Hi Everybody,
I'm having troubles (again and bad this time) with the old Gemini 300 BB (Varian
magnet) upgraded with Eth/CPU boards and Sparc 5 / VNMR 6.1.
I have no pulse and no spectrum, just noise and no band change.
The RF configuration (all have AP chip, except Kalmus) is:
Master clock,
PTS 160, BB transmitter, 0.1Hz option, 1H Xmitter-decoupler, BB-RF controller, Power Amplifier (Kalmus),
BB preamp, 1H preamp, Observe-Receiver .
I checked the Sparc, the cable and the transceivers and they were OK.
The Eth and CPU boards on the console went OK, the console goes idle.
The shims and lock shimming work fine, also spin on/off.
The shimm system is:
2H transmitter (AP chip),
2H preamp, 2H receiver (AP chip),
AutoDAC (on AP bus, without APchip), Shimm & Offset controll and Varian shim coils, all working.
No command passes on any pulse sequence, no click of any relay after "su" or "ga".
I found that there is no pulse/sequence configuration passed to RF boards and to PTS.
There is gating on LO but the frequency is not correct.
On Master clock 40 & 10 MHz are OK.
Btune command is executed, there is tuning signal on the high band.
There is no tuning signal on low band (BB transmitter and PTS do not receive any settings).
There is no gating on RF power amplifier (Kalmus) in pulse mode.
Kalmus receives command on both channels in CW mode when tuning or decoupling in a
13C experiment but RF signal is present on high band only.
My colleagues say that it appeared before, on occasions and briefly, and they
needed to make several experiment switching before the command was executed. It come
back OK after 2-3 back and forth between 1H and 13C, usually without rebooting the
computer and the console.
I have 2-3 spares for each board, except Eth which I have only one spare.
Please let me know what can I try from here (besides a new instrument).
Also, if you have technical reference manual for Gemini systems or any
functioning/service explanations + schematics for all digital boards (CPU, Ethernet,
Pulse controller and 100KHz-ADC) and functioning/service explanations for all BB
option boards (I have the schematics for these), it may be helpful.
Thank-you in advance and best regards,
Mircea
Dr Dumitru Mircea VULUGA
Centre for Organic Chemistry
Costin D. Nenitescu
Romanian Academy
202B Spl. Independentei CP 35-108
Bucharest 060023 ROMANIA
Phone: +40 213167900 ; +40 317101400
Fax: +40 213121601
Mobile: +40 726709957
vuluga_at_yahoo.com
mircea.vuluga_at_gmail.com
Received on Thu Jun 24 2021 - 02:43:10 MST