Resto Project: The DR504 horror show

[Pewtershmit]

Ladies and gentleman for your viewing pleasure, my next project!











This thing is a DISASTER. Clearly a mad mans electronics project (ni-cad rechargable AAA batteries wired to the preamp tubes!!!), I'm going to try to get this DR504 back to somewhat stock specs. From what I can tell this was a 1980 from a sticker on the chassis. Which makes sense considering the number of cap clamps inside. A Canadian market model. I'm going to strip it to bare metal and replace basically everything, except the transformers if they are working. While this was a PCB model I'm going to use turret, and I'd like to add a linked input on the front as well. Also you can't tell but every pot on the front is a push/pull.

If you could a couple of questions:

The trannies look correct, are these proper partridges?

Also. Mark mentions a supplier for turret board repros on hiwatt.org, would you guys still recommend him or is there another avenue to order hiwatt Resto parts. Where do you guys generally get parts if you don't go local?

I'll keep you guys updated!

[Dr.HI-TONE]

Holy *$@#@!

you have your work cut out.

This is a good educational moment for everyone new to Vintage HIWATTs. This is what point to point wiring looks like. Vintage HIWATTs were wired using turret board construction.
contact me at claytonc@hi-tone-amps.com and I'll set you up with better boards than the guy on Mark's page.

[Pewtershmit]

Excellent !

[OldSchoolDave]

Oh, the humanity .

The output transformer has been rotated 90 degrees, for some odd reason. But no sense in pondering that, as reason had nothing to do with the butchery shown in your pics .

Holy *$@#@!
This is what point to point wiring looks like.

I was about to comment on that as well. What some (mistakenly) think of as the "proper" way to wire an amp often results in a rat's nest that's nearly impossible to troubleshoot and repair. Not to mention all the exposed - possibly high voltage - connections.

@Pewtershmit - hope you are successful in restoring the amp from the gawdawful Franken-amp it is now to its original state. Please keep us posted on your progress.

Dave

[Pewtershmit]

I'm curious as to what the idea behind the AAA batteries wired to the preamp tubes was . Any ideas ?

[mhuss]

Not a clue. What an awesome mess.

--mark

[Pewtershmit]

Easy parts done. Amp has been gutted and painted the chassis. Have my Bill of Materials and Schematics together. Going to do an Early 70's turretboard preamp with a "linked" input on the front plate. I can't believe with all these holes drilled in the thing I have to do one more!

Thanks to Clayton for the email on the boards, will definitely go that avenue, probably pick up the proper caps from him as well!

[OldSchoolDave]

Thanks to Clayton for the email on the boards, will definitely go that avenue, probably pick up the proper caps from him as well!

Good move!

The chassis looks pretty good painted .

Dave

[Pewtershmit]

gents I've got all my parts in line here. Except for the 91k and 560k resistor. My supplier does not carry those, before I look elsewhere, is there an appropriate value I can sub for these? I was thinking an 82k and 510k respectively will get me close with tolerances, but since these are going right to V3 and V4 they are important values. thx

[thefatcyclist]

you could always try the ceriatone boards, and swap out any components that vary from Marks schematics, would be an easy road in maybe.

[mhuss]

82k or 100k would be fine. The 560k sets the bias, but I've seen 470k in there a couple times, so 510k should be okay.

--mark

[Pewtershmit]

Thanks Clayton!

The rest of the parts are on the way. Then the fun begins.

looking for some concrete info on this one. Did Hiwatt wire these up with only 22 gauge solid core, or did they use any thicker stuff anywhere in the power section?

[mhuss]

The same slim solid core wire was used everywhere, including the power tube heaters(!).

--mark

[mikhailwatt]

https://www.eol.ucar.edu/rtf/facilities ... e_Size.htm
Apparently 22 ga is good for 7 amps (conservative) for chassis wiring (free-air, not bundled).
If it's especially hot in there you might de-rate it.

Other than the heaters, these are high-voltage, low amperage circuits. Some sections are considerably higher than 300 volts...

But I figure the DR Rule applies.

[Pewtershmit]

evening gents. I have started wiring the Transformers, however, I have very limited knowledge on transformer wiring.

I've been pretty much going with Mark's DR504 Layout found here:

http://hiwatt.org/Layouts/DR504_Complete.pdf

However, the wires from the transformers are color coded differently then what he has, perhaps due to the transformer replicas he used. Can anyone point me to a better color coded layout, or shed some light on what color is what function of the transformer so I can go by the schematic ? This is the only stuff I'm really unsure of when it comes to amps.

LEFT

RIGHT