Crack not working after Speedball upgrade

robertone1 · 1739

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Offline robertone1

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on: May 30, 2016, 10:20:14 PM
Hi all,
finally got around to installing the Speedball upgrade today,but unable to work out why its not working.
Amp working fine before and passed all resistance and voltage checks.
Checked again before doing update and all oK.
Small board installed Ok and voltages Ok.
Small Board Voltages before install of large board

OA      71V
IA      190V
B-A/B     0V
IB      189V
OB       70V

However after large board upgrade something wrong,resistance check was Ok as it was higher than my meter would read.But voltage not good,
First no LED's are lit.
OA    1.4V
OB    1.7V
G       0V
B+    187V

Both tubes are glowing,but power transformer feels cold.Doesn't look like its warming up.
Checked install of TIP-50 transistor,but all looks same as instructions.
Looked at flowchart and Im confused where it says  'Is the B+ terminal wired to T5' ?  B+ for large board is suppose to be connected to 4U.
Tested point to point wires going into large board and no breaks(B/G/OA/OB),is there anyway to test TIP-50 connections for bad solder joints?

Hopefully I haven't stuffed up the transformer up or something else(How can I test thats its Ok since it doesn't seem to be warming up).

Update,have added photos of Large board removed from Crack Amp.Going to go back to stock till someone can help me sort out problem with SpeedBall.



« Last Edit: May 31, 2016, 09:45:23 PM by robertone1 »



Offline fullheadofnothing

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Reply #1 on: June 01, 2016, 05:14:23 AM
Your power transformer is working. If it wasn't, your tubes wouldn't glow and you wouldn't have proper voltage at B+.

Since you have incoming voltage to the board, the most likely culprit is bad solder joints. The middle leg of the TIP-50 on the right side of the underside picture almost appears unsoldered. Many of your joints look like the iron was not left in place long enough for the solder to properly flow. Reheat all the joints on the board to make sure they are solid.

Joshua Harris

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Offline robertone1

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Reply #2 on: June 01, 2016, 09:28:56 PM
I am going to get a desoldering pump and will try and resolder the large board again.
Going to leave it for a couple of days as Ive run out of patience, trying to sort this out.
Bit of a pain as I just got today a Tung-Sol 5998 vacuum tube to try,but can't.
Ill get back to the group either way soon.



Offline fullheadofnothing

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Reply #3 on: June 02, 2016, 04:01:11 AM
Your solder joints were not sufficently heated when they were made. You don't need a solder pump to fix this. In fact, with a pump, you will most likely make your problem worse.

You need to put your soldering iron on each joint one by one. Heat the solder until it flows evenly around the entire joint. Add a small amount of solder ONLY if there is not enough to properly flow. Some joints will requore more time than others.

Joshua Harris

I Write the Manuals That Make The Whole World Sing
Kit Packer Emeritus


Offline robertone1

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Reply #4 on: June 06, 2016, 12:07:53 AM
After a couple of days and getting no where,got replacement parts to take Crack back to stock setup again.
Completed it this morning,did resistance test and all O.K. Go onto Voltage test and crap still showing weird voltages again! Got close to Crack going out the window.
O.K thought about this again and how was it passing resistance test and failing voltage checks when it was working fine in stock form.
Then it hit me,resistance checks I was going as per the manual without the tubes,for voltage tubes are back in,could it be the simple that I got a bad tube.
Replaced both with spares I had and it now works in stock form again.
So not sure what happened when I installed large speedball board,but I must of shorted a tube(worked out that it was the 6080). But the 6080 tube was glowing when I checked them?
Since there might be a short still in my large speedball board Im getting another one and getting Shawn to assembly it for me,so I know its working before trying this again.
I have question about voltages but will post that in another thread.