Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Heathkit GD-1B
#14

Hello everyone, It's really an odd coincidence I found this thread just as I'm having some trouble in re-building one of these.
For such a simple circuit, I shouldn't be having any trouble but, it seems I am.
My plan was to change the electrolytic and selinium rectifier in my GD-1B.
On the way, I installed a grounded power cord and did some corrections to the original wiring.
So, I've spent quite a bit of time trying various schemes (I was going to try re-stuffing the original cap, but abandoned that idea.)
and figuring out ways to mount the new components.
So, here I am, everything complete, I've double, triple, quadruple checked all my wiring, tested all resistors, and everything looks great, but.....
My measured voltages are way too high!
I'm taking measurements with the variac at 50 VAC, which goes through the transformer, rectifier, supply caps.
On the schematic, it shows the output from the supply caps to be 95 VDC, then passing through a 6800 ohm resistor to arrive at pin 1 of the tube with 45-52 VDC.

So even though I'm not applying full voltage (50 VAC), my pin 1 voltage is 60 VDC and follows any change I make in line voltage.
I considered that I'm using a silicon diode to replace the selinium rectifier, but there is a 1K resistor between the 20 Mfd caps and adding another 100 ohm resistor seems like a drop in the bucket when the tolerance of that 1 K resistor is considered.
I've been measuring and inspecting everything I can think of and can detect no shorts or parallel circuit paths to explain the lack of a voltage drop across the 6800 ohm resistor, which I measure at 7100 ohms.
I'll try taking a few pics tomorrow,
If anyone has any ideas about what I could check, I'm all ears.
Thanks,
Robert


Messages In This Thread
Heathkit GD-1B - by vecher - 12-31-2018, 06:37 PM
RE: Heathkit GD-1B - by gregb - 12-31-2018, 06:44 PM
RE: Heathkit GD-1B - by Radioroslyn - 12-31-2018, 06:58 PM
RE: Heathkit GD-1B - by vecher - 12-31-2018, 06:59 PM
RE: Heathkit GD-1B - by vecher - 12-31-2018, 07:02 PM
RE: Heathkit GD-1B - by Steve Davis - 12-31-2018, 07:56 PM
RE: Heathkit GD-1B - by Steve Davis - 12-31-2018, 07:57 PM
RE: Heathkit GD-1B - by Radioroslyn - 12-31-2018, 08:03 PM
RE: Heathkit GD-1B - by vecher - 01-01-2019, 10:09 PM
RE: Heathkit GD-1B - by Chas - 01-01-2019, 11:17 PM
RE: Heathkit GD-1B - by vecher - 01-02-2019, 12:11 AM
RE: Heathkit GD-1B - by Radioroslyn - 01-03-2019, 11:28 AM
RE: Heathkit GD-1B - by vecher - 01-09-2019, 01:46 AM
RE: Heathkit GD-1B - by Surfur - 01-17-2019, 01:46 AM
RE: Heathkit GD-1B - by Radioroslyn - 01-17-2019, 10:52 AM
RE: Heathkit GD-1B - by Surfur - 01-17-2019, 01:24 PM
RE: Heathkit GD-1B - by vecher - 01-19-2019, 12:14 AM
RE: Heathkit GD-1B - by vecher - 01-19-2019, 09:39 PM
RE: Heathkit GD-1B - by Surfur - 01-20-2019, 02:58 AM
RE: Heathkit GD-1B - by vecher - 01-20-2019, 11:10 AM
RE: Heathkit GD-1B - by vecher - 01-20-2019, 04:56 PM
RE: Heathkit GD-1B - by KCMike - 01-20-2019, 05:53 PM
RE: Heathkit GD-1B - by vecher - 01-20-2019, 08:29 PM
RE: Heathkit GD-1B - by vecher - 01-21-2019, 12:04 AM
RE: Heathkit GD-1B - by vecher - 02-15-2019, 09:17 PM
RE: Heathkit GD-1B - by EdHolland - 02-15-2019, 09:39 PM
RE: Heathkit GD-1B - by Surfur - 03-12-2019, 10:12 PM
RE: Heathkit GD-1B - by EdHolland - 03-12-2019, 11:57 PM
RE: Heathkit GD-1B - by vecher - 03-13-2019, 03:00 PM



Users browsing this thread: 9 Guest(s)
[-]
Recent Posts
Shadow Meter Bulb
Not sure if anyone has tried this but there are 6.3 volt miniature lamps in bayonet and screw-in base options available ...GarySP — 11:31 AM
Shadow Meter Bulb
Any 6.3 volt pilot light will work. I would use the brightest one I could find in my workroom. Be sure the dial is clean...RodB — 10:45 AM
HiFi (Chifi) tube amp build - but my own design.
Tim, nice write up and thanks for sharing !! Sincerely Richardradiorich — 02:47 AM
HiFi (Chifi) tube amp build - but my own design.
Well, this was a real "Hum-Dinger" :lol: ! This will be kinda long, but hopefully it will help others having t...TV MAN — 01:55 AM
Shadow Meter Bulb
Phorum members, I am trying to find the bulb # for PHILCO Shadow Meter part number 45-2180 that is from a 37-640 chassis...georgetownjohn — 06:53 PM
Philco 41-608 changer coupler
3D-printing...short of machining, of course. Or molding.morzh — 05:20 PM
Philco 41-608 changer coupler
Thanks, Morzh. That solves the issue of the rubber pieces. Now, I need to find a way to replicate the pot metal piec...alangard — 05:07 PM
12' Philco
If it is 12', either Kareem or Andre would have to jump pretty high to look at the front panel. Kareem would have an e...morzh — 01:48 PM
12' Philco
And here's a story about the tires on the truck. Same "no-stoop" guy must have installed these! Take care a...GarySP — 01:17 PM
Hickok AC51 tube tester
I think they have only shown the secondaries of the transformer. Two of them feed the rectifiers' filaments.morzh — 12:58 PM

[-]
Who's Online
There are currently 7992 online users. [Complete List]
» 1 Member(s) | 7991 Guest(s)
Avatar

>