Pearl - PH-03 Phaser issue

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andre23
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Post by andre23 »

I everybody, I'm new here, I've bought an old Phaser made by Pear in the '80s, sold as "not working", I have changed all the opas,chacked all the voltage, and also the MC14069, the LFO section seems work well but with the pedal engaged I can only heard the clean sound without the effected sound of the pedal.
I also removed the buffer with a 3dpdt for true bypass, so the MC14007 and all the other components from the buffer section are missing.
I took from "8" the out for true bypass.
Down here the schematic
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Pearl Phaser PH-03.jpg

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Blitz Krieg
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Post by Blitz Krieg »

blown diodes in the power section?

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Post by Fender3D »

Hi and welcome to the forum,

you should definitely hear a "phased" sound, cause the 4 stages will affect your signal when mixed with "dry" even when LFO or IC4 don't work...
so, check you're actually getting your output at C10. It might be a schematic error...

Otherwise check IC2 and/or IC3
Blitz Krieg wrote:blown diodes in the power section?
Why????

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tube-exorcist
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Post by tube-exorcist »

andre23 wrote: ..... I have changed all the opas,......, and also the MC14069, ......
Unfortunately IC4 is NOT a MC4069.....
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."

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andre23
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Post by andre23 »

@tube-exorcist
I'm pretty sure about IC4 because I removed the old one, it was a MC14069 by Motorola.
Before installing a new MC14069 I've tried other hex-inverter with no good result.
@Blizt Krieg
I will check the diodes but I think they work well 'cause all the pedal has a correct power supply.
@Fender3D
I can't heard any phased sound come out from the pedal, the IC2 and 3 work and I've taken the out from the C10

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Post by tube-exorcist »

andre23 wrote:@tube-exorcist
I'm pretty sure about IC4 because I removed the old one, it was a MC14069 by Motorola.
Yes, that MC14069 maybe could have been inside because......:
andre23 wrote: ....I've bought an old Phaser made by Pearl in the '80s, sold as "not working",.....
...... another "brilliant" solder jockey - maybe the seller - will have put it there.

This doesnt change anything on the fact, that IC4 is NOT (has NOT been) a MC14069 originally.

Have a look at the datasheet of the MC14069 and you will see that pin 7 of that chip goes to gnd and pin 14 to Vdd.

Image

When you have a look at the schematic you will see that Pin 7 of IC4 does NOT go to ground and PIN 14 does NOT go to Vdd. So it can´t be a MC14069.....
andre23 wrote: Before installing a new MC14069 I've tried other hex-inverter with no good result.
.... or another hex-inverter. It will be SOMETHING LIKE the (obsolete) AM79C11 or similar - a quad FET.
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."

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Post by Fender3D »

Lift C9:
does sound change?

If not, you have no signal into IC2 and/or IC3, because since you have 4 phase stages mixed at IC1a, you MUST hear some difference, modulated if LFO and IC4 work, static (phased) if they don't...

@tube

4069 is not used as inverter here.
If you don't connect power supply, you have access to mosfet and may use them as variable resistors... :wink:

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Post by tube-exorcist »

Fender3D wrote: 4069 is not used as inverter here.

If you don't connect power supply, you have access to mosfet and may use them as variable resistors... :wink:
Feel free to dream on about that there is a 4069 used here.
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."

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Post by Govmnt_Lacky »

All of the research I have done/seen points to IC4 being a 4069 :secret:

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Post by lasermonkey »

It's a 4069 in mine! Like pretty much every pedal I have bought off ebay, mine wasn't working properly. When I looked at IC4 at an angle to the light, you could see that they had just gone over the top of the IC with a black permanent marker, but the writing was still legible. I swapped it for a new one and it worked fine.

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Post by Dirk_Hendrik »

I do have some trouble contardicting Tube Excorcist on the device in question not being a 4069 since TE usuelly does not say something unless it's backed up with proper argumentation.
At the other hand I see a lot of suggestions the device is a 4069... :scratch:
Sorry. Plain out of planes.

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Post by lasermonkey »

I can only imagine that there are two versions. Maybe the 4069 was revision 2, because the original IC became obsolete?
Just a thought.....

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Post by Blitz Krieg »

tube-exorcist wrote:
andre23 wrote:@tube-exorcist
It will be SOMETHING LIKE the (obsolete) AM79C11 or similar - a quad FET.
otherwise what kind of phaser topology is it? It's not OTA based or LDR based.

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Post by aion »

Maybe photo evidence can help clear things up... mine is a Motorola MC14069UB for IC4. The pads on the trace side are fully lacquered with the rest of the PCB, indicating it's never been replaced or repaired.
Pearl PH-03 PCB
Pearl PH-03 PCB
lasermonkey wrote:I can only imagine that there are two versions. Maybe the 4069 was revision 2, because the original IC became obsolete?
Like Dirk, I'm hesitant to contradict Tube Exorcist since he knows more than I probably ever will. But the IC shown in the schematic is a 4069, and I can offer an explanation of how it works.

Start here:
https://www.diystompboxes.com/smfforum/ ... ic=40414.0

From that thread (fifteen years old), Mark links to this Japanese site with an in-depth technical analysis of the PH-03, which is fortunately still online:
https://houshu.at.webry.info/200511/article_1.html
https://houshu.at.webry.info/200511/article_2.html
https://houshu.at.webry.info/200511/article_3.html
https://houshu.at.webry.info/200511/article_5.html

Google Translate via Chrome renders it fully readable, and all the diagrams are in English as well. Not only is it confirmation of the 4069 being used, but also an explanation of how it's implemented (the fourth article in particular). I won't try to summarize it since, again, it's way above my experience level, but I'd suggest checking it out if there are any lingering questions about the 4069.

I do plan on fully tracing my unit in the next few months just to verify all the values against the schematic, since I have seen other minor errors in Pearl factory schematics (notably the OD-05, which is the only other one I've studied). But the explanation on the Japanese site shows it working exactly as shown in the schematic, so I think it's safe to say the factory schematic gives an accurate view of the overall architecture of the effect.

It's still kind of silly that they said "exclusive use" instead of just naming the IC, especially when you can just open one up and see for yourself. Maybe they thought they could hide it at first (as lasermonkey mentioned his was blacked out) but then eventually gave up on it (as all the others I've seen are not blacked out). Who knows.

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Post by cluster »

hello!

what about the phaser Multibox SE-1?
C4 is a mistery!
the schematic es wrong!

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