I recently purchased a Phase Linear 700B. I decided to restore/get it running before white oak upgrade. Long story short I have put upgraded Watts Abundant power capcitors in it. I also replaced both 2N3403 signal transitors on both channels on the wired into the signal board but attached to the back plate.. I thought that was the problem. One of the transistors was shorted. It wasn't. Long story short, is there a diagnostic chart for Phase Linear 700B? I haven't found anything obvious to explain why the left channel went out. Also the power output doesn't seem to have a lot of power and I know that isn't normal. Thanks for any and all help.
Left Channel on Phase Linear 700B out
- Thread starter Ohioriver
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- Halfbiass...Electron Herder and Backass Woof
Well, I don't usually sell caps, unless someone asks when they order a relay board. I keep a dozen or so on hand.
Reading the 700 service manual, attached here, costs nothing. The manual has a very good troubleshooting section. Read the entire section on checking transistors. A decent meter, set on the diode scale, can identify troubles. Rarely do the dioes fail if on their own. Since one channel appears to be working, there is a reference. I do not favor wholesale parts change outs. That said, Q1/Q2 are on the top of the list of problem children the last couple years. The light bulb test set with a 100 watt incandescent bulb is mandatory.
Reading the 700 service manual, attached here, costs nothing. The manual has a very good troubleshooting section. Read the entire section on checking transistors. A decent meter, set on the diode scale, can identify troubles. Rarely do the dioes fail if on their own. Since one channel appears to be working, there is a reference. I do not favor wholesale parts change outs. That said, Q1/Q2 are on the top of the list of problem children the last couple years. The light bulb test set with a 100 watt incandescent bulb is mandatory.
Thanks for your response and yes I miss spoke. I recently purchase the output protection relay circuit from you and new power caps from white oak. I like to start with a good baseline and I am never afraid to fix something. That said I am a car guy. I can wire a house or a garage, but circuits are newish for me. Like you stated I am comparing the left channel to the right channel. The fix I would have done as a 15 year old ha ha. that said the only problem I have found was the 2N3404 signal transitions. Just wanted to see if there is a logical/better process. I have verified power and comparing one side to another. Fun fun fun.
Well, along with the NEW WA Protection board, and a pair of caps, you got a 40 year old ready to blow at any second, amplifier. A good baseline does you no good when you only use the transformer and meters for the transformation to a full blown WOPL. It is like comparing apples to blow jobs..... The baseline says nothing.
WOPL Sniffer. I not really sure how to respond, but thanks for you help and info. I had a PL 400 and loved it. It was my first real hifi amp. While it wasn't really audiophile quality it was close enough for me. I have restarted my two channel hobby after 20 years and I have this Phase Linear 700B. I want to listen to a Phase Linear 700B the way it was in the late 70's. I am planning to restore it and may never go any further than that. If I do build a White Oak (not Bob Carter Phase Linear) then I want to compare it to the original.
As you put it, it make no sense to me, to put money into a PLWO1000 that I have never listen to, hadn't heard about until I look at repairing my PL700B ,and I may not like the voice of the amp. The PLWO don't seem to be bringing a premium so the investment aspect isn't there, so if I don't like it I will be out $1600. In my world that does not make sense. This forum came up as a Phase Linear forum. I was looking for help from Phase Linear enthusiasts. I have heard many "high end" audio system that didn't sound good to me. Audio is subjective. I am hoping that the Phase Linear 700B has the same voice as a Phase Linear 400 that I previously had.
Also I am power a set of Snell Acoustic Type A, also is a restoration process.
As you put it, it make no sense to me, to put money into a PLWO1000 that I have never listen to, hadn't heard about until I look at repairing my PL700B ,and I may not like the voice of the amp. The PLWO don't seem to be bringing a premium so the investment aspect isn't there, so if I don't like it I will be out $1600. In my world that does not make sense. This forum came up as a Phase Linear forum. I was looking for help from Phase Linear enthusiasts. I have heard many "high end" audio system that didn't sound good to me. Audio is subjective. I am hoping that the Phase Linear 700B has the same voice as a Phase Linear 400 that I previously had.
Also I am power a set of Snell Acoustic Type A, also is a restoration process.
