Low Tide LPG and BBD not working

[DSonthebeat]

Hi guys,
first post here, I bought all the components in 2022 but only in the last week I found time to work on it.
Pedal power up, led ON, signal is passing both in bypass and with the pedal ON, mix knob passes signal on both dry and wet side and it seems to me that the sound gains some really subtle color plus the level between dry and wet is not the same and is affected in both cases by the Volume knob.
I can't hear any modulation at any settings at any turn of the BBD BIAS trim. I tried to take out the BBD and the pedal worked the same which I don't know if it means the chip is busted.
Gate (LPG) setting the trim it goes from flat to lowend bumps and white noise transitions, something is not right, never managed to make the filter stay almost closed even with the LPG knob at minimum.
The 3 possible pitfalls are: vintage MN3207 bought on ebay from cabintech, I used a through hole in socket J201s from Banzai in place of the 2SK208Y, just bought 2 and I don't know if they're good cause I don't know how to test them, third possible issue is the LM258P I bought from ebay.

These are some readings:

MN3207 Vintage Panasonic/Matsushita1024-Stage BBD Delay Line

pin 1 - 0v
2.50
2.77
4.69
5.02
2.48
1.63
1.65

LM258P

pin 1 - 1.07v
2.52
2.5
0
2.78
2.78
8.9

Q1 J201 alternative to 2SK208Y

1 - 5.26
2- 0.78
3 - 0

Q4 J201

1 - 2.07
2 - 0.42
3 - 0v

I tried to experiment with the boost and pad switches for the LPG but the best I accomplished is find those lowend peaks and subsequent noise burst.
Do the J201 and 2SK208Y have different pin layouts maybe?

One more thing, my 220uF capacitor is smaller than all the other build I encountered, it's the purple kemet in photo 4, it's rated 10v, could it be an issue?

 

[DSonthebeat]

Hi guys, small update, reading on the forum and checking online docs I realized J201 and 2SK208Y have different leg order, I twisted the drain and source to exchange them but unfortunately this didn't make any difference. I'll try to change those that appear to be 3k3 carbon resistors (didn't find metal film at the time on mouser) and randomly reflow joints removing ics before so I don't toast them. I really don't understand what's going on, the pedal doesn't do anything apart for the volume knob and mix knob. Please give me some help!

 

[DGWVI]

Through hole J201s follow the pin out of the screen print on the board. From your description, it sounds like the LPG is working, but there's something up with the BBD or Clock (CD4046)

Voltages for that chip will be helpful

 

[DSonthebeat]

Ok, small update, I swapped all the 8pin and 16pin ICs except the randomizer, BBD and the MCP602 (which I could find in my local store next week) plus I reflowed all the solder joints that seemed finnicky and replaced the 3k3 resistors with metal film ones, the 220uF capacitor and a 100nF one that seemed a little bit burned on the top.

LPG seems to do something more consistently now, a short burst of low-end thump happens at every note which sounds exactly like an envelope follower but it gates the signal abrupty and there's still the noise crackle at the end of notes plus it does that only at high LPG pot values (turned clockwise) while I thought the action of the LPG should be minimal at max and more closed at minimum, it seems it tries to open the envelope but can't keep it open after the transient even with boost engaged. Do you think I simply wasn't able to set the trim properly or something is still wrong?

One more finnicky thing is the Mix knob (B100K pot), I'll try to replace it because I cut the shaft with a small hacksaw and I fear I damaged the thing, if I tickle it fully turned clockwise (mix at 100% right?) it sometimes jumps in volume, the wire solder joints seem fine and it's the only pot that acts that way, I think it did that from the beginning.

The BBD doesn't do a damn thing, turning the BBD trim doesn't change the volume or sound, never did from the beginning, I don't understand how can it be that a BBD chip passes audio without functioning and the biasing doesn't change anything but since the LPG still doesn't work properly for now I would avoid ordering another expensive MN3207 from US (I'm in Europe) since the reissue is still unavailable everywhere.

