Hello friends i am new at mining. One of my cards on my a1 suddently stopped hashing(seems 0mh). I reboot my machine and i only see three cards(chains). I saw the log file and i thin i detect the problem, but i cant understand what it really is.

First a problem with chain 1
chain1: power down
Apr 06 04:28:52 rockchip cgminer[286]: fan0 speed:5760, fan1 speed:5880
Apr 06 04:28:53 rockchip cgminer[286]: chain1: encore first mode
Apr 06 04:28:56 rockchip cgminer[286]: dm_compat.c,5164: poll fail !
Apr 06 04:28:56 rockchip cgminer[286]: spi_cmd_reset poll fail !
Apr 06 04:28:56 rockchip cgminer[286]: failed to reset chain 1!,try again
Apr 06 04:28:57 rockchip cgminer[286]: fan0 speed:5820, fan1 speed:5880
Apr 06 04:28:59 rockchip cgminer[286]: dm_compat.c,5164: poll fail !
Apr 06 04:28:59 rockchip cgminer[286]: spi_cmd_reset poll fail !
Apr 06 04:28:59 rockchip cgminer[286]: failed to reset chain 1!,try again
Apr 06 04:29:02 rockchip cgminer[286]: dm_compat.c,5164: poll fail !
Apr 06 04:29:02 rockchip cgminer[286]: spi_cmd_reset poll fail !
Apr 06 04:29:02 rockchip cgminer[286]: failed to reset chain 1!,try again
Apr 06 04:29:02 rockchip cgminer[286]: fan0 speed:5790, fan1 speed:5820
Apr 06 04:29:05 rockchip cgminer[286]: dm_compat.c,5164: poll fail !
Apr 06 04:29:05 rockchip cgminer[286]: spi_cmd_reset poll fail !
.
.what is first and second mode?
.
chain1: encore second mode                          
Apr 06 04:29:17 rockchip cgminer[286]: fan0 speed:5790, fan1 speed:5820
Apr 06 04:29:21 rockchip cgminer[286]: dm_compat.c,5164: poll fail !
Apr 06 04:29:21 rockchip cgminer[286]: spi_cmd_reset poll fail !
Apr 06 04:29:21 rockchip cgminer[286]: failed to reset chain 1!,try again
Apr 06 04:29:22 rockchip cgminer[286]: fan0 speed:5850, fan1 speed:5880
Apr 06 04:29:24 rockchip cgminer[286]: 1: detected 72 chips
Apr 06 04:29:24 rockchip cgminer[286]: collect core success
Apr 06 04:29:24 rockchip cgminer[286]: chain1: pre init OK, retries:1
.
.and at the same session problem but with chain 3(only one card is off)
.first 54 ppls set ok
Apr 06 05:39:16 rockchip cgminer[292]: Chain 3 VID 0 voltage 410.6
Apr 06 05:39:16 rockchip cgminer[292]: Chain 3 unable to get above target voltage 425 by VID 0
Apr 06 05:39:16 rockchip cgminer[292]: B1 chain[3] set pll, start_pll:54, target_pll:120
Apr 06 05:39:16 rockchip cgminer[292]: T1 3 set default 54 PLL success
Apr 06 05:39:16 rockchip cgminer[292]: T1 3 set default 55 PLL success
.
.all between ppls are ok
.
Apr 06 05:39:21 rockchip cgminer[292]: T1 3 set default 91 PLL success
Apr 06 05:39:21 rockchip cgminer[292]: T1 3 set default 92 PLL success
Apr 06 05:39:21 rockchip cgminer[292]: T1 3 set default 93 PLL success
Apr 06 05:39:21 rockchip cgminer[292]: T1 3 set default 94 PLL success
Apr 06 05:39:21 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: Failed to set PLL Lv.95 on T1 3 in T1_SetT1PLLClock
Apr 06 05:39:21 rockchip cgminer[292]: set default PLL fail
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_write_reg0d poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
.
.same error multiple times
.
Apr 06 05:39:21 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: chain3 find_chain_vid: start_vid = 0, target_volt = 407
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: failed to read voltage for chain3 chip1
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: failed to read voltage for chain3 chip2
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
.
.
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: failed to read voltage for chain3 chip70
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: failed to read voltage for chain3 chip71
Apr 06 05:39:21 rockchip cgminer[292]: spi_cmd_read_register poll fail !
Apr 06 05:39:21 rockchip cgminer[292]: failed to read voltage for chain3 chip72
Apr 06 05:39:21 rockchip cgminer[292]: Chain 3 VID 0 voltage nan
Apr 06 05:39:23 rockchip cgminer[292]: spi_cmd_read_register poll fail !
.
.72 chips fails again
.
Apr 06 05:39:24 rockchip cgminer[292]: Chain 3 VID 0 voltage nan
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_read_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: dm_compat.c,5164: poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: spi_cmd_write_register poll fail !
Apr 06 05:39:24 rockchip cgminer[292]: fan0 speed:5790, fan1 speed:6240
Apr 06 05:39:25 rockchip cgminer[292]: chain_detect: chain: 0, n_chips: 0
Apr 06 05:39:26 rockchip cgminer[292]: Chain 0 Voltage information. Highest Vol:435, Average Vol:416, Lowest Vol:402
Apr 06 05:39:26 rockchip cgminer[292]: 0: found 72 chips with total 2304 active cores
Apr 06 05:39:27 rockchip cgminer[292]: Chain 0 Post Balance Voltage. Highest Vol:435.000000, Average Vol:416.000000, Lowest Vol:400.000000.
Apr 06 05:39:28 rockchip cgminer[292]: chain_detect: chain: 1, n_chips: 0
Apr 06 05:39:28 rockchip cgminer[292]: Chain 1 Voltage information. Highest Vol:438, Average Vol:419, Lowest Vol:397
Apr 06 05:39:29 rockchip cgminer[292]: 1: found 72 chips with total 2304 active cores
Apr 06 05:39:29 rockchip cgminer[292]: Chain 1 Post Balance Voltage. Highest Vol:438.000000, Average Vol:419.000000, Lowest Vol:397.000000.
Apr 06 05:39:29 rockchip cgminer[292]: fan0 speed:5880, fan1 speed:6210
Apr 06 05:39:30 rockchip cgminer[292]: chain_detect: chain: 2, n_chips: 0
Apr 06 05:39:31 rockchip cgminer[292]: Chain 2 Voltage information. Highest Vol:435, Average Vol:414, Lowest Vol:397
Apr 06 05:39:31 rockchip cgminer[292]: 2: found 72 chips with total 2304 active cores
Apr 06 05:39:32 rockchip cgminer[292]: Chain 2 Post Balance Voltage. Highest Vol:435.000000, Average Vol:414.000000, Lowest Vol:397.000000.
Apr 06 05:39:32 rockchip cgminer[292]: Detected the 0 B1 chain with 72 chips / 2304 cores
Apr 06 05:39:32 rockchip cgminer[292]: Detected the 1 B1 chain with 72 chips / 2304 cores
Apr 06 05:39:32 rockchip cgminer[292]: Detected the 2 B1 chain with 72 chips / 2304 cores
Apr 06 05:39:32 rockchip cgminer[292]: B1 detect finish

seems that chain 3 is dead but something wrong with chain 1? My miner its not new but second hand