Bogner - La Grange

longtallronnie · Post by **longtallronnie** » 02 Sep 2021, 14:24

FeVeR2112 wrote: ↑02 Sep 2021, 14:02 Can you attach a picture of the 7660D so we can see how these pins are folded? I have never seen a "D" before and can't find a data sheet on it.

Depending on the IC model, pins 1 and 8 are either connected or not. Pin 8 is the V+ input and Pin 5 is the Vout. If pin 8 does not receive a connection, that IC is not doing anything.

Sorry that was a typo! It's a 7660S

longtallronnie · Post by **longtallronnie** » 02 Sep 2021, 14:27

Pins 1 and 8 definitely not connected, I'll try and upload some pics once I've figured out how.

longtallronnie · Post by **longtallronnie** » 02 Sep 2021, 14:36

I couldn't capture the print on them but they read 7660S CPAZ V19134P

FeVeR2112 · Post by **FeVeR2112** » 02 Sep 2021, 16:41

I would connect Pin 8 on both for sure. These won't function without it connected. The Variac switch is for 9V / 18V operation - without the pin 8, this switch will have no effect. The ICs as a pair also provide a 0V negative reference to the opamp IC in circuit.

If you have one, an LT1054 IC may be the better option in this pedal.

FeVeR2112 · Post by **FeVeR2112** » 02 Sep 2021, 16:52

I would connect Pin 8 on both for sure. These won't function without it connected. The Variac switch is for 9V / 18V operation - without the pin 8, this switch will have no effect. The ICs as a pair also provide a 0V negative reference to the opamp IC in circuit.

If you have one, an LT1054 IC may be the better option in this pedal.

the 7660S is designed to have Pin 1 and 2 connected. LT1054, pin 1 /2 are not to be connected.

longtallronnie · Post by **longtallronnie** » 02 Sep 2021, 17:10

Thanks for the advice.

I did try connecting pin 8 having checked the pin out but it produced a high pitch noise so I disconnected it again - I didn’t try the functionality of the switches at the time.
I’ll order some LT1054s and see how I get on.

longtallronnie · Post by **longtallronnie** » 02 Sep 2021, 17:58

Someone from another forum sent me a gutshot of their LG and it has two TC1044S fitted, I might try these too as they seem to be easier to get hold of in the UK

FeVeR2112 · Post by **FeVeR2112** » 02 Sep 2021, 19:06

If you try the LT1054 - DO NOT connect pin 1.

Lithium_Grim · Post by **Lithium_Grim** » 19 Apr 2023, 06:09

I am currently making a <commercial> new version of the PCB </commercial> and reentered the rabbit hole after a few years acquiring a bit more knowledge. Ok, I think there are some mistakes:

If the trace picture is right, the schematic has a mistake in the Clock of Tone section. On the secret gooped part sits the 2N5088.

If you follow the trace it goes back to the analog part and there something strange happens (NB the image should be interpreted as flipped vertically as the boards are connected back2back!!).

The emitter goes directly to both lug 2 and R7 (47R), however the schematic states it only goes to the 47R. Is the trace wrong? I ask this because the schematic is in line with the COT, the trace however is not.
In the schematic, the input capacitor before the 2N5088 is 470n. This is quite high valued compared to the 100n on the COT. Looking at the picture it might be a 47n instead as it is a smaller sized box and 470n tend to be bigger. Can anyone test/check this?
As a mod I would suggests converting the emitterpart of the la grange to the COT by adding a 1k pot as structure.
Another mod would be to use a switching jack as external expression pedal input. this way you can wire it as a substitution for the gain pot instead of in parallel. The current setup results in ca 25 k with no exp pedal and ca 12k with exp pedal connected.

Lithium_Grim · Post by **Lithium_Grim** » 06 May 2023, 08:41

Here some pictures of the final build of the new PCBs

Bogner - La Grange [traced]