I built a Son of Ben with Fairchild through hole J201s from Banzai (the J201s in the Low tide are not Fairchild but from Banzai too) and it works well, the Low tide is really a heck of a complex build... the last thing I would try to replace are the through hole J201 but could they be the issue if the pedal volume knob works?

 

[chris.knudson]

Have you tried swapping out the LM258?

 

[DSonthebeat]

Yep, I put a LM358 (they told me is an equivalent at the local store and I found confirmation here on the forum on another thread), that was the one I was more worried about after the BBD because they both came from eBay.

 

[DGWVI]

Ok, small update, I swapped all the 8pin and 16pin ICs except the randomizer, BBD and the MCP602 (which I could find in my local store next week) plus I reflowed all the solder joints that seemed finnicky and replaced the 3k3 resistors with metal film ones, the 220uF capacitor and a 100nF one that seemed a little bit burned on the top.

LPG seems to do something more consistently now, a short burst of low-end thump happens at every note which sounds exactly like an envelope follower but it gates the signal abrupty and there's still the noise crackle at the end of notes plus it does that only at high LPG pot values (turned clockwise) while I thought the action of the LPG should be minimal at max and more closed at minimum, it seems it tries to open the envelope but can't keep it open after the transient even with boost engaged. Do you think I simply wasn't able to set the trim properly or something is still wrong?

One more finnicky thing is the Mix knob (B100K pot), I'll try to replace it because I cut the shaft with a small hacksaw and I fear I damaged the thing, if I tickle it fully turned clockwise (mix at 100% right?) it sometimes jumps in volume, the wire solder joints seem fine and it's the only pot that acts that way, I think it did that from the beginning.

The BBD doesn't do a damn thing, turning the BBD trim doesn't change the volume or sound, never did from the beginning, I don't understand how can it be that a BBD chip passes audio without functioning and the biasing doesn't change anything but since the LPG still doesn't work properly for now I would avoid ordering another expensive MN3207 from US (I'm in Europe) since the reissue is still unavailable everywhere.

I built a Son of Ben with Fairchild through hole J201s from Banzai (the J201s in the Low tide are not Fairchild but from Banzai too) and it works well, the Low tide is really a heck of a complex build... the last thing I would try to replace are the through hole J201 but could they be the issue if the pedal volume knob works?

It sounds like you just need to find the sweet spot for the LPG- I do so with the pad and boost functions disengaged, and with the external LPG pot set at half way. There's not a technically correct way to set this trimmer- it's mostly down to personal preference and how responsive you'd like it to be

The JFETs are being used as buffers with gain, so they shouldn't have any bearing on the function of the BBD

Could you provide voltages for the Randomizer, MCP602and CD4046?


Biasing procedure courtesy of bowanderror

 

[KR Sound]

I just built this last week, and there was definitely a very small obvious location on the BBD trim pot. The gate trim was at full turn clockwise. I used a 201 for both spots, but may swap in the SK to see if it makes much difference when I rehouse it.

Check out this for biasing it:

Post in thread 'Low Tide - LPG not working.'
https://forum.pedalpcb.com/threads/low-tide-lpg-not-working.12396/post-129330

And the actual user manual as well.

 

[DSonthebeat]

It sounds like you just need to find the sweet spot for the LPG- I do so with the pad and boost functions disengaged, and with the external LPG pot set at half way. There's not a technically correct way to set this trimmer- it's mostly down to personal preference and how responsive you'd like it to be

The JFETs are being used as buffers with gain, so they shouldn't have any bearing on the function of the BBD

Could you provide voltages for the Randomizer, MCP602and CD4046?


Biasing procedure courtesy of bowanderror

Thanks, I'll measure them on monday and report here (I got the pedal in my studio), do I have to set the pots at specific levels to measure the voltages?
Last time I measured directly on the IC leg, is that correct or do I have to touch the solder joint on the back of the pcb with the probe?

