Have a a7 Hc... Blown transistors.. Shematic diagram??
Hello.. One off the transistorleader have short surcuit to gnd in output channel.
Have changed all transistors but hven i power on the amp i get ca 40v dc on the speaker conections. Then i took the power off to not blow any thing. Transistors in power suply starting to get hot after a short time. What do i need to change??
I need a schematic diagram in pdf file. Can you help me??
Re: Have a a7 Hc... Blown transistors.. Shematic...
You just need to send this amp to cadence they will get it fixed in less then a week trust me i sent mine through ups it only cost me 35$ for shipping and they charged me a 1 dollar to fix and if you do not believe me i got proof.
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This website appears to have diagram for it. You will have to register to log in. http://elektrotanya.com/?q=hu/content/how-change-site-language-english May of been some other component burnt out. Only way is by test meter and testing. Quite possible transistor burnt out. You should be able to test it in circuit for Short circuits. If output transistors faulty make sure you check driver transistors as well. Hope some of that helps.
Tough one. I repair these for a living. A number of possibilities exist. Likely output transistors are blown on the bad channel. Fuses are likely blown. If the fuses are BLACK inside, don't just put new fuses in, more damage WILL occur. This is a bit more than 'good with a soldering iron' will fix. You need to know how to test an output transistor. You need to look up the transistor type so you know what it is. A service manual will be a big help (I could not find one online.) If more than two outputs are gone on the one side, all should be changed, they are supposed to be MATCHED. Remove and replace all damaged outputs, or replace them all if two are blown. Find the driver transistors and check them for short circuits. After repair, start the amp on a dummy load of a 250watt light bulb to prevent destroying the amp if there is a problem. If you are unsure of any part of this, find an electronics technician to help.
I would also replace 2sa992 (2pcs) and 2sc1845 on preamp board- sometimes they look ok when you test them by regular meter. Check 1.2 kOm and 4.7ohm resistors at preamp pcb. Check diodes on output pcb (could be smd type, connected from base of output transistors to emitter i think)
First of all you have to check The positive and negative 95V in the collector pin of all output tansistors. There should be +95V in the all collectors of MJ15024 and --95V in all collectors of MJ15025 poer the output transistors of faulty channel.ANd tere should be +/-- 0.5 volt in all output transistors base pin. All emitter pin should be aproximatly 0V. If not then you have to check the tansistors Q13 to Q16 and Q17 to Q20. Also the driver transistors Q9, Q10, Q11,Q12,.
If you need the schematic diagram that i will sent it to you.
Your TVs video output transistor [Red] has got shorted. Usually a transistors are used in most of the colour telivisions in video output stage.. If it is a transistorised video output stage, replacing red output transistor will solve the problem. In some modern sets there are so many types of Integrated Circuts [ICs] are used. If your TV uses Ic as video output, replace the Ic.
The cost of the replacement parts is minimal if there is no damage to the audio circuit. If there are shorted output transistors, the cost of replacement parts won't be significantly higher but it may be more difficult to repair. If you're going to try to repair it yourself, read through the following page: http://www.bcae1.com/repairbasicsforbcae1/repairbasics.htm
No you dont need to replace the intire power supply.its very easy to repair you can do it checked all the diodes ,for forward bias ,and for shortage and next the the capacitor for shorted, or busted you can see the apearance change,I know your is good because when put the fuse is blown away resistor good,only the diodes near in the transformer.and if see a transistor with heat sink check that maybe short also ill try to find a shematic diagram for you.
Were any fuses
blown? Check this first and
foremost before you do anything else. If there were blown fuses, you
then (if you are familiar with
how), need to check the output stages for shorts. NOT generally to
you have suggested.... but more between the center and outside pins
(collector emitter short we are looking for here) To check the output
transistors properly, you need to unsolder leg and
check each of the output transistors junctions base emitter, and base
collector, and also collector emitter for any leakage. Once you find
the offending channel(normally there is only one), you need to then
carefully check the driver transistors also. Pay attention to low value
resistors about the output stages, small signal and zener diodes and if
they are there, any power diodes. If you are unsure of the condition
of a part, then replace it to be sure :)
sounds like you may have a short to ground on the output transistors. Does it have transistors or an IC output. It is most likely that you have not replaced a mica washer or insulator. Check to ground with a meter from the case of the output devices.