News:
December 07, 2021, 11:29:39 AM

Author Topic: Speedball upgrade fail after a month, voltages way off [resolved]  (Read 664 times)

0 Members and 1 Guest are viewing this topic.

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #15 on: October 23, 2021, 11:58:48 AM »
What are the DC voltages on each side of each 270 ohm resistor in the power supply?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #16 on: October 28, 2021, 10:00:07 AM »
U15 - 124v
U21 - 187v
U13 - 50v

Are these the correct locations? 

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #17 on: October 28, 2021, 10:34:54 AM »
Can you try again with no tubes?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #18 on: October 28, 2021, 10:49:34 AM »
W/ no tubes:

U13 - 237
U15 - 241
U21 - 246

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #19 on: October 28, 2021, 10:53:56 AM »
Now try just the 12AU7 and post voltages on terminals 1-5.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #20 on: October 28, 2021, 11:10:20 AM »
W/ 12AU7 only:

1 - 73
2 - 231
3 - 0
4 - 231
5 - 74

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #21 on: October 28, 2021, 11:28:45 AM »
This is major progress!

Can you post some photos of the wiring around the octal socket that you have currently? 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #22 on: October 28, 2021, 12:23:50 PM »
I'm just glad that its looking like the whole thing isn't toast!

Also: there is only one LED on the octal.  I had some short/issue a little while back and I followed the advice on a post in this forum that swapped out a jumper for the 2nd LED (which worked).

Offline Thermioniclife

  • Sr. Member
  • ****
  • Posts: 522
Re: Speedball upgrade fail after a month, voltages way off
« Reply #23 on: October 28, 2021, 02:18:02 PM »
PB is looking for pics of the other socket. Octal= 8 pins, Noval= 9 pins.
Sometimes photos can be deceptive but check that the jumper you put in on the Noval socket is not shorted to pin 7.
That will give you all sorts of grief. In general you should not have that much uninsulated wire exposed. pin a2 is the way they should be.
Lee R.

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #24 on: October 29, 2021, 08:20:32 AM »
Of course, thank you, that socket does have 9 pins not 8!

The jumper is currently not shorting to the 7th pin.  I went ahead and wiggled the tube all around the noval and it doesn't appear that any wire is touching nor able to touch its neighbor.

I will pick up some liquid insulator and shore up those exposed bits asap though, thanks for the tip.
« Last Edit: October 31, 2021, 05:34:23 AM by goldencalves »

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #25 on: October 29, 2021, 08:39:26 AM »
The wire that's oddly routed at B8 is going to cause problems eventually.

The upper wire on B2 doesn't look to be well captured by solder.


You may find at this point that it's just easier to order a replacement big board + parts. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #26 on: October 31, 2021, 10:16:24 AM »
Thanks Paul, I am about to resolder those two wires on the oct.

Are there any other readings I can take to narrow down the issue on the big board?

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #27 on: October 31, 2021, 11:13:33 AM »
It's totally possible that the big board just didn't survive the flux event.  What is the DC resistance to ground that you get from OA and OB on the big PC board?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline goldencalves

  • Jr. Member
  • **
  • Posts: 28
Re: Speedball upgrade fail after a month, voltages way off
« Reply #28 on: October 31, 2021, 11:28:52 AM »
Resistance to ground from:
OA - 0
OB - 124.7

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 15851
Re: Speedball upgrade fail after a month, voltages way off
« Reply #29 on: October 31, 2021, 02:02:11 PM »
OK, can you post some photos of how the TIP50 is mounted on the A side? 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man