Gary's good tunes 700 build

[jbeckva]

This morning, I thought the best thing to do first would be tightening the terminal screws that still had the wires inserted. Starting with the leftmost blue wire going to the AC spot, I manipulated the board a little to hold it while using the screw driver, but that movement cause all the remaining wires (except the blue one) to pop out.

At the moment, there is:
one white wire coming from the topside of the back pane
a red wire coming from the topside of the back pane
two black wires contained in heat shrink running left to right along the amplifier's topside
and a second white wire coming up from the bottom
that have become detached.

Rather than guess which goes where, Jerry, can you please advise which wire goes to what terminal?

I should have labeled them but was not expecting them all to detach. That wire is pretty stiff stuff.

View attachment 17076 View attachment 17077

Keep that blue wire where it is on the AC leftmost terminal. It's paired white goes to GND next to it.

Then the two blacks go to the two GNDs above . if looking at the pic above and assuming the leftmost is #1, that would be the two GND terminals to the right (the white that is paired with the blue goes to the leftmost GND). Sidenote - those two GND connections are for the actual speaker left (LF) and right (RT) outputs, with....

Finally, the RED to the RT terminal, WHITE to LF.

The "tweak" was this... the diodes were relocated to right off the transformer AC wiring (so that it is DC going across the chassis). Then the diode that was connected via the leftmost AC terminal was bypassed with a jumper, allowing DC to pass directly through and onto the DCP circuit.

 

[jbeckva]

Hey Gary,

Your problem is most likely the screws backing out during transit. I've seen this a time or three with hardware that was designed to handle severe environments only to succumb to the transit environment. I have not installed a dc protect board in a 700 but Lee, Jer or Joe should be able to advise. If they're not available we can dig into the schematics and figure this puppy out. I think this gal will be singing real well soon.

Like I just emailed Lee, I'm wondering if tinning the wires should be done now (even though Joe says "no" lol). I've had a few of these pop outs occur on the phoenix connectors. My thought is by tinning, the ends are forced to "stand up" vertically and not compress with the guillotine contacts as it's tightened down. At least with the heavier gauge, perhaps?

 

[62vauxhall]

Thanks. I believe I have the wires connected properly but can you just have a look and confirm? I assume those two black ground wires are interchangeable between the two ground connectors?

 

[jbeckva]

Thanks. I believe I have the wires connected properly but can you just have a look and confirm? I assume those two black ground wires are interchangeable between the two ground connectors?

View attachment 17085

Correct, Gary - the two blacks are actually soldered to the same lug off of the buss bar, so interchangeable.

You got 'er... looks good.

 

[62vauxhall]

Like I just emailed Lee, I'm wondering if tinning the wires should be done now (even though Joe says "no" lol). I've had a few of these pop outs occur on the phoenix connectors. My thought is by tinning, the ends are forced to "stand up" vertically and not compress with the guillotine contacts as it's tightened down. At least with the heavier gauge, perhaps?

I've routinely tinned the ends of wire when the strands were soft copper. The strands of the wire you used are quite stiff and might not be malleable enough for the connectors to grip properly. If you did tin the ends of that wire, maybe the nice soft lead would give the connectors something to sink their teeth into?

 

[jbeckva]

I've routinely tinned the ends of wire when the strands were soft copper. The strands of the wire you used are quite stiff and might not be malleable enough for the connectors to grip properly. If you did tin the ends of that wire, maybe the nice soft lead would give the connectors something to sink their teeth into?

Thinking the same thing. Yeah if you can, put some lead on them.

 

[fitz43]

Like I just emailed Lee, I'm wondering if tinning the wires should be done now (even though Joe says "no" lol). I've had a few of these pop outs occur on the phoenix connectors. My thought is by tinning, the ends are forced to "stand up" vertically and not compress with the guillotine contacts as it's tightened down. At least with the heavier gauge, perhaps?

Not having looked at the connector (it's at home and I'm not) is it a guillotine or just the screw compressing the wire. If it's a screw there would be more surface area contact with the splayed out wire.

 

[62vauxhall]

Thinking the same thing. Yeah if you can, put some lead on them.

I'm good with it now. I carefully tightened them probably a bit more that you had them, gave them a tug test with a hemostat and they are secure. So far, the amp plays fine on both channels. The left would have cut out within a minute or two so I'm going to say problem solved.

When this problem started, I was convinced it was the preamp so I got another one. Seems I've got one too many of those now.

My friend Carol Ann's 12 year old dog Tyra just had a hysterectomy and mammary gland tumors removed. I spent six hours this morning making 6 dozen of these as a "recovery aid". Special gourmet liver biscuits.



