Watts Abundant Protect Board

hayabusa

hayabusa

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I've been viewing this site for a few years but more recently, became a member. I'm an old fart who's heavy into audio listening and repair, firearms/hunting and classic car restoration. In any event, this is my first post and of course, I have a question.

I'm in the process of adding Don's protect board to my PL400 S/N 544-022A. A about a year ago, I installed a White Oaks Rev C control board and cap kit. The amp works flawlessly and I couldn't be happier with the WOPL upgrades. At that time, I purchased Don's protect board however, I never got arround to installing it. So now it's time to get it done.

I went to Dons site for the instructions and it has a update message that says to follow White Oaks documentation (for signal input I believe) if you are using a White Oaks board. I spent a few hours searching the Phoenix and White Oaks site however, I couldn't find the info, I think I need. I'm assuming that it's an improved grounding layout however, I really don't know so I thought I would ask.

Is there's any recommended changes to Don's instructions when using his protect board in a WOPL?

Thank you in advance, for any assistance, you can offer......Gary
 
Welcome Gary! I am sure Joe, Lee or Jer will be a long to help you shortly. I am a listener myself, don't know shit about electronics repair
 
Northwinds said:
Welcome Gary! I am sure Joe, Lee or Jer will be a long to help you shortly. I am a listener myself, don't know shit about electronics repair
Click to expand...

Thanks for the welcome. I'm no pro when it comes to electronic repair however, I'm usually able to stumble through fixing most problems, given enough time and solder!
 
hayabusa said:
I've been viewing this site for a few years but more recently, became a member. I'm an old fart who's heavy into audio listening and repair, firearms/hunting and classic car restoration. In any event, this is my first post and of course, I have a question.

I'm in the process of adding Don's protect board to my PL400 S/N 544-022A. A about a year ago, I installed a White Oaks Rev C control board and cap kit. The amp works flawlessly and I couldn't be happier with the WOPL upgrades. At that time, I purchased Don's protect board however, I never got arround to installing it. So now it's time to get it done.

I went to Dons site for the instructions and it has a update message that says to follow White Oaks documentation (for signal input I believe) if you are using a White Oaks board. I spent a few hours searching the Phoenix and White Oaks site however, I couldn't find the info, I think I need. I'm assuming that it's an improved grounding layout however, I really don't know so I thought I would ask.

Is there's any recommended changes to Don's instructions when using his protect board in a WOPL?

Thank you in advance, for any assistance, you can offer......Gary
Click to expand...

Glads to see you out of the shadows Gary. Some answers may be found here...http://forums.phxaudiotape.com/showthread.php/2268-Joe-s-Improved-Grounding-Scheme

What you need to make sure of is to run the ground wires from Don's board all the way to the Star Ground point. The rest of Don's instructions should be pertinent.
 
laatsch55 said:
Glads to see you out of the shadows Gary. Some answers may be found here...http://forums.phxaudiotape.com/showthread.php/2268-Joe-s-Improved-Grounding-Scheme

What you need to make sure of is to run the ground wires from Don's board all the way to the Star Ground point. The rest of Don's instructions should be pertinent.
Click to expand...

Thanks Lee. I did see and read that thread earlier however, I wasn't sure how much of it should (or could) be utilized with the protect board. I'll just use your recommendation and keep it simple by using a single grounding point at the star.

Thanks again....Gary
 
When you put in the new driver board did you also go with Joe's improved grounding scheme??
 
It's in the archives Przem....you've done it yourself...
 
laatsch55 said:
When you put in the new driver board did you also go with Joe's improved grounding scheme??
Click to expand...

No I did not. I installed it just as the instructions said on White Oaks site.

When I purchased the Rev C board from Joe, it was when he had just announced it so, I'm not sure if his improved grounding scheme had even been discussed. Then again, maybe I just missed it.

I just finished the install of the protect board and it's working great.

I ended up running two ground wires, one from J3-2 on the protect board, and the other from the input jack ground. I terminated both, at the star ground on the caps.

