Electronics > Repair
HP54600B with spike problem with and without signal
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sacha:
 Hi, So is U33 worth trying as the first ic to change? But how is it possible that even if I only cool U25 the spikes still come back?
 Are HP spare parts available in your area?
 Thanks for the reply
T3sl4co1l:
Can you scope the pins?

Also wonder if the logic levels are indeterminate. Could be heat shifts both the output level / drive strength, and the input threshold, and both happen to work when warm, but they diverge when cold.  That could explain why the ASIC is affected.

Decayed transistors could happen, or corroded pins/bondwires (can be microscopic, inside the package).  And the RAM array itself, and readout, are very precise and can age too, maybe in terms of increased access time (before stable), maybe data corruption.

Tim
sacha:
Hi, I agree with everything you wrote :), I tried checking the U33 (ram) address input and data input/output levels, but found no apparent defects. I will try to change U33( Ram) with a faster one.

Can any of you tell me if the 1SL7-0001 ic is available in any stores?
Thank you.
T3sl4co1l:
The 1SL7- is an HP proprietary ASIC; it's basically only going to be available as replacement, or salvage from other boards.  (All the more reason to make sure everything is fine first..!)

Tim
sacha:
Hi T3sl4co1l  , if you give me an email or Telegram address I will send you the sequence of waveforms that I see on all the pins of the RAM, I can't send them here because they are too heavy.


On Telegram you can find me as: Shaca
while my email address is: conduel@libero.it




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