phase linear 400

[ABebar]

Adam, make sure your solder joints at the bridge are not cold. A couple of them look sketchy where the solder is not flowing into a meniscus on the bridge tab, rather it is a blob sitting on top of the tab. Very high peak currents exist at these connection points. Trying not to be critical but these should be improved up. You will need to leave your iron dwell on these connection points longer to fully heat the tab and let the solder flow. These tabs are designed primarily for Faston connections. When soldering, you have to overcome the thermal mass that exists here.

I'm literally here for constructive criticism. I truly appreciate the feedback and suggestions. I'll crank up my iron and reflow these.

 

[George S.]

Well, there would be a issue if you want to run a led light board rather than Cylon meters. Can't tell from photos what aux power wiring that trans has. Working today. Later.
Just saw your msg about the theater buy while typing this.
The S2 trans were internally wired for digital led meters, the S1 trans were were internally wired for light bulbs and analogue meters. Your probably going to have to run a S2 face plate with digital meters on that unit if you have one.
Compare S1+S2 transformers and schematics. Not the same in regards to meters.

 

[ABebar]

Well, there would be a issue if you want to run a led light board rather than Cylon meters. Can't tell from photos what aux power wiring that trans has. Working today. Later.
Just saw your msg about the theater buy while typing this.
The S2 trans were internally wired for digital led meters, the S1 trans were were internally wired for light bulbs and analogue meters. Your probably going to have to run a S2 face plate with digital meters on that unit if you have one.
Compare S1+S2 transformers and schematics. Not the same in regards to meters.

Aw man. I definitely want to run a WO light board with analog meters. That's what it came with (analog meters and original incandescent bulbs), but I have no idea how it was working. The listing said "both channels blown" on this one, so I didn't even bother plugging it in before tearing it down.

 

[George S.]

Aw man. I definitely want to run a WO light board with analog meters. That's what it came with (analog meters and original incandescent bulbs), but I have no idea how it was working. The listing said "both channels blown" on this one, so I didn't even bother plugging it in before tearing it down.

See what Joe says. Maybe you can. He would know for certain. I thought auxillary power voltages we're different between the series, but he would know, and check schematics, it might be shown. Working, Later.

 

[Gepetto]

White Oak can provide a light board plumbed for 15VAC operation, just ask Lee...

 

[George S.]

White Oak can provide a light board plumbed for 15VAC operation, just ask Lee...

Oh! Darcy's 700B running a dual primary transformer in Australia! I never thought about that. Cool.

 

[Gepetto]

Not the only one George

 

[Vintage 700b]

Good to know! I bought this 400s1, 10 (yes, ten) 700b's, and two 700s2's from a theater in San Francisco that closed because of the pandemic. They have been worked and reworked extensively. Some are in bad enough condition where they will be stripped for parts, but I'm hoping to end up with 4 or 5 WOPL's and a few rebuilt stock amps out of the best parts. This is the first of many for me.

Adam,
That is a nice score. You'll have a lot of fun working on those, congrats!

 

[laatsch55]

Not the only one George

I think we are on our 3rd one eh??

 

[laatsch55]

George, I had a 400 ser I that had 8.5 volt light legs..standard light board only.lasted 6 months. ..

 

[laatsch55]

Aw man. I definitely want to run a WO light board with analog meters. That's what it came with (analog meters and original incandescent bulbs), but I have no idea how it was working. The listing said "both channels blown" on this one, so I didn't even bother plugging it in before tearing it down.

Not a problem, just tell Joe what the light windings are putting out..BOOM..problem solved...

 

[George S.]

George, I had a 400 ser I that had 8.5 volt light legs..standard light board only.lasted 6 months. ..

I see. Was that caused by those early "hot" transformers?

 

[laatsch55]

Good to know! I bought this 400s1, 10 (yes, ten) 700b's, and two 700s2's from a theater in San Francisco that closed because of the pandemic. They have been worked and reworked extensively. Some are in bad enough condition where they will be stripped for parts, but I'm hoping to end up with 4 or 5 WOPL's and a few rebuilt stock amps out of the best parts. This is the first of many for me.

Remember Adam, all you need are the meterrs and a transformer...Joe has the rest..

 

[laatsch55]

I see. Was that caused by those early "hot" transformers?

George I didn't get a correlation like that...hell, I have a 400 trans that's 108 on the B-, B+ and only 6 on the lights..

 

[George S.]

George I didn't get a correlation like that...hell, I have a 400 trans that's 108 on the B-, B+ and only 6 on the lights..

Sounds like typical PL quality control. But, thinking about it, lots of consumer products from that era had similar issues.
Maybe Adam has a undocumented true Series 1 dual primary transformer, it coming from a San Fran club and all that. It'll be interesting to see what the light legs put out on his meter.

 

[Gepetto]

Sounds like typical PL quality control. But, thinking about it, lots of consumer products from that era had similar issues.
Maybe Adam has a undocumented true Series 1 dual primary transformer, it coming from a San Fran club and all that. It'll be interesting to see what the light legs put out on his meter.

I am shocked you would say that George

 

[gene french]

good morning....a little progress...i have checked every resistor, transistor, diode on the 400c board...i have checked all soldering pads and traces with a continuity meter...i have checked the bias transistors and diodes and resistors as well on the back plane...including the emitter resisters...those that did not test definitive in circuit were removed and tested stand alone...i rechecked all of the replaced caps....i feel secure all is ok on the board....waiting for replacement outputs....i have found several choices....i have enough outputs to test one channel or the other....should/could i do that without further damage??
ie. populate the left channel which was not affected by the damage...and test with the dbtester and check 5 amp fuses...if is ok...move to right side to test with dbtester and 5 amp fuses again???
thoughts...
thanks

 

[gene french]

Yahoo!

how is the upgrade coming along....i am in suspense...

 

[laatsch55]

You can test with just 2 rows of outputs . That would leave you with on drive and one output per column. All fuses should be in. Bring up on the DBT.

 

[laatsch55]

Q7 and Q10 tested good on each channel?? Those are the TO 39 cans towards the bottom.of the board. How about bias?? You know which.pot is for the bias?? Have your meter checking bias as you bring it up. You can have a 2N3403 that checks good but still lacks gain...