700B submerged in 6” of water....hmmmmm...

Wheel-right · Jul 19, 2019

Joe,

I have half a dozen chassis with 700/700B series 1 transformers in them that I'm building from scratch along with a bunch of 700 series II front panels. Since the 700B VU meters are practically unobtanium these days I have found it easier to buy broken 400 series II amps just to get the sub-fronts and LED VU meter displays out of them. (NOTE: Those 400 series II's then will have 400 series 1 front panels and VU meters installed in them.) I've bought half a dozen or so of the aforementioned 12.6V CT transformers and installed them in these chassis along with Dale 50W 5 ohm resistors in the Zobel network. There is no room to install Don's relay.

Follow me so far?

Having a 6V LED VU meter display would eliminate the need for the 12.6V CT transformers and allow me install Don's relay board.

I also had some requests over the years to change out the 700 and 700B series 1 front panels and install a LED style display instead. The front panels need not say Phase Linear on them or the need for a sub-front. One customer send me some artwork illustrating what he wants on the front panel along with his company's name on them.

The goal here is to have one of every pc board revision either made by Phase Linear, yourself, Nick Soudas, Steve Mantz, etc installed in them.

Currently I have around dozen 700's and a dozen 400's.

I've also installed some thermal cut-out switches (normally open) that are wired in series with the AC outlet (jn Phase Linear 700 series amps) so that the fan(s) will only turn on when the amp reaches a certain temperature. In this case, I have a supply of switches originally used in Hafler amps rated at around 55 degrees C. Phase Linear used a similar approach using a fan in the D-500 (no AC outlet here though). Albeit, if my memory serves me correct, the thermal-cutout (normally open) switch in the D-500 is rated at 70 degrees C.

Ed

Just curious but does this mean the VU meters on the 700B and the 400 series I are the same size even though I know they are different styles?
Also does anyone have a picture of a 700B without the colored screens on that cover the 700B logo between the meters or even a description of how it is assembled since I've never seen one? Thanks much for any help.

oldphaser · Jul 20, 2019

FredR said:

Fred,

I had as many as 150 Phase Linear amplifiers at one time.
I only wish I had them all (and the knowledge on how to repair them) back in the late 70's/early 80's when I was a sound-man.

Ed

oldphaser · Jul 20, 2019

Gepetto said:

Joe,

Good to know that your will work down to 5V.

Most of the LED meter displays I've seen use IC's which require at least 9 Volts or so.

I do have an interest in pursuing this.

Let's talk more about this after the summer season is over in a month or so.

Ed

oldphaser · Jul 20, 2019

Geegz said:

I have an interesting collection of very rare Phase Linear amplifiers including the following:
1.) Bob's 1 of 3 bridge amps built which was the first Phase Linear 700 built back in early 1970.
2.) Phase Linear 700 (Kelly DeYong) amp. Also early 1970. Has trim-pots in the protection circuit.
3.) Purple Phase Linear 700 series 1 built for Heil Sound.

I have posted pictures of Bob Carver with the bridge amp and Kelly DeYong amp. I have not posted any pictures of the Heil Sound amp.

I had at one time (3) Phase Linear 700 series 1 amps built for Bell Labs (which would do .25% THD at 100KHz at rated output). Dean has the first one. The other (2) I sold to a collector.

If the price is right, I may even consider selling off some of the aforementioned amps. Make me an offer I cannot refuse!

Ed

TelRay · Monday at 9:51 PM

Hello everyone,

I’d like to take this opportunity to both introduce myself and breathe new life into this thread.

Part 1: Introduction
My name is Federico, and I live in the San Francisco Bay Area. I’m a musician—though I hesitate to call myself a “pro musician,” as I lack both the skills and income to justify that title—and an audio enthusiast. I’m usually content with affordable consumer receivers, turntables, and similar gear, which I enjoy restoring by upgrading their usual suspects (caps, resistors and transistors) with higher-quality components.

Part 2: Reviving This Thread
This past weekend, I was fortunate to receive a generous gift from Bill Berndt—thank you, Bill! I inherited this amplifier (subject of the thread), along with another PL700 for parts, which includes the transformer, backplane (minus the transistors), and power capacitors.
I’m planning to take on the challenge of restoring this old fellow, which won’t be easy given the time it spent underwater. Here’s what I’ve done so far:

I managed to clean the faceplate to a pretty decent level (as Bill said, those controls were pretty much soldered to the pots and it took a lot of effort and WD40 to take them out)

I removed the transformer, which was swollen and rusty. I’m considering discarding it and using the one from the parts unit instead.

I’ve started cleaning the right VU meter, which was also submerged.

The Plan is to use the "donor PL700" transformer, but, here comes my first question: I am not sure if it's the same (as the original PT reads max power 750W and the donor one 960W). Both PT say 700B, so I guess it should be OK.

The second question is about the VU meter... i think it "maybe" could be saved (?). I was thinking spraying it with DEOXIT several times with intervals of 30 min or so. What do you think?

Additionally, this label was on the back of the faceplate. I couldn't find any information online about this.

Thank you guys in advance for the help

laatsch55 · Tuesday at 12:06 AM

I would do the deoxit . Had a bunch of controller circuit boards off the Magnetek BDP-515 drives that had rust between every pin on every IC. Saved em all. Patience is justly rewarded. Ya got nothin to lose on the meters...

If you find yourself needing a transformer , I have a few, pay the shipping and we're good.....

laatsch55 · Tuesday at 12:07 AM

Those Max Power numbers were INPUT power rating...

laatsch55 · Tuesday at 12:08 AM

Man.....gotta talk ya into having a video of powering up that transformer, that's gotta be interesting...

berndt · Tuesday at 12:32 AM

laatsch55 said:

I believe the second chassis and transformer came from you

laatsch55 · Tuesday at 7:21 AM

Hookay...

J!m · Tuesday at 11:38 AM

So, to attempt to clean the meters:

I would wash with plastic-friendly electrical cleaner. CRC QD I think is a good one. Then DeOxit (D100), soak and then repeat.

DO NOT TRY TO MECHANICALLY CLEAN THE METERS.

once they are reacting well, you may need to adjust them but get them clean first. I would not be surprised if a hairspring breaks with that much corrosion...

TelRay · Tuesday at 12:19 PM

thank you all for the replies and guidance!

laatsch55 said:

i'll try to measure the output voltages on the donor transformer in a few days and report back

laatsch55 said:

and that's why i have not attempted to measure output voltages on the original transformer

J!m said:

i have used Deoxit D5 so far and the needle started moving freely with no effort. I'll buy the D100 to continue with that one from now on

J!m · Tuesday at 4:03 PM

D5 is 5% deoxit (95% contact cleaner) and D100 is "pure" DeOxit. More economical where you can use and wash out with less expensive contact cleaner, or alcohol.

Gepetto · Tuesday at 5:11 PM

TelRay said:

Hello everyone,

I’d like to take this opportunity to both introduce myself and breathe new life into this thread.

Part 1: Introduction
My name is Federico, and I live in the San Francisco Bay Area. I’m a musician—though I hesitate to call myself a “pro musician,” as I lack both the skills and income to justify that title—and an audio enthusiast. I’m usually content with affordable consumer receivers, turntables, and similar gear, which I enjoy restoring by upgrading their usual suspects (caps, resistors and transistors) with higher-quality components.

Part 2: Reviving This Thread
This past weekend, I was fortunate to receive a generous gift from Bill Berndt—thank you, Bill! I inherited this amplifier (subject of the thread), along with another PL700 for parts, which includes the transformer, backplane (minus the transistors), and power capacitors.
I’m planning to take on the challenge of restoring this old fellow, which won’t be easy given the time it spent underwater. Here’s what I’ve done so far:

I managed to clean the faceplate to a pretty decent level (as Bill said, those controls were pretty much soldered to the pots and it took a lot of effort and WD40 to take them out)

View attachment 86333

I removed the transformer, which was swollen and rusty. I’m considering discarding it and using the one from the parts unit instead.

View attachment 86334

I’ve started cleaning the right VU meter, which was also submerged.

View attachment 86335

The Plan is to use the "donor PL700" transformer, but, here comes my first question: I am not sure if it's the same (as the original PT reads max power 750W and the donor one 960W). Both PT say 700B, so I guess it should be OK.

View attachment 86336 View attachment 86337

The second question is about the VU meter... i think it "maybe" could be saved (?). I was thinking spraying it with DEOXIT several times with intervals of 30 min or so. What do you think?

View attachment 86338

Additionally, this label was on the back of the faceplate. I couldn't find any information online about this.

View attachment 86339

Thank you guys in advance for the help

Federico, I would only use that transformer if you customer demanded really clean power...

TelRay · Tuesday at 6:01 PM

Gepetto said:

Hahahahaah... I agree, Joe!

Thanks for all the help with the PL400 over the past few weeks. I measured it at Peter’s (Quirk Audio), and the THD came in at 0.07%.
The plan is to keep this PL700B. Once I’ve confirmed everything else is working properly, I’ll be ordering all the WO upgrades

TelRay · Thursday at 9:37 AM

Quick update on the donor transformer testing.
I've got B+ 100V B- 100V (the original power caps that i measured to be at 9,000 -10,000 uF) and 5.3 VAC
I think the prospect of a "transplant" looks promising

Next step is to finish bringing back to life the rusty VU meter (Deoxit 100 should arrive tonight, however Deoxit 5 already made a nice job unblocking the pointer)
Does anyone have any leads for the lamps replacements? I will try to stay incandescent for the warm / vintage feel.

Hexis22 · Thursday at 2:22 PM

The warm white LEDs are very close in appearance to the stock incandescent bulbs with much better reliability and very little heat.

TelRay · Thursday at 4:14 PM

Hexis22 said:

yep, i am considering this my backup solution (the WO LED kit)

TelRay · Friday at 10:02 AM

Good morning all,

I was taking a good look at the transformer "donor" amp S/N 5832 and the "receiving" one S/N1273/0888 amnd have a couple of questions if I may (and many more to come, my apologies in advance

)

1.- DATE: i believe the receiving amp was manufactured in 12 1973 and the donor is an older version

- I've found this SWITCH present at the back of the receiving amp (LEFT) and removed or never installed on the donor (RIGHT).
What is it for and should I keep it if I am planning to go "full WO"?

(you can still see humidity under the heatsink of the receiving amp!!!)

2.- I've found this CIRCUIT at the input of the donor amp... what is it?

Thank you guys!

mr_rye89 · Friday at 10:52 AM

Might be for balanced inputs, the phone jack might actually be a TRS jack. Some of these were used in PA systems

700B submerged in 6” of water....hmmmmm...

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