Замена конденсаторов в цепях инвертора

взято тут http://zival.ru/content/narabotki-po-remontu-lcd-monitorov

Замена конденсаторов в цепях инвертора.

Технология ремонта

Чт, 23/05/2013 — 23:21

На просторах интернета довольно много материала по ремонту мониторов, который сводится к одному — разобрал, поменял конденсаторы, заработало, наслаждаешся трудовым подвигом. В принципе это близко к реальности, но если подойти к ремонту с точки зрения экономичности ремонта, все не так уж и радужно. Рассмотрим нюансы.

Первым делом меняем вспученные конденсаторы,особое внимание перед заменой уделяем конденсатору расположенному между блоком питания и инвертором на рис. 2 конденсатор С1. Это как правило конденсатор (200-600) мкФ на 35 если учесть, что остальные конденсаторы в фильтре стоят на 25в то найти этот конденсатор не составляет труда. Вспучивание этого конденсатора говорит о том, что один (очень очень редко два) из ключей в инверторе битый поэтому перед включением обязательно запишите для себя тип ключей, иначе если транзистор сгорит название будет прочесть сложно. Однако если схема подключения инверторакак на рис. 1, то конденсаторы С1 и С2 в принципе никогда не вздуются, а могут только высохнуть.

Рис. 1. Инвертор вариант №1

Рис. 2. Инвертор вариант №2

Есть еще один конденсатор который обязателен для замены, даже если он не вспученный. Это конденсатор в цепи питания ШИМ (обычно это конденсатор 47мкф*50в)

Последний конденсатор, это конденсатор фильтра со стороны горячей части блока питания. Обычно его пучит вниз и визуально его сложно определить на предмет вспученности, однако он себя выдает дребезжащй картинкойна экране, по экрану ползет полоса как помеха 50 гц на экране ЭЛТ

Function code

The function code (FC) in the telegram header identifies the telegram type, such as Request telegram (Request or Send/Request) and Acknowledgement or Response telegram (Acknowledgement frame, Response frame). In addition the function code contains the actual transmission function and control information that prevent loss and duplication of messages, or the station type with FDL status.

FC: Function Code Request

Request Telegramm

FCV = Alternating bit switched on

href=»http://profibus.felser.ch/en/funktionscode.htm#aufruffolgebit»>FCB = Alternating bit (from frame count)

0 (0x0)

CV = Clock Value (Clock synchronization)

other

Reserved

0 (0x0)

TE = Time Event (Clock synchronization)

3 (0x3)

SDA_LOW = Send Data Acknowledged — low priority

4 (0x4)

SDN_LOW = Send Data Not acknowledged — low priority

5 (0x5)

SDA_HIGH = Send Data Acknowledged — high priority

6 (0x6)

SDN_HIGH = Send Data Not acknowledged

7 (0x7)

MSRD = Send Request Data with Multicast Reply

9 (0x9)

Request FDL Status

12(0xC)

SRD low = Send and Request Data

13(0xD)

SRD high = Send and Request Data

14(0xE)

Request Ident with reply

15 (0xF)

Request LSAP Status with reply 1)

other

Reserved

1) this value is in the last version of the standard not defined anymore but only reserved

7	6	5	4	3	2	1	0	FC : Function Code Response
	0							Response telegram
0								Reserved
		0	0					Slave
		0	1					Master not ready
		1	0					Master ready, without token
		1	1					Master ready, in token ring
				0 (0x0)				OK
				1 (0x1)				UE = User Error
				2 (0x2)				RR = No resources
				3 (0x3)				RS = SAP not enabled
				8 (0x8)				DL = Data Low (normal case with DP)
				9 (0x9)				NR = No response data ready
				10(0xA)				DH = Data High (DP diagnosis pending)
				12(0xC)				RDL = Data not received and Data Low
				13(0xD)				RDH = Data not received and Data High
				other				Reserved

Frame Count Bit The frame count bit FCB (b5) prevents message duplication by the acknowledging or responding station(responder) and any loss by the calling station (initiator). Excluded from this are requests without acknowledgement (SDN) and FDL Status, Ident and LSAP Status requests.

