RCA jack. After that, measure your ground bus to the chassis.
 
Uh huh,
0 Ohms on the vom.

If they want to really isolate that ground they need another wafer on the outside (front) of the assembly cause those mounting screws are tightening the ground assy right to the chassis. Their stock assy only keeps the ground off the signal lead. Looks like their ground hooks to the chassis through the mounting screw hardware too.

I'll take 'em off line soon and check for that continuity to ground bus, hope none. Doesn't sound healthy.

Anyone try F&T caps in these in the PSupply? The 20@500 F&T?
I'de llike to upgrade my PS but with the price hike on the Atoms maybe F&T. Any experience with these? Heard they've been making caps for many decades. Any other suggestions for a good 20 and 40 at 450-500V?
 
I haven't used those caps, but my advise of going very easy with that first filter cap section stands. W5Ms are known to have kinda fragile HV windings and we don't want to stress them with a big turn on surge. Take a look on that auction site and you'll see W5Ms with blown HV windings. I would also suggest a slow turn on rectifier such as a 5V4.

My goal when I rebuild an amp is based on a few points:

1) Fix the design compromises that the accountants mandated.
2) Optimize the circuits for hifi.
3) Replace all of the passive components. Let's face it: We have MUCH better passive parts available to us today. I also consider tube sockets a passive component. Yeah, it's a PITA to replace them, but worth it.
4) Make the amp ready for its' next 50 years of trouble free service.

Suzerain, do you have a pair of RCA input jacks that have the proper isolation washers on both sides?
 
Roger all that,
and I love this thread, great work.
Was thinking of replacement right off the rectifier: 20 at 500, then 30 at 500 and again 20 at 500 - nothing radical, just good quality and fresh.
And yes I have a few RCA gold sets I wanted to install on my W7 and W5 and they have the inner and outer insulating washers so I'de like to settle this issue.
 
Depending on the rectifier, I would probably go lower in uF with that first cap or your B+ will most likely be too high. That was why I went with that gi-mungous 4uF 1KV oil-filled cap right after the rectifier. That brought the B+ right to spec.

I'm really interested to find out what resolves the issue with the RCA input jacks on your W5s.
 
ab0ez said:
Depending on the rectifier, I would probably go lower in uF with that first cap or your B+ will most likely be too high. That was why I went with that gi-mungous 4uF 1KV oil-filled cap right after the rectifier. That brought the B+ right to spec.

I'm really interested to find out what resolves the issue with the RCA input jacks on your W5s.
Click to expand...

I don't have access to good parts like that, so would you reccomend then a 10uF over a 20 at the first position? Was hoping to use the one 5R4GY supplied and get another.

Think then I should install a pair of the RCA's using the isolation discs supplied? Does seem better to have the signal ground off the chassis ground. Now you're getting me curious enough to consider pulling one and checking into ground bus to chassis resistance and looking to see how that RCA gnd is suppose to hook to the system.
 
Let me see if I have a couple of those 4uF oil filled monsters out in my storage shed. I'l send 'em your way if I do have them.

Ye, install those RCA jacks with the isolation discs supplied and then see if that solves the problem.
 
Wow,
that would be incredible. I'de be thrilled with the gi-normous! Reminds me of the "Humungous" from Road Warrior.
and WOW,
jsut checked the ground bus to chassis - continuity ! After looking at it...... this isn't right is it. If that was right there would be no isolating wafers on the FT cans the ground bus is hooked to!!
getting curious I loosened the RCA assy from the chassis, pushed it away a tad and holy smoke, no more continuity of RCA gnd nor the ground bus to chassis!! Good grief and it's run like that for hours.

Did the kit builer forget a wafer between RCA assy and the chassis ?? I'm going for the manual.
 
Wow! I'm not sure what happened with the builder, but there should not be continuity between the ground side of that jack and the chassis. You, Sir, are on the way to fixing your amp!

Another good option for limiting the inrush current to your amps that also lowers the B+ a bit is a surgistor on the primary side of your power transformer. I highly recommend one in each.
 
