!987 Dropping Plate Voltage

Brokenguitars · 08-16-2008, 06:14 PM

Just finished building a plexi kit and when I plugged it in, my voltage drops from 490 to 300 when preamp kicks in and makes a loud noise. My coupling caps seem good. Any ideas?

Pete240885 · 08-17-2008, 05:10 AM

As you built it from a kit i'm assuming you have a schematic? if i could take a look at this i may be able to make some suggestions

Brokenguitars · 08-17-2008, 03:15 PM

I was wondering if anyone has had this problem and could help. When I put the meter on the cathode the mA rises with the preamp kicking in. I can't get a stable bias. It will play for a sec then it gets noisy and have to switch it off.

Pete240885 · 08-17-2008, 03:31 PM

what kind of noise is it? is it present at low volumes?

Brokenguitars · 08-17-2008, 04:52 PM

Well, it appears that a bad soldered joint on the A.C. ground was the culprit. Sings like a bird now!

Thanks Pete for offering help.

Pete240885 · 08-17-2008, 05:42 PM

08-16-2008, 06:14 PM	#1 (permalink)
Brokenguitars Junior Member Join Date: Jan 2008 Posts: 4	!987 Dropping Plate Voltage Just finished building a plexi kit and when I plugged it in, my voltage drops from 490 to 300 when preamp kicks in and makes a loud noise. My coupling caps seem good. Any ideas?

08-17-2008, 05:10 AM	#2 (permalink)
Pete240885 Senior Member Join Date: Jul 2008 Location: Yorkshire, UK Posts: 230	Re: !987 Dropping Plate Voltage As you built it from a kit i'm assuming you have a schematic? if i could take a look at this i may be able to make some suggestions

08-17-2008, 03:15 PM	#3 (permalink)
Brokenguitars Junior Member Join Date: Jan 2008 Posts: 4	Re: !987 Dropping Plate Voltage I was wondering if anyone has had this problem and could help. When I put the meter on the cathode the mA rises with the preamp kicking in. I can't get a stable bias. It will play for a sec then it gets noisy and have to switch it off.

08-17-2008, 03:31 PM	#4 (permalink)
Pete240885 Senior Member Join Date: Jul 2008 Location: Yorkshire, UK Posts: 230	Re: !987 Dropping Plate Voltage what kind of noise is it? is it present at low volumes?

08-17-2008, 04:52 PM	#5 (permalink)
Brokenguitars Junior Member Join Date: Jan 2008 Posts: 4	Re: !987 Dropping Plate Voltage Well, it appears that a bad soldered joint on the A.C. ground was the culprit. Sings like a bird now! Thanks Pete for offering help.

08-17-2008, 05:42 PM	#6 (permalink)
Pete240885 Senior Member Join Date: Jul 2008 Location: Yorkshire, UK Posts: 230	Re: !987 Dropping Plate Voltage

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode