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May 22, 2019, 10:01:54 pm

Author Topic: Extended FP III Shunt Reg problem  (Read 1735 times)

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Offline pdxgrampa

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Extended FP III Shunt Reg problem
« on: November 04, 2017, 10:10:56 am »
This is not a new build has been in service off and on for a few years.
It would drop out briefly and then recover and then failed completely.
A side LEDs were on B side not then A side LEDS were off but MJE 350 was conducting.



H1: 24.5 VOLTS
H2: 29.4 VOLTS

A SIDE HIGH VOLTAGE                              B SIDE HIGH VOLTAGE
7:   223   VOLTS                                                  7:    222   VOLTS                                                 
9 :  213   VOLTS                                                  9 :   221   VOLTS
10; 204   VOLTS                                                 10:   221   VOLTS

 
TERMINAL
12: 116 VOLTS
15:  78  VOLTS

21: 115 VOLTS
22:  21  VOLTS

31: 78   VOLTS
32: 115 VOLTS
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline Paul Birkeland

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Re: Extended FP III Shunt Reg problem
« Reply #1 on: November 04, 2017, 06:29:00 pm »
Are you able to post photos of the PC boards?

For the most part, on just about every Extended Foreplay III that I have serviced that was initially in working order, I end up building a new center PC board for the high voltage shunt regulator.

It's very easy to see if this is the issue, as the center board you have now will be a bit black under where the MJE-350s each sit.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #2 on: November 05, 2017, 03:11:54 am »
This the B side MJE 350
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline Paul Birkeland

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Re: Extended FP III Shunt Reg problem
« Reply #3 on: November 05, 2017, 04:25:35 am »
Can you tell me what voltages you get at:

1.  The metal tab of each MJE-350 on the center board.
2.  Kreg A and Kreg B on the center board.
3.  The metal tab of each MJE-350 on the outer boards.
4.  The metal tab of each MJE-340 on the outer boards.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #4 on: November 05, 2017, 04:45:27 am »

Paul here is what you asked for:

All voltages referenced to terminal 18

The voltages on the side MJE 350s and 340s are all 78 volts

Tab on A side shunt reg board 350 is 117 volts dropping slowly from 123 at first measurement.
Tab on B side is 116 down from 126

A side Kreg is 0 volts
B side Kreg  7.5 volts
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #5 on: November 05, 2017, 05:31:16 am »
Doesn't look like picture made it .

I'll try again
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline Paul Birkeland

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Re: Extended FP III Shunt Reg problem
« Reply #6 on: November 05, 2017, 06:46:07 am »
Pull the outer two 12AU7s and retest the center PC board.

(Also, the MJE340 tabs should be a volt or two higher than the MJE350 tabs on the outer PC boards when all the tubes are plugged in and running)
« Last Edit: November 05, 2017, 08:19:20 am by Caucasian Blackplate »
Paul "PB" Birkeland

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Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #7 on: November 05, 2017, 07:28:57 am »


Ok tubes out:

 A side                                 B Side                              Shunt Reg
350: 146.8 volts                  350: 146.8                        A side 350: 149
340: 150.9                          340: 150.0                        B side 350: 148.5
                                                                                  A side Kreg; 0
                                                                                  B side Kreg: 8.72
                                                                               
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline Paul Birkeland

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Re: Extended FP III Shunt Reg problem
« Reply #8 on: November 05, 2017, 08:20:28 am »
                                                                                  A side Kreg; 0
                                                                                  B side Kreg: 8.72
                                                                               
It's odd that the A side Kreg is stuck at 0V but the regulator appears to work.  With 0V available for the TL431 to operate, I would expect your regulated voltage to be just a volt or two less than your unregulated voltage. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #9 on: November 05, 2017, 10:51:25 am »

PB,

Unless there is something else to measure/try

Should I just contact the Queen on Monday for a board and Parts?

Thanks for your help

Greg
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline Paul Birkeland

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Re: Extended FP III Shunt Reg problem
« Reply #10 on: November 05, 2017, 03:33:25 pm »
That particular PC board is NLA, and several of the parts are also no longer stocked in our inventory.  There are some workarounds for this situation; feel free to contact me and we can go over the options to get you back up and running.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #11 on: November 05, 2017, 04:54:43 pm »
Thanks Paul,

 I didn't see a way to PM you.
 so I will call the store on Monday if that works for you.

Greg
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.

Offline Paul Birkeland

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Re: Extended FP III Shunt Reg problem
« Reply #12 on: November 06, 2017, 03:55:49 am »
You can e-mail me at pb(at)bottlehead(dot)com.
Paul "PB" Birkeland

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Offline pdxgrampa

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Re: Extended FP III Shunt Reg problem
« Reply #13 on: November 06, 2017, 06:37:30 am »

Will do Paul

Greg
Greg
Music Hall 5.1SE,EROS. OPPO 980HD, Music Hall 25.3 Dac. BeePre/BeeQuiet. Paramount V1.1 300B,Orca Deluxe W/ Subs/SPA250s.Stereomour W/Orca Deluxe. Crack W/Speeball(2) .Beyerdynamic 990s.Crackheadphone.