 

[DGWVI]

Thanks, I'll measure them on monday and report here (I got the pedal in my studio), do I have to set the pots at specific levels to measure the voltages?
Last time I measured directly on the IC leg, is that correct or do I have to touch the solder joint on the back of the pcb with the probe?

IC legs are fine for multimeter

Here's an older thread with symptoms relating to yours

I'll try to get voltages from one of mine later to compare

 

[DSonthebeat]

Hi guys, first of all I replaced the B100K pot and it doesn't crackle anymore, bad news is that with the B100K (MIX) at 100% there's no setting of the LPG that let's the signal pass apart from minimum at a veeeery low volume, the filter frequency actually seems to be always too low so the sound is "closed" but with the LPG at max it just opens for a pop, then small hiss tail or light crackle and silence. I tried to bias it but it doesn't change much. It seems a biasing issue but it really also seems like a gain component which is not working correctly, no matter the setting. I reconfirm that with MIX at 0 the signal passes and the VOL works as it should.

I'm sorry if maybe I said something different before about the pedal passing signal in both cases, maybe the defective B100K pot was deceiving me.

I measured the ICs you requested AND the transistors so maybe you can tell me if there's something weird. VOL about 50%, DAMP at minimum, RATE about 50% and DEPTH at 100%, LPG at 0%.

Randomizer

4.70
2.96
5
0
from 0 to 3.5
5.02
5
5.02

MPC602

from 0 to 3.14
from 0 to 3.14
from 0 to 3.14
0
2.15
2.15
from 0 to 3.45
5.02

CD4046 (replaced one)

0
2.47
2.55
2.55
0
from 0.63 to 0.77
from 0.63 to 0.77
0

from 0 to 3.5
from 0 to 2
from 0 to 1.5
from 3.17 to 3.5
0
5.02
0
5.02

LM13700N

0
5.02
4.47
4.41
0
0
0
0.72

0.04
0.04
8.9
0
4.24
4.25
4.5
0.01

Q2 2N3904

4.6
5.26
8.9

Q3 2N3904

3.19
3.76
5.73

Q4 J201

2.08
0.42
0

Q5 2N3904

1.42
2.08
8.9

IC1 LM78L05

5.02
0
8.9

I confirm the previous readings, also in the MN3207 although it varies a bit because in these days I changed the BIAS trim position.

 

[basmaster003]

Not sure if it's helpful but i wasn't really getting any modulation on mine at first but after reseating all the chips it works perfectly. I think i might have pushed one too hard into the socket.

 

[andare]

Not sure if it's helpful but i wasn't really getting any modulation on mine at first but after reseating all the chips it works perfectly. I think i might have pushed one too hard into the socket.

Mine does nothing. As I turn up the Mix, the dry volume goes down, as expected. I replaced all kinds of chips and checked the J201 orientation multiple times. It is now an expensive specimen in my hall of shame. I also had trouble fitting the 6 pots to my hand-drilled enclosure.
I hate this pedal haha

 

[basmaster003]

I don't know about the voltages but have you checked the transistor sockets? I've never had good luck with those circular style ones with transistors. I used them on a fuzz factory build and if i breath on them or the enclosure gets disturbed in the slightest they lose connection.

 

[Cybercow]

Hi guys, small update, reading on the forum and checking online docs I realized J201 and 2SK208Y have different leg order, I twisted the drain and source to exchange them but unfortunately this didn't make any difference. I'll try to change those that appear to be 3k3 carbon resistors (didn't find metal film at the time on mouser) and randomly reflow joints removing ics before so I don't toast them. I really don't understand what's going on, the pedal doesn't do anything apart for the volume knob and mix knob. Please give me some help!

FWIW, the Drain & Source legs of all JFETs are interchangeable. So twisting the legs of the Drain & Source is not necessary. Where the gate goes IS important.

 

[Cabintech]

If you find the MN3207 is faulty, we will replace it with a V3207 at no charge. We stopped stocking most NOS vintage BBD chips because fallout rates were too high and unpredictable.