Reverb tank into Squier 15 SS amp

[SpareRibs]

Hello g1,
The amp is made in Taiwan. The two pieces mounted on the heat sink are D313-E7F3. Each piece has those two numbers on them. They are part of the output.
I cannot take a picture of the face plate right now as it is disassembled.

[Enzo]

everything is there, in out ect. just the values missing

You had been asking WHERE to tap in and out.  Thoe extra parts for THEIR circuit have no values, but you should be able to tell where in teh dry circuit they tapped.   Then you can use any drive and recovery circuit you like using those tapping points.   One could probably use similar circuits to fill in the spaces, ignoring the part numbers.

[SpareRibs]

Hello,
It has in and out for a reverb tank, not into and out of the existing circuit. Without a schematic showing where to tap into and out of the circuit I am still at a loss, as well as what parts are needed.
I already know it's just a cheap amp to you but, I would like to upgrade it as I have had it since 1987. It has been very useful and dependable.
The few upgrades like the 12" speaker and staggering the clipping diodes made a remarkable difference. Now I think adding a reverb tank would only enhance all of that.
I am sorry to have created such a problem for you, I only ask on this forum because I thought it would solve the problem for me, was I wrong ?

[g1]

I think the last page of attached schematic should make you happy. 
Just does not give the number for the transistors or reverb tank.  Maybe Fender could tell you that.

edit:  8EB2C1B should be the correct tank

[Enzo]

The board has the connector places labelled in and out for the pan, but the rest of the circuit traces are still there for the reverb circuit.  So we look for the parts in the existing stuff that has the takeoff and return feeds for the reverb circuits.  For example, follow the traces back from the top of the reverb pot and see where they come from.

But g1 appears to have found the relevant drawing, so it becomes moot.

[SpareRibs]

Hello,
While looking on the internet today, I found that in 1986 Fender marketed a Squier 15 reverb amp for sale in Japan. That may be why my amp has the reverb circuit traced onto the PCB board.
If I can get Fender to send the schematic for that I think the problem will be solved.

[Enzo]

Did you look at the last page of the file g1 posted?

[SpareRibs]

Hello,
Thank you g1, that was very informative. I will have to look into the transistors. I printed out the last page. I was so glad to get that much information at one time.

[Enzo]

Q101, Q103 can be general purpose NPN transistors, originals were probably 2SC1815 or similar.  Q102 would probably work fine with another 2SC1815.  The series 330 ohm 2 watt resistor tells me that for that resistor to dissipate 2 watts, there would have to be 77ma current.  I am sure they never designed it even close to that, and teh 2SC1815 is good for 150ma anyway.

ANy general NPN type should work, lower the noise the better.  I recommend you stay with Asian types, the 2SC or 2SD series.  You could use 2Nxxx US types, but the leads won't line up with the holes right.

The resistors are on the drawing, and other than the two 330 ohm 2 watt, make the rest the same wattage as the rest of the resistors in the amp.

Cap voltage isn't on there, but the most across the circuit is 42v.  And I don't see more than 20 volts or so an any of them.  SO 35v or 50v should suffice.

[SpareRibs]

Hello,
OK Enzo, that all seems very reasonable. Another thing that has perplexed me is C-102 that simply states 100 with no decimal point and C-107 that just has 22. The rest looks all right. I made a list for the capacitors and resistors, and now the transistors.
I will now just have to research which reverb tank to use. I don't want to use one that is either not large enough or to to big.
It also seems that the Fender and the Squier circuit are almost identical other than the reverb.
Thank you for the thought and effort you put into explaining the transistors

[Enzo]

The size of the reverb doesn't matter to the circuit, only the impedances.

All caps are on the print in microfarads unless otherwise noted.  So 100 and 22 are 100uf and 22uf, the rest are also in uf.  Look upper left at C2, C3, note they are 10pf and 47pf?  They have the units written, all the other ones don't, and are thus in uf.

[g1]

Reverb tank is 8EB2C1B.

[SpareRibs]

Hello,
Thanks g1. I have one more question. Q7 and Q8 are marked D313-E7F3. Next to that are the the 3 holes on the PCB for another transistor, marked 102. In addition there is a hole drilled in the heat sink to mount it. so could 102 also be a D313-E7F3 ? All 3 are in line.

[Enzo]

A 2SD313 would work.  But the fact the two output transistors are that type is irrelevant.

[SpareRibs]

Hello,
Thank you Enzo. The space for the 2SD313 is configured for that transistor. the other two spaces have the flat sided circle are the 101 and 103 that would use the 2SC1815.