Resto Project: The DR504 horror show

[mhuss]

Unfortunately, the color coding was not always consistent through the years, although the blue and green for the OT was. You might want to look at gut shots of existing DR504s for clues.

http://hiwatt.org/ipage.php?n=2

--mark

[Pewtershmit]

hi guys a little update. I have everything done save for firing up this thing and figuring out what my voltages are for my Power Transformer. I'm going to wire it without the voltage selector in play, since it would have been not wired anyway since it was a Canadian import.

My confusion at the moment is the schematic for the output stage shows 4 wires for the various impedance taps, however, I only have a twisted pair of green, blue, and black coming out from there. This is the same as all the pictures I've seen of OT's from Hiwatts, however, the layout I have from marks site, and his schematic say otherwise. so color me confused.

I'm also a bit off on the secondary side of the Power Trans. I have 3 thicker gauge wires that are black, green and blue. and 3 thinner gauge wire that are black brown and orange.

My best guess would be as follows, based on the layout and pictures I've found.

Thick Black, Pin 2 of Power Tube
Thin Black, to HT mains fuse and to ground
Green (thick gauge), Pin 7 of Power tube
Blue (thick gauge), To ground beside power tube
Orange (thin) to last peg right on power turret board
Brown (thin) to 2nd last peg right on power turret board.

thoughts?

thanks and sorry for my novice!

[Dr.HI-TONE]

see this:
http://hiwatt.org/pix.php?p=DR504_topR
http://hiwatt.org/pix.php?p=DR504_topL

the OT is easy.
the pair of green wires is the 16ohm tap
the blue pair goes to either the 4ohm or 8 ohm taps with a piece of buss wire connecting the 4 & 8 ohm lugs.

[Pewtershmit]

thanks. one other quick one. The secondaries of the OT have a grey and black going to the power tubes, and a brown and yellow wir that looks like from the pictures I've seen are bundled together and soldered to the same post for HT1. Is this right?

[Pewtershmit]

hi guys an update here. I've got it powered up and am testing voltages. Everything was reading what it should then all of a sudden my diodes in the rectifier circuit have started blowing. I'm using 1000v 1A, but have tried 3a and still the same problem. any thoughts here?

[mhuss]

Are you measuring without the tubes installed?

--mark

[Pewtershmit]

yes no tubes at this point.

I found a piece of solder that was causing voltage to go to from the heaters to some wrong pins on the V4 preamp tube which I'm thinking was causing excess current to be drawn. but I'll try it tomorrow when I have more time. If you have any troubleshooting tips that would be great. We're CLOSE!

[Pewtershmit]

Hey guys. I've had a break with this one and I'm back at it. I'm still unable to figure out how the OT is wired. Looking at the heyboer replacment schematics and the layout that mark has on his site. There are only 3 wires coming from the OTs input side. Mine has 4. Looking at pictures above in this thread, it appears the orange and brown are tied together and going to HT1 on the layout. Is this accurate?

Im going by this http://hiwatt.org/Layouts/DR504_Complete.pdf

[mhuss]

I can't really tell from the pix. Try measuring continuity between orange and the output tube pin 3 connections, and the same with the brown. If there are two separate secondary windings, the brown should be low resistance to one pin 3 and the orange to the other pin 3. If this is the case, then, yes, connect them together to HT1.

--mark