[time-nuts] ESE ES-188 Master Clock : Repair

[Gregory Beat]

ESE ES-188 Master Clock : Repair
 
Another ESE Master Clock bargain ($100) arrived this summer on the time-nuts bench, from an eBay dumpster diver/flipper.  The ES-188 NTP Referenced Master Clock/Time Code Generator.
The clock’s internal TCXO is synchronized via the Internet (NTP).

The ES-188 receives accurate time and date information from a user selected NTP server and supplies this data to the user in the form of five (5) different types of time code (SMPTE/EBU, IRIG-B, ASCII, TC89 and TC90) and a front panel nine-digit display (.56” yellow LEDs).
This Master Clock is used at locations without ability to mount an external GPS antenna, or facilities that desire an alternative time synchronization method (not GPS based). 
—
FIRST Step, Request the full ES-188 manual, with schematic and parts list, from ESE Support - who delivers electronically (e-mail attachment).

Initial bench assessment confirmed the eBay reseller could not differentiate working, from non-working (Outrageous initial eBay asking price of >$300).
The 6 Volt, 1.3 Ah rechargeable battery and BR-2330 lithium coin cell were dead (config not retained), as expected.
 
The ES-188 has three (3) user access ports on rear panel: 
RS-232(serial); USB; and Ethernet provide by Lantronix Xport (IPv4) model.  
 
The Ethernet port acquired an IP address (DHCP), but did not respond with IP tools.
ESE provides PC software (Master Control Panel) for RS-232 and USB access from a PC.
The RS-232 port (MAX233) was not responsive.
The USB port (FTDI FT232BM) was recognized by the PC (Drivers loaded by Windows 10), BUT odd behavior was observed (worked sometimes).
 
Time to open up the ES-188 rack case to visual inspect inside.
The Six (6) electrolytic capacitors in the power supply section were bulging.  An obvious failure of those smoothing capacitors, that provide DC to the LM317, 7805, and +3.3 volt regulators.
This ES-188 was built ~2008, so the Meritek 85° electrolytics (3300 uFd, 4700 uFd) used by ESE did not last 12 years.
—
SECOND Step, Order Parts and Install.

Panasonic EEU-FK radial electrolytic capacitors (25V, 105°) were purchased from Digi-Key for replacement, that matched the PC board lead spacing (7.50 mm) and diameter.
The new Panasonic capacitors were shorter (height).
 
Looking at the Schematic diagram, the ES-188 main processor is the 87C530QNL-188 (PLCC-52).
This Maxim processor sells for ~$50 (blank, no firmware in ROM).
https://www.mouser.com/datasheet/2/256/DS83C530-DS87C530-1511768.pdf
This microcontroller has multiple I/O lines and supports Intel 8051-instruction set (firmware).
There are three (3) ICs that connect to this processor for external user ports:
 
74HCT04 : HEX Inverter, six independent inverter gates
74HCT08 : AND Gate, four independent 2-input AND gates
MAX233CPP : 5 Volt, RS-232 Driver/Receiver
 
All three (3) of those chips were damaged, likely from nearby unstable DC power or an ESD event.
** The surface mounted FTDI FT232BM (USB bridge IC) was NOT damaged. **

Replacing the six (6) bad electrolytic capacitors, three (3) bad ICs, and two (2) new batteries for less than $20 (parts) restored the ES-188 to operation.  The ES-188 then successfully sent IRIG-B time codes to my remote clock display.
—
LAST Step, Configure Master Clock and Operate.

I configured the ES-188 settings, via its Ethernet port (telnet), on a menu.

Set the initial Master Clock, Date and Time.
Set the ESE-188 local network address (IPv4), Gateway, and DNS Server.

For the NTP Primary Server, do not use the NIST or WWV time servers, Use your local ISP.
For example, my local Comcast/Xfinity (IPv4) server: 73.15.134.22
For the Secondary Server, select a reliable NTP server.
==

greg, w9gb