D-Lator start-up issues

[martin manning]

Ok, hang on- perhaps this is a measurement issue on the input stage. Your meter may be messing up the bias. Measure across the bias resistor to check it. The recover stage grid should be zero, though, so something doesn't seem right there.

[Structo]

The two inside jacks need to be the switching jacks.

There is a jumper between the two, the middle lug.

[jlatrace]

Thanks Tom. I've seen it drawn both ways and it seems like it would work as long as one jack was a shorting jack wired from teh shorting lug to the hot lug on the return. Am I looking at this wrong?

[jlatrace]

Okay yesterday I fixed my problem as follows:

First, I tried to clean the contacts, but never could get the switchcraft jack (or any replacement switchcraft jack in my supply) to make a good contact between the tip and the switch.

Next, I pulled the switcraft jacks out and replaced them with cliff style jacks and my problem was solved.

As for my voltages, I'm going to remeasure them because the unit is working and sounding fine.

Thanks for everyone's help.

[jlatrace]

Ok, hang on- perhaps this is a measurement issue on the input stage. Your meter may be messing up the bias. Measure across the bias resistor to check it. The recover stage grid should be zero, though, so something doesn't seem right there.

Here are my voltages after replacing the switchcraft jacks with cliff style jacks:
Transformer = 138 vac
B+ at 47 uf cap = 380 vdc
B+ after 15k resistor = 346 vdc
B+ after 100k resistor = 243 vdc

Input stage:
pin 1 = 243 vdc
Pin 2 = 15 vdc (27 vdc after 1 meg resistor)
Pin 3 = 29 vdc

Recover stage:
pin 6 = 219 vdc
pin 7 = 0 vdc
pin 8 = 1.58 vdc

Do these look more like what you expected?

Thanks for your help Martin.
Les

[martin manning]

Those look good. I wonder why your recover stage grid wasn't zero before, though.

FWIW I think the best way to wire the loop jacks on the amp and on the D'lator is to jumper from the tip of the send to the switch on the return. That way you can take a line-out from the send without breaking the signal, and if you want to bypass the loop you can just pull the plug from the return. No separate switch needed.

[jlatrace]

I discovered that my Wavetek DIMM was malfunctioning. It reads VAC in a crazy way and it is consistently off on vdc. I took the newer voltages using my TPI 135 DIMM.

Great suggestion on the loop, but I already drilled a hole and wired up the bypass switch. Next time I'll know.

[Structo]

When I was researching my D'lator, I was told to get the cathode voltage on the follower to around 30v which is what I did.
Also the cathode bypass cap I was told it is a 47uF in the real deal.
Not 4.7uF

I like the bypas switch because it can be a troublshooting tool during setup if something goes haywire in your cabling.

[jlatrace]

Thanks, I checked and 47uf is the value of my cathode bypass cap.