Just soldered the new RCA in with the 2 white isolations in place and bingo, no more problems there. I'm quiet sure the situation is the same in it's mate.
That "phono" assy butts right up to the chassis and is tightened down to it.
Is this a design error?

So what did I have before, hot chassis? all grounds together? Thats crazy. I read the manual and it jsut says attach the phono assy with hardware, no pic, no details.

Absolutely right, on the path to getting this thing in order, how the heck was it working?

Anxious to get to the other and plug em back in line.
 
and that wire to the ground of the OPT, that should be reconnected to the new RCA gnd tab too right?

ALERT: w/out the ground bus to chassis connection (with new RCA and 2 insulators) my B+ is not developing but maybe 100Vdc !! I put a jumper from gnd bus to chassis and get full B+ again. What's going on with this circuit?
 
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suzerain said:
Just soldered the new RCA in with the 2 white isolations in place and bingo, no more problems there. I'm quiet sure the situation is the same in it's mate.
That "phono" assy butts right up to the chassis and is tightened down to it.
Is this a design error?

So what did I have before, hot chassis? all grounds together? Thats crazy. I read the manual and it jsut says attach the phono assy with hardware, no pic, no details.

Absolutely right, on the path to getting this thing in order, how the heck was it working?

Anxious to get to the other and plug em back in line.
Click to expand...

Sounds more like you had the potential for a big ground loop. Most likely it was not a design error but rather a builder error.
 
Yeah,
a bunch of shared grounds, not good.
Scratch that last Alert of mine, just have to measure B+ to ground bus now, not to chassis as I'm accustomed.
Music sounded great on my test speaker.
Interesting that I had no hum or any noise at all before.

I will install Cl-90's or should they have to be 120's for surge?

Thanks Jim, should I start a new thread for all this? I'm polluting your instructional thread I fear.
 
suzerain said:
Yeah,
a bunch of shared grounds, not good.
Scratch that last Alert of mine, just have to measure B+ to ground bus now, not to chassis as I'm accustomed.
Music sounded great on my test speaker.
Interesting that I had no hum or any noise at all before.

I will install Cl-90's or should they have to be 120's for surge?

Thanks Jim, should I start a new thread for all this? I'm polluting your instructional thread I fear.
Click to expand...

Nah, let's keep it all here, this is a learning thread.

I've had great luck with 120's with the the W5M.
 
Yes Jim,
I can post a pic, but amps are back in line now. It's the wire from the OPT ground terminal to the "phono assy" ground tab. I reconnected to new ground tab.
Well, mixed feelings on the sound now. I think the imaging and detail has picked way up in the amps now, noticing things sound a bit different, better!
My imagination? I don't think so really.
However, I now have a slight buzz in both sides that is new. Sounds like a power supply buzz of sorts mostly in the mid a tad in the woofer, very mild but the Cornwalls do reveal it (not noticed on the bench with small 4" speaker.)
I have soldered the lead usually tied up from the PT to the ground bus very close to where power filter case hooks on (instructed when not powering a Heath or other preamp with the W5's.)
 
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Keep in mind your amps still need rebuilt. The W5s and Cornwalls will be a great combo. I run 4 very modified Khorns fed by four home built tube monoblocks in my man cave. When all is said and done, you're gonna love the combo of tubes and Cornwalls.
 
Yes,
none of the 40uF and only one of the 20uF changed in PS of one, the other has 3 cheap new 20uF's. Both have all new other lytics and couplers under chassis.
Was thinking of F&T for the 20's since atoms are getting pricey.

I do love the blonde Cornwall 1's in the livingroom and often think they need recapping as well, but sounding good now. Haven't checked for a crossover rebuild thread, done yours?
 
I'm running custom crossovers in mine that I made, 300Hz and 4,5Khz crossover freqs. I am running four EV HR9040A midrange horns, four EV DH1012 drivers and four EV T-350 tweeters.

Yes, the mid horns are wider than the bass horns, but oh what a sound!

Recapping your Corns is a great idea. The one thing I don't like about the Klipsch crossovers is they run the mid horn wide open on the top end with no upper cutoff. The K55 mid driver has a nasty peak at about 9Khz that needs to be axed. Or, are you running the vertical mid horns?
 
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