For the security sequence, the initiator must carry an FCB for each responder. When a Request telegram (Request or Send/Request) is sent to a responder for the first time, or if it is re-sent to a responder currently marked as non-operational, the FCB must be set as defined in the responder. The initiator achieves this in a Request telegram with FCV=0 and FCB=1. The responder must assess a telegram of this kind as the first message cycle and store the FCB=1 together with the initiator’s address (SA) (see following table). This message cycle will not be repeated by the initiator. In subsequent Request telegrams to the same responder, the initiator must set FCV=1 and change the FCB with each new Request telegram. Any responder that receives a Request telegram addressed to it with FCV=1 must evaluate the FCB. If the FCB has changed when compared with the last Request telegram from the same initiator (same SA), this is valid confirmation that the preceding message cycle was concluded properly. If the Request telegram originates from a different initiator (different SA), evaluation of the FCB is no longer necessary. In both cases, the responder must save the FCB with the source SA until receipt of a new telegram addressed to it. In the case of a lost or impaired acknowledgement or response telegram, the FCB must not be changed by the initiator in the request retry: this will indicate that the previous message cycle was faulty. If the responder receives a Request telegram with FCV=1 and the same FCB as the last Request telegram from the same initiator (same SA), this will indicate a request retry. The responder must in turn retransmit the acknowledgement or response telegram held in readiness. Until the above-mentioned confirmation or receipt of a telegram with a different address (SA or DA) that is not acknowledged (Send Data with No Acknowledge, SDN) the responder must hold the last acknowledgement or response telegram in readiness for any possible request retry. In the case of Request telegrams that are not acknowledged and with Request FDL Status, Ident, and LSAP Status, FCV=0 and FCB=0; evaluation by the responder is no longer necessary.

Bit position

FCB

FCV

Condition

Meaning

Action

DA = TS/127

Request without acknowledgement
Request FDL Status/ Ident/ LSAP Status

Delete last acknowledgement

0/1

DA # TS

Request to another responder

Delete last acknowledgement / response

DA = TS

First request

FCBM := 1
SAM := SA
Delete last acknowledgement / response

0/1

DA = TS
SA = SAM
FCB # FCBM

New Request

Delete last acknowledgement / response
FCBM := FCB
Hold acknowledgement / response in readiness for retry

0/1

DA = TS
SA = SAM
FCB = FCBM

Retry Request

FCBM := FCB
Repeat acknowledgement / response and continue to hold in readiness

0/1

DA = TS
SA # SAM

New initiator

FCBM := FCB
SAM := SA Hold acknowledgement / response in readiness for retry

FCBM stored FCB in memory SAM stored SA in memory

Checksum

The FCS (Frame Check Sequence) checksum required in the telegram for Hamming distance 4 is always located directly in front of the end delimiter (ED) and has the following configuration:

7	6	5	4	3	2	1	0
0 to 255								Checksum

For the without-data format (SD1) the checksum must be formed by the arithmetical sum of DA, SA, and FC without start delimiter (SD) or end delimiter (ED) and disregarding sums carried over. For the fixed length format with data (SD3) and the variable length format (SD2) the checksum must also include the payload (PDU). Example of bytes added together in the FCS:

SD2

LEr

SD2

DSAP

SSAP

PDU

FCS

Пн	Вт	Ср	Чт	Пт	Сб	Вс
1	2	3	4	5	6	7
8	9	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30

7	6	5	4	3	2	1	0	DA: Destination address
	0 — 127 (0x7F)							Destination address
0 1								no DSAP (SAP = NIL) DSAP present

7	6	5	4	3	2	1	0	SA : Source address
	0 – 126 (0x7E)							Source address
0 1								no SSAP (SAP = NIL) SSAP present

Информационно-техническая свалка, как свое так и из сети (ДЛЯ ЛИЧНОГО ИСПОЛЬЗОВАНИЯ)

Для личного использования. Информация, взятая из сети сопровождается ссылкой на источник

Function code

Length information

Checksum

Address byte