Standel blue module transistors

[GregS]

Hello,

I'm presently restoring a 1967 Standel transistor amp and am rebuilding one of the blue epoxied pre-amp modules. I have the schematic for the blue module from the Standel site. It is not clear what part value one of the transistors is. The one closest to the input is labelled "Q1" on the schematic. There are some part numbers for "Q1" and "Q2" on the diagram. There is also a different set of part numbers for "TI" on the diagram. The transistor in the next stage is not labelled in the schematic so I don't know if it corresponds to "Q2" or "TI". I have done a Google search and am not able to find any information to clarify this.

If anyone here has rebuilt the blue module, are the two transistors in the circuit the same or is the second stage transistor a different part?

Thanks,
Greg

[Enzo]

It would be useful if you posted or linked the relevant schematics.

I happen to have the blue module one myself, can't speak for others.

Q1 and Q2 are the same type. Any good audio PNP transistor will work.

The drawing specifies either Fairchild 2N4249 or TI (Texas Instrument) 2N4062 as suitble types. That is not two sets of parts, it is just a list of possibilities for Q1,2. That "or equivalent" tells the whole story. Those were good types 50 years ago when this was made. If you find those types, they would still be good, but many other more modern PNP parts would work as well. Select low noise types.

Is your blue module defective?

[gbono]

Assume Q1=Q2 since they are both PNPs. The person who drew the schematic is referencing Fairchild (2N4249) and Texas Instrument (TI) (2N4062/4058) transistor part numbers. You are looking for a low noise PNP GP transistor in a TO-92 (discontinued) package. Someone might chime in on a replacement.

schematic can be found here (please post): http://bmamps.com/Schematics/Standel...xy_modules.pdf

[DrGonz78]

Since he mentioned the Standel site, here is a direct link to it.
Standel | Schematics

I think it is really cool to see a website still for Standel amps!

[GregS]

Thanks for the replies. That clears that up.

One of the blue modules is missing entirely from the amp - the one for the normal channel. The one for the reverb channel is still there and works fine. So to get the normal channel working again I thought it would be easier to just build a new module than try and find a replacement. The replacement transistors I have are a NTE 159 for the Fairchild 2N4249 and a NTE 234 for the Texas Instruments 2N4062. As I understand from the responses to this thread, either type will work so I could either use both of one type or mix them.

Thanks again,
Greg

[Enzo]

If you already have the NTE parts, go ahead and use them. But if you are ordering parts, just get the real parts.

[gbono]

The issue is no one supports TO-92 packaged parts anymore

The venerable 2N3904 has even been discontinued. Your best bet is to stock up on these little guys (if you haven't already) before they are as scarce as the small signal metal can transistors.

[Enzo]

On the other hand Mouser has 7200 MPS5087 in stock

Mouser has over 80,000 2N3906 in stock, with another 40,000 on order from Fairchild.

[GregS]

Thanks. I just finished building a new "blue module" with the NTE 159 transistors that I already had for the normal channel. It works fine and sounds just as good as the existing blue module for the reverb channel.

Greg