I feel good for doing that and am happy that the amp is chugging along.

It's a good day and once again, thank you!

 

[62vauxhall]

Not having looked at the connector (it's at home and I'm not) is it a guillotine or just the screw compressing the wire. If it's a screw there would be more surface area contact with the splayed out wire.

I looks like there is metal in there.

 

[fitz43]

Hey Gary,

Your problem is most likely the screws backing out during transit. I've seen this a time or three with hardware that was designed to handle severe environments only to succumb to the transit environment. .

Can this be cured with a spot of nail polish? You choose the color.

 

[NavLinear]

Can this be cured with a spot of nail polish? You choose the color.

How about red?

 

[fitz43]

How about red?

Red is fine with me.

 

[laatsch55]

Fuck Me Red is even better...

 

[gadget73]

that color goes best with fuck me pumps.



Those screw terminal connectors are pretty common in industrial controls. Normally the wire is not tinned, its just twisted and inserted. The trick with it seems to be stripping enough wire to bottom out in the cavity and holding it there while you tighten the screw. It has to be tighter than would seem reasonable to hold the wires too, but once installed they stay pretty good. We've got a lot of stuff in this building with those terminals or similar types in panel boards. Its mostly wired with 14 or 16 awg stranded wire, nothing exotic and no high strand count stuff.

 

[laatsch55]

Amen....


I find myself almost embarrassed before I stop tightening those...

 

[Northwinds]

Yep, damn if it doesn't also vibrate out those nuts on the 400 DCP's too. That's why I started to solder them right onto the speaker posts. That was also Ron's problem initially with ole "Blackey" and how he kept having to replace a fuse now and then.

LOL, I still have the blown ones in a box, I count 12 of them!!!

 

[62vauxhall]

One channel intermittent again - and more

I'm wondering it I have a defective relay protection board after all - or something worse?

Last fall, one channel was intermittent and the suggestion of tightening the nuts holding the protection board to the speaker terminals seemed to do the trick but the problem re-occurred. It's at low volume levels (as before) and turning the preamp volume up just a bit (also as before) makes the channel come back on. I have yet to get inside and re-tighten the nuts but last night and today something else started happening.

BTW, when the channel (speaker) cuts out, the meter still registers.

Last night I thought I was hearing thunder claps and since a thunder storm was forecast, thought nothing of it. The sounds got more intense and closer together so as I went to a window to investigate I realized it was not thunder, it was coming from the 700B. Not sure how to describe the sound, kind of a low frequency crackle of varying intensity and not constant, it starts and stops. the amp was on but no music was playing so it was just at idle.

I got home about 2 hours ago, turned on the system, let it idle and waited. After 40 minutes or so, it started up with the noises and to make sure it was the 700B, I turned the pre-amps volume up and down but it had no effect on the noise so the 700B is producing it. I happened to look at the meters while this was going on and the right one would shoot up and hit top end. Another odd thing was the LED's on that meter dims during this noise - as the needle goes off the scale.

Early this week when I thought I was just experiencing an intermittent channel, I e-mailed Don Imlay asking his thoughts on if a relay on his board might be defective - bad contacts or something. He has not replied yet and I know I am asking for speculation but can this be something relatively simple like a bad relay or is there something more serious afoot?

 

[laatsch55]

Could be a number of things. We haven't experienced a bad relay on the 700DC protect relays yet. I did have one go bad but that was because I had an output go south and burnt the relay contacts. The board did it's job.
The dimming of the lights mean some serious current draw happening. Has it blown any rail fuses?

 

[62vauxhall]

Nope, fuses did not blow. I thought it strange that something intense enough to make the needle swing hard to the top like it did wasn't more horrifically loud and speaker damaging.

 

[62vauxhall]

False alarm

Seems the 700B is OK. I did what I do best and assumed....that since rotating the preamp's volume control did not increase or decrease the spurious noise, that the cause must be within the power amp.

I disconnected the PL and placed it where I could keep a convenient eye on it at idle while hooked up to a small pair of speakers. Several hours passed and no noise. I then installed a different power amp in the system and there was the noise. This is somewhat distressing because the preamp I've been using for the past 2 or 3 weeks was the one in which I replaced 41 capacitors and it was fine until recently. My hope is the fact the noise is not affected by the volume control, that it will narrow down where I should be looking for a fault.

That preamp is in front of me as I type this, powered up with a a pair of headphones plugged in and I now know that operating any control or switch does not affect the noise at all. It is sporadic, just on the right channel and nothing increases or decreases it's loudness.