Jan, the tone of this post isn't necessary. It is a pre-amp and the cable modified is the power umbilical, not the mains cable. I agree that the modification was a bad idea.
To the OP, the best path forward is to undo the modification which in any case is ineffectual.. I would guess you have either a broken conductor or connector. Perhaps you have fried the particular filament regulator, check it.
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Not sure how you added resistors (or whatever) , to "bleed RF" or whatever.
A multi pin connector such as that shown way to late in the thread does NOT have space to add anything.
Care to explain what you did, show some pictures (if any available before/after side by side even better).
I can't wrap my mind around the "logistics" side of this problem.
A multi pin connector such as that shown way to late in the thread does NOT have space to add anything.
Care to explain what you did, show some pictures (if any available before/after side by side even better).
I can't wrap my mind around the "logistics" side of this problem.
No.
Wire resistance is minimal, so voltage loss is minimal.
Removing half of the strands means it is now 2X minimal, so not significant.
Definitely NOT losing half the voltage.
That means there are large capacitors involved.
Look carefully for shorts between the pins at the back of each connector (total of 4 places).
Or - gasp - use a multimeter to check for continuity and shorts?
Its a revolutionary idea in the tech world! It's an advanced concept called 'fault finding' .
Jan
Its a revolutionary idea in the tech world! It's an advanced concept called 'fault finding' .
Jan
Drop a tea bag in a cup, add boiling water, wait 5 mins, extract tea bag, add milk & enjoy.
Then go back and recheck everything.
Because you are now not stressed and can think clearly you will find the fault.
Then go back and recheck everything.
Because you are now not stressed and can think clearly you will find the fault.
Those CPC connectors are notorious for pins and sockets sliding back as you plug them in, then popping back out when you unplug them to make it look like they are okay. Try pushing on each pin one at a time to see if they are all latched into the housing. These have stumped many Thermo King reefer mechanics for hours. Amp makes a special pair of tweezers to properly insert them.
The mod is a documented internal ARC process. See attached document. The procedure is to attach a 1000 pF ceramic disc capacitor around each wire where it meets the pin, with shielding applied to the lead to prevent shorts. You are correct that it is tricky to accomplish, but it is possible.
I had actual accomplished this mod before I got myself in trouble. I had bad radio frequency signals coming through the umbilical. Four ferrite bands was sufficient to eliminate it, but I wanted something integrated. My first attempt, while messy, and with a few broken cap leads, worked great, it completely eliminated the RF signal intrusion. However, I wanted to redo it to fix the broken cap leads, and to overall clean things up. It was when I completed the "redo" that I had the trouble.
@jan.didden You clearly don't understand what I was trying to accomplish, nor do you have any interest in understanding it. If you have nothing nice or useful to say, please bow out of this discussion.
For the rest of you:
My fear is that I have damaged the wire-to-pin connections, created shorts, or both. I do have the correct tool to remove the pins, and I am taking pains to ensure they are locking in place. Having redone this mod twice, and now having redone the plug several times in my debugging, the wires and pin connections are getting stressed. I've ordered a complete set of replacement pins which I will install as needed to correct this issue.
I've traced continuity over every wire back to the regulator. There is continuity on every one. I am a bit confused on how to check for shorts. Some of the wires seem to have continuity to other filament wires naturally through the common lead? If I connect my meter between two adjacent pins, and I see continuity, how do I know if its normal continuity, or a short?
I don't believe I've killed any of the regulators. I've tried swapping filament connections around, and regulators that had been producing no volts will produce volts with the different connection. This leads me to believe I have a common return problem (no volts meaning the common wire isn't getting back to the power supply).
I just tested the filament regulators with no umbilical connected. One set of three produced ~14.5v to its return, the other set produce 0v, 0v, ~3.9v. That would seem to indicate I killed one bank of regulators. What would be the process to test this theory? Remove the transistors and test? If I did fry them, would the transistor be the thing that fried, or would I need to back-trace further up the circuit?
I had actual accomplished this mod before I got myself in trouble. I had bad radio frequency signals coming through the umbilical. Four ferrite bands was sufficient to eliminate it, but I wanted something integrated. My first attempt, while messy, and with a few broken cap leads, worked great, it completely eliminated the RF signal intrusion. However, I wanted to redo it to fix the broken cap leads, and to overall clean things up. It was when I completed the "redo" that I had the trouble.
@jan.didden You clearly don't understand what I was trying to accomplish, nor do you have any interest in understanding it. If you have nothing nice or useful to say, please bow out of this discussion.
For the rest of you:
My fear is that I have damaged the wire-to-pin connections, created shorts, or both. I do have the correct tool to remove the pins, and I am taking pains to ensure they are locking in place. Having redone this mod twice, and now having redone the plug several times in my debugging, the wires and pin connections are getting stressed. I've ordered a complete set of replacement pins which I will install as needed to correct this issue.
I've traced continuity over every wire back to the regulator. There is continuity on every one. I am a bit confused on how to check for shorts. Some of the wires seem to have continuity to other filament wires naturally through the common lead? If I connect my meter between two adjacent pins, and I see continuity, how do I know if its normal continuity, or a short?
I don't believe I've killed any of the regulators. I've tried swapping filament connections around, and regulators that had been producing no volts will produce volts with the different connection. This leads me to believe I have a common return problem (no volts meaning the common wire isn't getting back to the power supply).