I did not install the ground wire that is suppose to go from the ground terminal strip in back of the transistors to J3-2 on the protect board. It's the one that's shown in Don's instructions. That eliminated another grounding point that would have been redundant being I already grounded J3-2 at the caps.

I'm sure it's not as effective as Joe's recommendations however, it does seem to work well.
 
And that's what counts Gary. But , even the old wiring scheme had 2- #16 grounds going to the -(minus) speaker outs. If you piggybacked that or ran a jumper for the relay ground you COULD pick up a ground loop. The RCA input ground plane should be isolated from everything. There should only be shielded cable grounds and shield on that anymore. Did you cut the bare wire tying the RCA input ground plane to the minus speaker posts? The single #20 wire tying the old driver board ground to the 3 tab terminal strip on the back wall should also be gone by now...
 
laatsch55 said:
And that's what counts Gary. But , even the old wiring scheme had 2- #16 grounds going to the -(minus) speaker outs. If you piggybacked that or ran a jumper for the relay ground you COULD pick up a ground loop. The RCA input ground plane should be isolated from everything. There should only be shielded cable grounds and shield on that anymore. Did you cut the bare wire tying the RCA input ground plane to the minus speaker posts? The single #20 wire tying the old driver board ground to the 3 tab terminal strip on the back wall should also be gone by now...
Click to expand...

I hear you and you are absolutely right, it's working great, but there's more that could be done, to further improve it. I'm going to order the Rev B LED kit and during the install, I'll make the changes. In the meantime, I have a McIntosh 2205 that needs a recap so that's my next project.

Thanks for taking the time to provide the additional detail.

P.S. I did cut the bare wire tying the RCA input ground plane to the minus speaker posts.
 
laatsch55 said:
How about a thread on that 2205????
Click to expand...

NavLinear said:
How about barely a thread? Welcome Gary to Phoenix!
Click to expand...

Thanks for the welcome Nav! Regarding the thread on the 2205, let me give it some thought. I don't think there's anything I could add that hasn't already been documented by gregory, during his outstanding restoration. I just finished an Audio Research D90-b that would have been a great candidate to document being you don't see much about them.

As you can tell by my number of posts, I'm not a big communicator on the net. I've been a member of Audiokarma for many years and I have well under 100 posts. However, one thing that I have noticed about the Phoenix forum that's different from most other ones, is there's no attitude and it's also about having some fun. I see to many people on other forums, getting into pissing contests and that's not for me. I like keeping things fun while informative so, I promise I'll be more actively involved here.



I forgot to mention something I discovered during the protect board install. I went to check the impedance of the test speakers, that I had hooked up to the Phase. I expected to be able to measure it, even though they were hooked up, because the protect board relay is de-energized, and the speakers should be isolated. So I thought.

Here's what I found;

Measurement on right channel from the speaker output plus to minus was 7.2 ohms. That turned out to be the nominal impedance of that speaker and about what I was expecting.

Measurement on left channel from speaker output plus to minus was .5 ohms! Not at all what I was expecting.

Okay I'm thinking WTF is going on. So, I disconnect both speakers and take the measurements again. Now I have .5 ohms on the left channel and an open on the right. Next, I pull the protect board relay and both measurements now show open. So the path to ground on the one output was through the protect board relay normally closed contact. I'm thinking, why isn't there the same path to ground on the other set of normally closed contacts.

After doing a few other checks, I discovered the problem was internal to the relay. I took it apart and found one side of the normally closed set of contacts, were not making contact. I had to reform it so that the relay (in it's de-energized state) would have continuity on both sets of contacts. Apparently, the protect board has the speaker outputs go to ground, maybe through a small resistor, when the relay is de-energized.
 
hayabusa said:
Thanks for the welcome Nav! Regarding the thread on the 2205, let me give it some thought. I don't think there's anything I could add that hasn't already been documented by gregory, during his outstanding restoration. I just finished an Audio Research D90-b that would have been a great candidate to document being you don't see much about them.

