vintage Philips AH718 tuner amplifier transistor No.

[tunerlover]

dear every one I have Philips vintage AH718 tuner Amplifier! few day back No sound, see many makenic and say transistors burn. I say changd. but transistor No. not clear look (BDXXX) also tow pics attchd. so any one pls help.
my E-mail [email protected] ,
name-shiv Kumar, contect No 07532926794
MERY ENGLISH KAMJOR HAI ISKE LIYE MUAFI CHAHTA HUN.

 

[omishra]

Looks like paralleled BD139, BD318 connected near +ve power supply rail. And another pair might be BD140, BD317 connected near -ve power rail. It looks like AB power amplifier. Please clean it and verify under light using magnifying lense.

 

[tunerlover]

dear friend thxs for reply me. I do try this verywell. but I seen (BD) 1st No. and last No. are not clear. but mid No.is 7. pls help

 

[omishra]

You have look at it from different light angles and using magnifying glass. Or if it has groove then use some heat paste to fill it and see.

 

[adityapm]

These are darlington power transistors, and not the BD139/140 normal types.
As the physical size is the same for both the types, it is easy to get confused.

Pls buy 2 pairs of either of these:

BD675(NPN)/BD676(PNP),

or

BD677(NPN)/BD678(PNP).

Any of these pairs will work.

Pls note the NPN/PNP positioning while fitting.

Goodluck.


Aditya

 

[reubensm]

That PCB does not look tampered with and should be an easy fix. Its a good idea to check the board completely before changing the output transistors. The failure of these transistors may be due to some other root cause so not a bad idea to check.

 

[omishra]

Also it's tuner means inbuilt power amplifier may not be more than 5-10W output. So in case originals are not confirmed then replaced with other substitute darlington transistor may not be problem. So near positive rail, PNP output device with NPN driver and reverse on -ve rail.
But all above are speculation in absence of exact schematic and PCB diagram.

 

[tunerlover]

Hi, aditya Thanks for replying me .Firstly I am not getting from which side these transisters will start ,left or right .I am realy confuse ! I am sending pics ,pls tell which one is corrects.?

Regard :
Rakesh kumar (Delhi)
my contect No. 9891387183

 

[sachin_k5]

That PCB does not look tampered with and should be an easy fix. Its a good idea to check the board completely before changing the output transistors. The failure of these transistors may be due to some other root cause so not a bad idea to check.

Rightly said. Are you sure the transistors are blown? Transistors generally have a longer life than the capacitors and if they are blown then there could be a short somewhere. If those shorts are not cleared simply changing the transistors will blow them again.

 

[tunerlover]

Hi, aditya Thanks for replying me .Firstly I am not getting from which side these transisters will start ,left
or right .I am realy confuse ! I am sending pics ,pls tell which one is corrects.?
Regard :
Rakesh kumar (Delhi)
my contect No. 9891387183:sad:

 

[adityapm]

Hi, aditya Thanks for replying me .Firstly I am not getting from which side these transisters will start ,left
or right .I am realy confuse ! I am sending pics ,pls tell which one is corrects.?
Regard :
Rakesh kumar (Delhi)
my contect No. 9891387183:sad:

The picture with the "RED" markings is the right one.

Fit the new transistors properly with the supplied washers/spacers etc, and check for any body/chasis short. This is important.

Remove the fuses, and power on the set after the transistor replacement.

Check the voltage at the fuse-holder, and it should be around 25-to-30 volts. Then check the current across the fuse-holder, and it should be around 15-to-25 mA.

When all is well, you can switch off, put the fuses back, and switch on again.


Goodwishes

Aditya

 

[tunerlover]

The picture with the "RED" markings is the right one.

Fit the new transistors properly with the supplied washers/spacers etc, and check for any body/chasis short. This is important.

Remove the fuses, and power on the set after the transistor replacement.

Check the voltage at the fuse-holder, and it should be around 25-to-30 volts. Then check the current across the fuse-holder, and it should be around 15-to-25 mA.

When all is well, you can switch off, put the fuses back, and switch on again.


Goodwishes

Aditya

Hello.... Aditya sir please help again........

 

[Veerite]

Also it's tuner means inbuilt power amplifier may not be more than 5-10W output. So in case originals are not confirmed then replaced with other substitute darlington transistor may not be problem. So near positive rail, PNP output device with NPN driver and reverse on -ve rail.
But all above are speculation in absence of exact schematic and PCB diagram.

Please confirm exact power output of this AH 718 , I have it in good condition, all bands including SW working fine, I’m planning to attach B&W 606 speakers with 120 watts capacity, can I do it ?

 

[Chulbulee]

The last tuner amplifier I saw (not remembering model number), was max 20 watts. It had a green Contour switch on front.

 

[samim_kp]

These are darlington power transistors, and not the BD139/140 normal types.
As the physical size is the same for both the types, it is easy to get confused.

Pls buy 2 pairs of either of these:

BD675(NPN)/BD676(PNP),

or

BD677(NPN)/BD678(PNP).

Any of these pairs will work.

Pls note the NPN/PNP positioning while fitting.

Goodluck.


Aditya

BD677(NPN)/BD678(PNP) 2 nos. each. is mounted in mine AH-718