FET Audio | Hi-End Audio & Electronics DIY Electronics & Repair

June 30, 2021

Tektronix PS280 Power Supply RE-Cap

Filed under: Test Equipment — Spencer @ 4:18 pm

This is a power supply branded Tektronix but actual is OEM in Taiwan. The quality of PCB used is not that great as it is using fibre board. Spec of this supply is two output with 0-30V 2A and one output 5V 3A. This supply was made more than 20 years ago and the casing and some screws are already getting little rusty! All e-cap are make by Jamicon!

  1. Big capacitor is changed from 4700uf 63V to 6800uf 63V. Use Rubycon.
  2. 470uF 35V to 560uf 35V, 100uF 25V use same but all Panasonic FC grade in filtering section board.
  3. Control board two 47uF change to Nichicon; 4.7u change to 12uf x 2 Pana FC. 6800uf 25V to 10000uF 16V, rubycon.
  4. Display control board for supply filtering change 1000uF to 2200uf Pana FC grade. 100uf use same value.
  5. The fan supply board also upgrade two capacitor to Panasonic FC grade.
  6. After that I follow the service manual do adjustment/verification and the set is found within 0.1V/0.1A accuracy. Thus I can say even an OEM product branded Tektronix also very stable for over 20 years life time!

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June 28, 2021

hp 3324A functional generator service and repair

Filed under: Test Equipment — Spencer @ 12:04 am

The equipment also have RIFA cap and thus cleaning and service is needed.

  1. Some inside photos.
  2. Changed all 3 RIFA capacitors as they have body crack.
  3. This set come with precision time base 10Mhz clock but the clock do not look very square wave in scope. Jitter is about 30ps, not the best in class.
  4. The battery inside still above 3.2V after >25 years.
  5. After assembly back, found the output amplitude is not able to set within 1 to 10V, thus there is an issue with the amplifier section which need further trouble shoot! Frequency setting is fine.
  6. The problem on this sig gen was identified as the power switch one side open circuit at power ON position. Fixing the power switch and the signal gen is back to normal.
  • Main board
  • Output section, relays
  • Rear side
  • High level o/p option
  • Battery is still above 3V
  • Transformer
  • X2 and Y capacitor see crack issues
  • X2 and Y caps replaced
  • Case is clean with WD-40
  • 10Mhz option
  • The two connected pins is OPEN when the switch is pressed at ON position.

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June 27, 2021

Repair Panasonic Rick cooker

Filed under: Others — Spencer @ 11:52 pm

The cooler serve me about 10 years and start to give me some issue like timing set but auto cut off or some intermittent issue.

  1. Open up and see the bottom very dirty and sticky and need full cleaning to remove all the dirty.
  2. The pcb is very dirty and a lot of flux, thus clean with IPA to remove the excess flux.
  3. There are two 10u 400V capacitor on the pcb and this is NO brand type. Thus replaced them with Nichicon 6.8u 400V long life type even the original cap measure good.
  4. I want to highlight that the clips used in this cooker has a lock spring in it, just press down and then the pin can easily pull out from the IEC socket!
  5. Bottom 4 screw no need to remove. a) IEC socket need to remove by one screw and one cover. b) Top cover hinge remove with 1 screw and also a cover, pull out from bottom of cover. c) then under the cover use flat screw driver to pull up the top section at hinge side. No solder is required for all dis-assembly steps.

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hp 6632A service and add front connectors

Filed under: Test Equipment — Spencer @ 11:41 pm

This is a very old hp power supply with HPIB control capability. It is 20V and 5A max. There is a fan to cool the set and thus it is a bit noisy when using this supply. Here is the work done to service it:

  1. There is lots of dirty stick on the fan and thus cleaning is a must. Also remove the pcb assembly and all item from the case to do 100% cleaning the IPA.
  2. Oh RIFA again and crack on surface, so leaking a bit is the norm!
  3. Added front supply connector with sink in type banana socket. Do not want it to extend out as the front panel is also nothing much protruding from the surface.
  4. No calibration is required as it is still quite accurate.
  • Rifa caps crack
  • Fan sticky with black oily dirt
  • AC filter caps replaced
  • Added front output sockets inside photo – washer need to cut on one side to fit the space

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June 24, 2021

Tektronix 1103 probe power supply

Filed under: Test Equipment — Spencer @ 4:39 pm

This is a very useful power supply and still selling a good price as Tektronix had made many good probes for use. Example P6247 and ADA400A etc. With this supply, the old probes can be used in modern oscilloscopes. I open up my set and check if there is any RIFA capacitor inside to cause trouble. Luckily there is non as the supplier use a EI transformer. The regulator ICs are just normal type LM317 and LM337 TO-220 type. I see my set was replaced one of them with lots of flux near the diodes! E-cap looks good shape and brand, no need any replacement!

  1. P6247 1GHz probe which is good for measuring jitter on any circuit with differential input mode.
  2. ADA400A is very good for very low level signal even for Biotech usage with extreme high input impedance. It has 0.1, x1, x10 & x100 times and thus 1mV / DIV will become 10uV / DIV in the scope! Also differential design and very good CMRR ratings but limited to 1Mhz bandwidth only. You know what, today Tektronix is still selling this probe!!!
  • Tek 1103
  • Tek 1103 top view
  • One regulator seems replaced before
  • Tek P6247 tips to measure jitter of Hifi Sperry digi Pro clock jitter
  • Tek prob P6247
  • Tek ADA400A
  • ADA400A prob input levels – Ch1 5V x100 times, Ch2 50mV.

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