As you can tell by my number of posts, I'm not a big communicator on the net. I've been a member of Audiokarma for many years and I have well under 100 posts. However, one thing that I have noticed about the Phoenix forum that's different from most other ones, is there's no attitude and it's also about having some fun. I see to many people on other forums, getting into pissing contests and that's not for me. I like keeping things fun while informative so, I promise I'll be more actively involved here.



I forgot to mention something I discovered during the protect board install. I went to check the impedance of the test speakers, that I had hooked up to the Phase. I expected to be able to measure it, even though they were hooked up, because the protect board relay is de-energized, and the speakers should be isolated. So I thought.

Here's what I found;

Measurement on right channel from the speaker output plus to minus was 7.2 ohms. That turned out to be the nominal impedance of that speaker and about what I was expecting.

Measurement on left channel from speaker output plus to minus was .5 ohms! Not at all what I was expecting.

Okay I'm thinking WTF is going on. So, I disconnect both speakers and take the measurements again. Now I have .5 ohms on the left channel and an open on the right. Next, I pull the protect board relay and both measurements now show open. So the path to ground on the one output was through the protect board relay normally closed contact. I'm thinking, why isn't there the same path to ground on the other set of normally closed contacts.

After doing a few other checks, I discovered the problem was internal to the relay. I took it apart and found one side of the normally closed set of contacts, were not making contact. I had to reform it so that the relay (in it's de-energized state) would have continuity on both sets of contacts. Apparently, the protect board has the speaker outputs go to ground, maybe through a small resistor, when the relay is de-energized.
Click to expand...

Don routes the NC contacts hard to ground when the speakers are disconnected, not through a resistor. So with amp off you should measure close to short on the +/- speaker terminals.
 
I put the Watts board in before the PL20- used the original Watts instructions.

I don't think there's any real danger, but I'll make that change now that you remind me.
 
Gepetto said:
Don routes the NC contacts hard to ground when the speakers are disconnected, not through a resistor. So with amp off you should measure close to short on the +/- speaker terminals.
Click to expand...



Thanks Joe for the info. I figured that's what he did however, I got thrown off a little when the two channels measured differently. I'm glad all that was required was a little "tweaking" of the relay, to fix it.
 
hayabusa said:
....I forgot to mention something I discovered during the protect board install. I went to check the impedance of the test speakers, that I had hooked up to the Phase. I expected to be able to measure it, even though they were hooked up, because the protect board relay is de-energized, and the speakers should be isolated. So I thought.

Here's what I found;

Measurement on right channel from the speaker output plus to minus was 7.2 ohms. That turned out to be the nominal impedance of that speaker and about what I was expecting....
Click to expand...

There are no practical relays out there with contacts rated for 100VDC. If a an amp fails and puts out 80-100VDC it is very possible the relay contacts will arc and weld. The output relay is chosen with a "form C" contact. A form C has a normally open (N.O.) and a normally closed (N.C.). Normal is defined as shelf state/de-energized. When the relay circuit trips the relay coil is de-energized. The N.O. contact disconnects the speaker from the amp. The N.C. contact closes across the speaker acting as a crowbar (short) across the speaker which adds additional speaker protection.

Summary: If you read the resistance across the speaker terminals when the amp is turned off you'll read zero ohms. To actually read zero ohms the meter lead resistance has to be eliminated. If using a Fluke 87 or similar this is accomplished with the "Rel" function.

Rod Elliott has a great article on detector circuits and a separate one for relays. http://sound.westhost.com/articles/relays.htm. I think that this one may be fairly new as I don't recall seeing it when developing the P/l relay circuits. Although lengthy, it is a must read if you want to know anything about a relay.

The output relay protection in most amps and receivers only uses a normally open contact. Consequently speakers are often damaged despite having an output relay. I repaired a Marantz 140 a couple years ago that had the output relay contacts welded. Unfortunately I can't find the picture I took of the molten contact.
 
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