Ohioriver, your not alone in your thought process. I think Perry is expressing his long time experience that in the end the WOPL upgrade will be the final destination and there for not worth spending money twice. However like you I wanted to verify that the White Oak road was right for me. I can’t speak about the 700B but the WOPL 400 and the WOPL D500 are both improvements over the stock amps while maintaining the Phase Linear “voice”. For me, I like owning both the stock amps and the upgraded amps but any PL amp that goes in my systems MUST have the Wattsabundant speaker protection relay for safety. The “ collector” side of me wants to keep a few amps stock but the “performance and reliability “ side appreciates what the White Oak design accomplished. In the end neither road is wrong and I think it is fantastic that we have choices on how to keep these old jewels alive.
Three things to check first that are easy to do and often overlooked are cleaning the attenuators with Deoxit and checking them with a ohm meter, making sure the correct value and length of fuses are installed and checked for continuity, and making sure the inner spring contact on the RCA jacks are actually contacting the plug and not bent.
If all of those items check out, then voltage checks are next.
Also make sure you have the polarity of those new storage caps correct. B+ wiring is at the top, B- wiring is at the bottom. The copper buss bar connects to the upper cap - terminal and the lower cap + terminal.
If your control board solder pads or traces are messed up or you find you need some unobtanium part you can't find new, then PM me. I live near Cleveland OH and have 3 control boards I'll never use that were pulled when upgrading the amps. I have no idea if they're good as I never plugged the amps in before tearing them down.
If all of those items check out, then voltage checks are next.
Also make sure you have the polarity of those new storage caps correct. B+ wiring is at the top, B- wiring is at the bottom. The copper buss bar connects to the upper cap - terminal and the lower cap + terminal.
If your control board solder pads or traces are messed up or you find you need some unobtanium part you can't find new, then PM me. I live near Cleveland OH and have 3 control boards I'll never use that were pulled when upgrading the amps. I have no idea if they're good as I never plugged the amps in before tearing them down.
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I'm with you.
I restored a 71 Land-Rover (points and all) to get the "1971 Land-Rover experience". And that itch was scratched. I even took it to Africa a few months.
And there I learned that it really is not the ideal version for that sort of thing (expeditions), so I ended up "upgrading" to a Diesel powered Defender 110. Because every facet of the 110 (other than the leaking door seals, patented by Land-Rover), is superior in every way.
I restored a 71 Land-Rover (points and all) to get the "1971 Land-Rover experience". And that itch was scratched. I even took it to Africa a few months.
And there I learned that it really is not the ideal version for that sort of thing (expeditions), so I ended up "upgrading" to a Diesel powered Defender 110. Because every facet of the 110 (other than the leaking door seals, patented by Land-Rover), is superior in every way.
Well, it's not a spring like a coil, it's the inner contact that's a flat piece of sprung metal. Over the years they no longer make good contact and may need bent out some with a small screwdriver. Grab a RCA cable, plug it in, and check for continuity. Ain't no telling what people have tried plugging into them over all those years. My 400 S1 was being used as a guitar amp by the prior owner.
Also make sure the issue is the amp, not the cables or associated equipment. Swap things around.
Also make sure the issue is the amp, not the cables or associated equipment. Swap things around.
Here's your 700B service manual, it's listed under Phase Linear 700. You'll have to register to download it.
https://www.hifiengine.com/manual_library/phase-linear/700.shtml
https://www.hifiengine.com/manual_library/phase-linear/700.shtml
I had a chance to check that my RCA's are passing signal. I check with the unit powered on that I have power at the fuses and 200 VDC on the transistor rails. Is that correct. I have check al transitions (in the chase) and test out ok doing a diode test from DC voltage drop.
When I check the resistance coming out of the pots both channels seems to be the same and reaching the same when adjusting.
As much as I hate to through in the towel, I am thinking about the board replacement, so I can get this thing up and running and sounding good. It seems to me as if there is a problem in the board that I am not able to find and if so a board replacement would "fix it". Am I being to simple about this?
When I check the resistance coming out of the pots both channels seems to be the same and reaching the same when adjusting.
As much as I hate to through in the towel, I am thinking about the board replacement, so I can get this thing up and running and sounding good. It seems to me as if there is a problem in the board that I am not able to find and if so a board replacement would "fix it". Am I being to simple about this?