PL 700B blown fuses and transistors

mlucitt

Veteran and General Yakker
Joined
Jun 24, 2011
Messages
3,412
Location
Jacksonville, FL
#21
What do you think and can you supply these items and how do I proceed to acquire them? Phase Linear 700B, Serial Number 6415.
I have all these parts for you (we have replaced the 180 Ohm bias resistor connected from the Base to the Emitter of Q11 and Q12 with a 150 Ohm resistor in the same location). We also substitute a single 5.1 Ohm 5W resistor for the two 10 Ohm 2W resistors Phase Linear used on the output Zobel Network. This makes things a little simpler.
PM me with your address and I will send them to you. Or you can order them from Mouser, here are the P/N's you need:
(2) 5.1 Ohm 5W Zobel Resistors.....................279-ROX5SSJ5R1
(2) 0.1 uF 630V 5% Zobel Capacitors............75-MKP1839410634HQ
(4) 10 Ohm 1% 1/2W Bias Resistors..............273-10/REEL-RC
(4) 150 Ohm 1% Q11/Q12 Bias Resistors....660-MF1/2CCT52R1500F
(20) 0.33 Ohm 2% Emitter Resistors..............660-MOSX3CT631RR33G
 

BobPep

New Around These Parts
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Feb 29, 2024
Messages
3
Location
West Hempstead, New York
Tagline
Love spending time with my kids and grandkids
#22
Hi ,

My names Bob, and I'm new to this forum and I just got a beat-up old Model # 700, Serial # 172-27 amp that I'm upgrading.

Are there any pictures (or videos) detailing the installation of the new WO backplane kit along the new WO Control board kit for my amp?

Does the new WO backplane kit contain all the resistors and capacitor that are in the existing amp?

Finally, do you recommend the Phoenix connection option with the WO Control Board kit?

I appreciate any help with my upgrade.

Thanks.

Bob
 

Hexis22

Chief Journeyman
Joined
Dec 28, 2022
Messages
568
Location
Wisconsin
#23
Hi ,

My names Bob, and I'm new to this forum and I just got a beat-up old Model # 700, Serial # 172-27 amp that I'm upgrading.

Are there any pictures (or videos) detailing the installation of the new WO backplane kit along the new WO Control board kit for my amp?

Does the new WO backplane kit contain all the resistors and capacitor that are in the existing amp?

Finally, do you recommend the Phoenix connection option with the WO Control Board kit?

I appreciate any help with my upgrade.

Thanks.

Bob
Upgrading the original 700 with a full White Oak treatment is not for the faint of heart.

The WO backplane boards will not work with the original 700 chassis or heat sinks.. Fortunately WO has replacement housing and heat sinks available.

See a detailed build here: https://forums.phxaudiotape.com/threads/700-series-1-build.11076/
 

George S.

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Feb 18, 2020
Messages
4,710
#25
Absolutely. I use them on the backplanes and the control board, twice the amount that most builders use.
Just closely check them for fit on the 700 backplanes, the solder tabs need to be slightly bent to shift them sideways away from a close trace.
 

oldphaser

Chief Journeyman
Joined
Sep 8, 2012
Messages
848
#27
My output transistors are marked F 722 PL909 Hongkong, does that correspond to the MJ211996G ? Someone else suggested checking the emitter resistors. Thanks
In the case of the Fairchild FPL909's, the (3) digit date code "722", the first number indicates the year 1977 and the 2nd and 3rd numbers indicate the 22nd week of that year.

The FPL909 is a Fairchild FT411. Similar to Delco DTS411's (Phase Linear PL909's and XPL909's), Motorola MJ411's, International Rectifiers IR411's, and RCA411's. Notice a pattern here?

The Fairchild FT410's and FT411's were first introduced in Electronic Design magazines January 4, 1974 issue on page 178. The data sheets can be found in the Fairchild Power Data Book (1976) on pages 6-212 and 6-213. NOTE: The S.O.A. (Safe Operating Area) plot shows approximately .7A at 80V and .5A at 100V. I don't have any specific details about how the S.O.A. testing was done by Fairchild at that time.

The GM/Delco DTS411's have a S.O.A. plot with the following notation: "Square Wave Pulses Of The Specified Length At A Duty Cycle +/-.4%" and "NOTE: The safe operating curves are not constant power hyperbolas. Power derating is required to take into account changes in thermal resistance and other factors." One axis on the plot indicates volts and on the other axis current (like many other plots I see) along with curves for 500us, 1ms, 2ms, 5ms, 10ms, and DC.

NOTE: The GM/Delco DTS411 first data sheet (4 pgs) was in March 1966 and the DTS410 (4 pgs) in August 1966. The first ads appeared in Electronics and Electronic Design magazines in August 1966. This was (8) years prior to the Fairchild FT411's. By the way, GM/Delco made some other DTS series TO-3 style transistors in 1966 which were higher rated parts. However, they were much more expensive at that time.


Ed
 

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oldphaser

Chief Journeyman
Joined
Sep 8, 2012
Messages
848
#29
Ed,

It's good to hear form you. I had concluded you gave up on us.
I stayed in touch with Lee over the years and we talked occasionally by phone whenever he had a question for me.

The last few years have been interesting. I've been very busy.
I've sold many pieces of test equipment and bought a number of others.

Along the way, I've learned so much more about audio, electronics and component testing.
I will share more when time permits.

I also went back to work last year for (5) months as a contract employee for that large aerospace manufacturer I had retired from in 2015.
My job title was Metrology and Test Equipment Services - Senior Engineering Technical Specialist (Level 5). The highest level possible in this job family.

Ed
 

George S.

Veteran and General Yakker
Joined
Feb 18, 2020
Messages
4,710
#30
Way to go Ed. I joined the forum after you became inactive, but read all the old post before I ever first posted. I feel like I know you somewhat.
Welcome back!
 

wattsabundant

Chief Journeyman
Joined
Apr 26, 2011
Messages
878
Location
Central Ohio
#32
I stayed in touch with Lee over the years and we talked occasionally by phone whenever he had a question for me.

The last few years have been interesting. I've been very busy.
I've sold many pieces of test equipment and bought a number of others.

Along the way, I've learned so much more about audio, electronics and component testing.
I will share more when time permits.

I also went back to work last year for (5) months as a contract employee for that large aerospace manufacturer I had retired from in 2015.
My job title was Metrology and Test Equipment Services - Senior Engineering Technical Specialist (Level 5). The highest level possible in this job family.

Ed
I believe that aerospace company may have been in the news a few times the last few years. I got to commission some systems at the same company's wind tunnel many many years ago.
 
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