AnsweredAssumed Answered

HP 33120A test failures and schematics

Question asked by arekmx on Dec 18, 2013
Latest reply on Dec 23, 2013 by arekmx
  • Comment • 3
Hi.

I'm trying to fix old HP 33120A. Test reports few errors:
- "603 Waveform RAM readback failed"
- "604 Modulation RAM readback failed"  (this one seems to be fixed by replacing 32k x 8 SRAM memory)
- "606 Waveform ASIC failed"
- "608 SYNC signal detection failure, Elliptical filter path"

My guess is that "606 Waveform ASIC failed" is due to more failed SRAM memory. Unfortunately this old revision/model uses ancient TC55417J-15H (SOJ24 package) 16k x 4 type of SRAM. These kinds look no longer produced.

So:
- looking for HP 33120A schematic (not Agilent 33120A since Agilent variant uses moden memory while my HP 33120A uses some ancient, no-one-sells-now type of ram)

- anyone having TC55417J-15H pinout, so I could replace it with something modern? I found that this is:

"Memory Category SRAM Chip
Organization
Density 66 kbits
Number of Words 16 k
Bits per Word   4 bits
Packaging
Package Type    SOJ, 0.300 INCH, PLASTIC, SOJ-24
Pins    24
Logic Family    CMOS
Power Characteristics
Supply Voltage  5V
Access Time     15 ns
Operating Temperature   0 to 70 C (32 to 158 F)
"
so looks like a weird one.  
No one else has this question

Outcomes