home studios equipment staff/friends booking/rates for sale forum contact

Electrical's Old Repair List

All your geeky questions about electronics, microphones, tape machines, etc.

Moderators: kerble, Electrical-Staff

Postby greg on Mon Apr 21, 2008 4:42 pm

Date: 5/26/02
Equipment: Schoeps 221 PSU
SN: 7111261
Problem: no output on mic
Out to:
Repaired: blown 2.2k resistor replaced
Date: 5/28/02

Date: 6/15/02
Equipment: Schoeps 221
SN: 7111231
Problem: mic cutting out
Out to:
Repaired: bad wiring at mic cable conn.
Date:

Date: 7/15/02
Equipment: Ampex 351 mic pre
SN: #1
Problem: buzz on output
Out to:
Repaired: BAD spague PS filter cap replaced
Date: 7/15/02

Date: 7/02
Equipment: check and label lomo cables
SN:
Problem:
Out to:
Repaired:
Date:
Last edited by greg on Tue Apr 29, 2008 9:39 am, edited 1 time in total.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon Apr 21, 2008 4:54 pm

Date: 8/08/02
Equipment: Neotek Elite spare channel
SN:
Problem: no 'odd' buss send
Out to:
Repaired: buss pan pot shorting odd wiper trace, replaced pot
Date: 8/02/02

Date: 8/08/02
Equipment: Studer 820 16-tk head block
SN:
Problem: static noise on repro due to lame head core grounding
Out to:
Repaired: Flux Magnetics repro head core painted to ground with silver paint (where head core meets the side)
Date: 8/08/02
*Not Final Solution*

Date: 8/06/02
Equipment: Lomo 19a18 PSU
SN:
Problem: B+ gone - components fried
Out to:
Repaired: built new power supply (VTPSU9B) works like a charm
Date: 9/02
"VTPSU9B" stands for Vacuum Tube Power Supply Unit 9b. It is my soft start tube mic power supply. Clever name huh? It turns on the filament voltage first, then, after 60 seconds ramps up the B+ voltage, slowly fading the pretty sound up. There is a bi-color status led that is red during the warm up, then switches to green when the mic is on and ready. It is now used for the AKG C-24, and dual supply for the Schoeps 221b.



We are now entering the period of recent memory. Things will be a little more fleshed out... maybe/
Last edited by greg on Tue Apr 29, 2008 9:42 am, edited 2 times in total.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon Apr 28, 2008 4:08 pm

Date: 8/13/02
Equipment: Alec 175 PSU
SN:
Problem: buzz on output
Out to:
Repaired: Power transformer had a stronger than normal magnetic field. The output transformer was picking that up.
Date:

Date: 8/13/02
Equipment: Neotek Series II
SN: CH33
Problem: Noise on Mic Pre
Out to:
Repaired: 'sploded 48V DC Blocking Cap (C103), and diode between 100 ohm resistor (to -18V) and C103 failed.
Date:

Date: 9/8/02
Equipment: Phantom PSU (for 351s in studio b)
SN:
Problem: dead
Out to:
Repaired: blown cap between secondary windings
Date:
I am not sure what happened here.

Date: 9/17/02
Equipment: Neotek Elite
SN: CH14
Problem: When in-place soloing the channel, the left side would cut in and out.
Out to:
Repaired: Replaced bad solo button
Date: 9/18
I don't remember if I tried to clean it
Last edited by greg on Tue Apr 29, 2008 9:44 am, edited 3 times in total.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon Apr 28, 2008 4:18 pm

Date: 10/21/02
Equipment: Neotek Elite
SN: CH37
Problem: Fader polarity reverse switch cuts level in half when fader source is Line 1 input
Out to:
Repaired: R312 wasn't removed at factory causing a feedback path for the op amp when L1 was selected. This section was changed as part of the customization of our Elite.
Date:

Date: 10/21/02
Equipment: Neotek Elite
SN: CH29
Problem: NO output on monitor fader (direct out, buss, and solo)
Out to:
Repaired: No problem found on test bench. May have been a loose connection? Worked when reinstalled.
Date:

Date: 10/02
Equipment: Z-vex pedal
SN: Super hard-on
Problem: dead
Out to:
Repaired: replaced FET BS170P, works (we got 9 more fet's)
Date:
Last edited by greg on Tue Apr 29, 2008 9:48 am, edited 1 time in total.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon Apr 28, 2008 5:27 pm

Date: 11/7/02
Equipment: Josephson
SN: 609 SN 2674
Problem: popping noise when moved
Out to:
Repaired: pin 1 connection cold
Date: 11/7/02

Date: 11/7/02
Equipment: ATR
SN: #1
Problem:
Out to:
Repaired: calibrated I/Os
Date:

Date: 11/11/02
Equipment: ATR
SN: #4
Problem: Shuttering noise while capstan is achieving lock
Out to:
Repaired: Adjusted capstan tach sensor gain
Date:

Date: 11/11/02
Equipment: Neotek Elite
SN: CH 19
Problem: No Aux A send
Out to:
Repaired: Replaced Aux A/B gain pot
Date:

