Don't run the amp with the resistors too long or play it too loud ..OK

 

Don't run the amp with the resistors too long or play it too loud ..OK

Okay ill remove the 22R then

 

listen....adjust the bias to 0.55V acr0ss Base and emitter.

Check all the output transistors. If the voltage stays the same after warmup then all's good. U can remove the 22R's.

Measure the DC at speaker terminal per service manual.

U did a good job for a 14 year old kid.

 

Measure the DC at speaker terminal per service manual.

I have about 45 mV at the speaker terminals. I cant find anything in the manual that says what voltage it should be

 

A perfectly biased output stage will have 0mV at the speaker terminal.

Nothing is perfect as usual.

Then it's OK for such old amps.

 

A slip of the probe and u will be crying.

Well guess what, it happened. I was testing the transistors ONE LAST TIME!!!!!... And the probe slipped

 

Well guess what, it happened. I was testing the transistors ONE LAST TIME!!!!!... And the probe slipped

Nevermind, i fixed the problem

 

Remember, it's always the last climb/jump/ride/flight that kills you.

 

Yayyyy it works now

 

Yayyyy it works now

The stereo works??

 

The stereo works??

Yepp...........

 

Congratulations Earl and R!f@@.

Good to see tough problems get solved on AAC over 16,000km (10,000 miles) via the internet.

Well done!

 

Reading the 20 pages of trouble-shooting is more exciting than watching the Indiana Jones' Adventures. There are climaxes, ups and downs plus a good lesson learned from R!f@@ on trouble-shooting.

But I can't find datasheets for the 2SD290. And its metal casing looks like the old 40250 transistor. I got its picture from the web site here....

http://www.geocities.jp/craft_3/Semiconductor/SONY_Transistor/sony_tr.html

Anyway, well done Earl and R!f

Allen

 

U know what !

A heartfelt congrats it's far better than any dollar !

 

Reading the 20 pages of trouble-shooting is more exciting than watching the Indiana Jones' Adventures.

+1
Early on I was pretty sure this thread wasn't going to end well - it looked bleak. Burned components, evidence of previous alterations. Smoke.

As it moved forward, glimmers of hope began to emerge, mostly because the two heroes were clearly not giving up.

In the end we've all seen a good lesson on persistence and the triumph of a careful and methodical approach.

Well done.

 

Persistence pays off. Let's see how we do with Steve's keyboard down under.

 

Reading the 20 pages of trouble-shooting is more exciting than watching the Indiana Jones' Adventures. There are climaxes, ups and downs plus a good lesson learned from R!f@@ on trouble-shooting.

The Film rights must be worth a few shilling!

Reminds me of this
http://en.wikipedia.org/wiki/84_Charing_Cross_Road_(film)

By the way I learnt a huge amount from this thread especially the neat trick of using the 22Ω resistors to prevent frying any bits while under test.

 

Yeah, i had my doubts about rather my stereo was ever gonna work again (my parents sure didnt think so). Funny thing is, i had this radio for only 2 days before it broke, and my parents were pretty pissed because they didnt think I should get it in the first place (they dont see the value in vintage stuff, they also think im crazy because i listen to vinyl records too lol), but were they shocked when they heard it working in here the other day. Theres still a few bugs to be worked out, I can hear a slight bit of hum in the speakers, but nothing a good recap probably cant solve. And I thInk the FM stereo needs some adjustments, but i think i know my way around it, if i dont, ill just post another thread

 

Yeah, i had my doubts about rather my stereo was ever gonna work again (my parents sure didnt think so). Funny thing is, i had this radio for only 2 days before it broke, and my parents were pretty pissed because they didnt think I should get it in the first place (they dont see the value in vintage stuff, they also think im crazy because i listen to vinyl records too lol), but were they shocked when they heard it working in here the other day. Theres still a few bugs to be worked out, I can hear a slight bit of hum in the speakers, but nothing a good recap probably cant solve. And I thInk the FM stereo needs some adjustments, but i think i know my way around it, if i dont, ill just post another thread

Your parents think you're crazy for listening to vinyl records? You must have very young parents

I grew up with vinyls, and to tell you the truth, I often still prefer them over modern CDs. Nothing beats the old hisses, crackles, and pops throughout a song. It's like a testament of the entire life of the record

 

I grew up with vinyls, and to tell you the truth, I often still prefer them over modern CDs.

We may be straying off topic, but I think you should read this and this.

View attachment The Death of High Fidelity _ Rolling Stone.pdf

The point is, digital music can and should be far superior to older delivery methods, but today's producers are ruining the recordings, on purpose. "Remastered" can equal FUBAR.