OK ,so I have the other Citation XX amp that was purchased by another AKer from the Lansing site.
It's a good looking and extremely heavy beast!
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Like Wardsweb's it came in a custom box.
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It was purchased knowing that it wouldn't come out of it's protection circuitry.
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After a thorough visual inspection which included checking the main fuses.
Someone has "hamfisted"the left channel fuse cap!
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The fuses were fine and looked to be original.
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I hooked it up to my DBT but this amp requires a BIG dim bulb resistance because of it's two massive power transformers.
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The DBT glowed bright!!
(A 200 watt and 100watt bulb in parallel with an extra 100 watt bulb in reserve.)
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And then settled down after a few seconds as the four 10k caps charged up.
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I believe the "Infrasonic Protection" is a fancy way of saying "excessive DC voltage " on the speaker outputs.
A check of the simply massive speaker binding posts revealed 0.0 VDC on the right speaker terminals but a whopping 15.1 VDC on the left terminals!
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The amp has quite a bit of circuitry packed into very tight spaces so the only way to get readings on the amp boards was to split them apart.
Once you realized that the back plate was just a thin cover it was apparent that this was set up in a modular fashion.
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This allowed the individual amp modules to be separated enough to work on!
To protect all the beautiful black anodized surfaces from scratches I covered them with painters tape.
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I looked over the left channel amp board and didn't see anything burnt,etc.
In-circuit tested most of the transistors and all the outputs while getting acquainted.
It should be noted at this time that there is very little info out there on this amp.
The schematics that we have been able to find so far do not include ANY of the amp board circuitry,making troubleshooting a little harder.
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After finding 486 mv dc on the input signal wiring I isolated it at the amp board to see if it was coming from the headend circuitry or the amp module.
With that done the input of the amp remained at 486 mv while the headend section was 0.0 mv.
Also tested were the main high current dual power supplies for each channel.
They were both nearly identical at 150.1 and 150.2 vdc respectively.
This amp has secondary dual power supplies at 177 and 176 vdc each.
(In reference to each of their isolated grounds they are 75 vdc and 87 vdc.)
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The voltage output of the D3 and D4 bridge rectifiers is 177 vdc each when measured at the output of R1/R3 and R2/R4 respectively.
The right channel +HVR to G is +85vdc and -HVR to G is -87 vdc.
However the left channel +HVL to G is -16vdc and -HVL to G is -72 vdc.
Measurements on right channel Q2 are:
E +85vdc
C +65vdc
B +85vdc
Measurements on left channel Q1 are:
E -15.7vdc
C -15.0vdc
B -15.5vdc
Something is very wrong here!
IC1-4 have the same appearance as mje15033 transistors but not sure at this point if they have a different purpose.
I can swap IC1 and IC2 and see if the issue reverses.
Any input is always and greatly appreciated!!!!
Bob
It's a good looking and extremely heavy beast!
Like Wardsweb's it came in a custom box.
It was purchased knowing that it wouldn't come out of it's protection circuitry.
After a thorough visual inspection which included checking the main fuses.
Someone has "hamfisted"the left channel fuse cap!
The fuses were fine and looked to be original.
I hooked it up to my DBT but this amp requires a BIG dim bulb resistance because of it's two massive power transformers.
The DBT glowed bright!!
(A 200 watt and 100watt bulb in parallel with an extra 100 watt bulb in reserve.)
And then settled down after a few seconds as the four 10k caps charged up.
I believe the "Infrasonic Protection" is a fancy way of saying "excessive DC voltage " on the speaker outputs.
A check of the simply massive speaker binding posts revealed 0.0 VDC on the right speaker terminals but a whopping 15.1 VDC on the left terminals!
The amp has quite a bit of circuitry packed into very tight spaces so the only way to get readings on the amp boards was to split them apart.
Once you realized that the back plate was just a thin cover it was apparent that this was set up in a modular fashion.
This allowed the individual amp modules to be separated enough to work on!
To protect all the beautiful black anodized surfaces from scratches I covered them with painters tape.
I looked over the left channel amp board and didn't see anything burnt,etc.
In-circuit tested most of the transistors and all the outputs while getting acquainted.
It should be noted at this time that there is very little info out there on this amp.
The schematics that we have been able to find so far do not include ANY of the amp board circuitry,making troubleshooting a little harder.
After finding 486 mv dc on the input signal wiring I isolated it at the amp board to see if it was coming from the headend circuitry or the amp module.
With that done the input of the amp remained at 486 mv while the headend section was 0.0 mv.
Also tested were the main high current dual power supplies for each channel.
They were both nearly identical at 150.1 and 150.2 vdc respectively.
This amp has secondary dual power supplies at 177 and 176 vdc each.
(In reference to each of their isolated grounds they are 75 vdc and 87 vdc.)
The voltage output of the D3 and D4 bridge rectifiers is 177 vdc each when measured at the output of R1/R3 and R2/R4 respectively.
The right channel +HVR to G is +85vdc and -HVR to G is -87 vdc.
However the left channel +HVL to G is -16vdc and -HVL to G is -72 vdc.
Measurements on right channel Q2 are:
E +85vdc
C +65vdc
B +85vdc
Measurements on left channel Q1 are:
E -15.7vdc
C -15.0vdc
B -15.5vdc
Something is very wrong here!
IC1-4 have the same appearance as mje15033 transistors but not sure at this point if they have a different purpose.
I can swap IC1 and IC2 and see if the issue reverses.
Any input is always and greatly appreciated!!!!
Bob