I just tested the filament regulators with no umbilical connected. One set of three produced ~14.5v to its return, the other set produce 0v, 0v, ~3.9v. That would seem to indicate I killed one bank of regulators. What would be the process to test this theory? Remove the transistors and test? If I did fry them, would the transistor be the thing that fried, or would I need to back-trace further up the circuit?
Attachments
In the first post you said resistors. That's quite useless to drain RF. Now you say it's caps, that's a totally different game.
From your posted manual page it looks like connecting caps from each lead to ground.
And yes, the smart move is to diagnose the problem - measure the cable wires for shorts or discontinuity.
All that pulling back of the cable insulation can easily break a connection or short two neighbouring cables together, or both.
A random search can keep you employed for weeks with no progress to show for.
Jan
From your posted manual page it looks like connecting caps from each lead to ground.
And yes, the smart move is to diagnose the problem - measure the cable wires for shorts or discontinuity.
All that pulling back of the cable insulation can easily break a connection or short two neighbouring cables together, or both.
A random search can keep you employed for weeks with no progress to show for.
Jan
Take the cable and use a multimeter on resistance range to measure the resistance from a pin on one end to the like pin at the other end. It should show a very low (single digit ohms) resistance. If the meter has a beeper function on the resistance range, it should beep to indicate a good connection.
Then measure the resistance of each cable pin to all other cable pins.
There should be very high resistance (often shown as 'overload' on the resistance range) and absolutely no beeps.
If each cable passes these tests, the cables are most probably allright.
Needless to say it is very unwise to attempt any modification on a valuable piece of equipment without a simple cheap multimeter in your arsenal.
Jan
Then measure the resistance of each cable pin to all other cable pins.
There should be very high resistance (often shown as 'overload' on the resistance range) and absolutely no beeps.
If each cable passes these tests, the cables are most probably allright.
Needless to say it is very unwise to attempt any modification on a valuable piece of equipment without a simple cheap multimeter in your arsenal.
Jan
I can do that. Is it possible that two filament wires would register a low resistance because their returns both connect to the same pad?
Measure the voltages without umbilical connected.
If you get input voltage of 22.5V but no output voltage of 15V, it mean that regulator IC (not a transistor) is damaged.
To make sure all filament connections are in the correct position, my suggestion is remove all tubes, connect the
umbilical cable and measure continuity from tube socket filament pin to the PSU pads, and also make sure that tube filament is return to the same regulator band.
For example, if V1 one filament pin is connected to pad #13, the other filament pin must be connected to pad #14, and so on...
umbilical cable and measure continuity from tube socket filament pin to the PSU pads, and also make sure that tube filament is return to the same regulator band.
For example, if V1 one filament pin is connected to pad #13, the other filament pin must be connected to pad #14, and so on...
Plan B: consider that umbilical damaged.
Build a new one, with fresh wire, pins, housing.
Were chassis mounted connectors also messed with?
If so, replace them too.
Keep original wires, of course, but cut 1mm of the tips so you can junk old pins
Use fresh pins and for sake of completeness, new chassis mount housings.
Your choice but I would forget the added capacitor Mod, Factory itself called it "tricky" and they are assembling those preamps all they long.
IF the ferrite beads worked, use them.
You can insert wires through them before assembling the connectors.
In my book that counts as "permanent".
In any case I much prefer an ugly but perfectly working solution than a nice looking one that gives me headaches.
Good luck.
PS: and if you insist on the capacitors, do not add them at the connector or cable but follow preamp internal wiring and add them at the board itself.
All those wires lead "somewhere". 😎
Build a new one, with fresh wire, pins, housing.
Were chassis mounted connectors also messed with?
If so, replace them too.
Keep original wires, of course, but cut 1mm of the tips so you can junk old pins
Use fresh pins and for sake of completeness, new chassis mount housings.
Your choice but I would forget the added capacitor Mod, Factory itself called it "tricky" and they are assembling those preamps all they long.
IF the ferrite beads worked, use them.
You can insert wires through them before assembling the connectors.
In my book that counts as "permanent".
In any case I much prefer an ugly but perfectly working solution than a nice looking one that gives me headaches.
Good luck.
PS: and if you insist on the capacitors, do not add them at the connector or cable but follow preamp internal wiring and add them at the board itself.
All those wires lead "somewhere". 😎
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My suggestion was to test the cable in isolation, not connected to anything. The idea is to make sure the cable is fine.
The next step would be to connect the cable and again, for each pin, to measure what goes in on the supply side and what comes out on the amp side, which of course should be identical for each wire.
For that step, you should write up a list of each wire, what is supposed to be on it (AC, DC, voltage level) so you can measure it correctly.
The next step comes after you find the problem.
Jan
The next step would be to connect the cable and again, for each pin, to measure what goes in on the supply side and what comes out on the amp side, which of course should be identical for each wire.
For that step, you should write up a list of each wire, what is supposed to be on it (AC, DC, voltage level) so you can measure it correctly.
The next step comes after you find the problem.
Jan
Each of the 3 regulators is "in parallel" with each other, so they aren't likely to be the problem if all 3 put out 0 VDC.
Check the INPUT DC voltage to the regulators instead. Maybe a rectifier diode is open or the input filter cap is shorted?
Or just a bad connection on the secondary winding.
Check the INPUT DC voltage to the regulators instead. Maybe a rectifier diode is open or the input filter cap is shorted?
Or just a bad connection on the secondary winding.