Date: 11/11/02
Equipment: Neotek Elite
SN: CH 13
Problem: Signal leaks to Aux B bus when level is down
Out to:
Repaired: Replaced Aux A/B gain pot
Date:
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon Apr 28, 2008 5:31 pm

Date: 11/11/02
Equipment: Ampex 351 Mic Pre
SN: #4 (St A)
Problem: Signal dead w/ pad on
Out to:
Repaired: bad switch replaced w/ greyhill 71BD30-02-2-AJN
Date:

Date: 11/13/02
Equipment: UREI LA22
SN:
Problem: bypass distortion
Out to:
Repaired: bad relay replaced, spares are in UREI file
Date: 11/15/02

Date: 11/14/02
Equipment: Studer 820 24tk (studio A)
SN:
Problem: low o/p track 24
Out to:
Repaired: bad punch at punch-block
Date:

Date: 11/14/02
Equipment: Manley Elop
SN:
Problem: Noise on Rt. Chan.
Out to:
Repaired: noisy tube 5814A (12AU7/6189), replaced both channels with new tubes also replaced burned-out meter bulbs
Last edited by greg on Tue Apr 29, 2008 9:49 am, edited 1 time in total.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon Apr 28, 2008 5:38 pm

Date: 11/3/02
Equipment: Sytek MPX 4A
SN: 610-034
Problem: CH 1 sounding f'ed up
Out to:
Repaired: DC(48V) blocking cap blown on one leg of input - replaced both caps
Date: 11/?/02

Date: 1/23/03
Equipment: EV PL-20
SN:
Problem:
Out to: Telex, inc.
Repaired: done
Date: 2/03

Date: 1/23/03
Equipment: Sennheiser 441
SN:
Problem: Smashed mic from someone using it like a lawn dart.
Probably fell off a stand. Steve uses these for talkback mics. What a snob.
Out to: Sennheiser
Repaired: done
Date: 2/03
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Tue Apr 29, 2008 6:10 pm

Date: 1/23/03
Equipment: Royer SF-12
SN:
Problem: blown bottom ribbon
Out to: Royer, inc.
Repaired: done
Date: 2/03

Date: 1/23/03
Equipment: Earthworks QTC-1
SN:
Problem: noisy
Out to: Earthworks, inc.
Repaired:
Date:

Date: 1/23/03
Equipment: RCA BK10, RCA 44DX
SN:
Problem: blown ribbons
Out to: Clarence Kane of Enak
Repaired:
Date:

Date: 2/18/03
Equipment: Manley Elop
SN: 308 (early, black pcb)
Problem: No Audio on left channel,
Out to: manley for new main pc board 2/03
Repaired: yes
Date: 3/03
B+ jumper burned up after left channel B+ bypass electrolytic cap failed (shorted). Circuit board became resistive around the scorched area. I didn't know that could happen. It caused problems when I replaced the destroyed parts.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Tue Apr 29, 2008 6:17 pm

Date: 2/28/03
Equipment: GML EQ
SN:
Problem: right channel noisy
Out to: GML for repair and recalibration 3/03
Repaired: return
Date: 3/03

Date: 2/29/03
Equipment: Josephson 609
SN: 2744
Problem: low output on mic
Out to: Josephson
Repaired:
Date: 5/04

Date: 4/15/03
Equipment: Harmonic Percolator
SN:
Problem: Bypass not working
Out to:
Repaired: cold/broken solder joint on foot switch
Date: 4/15/03

Date: 4/20/03
Equipment: Josephson 609
SN: 2673
Problem: high level / distortion
Out to:
Repaired: set screws not making good contact for ground
Date:
Later replaced with new screws, which did the job better.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:02 pm

Date: 4/03
Equipment: Senn MKH405
SN:
Problem: Only accepts "T" 12 volt phantom power
Out to:
Repaired:
Date:

Date: 4/03
Equipment: Traynor mono block
SN:
Problem:
Out to:
Repaired: Installed new power switch, IEC connector and cleaned inside
Date:

Date: 1/03
Equipment: Lomo 19-9
SN: 640295
Problem: wind noise
Out to:
Repaired: replaced tube and cleaned connections
Date:

Date: 5/06/03
Equipment: Josephson 606S and 609
SN: 3179, 3178, 3175, 2673
Problem:
Out to: josephson for screw mod
Repaired:
Date:
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:04 pm

Date: 5/06/03
Equipment: Str'a'sser
SN: CM060
Problem: hum on power supply
Out to:
Repaired: improper grounding at AC power connector
Date: 5/06/3

Date: 5/07/03
Equipment: RCA BK-5, RCA 74
SN:
Problem: No o/p
Out to: Clarence Kane
Repaired:
Date:

Date: 5/08/03
Equipment: 1178 Black Face
SN: 5773
Problem: Power and Ratio buttons intermittent
Out to:
Repaired: replaced with new switch arrays from Purple Audio
Date:
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:06 pm

Date: 5/03
Equipment: Neve 2-pack
SN:
Problem: phantom power switch faulty
Out to:
Repaired: replaced w/ 18-237,035 Newark EAO sw.
Date:

