HP 58503A GPS Frequency Reference - Flashing Front Panel LEDs

[rambln.wreck]

I recently purchased an HP 58503A from eBay. Here is the listing: https://www.ebay.com/itm/HP-58503A-GPS-Time-and-Frequency-Receiver/132512266569?epid=1639264426&hash=item1eda58b949:g:GygAAOSwkPJajH5o

When I power it on, with or without an antenna, the power LED illuminates on the front panel, followed by each LED one at a time. Then, after a moment, the unit alternates between all front panel LEDs being illuminated and only the power LED at a rate of about once every 3 seconds. I opened the unit and checked the rail voltages. I have 5.22V, +15.01V, -15.00V. No obvious visual issues (all caps look okay, no water or mechanical damage, etc.) The oven is warming. There are some LEDs on the board near the antenna jack and I have two red illuminated and a single green. I can’t get anything on the serial port. No scpi> and I can't send commands to the unit. It seems like it is not getting past the self-test routine.

Has anyone seen this before? I have a 30 day ROR but I like this model and would love to fix it if anyone has any advice.

[babymaaaan]

Hi

i ve got the same issue, i replaced the 10 mhz

and at power up after 30 seconds  led red ALARM , i do not know where is the problem