Boss PH-1r

[R.G.]

With Ry's help, I've traced out the PH-1r from the picture links he posted.

I'll get it posted as soon as I've gotten most of the sticks, pebbles and bugs combed out of it.

Notable things about the PH-1r compared to other phasers.
1. They divide the incoming signal down by half to get a lower signal level into the phase line. It's later amplified back up in the final mixer.
2. They use drain feedback to linearize the phase FETs, as in the P45 but not the P90.
3. They do a really odd connection of their power adapter jack that floats the - side of the power adapter jack one diode plus the drop on a 100R resistor below signal ground. This is not a mistake in my tracing, as I initially thought it was. The factory PH-1 schemo has the same thing. What that means is that these pedals may not work and play all that well with other pedals when they are all daisy chained onto a single large DC power supply.  I'm still mulling over what if anything needs done to that.

[Arno van der Heijden]

3. They do a really odd connection of their power adapter jack that floats the - side of the power adapter jack one diode plus the drop on a 100R resistor below signal ground. This is not a mistake in my tracing, as I initially thought it was. The factory PH-1 schemo has the same thing. What that means is that these pedals may not work and play all that well with other pedals when they are all daisy chained onto a single large DC power supply.  I'm still mulling over what if anything needs done to that.

Maybe this is related to the fact that the older style Boss pedals require an unregulated adapter?
If I'm not mistaken these measure roughly +12V without load.

[R.G.]

Could be. That means that they will not work all that well on a daisy chained pedalboard using today's practice. Filtering in the signal ground/negative side is a problem.

[m_charles]

What that means is that these pedals may not work and play all that well with other pedals when they are all daisy chained onto a single large DC power supply.  I'm still mulling over what if anything needs done to that.

Hey RG, what would be the easiest fix for this? Or are you still mulling it over?
Thanks!

chuck

[DougH]

Maybe this is related to the fact that the older style Boss pedals require an unregulated adapter?
If I'm not mistaken these measure roughly +12V without load.

I have a couple of old Boss wall warts that measure +16v unloaded (!). I haven't had any problems running my Boss gear from the OneSpot though (so far).

[rmachado]

Hello friends, sorry if I posted in the wrong place, but here it goes:
I recently bought a Boss PH-1r, and it not looks a lot like another PH-1r I had a few years ago.
What does the bias trimpot?, as shown in the schematic at this link:

http://www.geofex.com/FX_images/Boss%20PH-1r.pdf

Sorry my english.
Thank you all.

[cobra94]

Arno is correct regarding the power supply adapters supplied by Boss.  The original adapters "ACA-120" were unregulated 12V units, while the newer "PSA-120" are 9V regulated versions.

This being said the diode resistor combination are effectively bypassed when you daisy chain a few pedals together thus making it usable with a 9V reg. supply.  If the pedal is used by itself on 9V reg. you will notice the led being dim and the sound not so good.

What I think you are missed in your schematic R.G. is that usually (if you look at Boss service notes for older pedals of the ACA type) they usually have a 11V zener p/n RD11EB where you have your PD (I assume you meant protection diode) as a form of crude regulator for the 12v unregulated supply.

Cheers

[rmachado]

Hello Cobra94.
Actually I already removed the diode and resistor, made ​​a short in them.
I would really like to know how is trimpot.
Sorry my english.
Thanks!

[zombiwoof]

Arno is correct regarding the power supply adapters supplied by Boss.  The original adapters "ACA-120" were unregulated 12V units, while the newer "PSA-120" are 9V regulated versions.

This being said the diode resistor combination are effectively bypassed when you daisy chain a few pedals together thus making it usable with a 9V reg. supply.  If the pedal is used by itself on 9V reg. you will notice the led being dim and the sound not so good.

What I think you are missed in your schematic R.G. is that usually (if you look at Boss service notes for older pedals of the ACA type) they usually have a 11V zener p/n RD11EB where you have your PD (I assume you meant protection diode) as a form of crude regulator for the 12v unregulated supply.