Date: 6/03
Equipment: BSS Compressor
SN:
Problem: Left Ch. distorted
Out to:
Repaired: re-seated VCA pack
Date:

Date: 6/03
Equipment: Altec 175
SN:
Problem: buzz
Out to:
Repaired: 22k resistor btw. cathode and ground broke open, replaced
Date:

Date: 7/03
Equipment: Klark-Teknik DN-34
SN:
Problem: oscillating and distortion on o/p
Out to:
Repaired: Yes but how ?
Date: 7/03
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:22 pm

Date: 7/03
Equipment: Studer 820, MD unit Master TD Control Boards
SN: blacksides
Problem: LEDs and counter displays matrixed-out after power surge. Displays freaked out, blacked out, then started scrolling (ghost in the machine type freak-out) Problem did not go away after cycling the power and resetting the MPUs.
Out to:
Repaired: replaced a 6801 chip on Master MPU, and TD Control, and shorted (erased) all ram chips
Date: 7/03

Date: 7/03
Equipment: Lomo 19-18 + cable
SN: cap 680048, bnd 690039
Problem: crackling noise
Out to:
Repaired: Mics ok, cable had bad shield/ground termination. Made new cables out of mogami tube mic cable.
Later, the connectors on the mic and cable were changed to 5-pin xlr type because of a similar bad ground conduction problem. A highly recommended modification.
Date:
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:24 pm

Date: 7/03
Equipment: 1176 whiteface
SN:
Problem: no o/p dist o/p
Out to:
Repaired: broken lead to 797 board (Alactronics Mod)
Date: 7/03

Date: 7/03
Equipment: Studer 820MCH Blacksides
SN:
Problem: CH19 sync repro level low and failing (auto cal), chan 3-8 repro level is low or irregular at 1K
Out to:
Repaired: replaced C6, C5, C7 elec. caps on repro board, recapped 1st (1-8ch) repro pre-amp board 470uf caps, it improved level on average of 6dB! Recapped the other to head preamp boards.
Date: 7/03
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:28 pm

Date: 7/03
Equipment: RCA 74B
SN:
Problem: no o/p
Out to:
Repaired: broken solder joint between red transformer wire and ribbon
Date: 7/03

Date: 8/01/03
Equipment: Studer 820MCH St A machine
SN:
Problem:
Out to:
Repaired:
Date:
Interesting. I wonder what that was about?

Date: 8/04/03
Equipment: Josephson 609
SN: 2746
Problem: distorts on toms
Out to:
Repaired: bad set screw connection
Date:

Date: 8/04/03
Equipment: Altec 175
SN: #1
Problem: ping noise on snare after being hit by drumstick
Out to:
Repaired: Reseated tube and saw dirt under diaphragm creating 'tents' possibly shorting the diaphragm to back-plate. disassembled capsule housing and cleaned parts carefully.
Date: 8/06/03
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:33 pm

Date: 8/8/03
Equipment: Sony C-17
SN:
Problem:
Out to:
Repaired: Modified power connection and ground for our balanced power
Date:

Date: 9/25/03
Equipment: Studer A820MCH
SN: blacksides
Problem: CH2 Sync LFO 'heartbeat' noise
Out to:
Repaired: recapped repro board, works now
Date: 9/25/03

Date: 9/25/3
Equipment: ATR #2
SN:
Problem: Right channel sputtering noise on repro at 30ips only
Out to:
Repaired: replaced Q5 on right channel padnet pwa audio card
Date: 9/29/03

Date: 10/3
Equipment: ATR #2
SN:
Problem: Speed not changing from 30ips
Out to:
Repaired: SSA and SSB busses shorted together at controller connector (remote)
Date: 10/03/03

Date: wurlitzer
Equipment:
SN:
Problem: smoke coming out after wrong fuse was installed
Out to:
Repaired: rectifier diode exploded, repaired, cleaned
Date: 10/07/03
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:41 pm

Date: 10/16/03
Equipment: ATR #2
SN:
Problem: radio noise on left chan
Out to:
Repaired: A mismatch of meter I/O + audio PWA versions caused grounding improper grounding of the audio. This was probably caused by swapping I/O modules or audio boards when I was trouble shooting the sputtering noise problem above.
Date: 10/03
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby greg on Mon May 19, 2008 4:51 pm

User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

Postby r0ck1r0ck2 on Mon May 19, 2008 5:30 pm

well done.

saludos all around.
User avatar
r0ck1r0ck2
saw big cat
saw big cat
 
Posts: 1767
Joined: Sun Feb 19, 2006 1:31 pm
Location: Hospitalet-de-Loebregat

Postby greg on Mon May 19, 2008 5:33 pm

I feel much better now..

If you guys have questions please ask. This was transcribed pretty quickly so there might be some confusion.
User avatar
greg
Master Of The Computer
Master Of The Computer
 
Posts: 4916
Joined: Wed May 14, 2003 7:26 pm
Location: Chicago

PreviousNext

Return to Tech Room

Who is online

Users browsing this forum: Bing [Bot], JohnnySomersett, Riff Magnum and 6 guests