Transistor and Diode subs help needed

[bhuskins]

I'm restoring an old reel to reel and finished the recap but the internal amp is still really noisy and distorted, so I figured I would replace the transistors and diodes as well. This unit is definitely old school solid state...no circuit boards just a big mess of parts.

Here's what I'm looking to replace:

3 types of transistors:
Q1, Q5 are for the Preamp and are listed as S1331 with equivalents listed as DS-66, GE-10, TR-21 or SK-3020
Q2, Q3, Q6, Q7 are for the AF Amp and are listed as S1221 with equivalents also listed as the same DS-66, GE-10, TR-21 or SK-3020
Q4, Q8, Q9, Q10 are for the Output and the Bias Oscillator and are listed as SC-4131-1 the parts list doesn't show replacements for them.

On the diodes there are 2 types:
X1, X2 are listed as SR-120 .18A and show equivalents as GE-504A or GE-505, 5A4-D or SD500, A300 or 1N539, SK-3016 or SK-3017A, F-4 or 40C
X3, X4 are listed as CR-1N456 with no equivalents listed on the parts list.

Anybody have any suggestions or modern replacements for the above?

Trying to avoid NTE stuff...searching showed nte128 might be a sub for the sc-4131-1 and nte123 might sub for both the s1331 and s1221, so maybe that would help someone tell me what might work that's not NTE.

Not sure on the diodes though...

 

[larryderouin]

SR-120 you can use a 1n4004
1n456 you can use a 1n60A

For the transistors try www.alltransistors.com

Larry

 

[electrohifi]

in60, yep funny how many amps were still using germanium diodes even in the mid to late 70's. I just bought a bunch on ebay for cheap, nothing beats original parts for a restoration.....stupid marantz is full of them things

 

[bhuskins]

Is there anything from mouser that would sub for the 1N60A diode?

Cant find anything on alltransitors either...

 

[avionic]

Is there anything from mouser that would sub for the 1N60A diode?

Cant find anything on alltransitors either...

http://www.mouser.com/ProductDetail/NTE/NTE110MP/?qs=/ha2pyFaduhyPP0hesUjRzH77zI0UYThvEK4JdkqQ50=

 

[larryderouin]

Q1 & Q5 Q2-Q3-Q6-Q7 use a 2n2222. Different pkg. When you use all transistors, you can edit out parameters in the list. Edit out the package. A different package x55 vs to-92 won't hurt. Makes it easier to get modern replacements.

Q4,Q8-9-10 2n3019 http://www.mouser.com/ProductDetail...ha2pyFaduj1QrPW3EEFXqI0DjcR%2bPhCIuVGbUdyiDU=

 

[bhuskins]

So to recap...here's what I've got so far

From Mouser
SR-120 => 512-1N4004
1n456 => 526-NTE110MP
S1331 => 863-P2N2222AG
S1221 => 863-P2N2222AG
SC-4131-1 => 511-2N3019

My only question is whether or not mouser has an option for the 1N60A that's not an NTE option? So if NTE11-MP = 1N60A = 1n456 - any other modern options?

thanks!

 

[avionic]

My only question is whether or not mouser has an option for the 1N60A that's not an NTE option? So if NTE11-MP = 1N60A = 1n456 - any other modern options?

NTE is the only game in town for germanium relics

 

[bhuskins]

Is germanuim required though? that's why I was asking if there is another way to go or will modern diodes not behave the same?

 

[hardwareguy]

Is germanuim required though? that's why I was asking if there is another way to go or will modern diodes not behave the same?

MANDATORY. Ge has a lower forward voltage drop than Si. You'd have to fully analyze the circuit to determine suitability of replacements.

 

[Hyperion]

You could use schottky replacements if it was just to maintain the forward voltage drop - like 'BAT42' for example (available from Farnell for example).

OR a bit more expensive www.littlediode.com - for germanium originals

or http://markhindes.easywebstore.co.uk/ - same but cheaper

 

[bhuskins]

Just to be sure...

When I trace the circuit, the parts I show that are "supposed" to be the 1N456 germanium diodes look like the attached pic.

Those don't look like any germanium diodes I've seen before...are they just an older type?

They pass voltage in both directions so, if that's what they are they definitely need replacing unless germanium tests differently.

Any suggestions?

 

[Hyperion]

Picture not clear enough - can you get closer - and/or ring the components you are trying to ID - I can see what looks like a glass diode in the top right....

 

[bhuskins]

The 2 big green barrels with red and black horizontal stripe....that's what I'm talking about...about is close as its gonna get

 

[bhuskins]

This whole device only has 4 diodes...and those green barrels are physically in place were the schematic shows the 2 diodes to be

 

[Hyperion]

Oh I see, - they don't look like any semiconductor I have ever seen. Pass current in both directions? was this measured 'out of circuit' ?

 

[bhuskins]

Yes passes both directions in and out of circuit.

I've never seen them before either...unit was made in England

That's why I asked because they didn't look like diodes

 

[Hyperion]

Yes passes both directions in and out of circuit.

I've never seen them before either...unit was made in England

That's why I asked because they didn't look like diodes

The brown tubes on the middle might mean they are selenium rectifiers. I have seen some like this, but without the colourful green extra bit with stripes

Do you have a schematic? - does it mention anything about these to confirm if they are even rectifiers?

 

[bhuskins]

Ill post this portion of the schematic when I get back in a bit...these are listed as x3 and x4 on it

 

[bhuskins]

I think I figured it out...at least the parts location. Those 2 green cans are 3.3 ohm 1 watt resistors...The reason I couldn't find the 2 diodes is that they are attached to the back of the VU meters back I believe. See attached pic