Cheers

Actually, the ACA adaptors were unregulated 9 volt adaptors, that put out over 12 volts.   They say "9 volts" on them, but put out much more.   When I measured my ACA adaptor without it being hooked up to a pedal, it puts out 14.2 volts, although most people usually say 12 volts, because a regulated 12 volt power source will work with those pedals.  And as stated, the extra two components in there acted to reduce the voltage of the unregulated ACA adaptor to around 9.6 volts, or whatever a standard 9 volt battery puts out.

Al

[cobra94]

Actually, the ACA adaptors were unregulated 9 volt adaptors, that put out over 12 volts.   They say "9 volts" on them, but put out much more.   When I measured my ACA adaptor without it being hooked up to a pedal, it puts out 14.2 volts, although most people usually say 12 volts, because a regulated 12 volt power source will work with those pedals.  And as stated, the extra two components in there acted to reduce the voltage of the unregulated ACA adaptor to around 9.6 volts, or whatever a standard 9 volt battery puts out.

Um...not exactly.

There were two diffierent outputs of the ACA-120 (actually 4 versions for different input voltages).  The first was the 12V unregulated that was later changed to 9V unregulated.  The second was offered at the same time the PSA (regulated verson) came out.  The link explains it more in detail.

http://www.bossarea.com/other/aca.asp

While the resistor and diode in series lowered the input voltage on the negative side, they also added a Zener diode (S5500G or RD11EB) on the positive side of the power supply.  This was my original observation to R.G.'s schematic pointing out it was replaced with a "regular" diode for protection.  This BTW is perfectly fine if running from a regulated PS.

Cheers

[Fender3D]

Um...not exactly.

There were two diffierent outputs of the ACA-120 (actually 4 versions for different input voltages).  The first was the 12V unregulated that was later changed to 9V unregulated.  The second was offered at the same time the PSA (regulated verson) came out.  The link explains it more in detail.

http://www.bossarea.com/other/aca.asp

While the resistor and diode in series lowered the input voltage on the negative side, they also added a Zener diode (S5500G or RD11EB) on the positive side of the power supply.  This was my original observation to R.G.'s schematic pointing out it was replaced with a "regular" diode for protection.  This BTW is perfectly fine if running from a regulated PS.

Cheers

Not every Boss pedal sports a zener...
some of them have a 1N400x for reverse polarity protection.
Some schematic indicates for both 1N400x or S5500G too.

[zombiwoof]

Actually, the ACA adaptors were unregulated 9 volt adaptors, that put out over 12 volts.   They say "9 volts" on them, but put out much more.   When I measured my ACA adaptor without it being hooked up to a pedal, it puts out 14.2 volts, although most people usually say 12 volts, because a regulated 12 volt power source will work with those pedals.  And as stated, the extra two components in there acted to reduce the voltage of the unregulated ACA adaptor to around 9.6 volts, or whatever a standard 9 volt battery puts out.

Um...not exactly.

There were two diffierent outputs of the ACA-120 (actually 4 versions for different input voltages).  The first was the 12V unregulated that was later changed to 9V unregulated.  The second was offered at the same time the PSA (regulated verson) came out.  The link explains it more in detail.

http://www.bossarea.com/other/aca.asp

While the resistor and diode in series lowered the input voltage on the negative side, they also added a Zener diode (S5500G or RD11EB) on the positive side of the power supply.  This was my original observation to R.G.'s schematic pointing out it was replaced with a "regular" diode for protection.  This BTW is perfectly fine if running from a regulated PS.

Cheers

I know about that link and have read all of the info around about the ACA/PSA thing, and I have an early ACA adaptor.   AFAIK, they always SAID 9 volts on them, and were unregulated.  Unless someone can show me a picture of one that actually says 12 volts on it, that's my opinion.   I've seen a number of them and they all said 9 volts on them, mine does and as I said it actually puts out 14.2 volts.

Does anyone have a pic of an ACA adaptor that says 12 volts on it?.  I've never seen one.  I'm not above being proved wrong!.

Al