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If LD 1 red is totally dead you might having more success by looking at LDR1 and LDR6 (those on TX4D). LDR6 comes before V3B and LD1 Red tone stack LDR1 comes after LD1 Red tone stack

1- Ribbon cable 2- Bad IC4 OP amp (TL072). Most common. 3- Less common: Bad multiplexer

Look for bad tantalum (yellow) capacitors and 75492 circuit (IC on the left). They are part of the switching system.

Thanks for the feedback. I've had the same issue recently with the master volume. It works right now but I think I'm gonna replace the ribbon cable connectors. These seems to get loose over time.

The screenshot below shows LDR19 has five legs. There are three holes for the cell on the left side of it's position. http://imgur.com/gallery/ManV1c1 The table you shared confirm this since LDR19 is used for proportional control. https://flic.kr/p/2hadw86

Here's a much more detailed view of TX4 board. http://imgur.com/gallery/9XMp4L2

Try to clean the connectors with Deoxit. If it dosent work, change the flat ribbon cables and IDC connectors. Does your TriAxis has colored or gray ribbon cables ? LD2 and Presence share IC4. Master vol. and DV share IC2. If you need to look at other digipots functions (LD2, Master vol...

LDR24 and LDR25 are missing on screenshot Circles: Red: LDRs Green: Trim pots Yellow: Calibration switches http://imgur.com/a/ManV1c1

[/url]https://www.flickr.com/photos/184069038@N07/48674691976/ [url] The original TX1 implementation can be found on YouTube. It clearly shows that the position of LDR 27 and LDR28 are not the same as the layout posted on this thread. Video title ”NAB 35 Reparaciōn de un Mesa Boogie Triaxis"...

I only have the pdf found on the internet. I think a part of your issue may come from the TX1 LDR diagram of this thread. Look at the printscreen Ive got from a YouTube video (LDR surrounded by red circles) . We can see that LDR27/28 are not at the same place. http://imgur.com/a/ManV1c1

When I changed mine, I bought 16 pins DIP sockets (7. 62mm x 2.54mm) and solder them to the board rather than soldering the components. Good luck

Positive lead on Pin 3 and negative on common side of resistors. But be sure to disconnect the TL072 tied to the function your'e testing.

HEF4051BP and MC14051BPC are both eight channels analog multiplexer/demultiplexer. They are used here for the same function. 4042 gives the logic state to 4051 pair. There is one 4042 for each set of 4051. In others words, it tells 4051 which resistor value to send to TL072. Look at the table...

Follow the signal path from TX3A to TL072 to LDR as I said above. You will find Bass, Treble and Mid digipots (HEF4051BP + set of resistors) right there: https://imgur.com/bJripC8 1- From TX3A, look for one of the defective parameter 2- For instance, change Mids keypad settings by...

These switches are used to isolate some LDR during calibration. Look on top of the switch, you will see a dot built in the switch (white part on top). When the dot is visible, the switch is in operation mode. When the dot is hidden, the switch is set for calibration mode. Dont forget to turn all...

Good point. These two trim pots are easy to find since they are identified on the board as "MD" for Mids and "B" for Bass. The calibration procedure says TP5 for Bass and TP6 for Mids. There are good chances to find a bad OP Amp here ( 8 pins IC TL072). If your OP Amps are seated in DIP...

Here's a link to both models https://www.thonk.co.uk/Documents/xvive/Xvive5C9%20Non-RoHs.pdf http://www.farnell.com/datasheets/1674291.pdf?_ga=2.109305733.1875830588.1576699543-1173307783.1576699543

Yes Only LDR18 is used for the low gain section. LDR19, the one on top has only two legs (5C9). I looked at mine (T-7542) which is from an early 2000 production. I dont have these LDR either. Mine has the FAT mode. These two LDR where present on V1 and V2 Recto. Tantalum switching capacitors...

From top left: 4th block: LDR13 5th block: LDR11/Top, LDRX1/Bottom 6th block: LDR10 7th block: LDR9 FX Loop LDR from left to right: 1st block: LDR5 2nd block: LDR4/top, LDR3/Bottom 3nd block: LDR2/Bottom, LDR1/Bottom I think there is only one pair on the bottom left of the main board (5C9...