I was repairing a HP 3560A that does not start up at all. The system is very modular that there are only 3 main units: LCD/keyboard/DSP board (A1), Main Processor board (A2) which manages power sources and contains the backlight inverter as well, and the analog section (A3).
Obviously the first thing to look for is where the power is managed, which is the main processor board (A2). I bought another unit (with a different defect, i.e. it boots) hoping to use it as a reference but to my surprise, the A2 board is slightly different! In fact, the LT1120 voltage regulator that I’m seeing unusual pulses in V_out pin (should be flat) is not even there!
I’ll save the repair story for another post, but for information preservation purposes, I took pictures of the two different revisions of the A2 assembly from 3 units, shown below:
- New: 03569-66502 Rev B
- Old: 03560-66502 Rev B, Rev C
The top part of the board is essentially the same. The new board uses Toshiba TC551001CP-85L while the old board uses Sony CXK581001P-70L for Static RAM. They are likely pin compatible and it’s just availability differences. (Ignore the randomly placed caps at the bottom of the new A2 board. I desoldered them to test if they are good).
If you pay close attention, at the top of the new revision board, it has an unpopulated DIP-8 socket and an extra 74HC174N chip, and an extra digital I/O port at the mid-bottom left edge below the SRAM. They are reserved for 3569A (a better version with a noise tracking generator) as it uses the same board. The old revision A2 board works for 3560A only. It’s a topic for another post.
The bottom part is quite different. The classical 4-diode full-bridge rectifier on the new board is not shown at the main side of the circuit board for the old A2 assembly. The new board looked much denser.
Most importantly, the old board uses MAX666 as the 5V voltage regulator while the new board uses LT1120. The pinouts are different and chip features varies a little bit, so the power management section is not topologically identical.
There are no components on the back side of the new revision A2 board (they are both supposed to be single sided PCBs), but two diodes are squeezed in at the back of the old revision A2 board, and there’s an extra resistor flyover:
My suspicion is that the diodes are intentional as there are specific through-holes for them (most like they other half of the bridge rectifier), but the resistor is an after-spin rework.
Finally, for information preservation, I also took pictures of the old A2 board (03560-66502 Rev B) from another unit I have:
If you consider the relative ease of use for less computer savvy people, 3560A/3569A is versatile yet designed specifically for the most commonly used measurements in acoustic and mechanical vibrations. It’s still excellent value for what it offers despite it’s a made decades ago since it doesn’t overwhelm you with convoluted choices so you can gets the job done once you’ve setup your recipe.
HP has designed the unit very well, with the exception of the LCD screen which cannot be found on earth, all through-hole components on single layer board and well organized structure and silkscreen makes servicing a pleasure.
I can repair and rebuild 3560A / 3569A with new battery pack and clock battery. The hardest problem to track down is no-boot, and the hardest surgery to make is the backlight. I also know how to talk to the unit from modern computers as well, so data capture is not a problem. Call me at 949-682-8145 for consultation.
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I’m from Brazil and I recently received an HP3560A, but it’s not turning on. The battery is dead, and I disconnected it from the device and put only the 9 VAC – 1A charger, but the display does not light up. Is it necessary to have the battery in good condition for the device to work? ThanksReport
Hello… I have an HP 3560A and the screen (LCD) is not working. The battery is also bad and has been removed. Does this device need a battery along with the power supply to work? I am using a 9 VAC 1A supply. Thanks!Report
Weird that I couldn’t reply to you without doing it from the admin page. If you have a dead battery, you’ll need to unplug it from the unit before using the external power supply or else the battery will drag the voltage down to prevent the unit from starting (there’s a voltage monitoring circuit there). You’ll need 1.5A or better if you want to use the unit and charge the battery at the same time.Report
I have an old HP3560A that’s had lots of use in the field taking vibration, pulsation and modal impact testing data. Sadly, the display is very weak and unreadable. It does come on, but back light does not. Yeah sure batteries are gone, but that just means a fresh set of five nicad’s serially daisy chained together for 7.5 and I’d be back in business except fo the display!. I cannot find an compatible like replacement, I’ve tried for days…. If you know of a source please kindly share the vendor. There are two other ways around the problem. \… Read more »
Are you sure it’s just the back light? The LCD display is impossible to find but I might be able to fix a bad back light. I have good units available for sale and I can include a fresh battery pack. Maybe we can do a trade-in. Please reach me at 949-682-8145 or email@example.com If I can repair the back light, it should be around $600 and I’ll toss in the said battery pack.Report