Phonoland

Hi

What do you recommend as a replacement for the 4 transistors in the SHP3 amp? and a good place to buy them?

Thank you in advance

Best
Darrell

Too ad to that: these are the driver transistors. we have a bad Q5125 it went thermal with a buzzing , that I thought at 1st was a bad light ballast. the number is EGC 196, the pair up is EGC 197. we need to know if these must be replaced in pairs? this is an overall noisy amp, but I don't want to just go overboard or go cheapo in the repair as this is a sell juke. Thanks all. Mark

Hi Guys,
I am not familiar with the EGC numbers you have ? I use only TIP-31C and 32 C's. I always replace in pairs--even if different brands. Ron Rich

Ron Rich wrote:Hi Guys,
I am not familiar with the EGC numbers you have ? I use only TIP-31C and 32 C's. I always replace in pairs--even if different brands. Ron Rich

Yes, ECG is now called NTE - same numbers.

Hi Mattie,
Yes--NTE and ECG parts, for the most part used the same numbers ( My point above is that I have never used those NUMBERS, for this application and I do not know if that is a "good cross", or not ?)--ECG was originally owned by Sylvania. I think they became "independent" for awhile--not sure--anyway sometime -a long, long time ago NTE adapted the same numbering system--Whomever owned EGC at that time filed a law suit-won, and NET changed from using the "ECG" to TCC. Later they changed that to NTE ( Nippon Telephone Electric), which now ( in the last 5, or so years?) has purchased the ECG trademark. Ron Rich

[quote="mb9513"...... this is an overall noisy amp, but I don't want to just go overboard or go cheapo in the repair as this is a sell juke. Thanks all. Mark[/quote]

Other than a very slight mechanical hum from the power transformer, any 'noise" is abnormal.

The final section is DC coupled. Any time a transistor in that area is defective, it is a good idea to test the remaining devices with a meter (diode test). The power transistors must be removed for the test, but the driver can be tested if the board is removed.

In reality, this is a 34w/ch amp and should not be fused higher than a 2amp-fast. I've measured less them 1 amp in normal conditions so I use a 1½ fast. I suggest that the idle bias not be above 2ma.

Rob-NYC

Rob-NYC wrote:[quote="mb9513"...... this is an overall noisy amp, but I don't want to just go overboard or go cheapo in the repair as this is a sell juke. Thanks all. Mark

Other than a very slight mechanical hum from the power transformer, any 'noise" is abnormal.

The final section is DC coupled. Any time a transistor in that area is defective, it is a good idea to test the remaining devices with a meter (diode test). The power transistors must be removed for the test, but the driver can be tested if the board is removed.

In reality, this is a 34w/ch amp and should not be fused higher than a 2amp-fast. I've measured less them 1 amp in normal conditions so I use a 1½ fast. I suggest that the idle bias not be above 2ma.

Rob-NYC[/quote]

2 MA?
Knowing solid state amps, that seems kinda low, almost inviting crossover distortion.
Generally a 7-20ma setting for class a/b amps.

2 MA?
Knowing solid state amps, that seems kinda low, almost inviting crossover distortion.
Generally a 7-20ma setting for class a/b amps.

Seeburg recommends 4-8ma. While this is a standard quasi-comp the quiescent bias can be set unusually low. I have seen some with bias at 0 and still clean at room temp. I generally find 1.5 to 2 ma to be best overall considering ambient temperatures. These amps use a circuit that senses emitter current exceeding a preset level and uses that to bias-off the input stage. It uses an unbiased transistor as a switch. Idling too high can cause simple transients to trigger the cutoff.

Rob