TG1 - advice from any one who has built it...
- Thread starter mathsieve
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Help Support GroupDIY Audio Forum:
Well guys,
it's the new year and I've decided to try my luck again with the TG1 doorstopper / boat anchor that I have stashed away in hopes of some time getting it together..
Anyway, the +- 20V points are good as are the +- 28V and the signal is entering the board, however it gets beat up in the process..
This is a spectrograph power cycle of the board.. first you have a nice healthy signal coming through the relays and when you switch it on through the opamp input, look at the spectrograph. There's a click, some weird harmonics (weak weak signal). The other click and healthy signal is of course when I switch it off and relays click the signal back. I can only get this weak signal if I turn compression on (THD off) and take HOLD to the rightmost extreme (which puts the VU to above +10 on sintech's VU scale).
These are the oscilloscope scans of the testing points on the PCB:
T_A
T_B
T_C
T_D
T_E
T_F
T_G
T_H
T_J
T_K
I could use some help debugging this, as it's way over my head, all these transistors and how it works together. Just so to repeat, symptoms are extremely low output signal and high distortion.
it's the new year and I've decided to try my luck again with the TG1 doorstopper / boat anchor that I have stashed away in hopes of some time getting it together..
Anyway, the +- 20V points are good as are the +- 28V and the signal is entering the board, however it gets beat up in the process..
This is a spectrograph power cycle of the board.. first you have a nice healthy signal coming through the relays and when you switch it on through the opamp input, look at the spectrograph. There's a click, some weird harmonics (weak weak signal). The other click and healthy signal is of course when I switch it off and relays click the signal back. I can only get this weak signal if I turn compression on (THD off) and take HOLD to the rightmost extreme (which puts the VU to above +10 on sintech's VU scale).
These are the oscilloscope scans of the testing points on the PCB:
T_A
T_B
T_C
T_D
T_E
T_F
T_G
T_H
T_J
T_K
I could use some help debugging this, as it's way over my head, all these transistors and how it works together. Just so to repeat, symptoms are extremely low output signal and high distortion.
Maybe you already got asked this but did you use the right version of the BC214 ? There are 2 different pin outs for this transistor. The pcb has the ebc pins marked. If you bought the BC214L (I think) then the pin outs will be wrong & you will need to turn them round.
If you have the right ones then please ignore the above !
You can check the V's on the transistors in a basic way by checking that there is around 0.6v between base & emitter. But this may not hold true for all configurations.
If you have the right ones then please ignore the above !
You can check the V's on the transistors in a basic way by checking that there is around 0.6v between base & emitter. But this may not hold true for all configurations.
Thank you for a prompt reply.. I bought transistors from Frank (electrochronic), this is what came with them:
Transistor mapping , refer to silkscreen on PCB
BCY71
(qty 11) = VT1, VT2, VT3, VT4,VT7, VT12,VT15,VT18,
VT21,VT22, VT25,
BC109
(qty 15) = VT5, VT6, VT8, VT9,VT10, VT11,VT13,VT14,VT16,VT17
VT19, VT20,VT23,VT24,VT26
BCY34
=VT27
2N4910
= VT28
2N4898
= VT29
The small signal transistors are all metal can type with a tail that indicates the E pin. I didn't rotate any pins, so it was a simple method of matching the tail indicated pin to the silkscreened "E" on the board.
Transistor mapping , refer to silkscreen on PCB
BCY71
(qty 11) = VT1, VT2, VT3, VT4,VT7, VT12,VT15,VT18,
VT21,VT22, VT25,
BC109
(qty 15) = VT5, VT6, VT8, VT9,VT10, VT11,VT13,VT14,VT16,VT17
VT19, VT20,VT23,VT24,VT26
BCY34
=VT27
2N4910
= VT28
2N4898
= VT29
The small signal transistors are all metal can type with a tail that indicates the E pin. I didn't rotate any pins, so it was a simple method of matching the tail indicated pin to the silkscreened "E" on the board.
maxwall
Well-known member
- Joined
- Nov 17, 2004
- Messages
- 1,137
What TG Board version are you working with , Fester or other ?
The transistors are tested prior to shipping , but I always identify
pin leads and test for beta prior to soldering in the circuit. This eliminates
tiresome trouble shooting of dead or problematic components which can exist even in
a brand new batch of parts.
The 2N4898 & 2N4910 should not be lying against the PCB board and
insulators are required.
BC109 (NPN) - tab is closest to Emitter, middle pin is base , last pin is collector
BCY34 (PNP) - tab is closest to Emitter, middle is base, last pin is collector
BCY71 (PNP) - tab is closest to Emitter, middle is base, last pin is collector
Make sure the 2N4898 and 2N4910 have not been installed in the wrong PCB pad
One is PNP and the other NPN, and the pad orientation is the same footprint for both.
Check to make sure all diodes are good and none are installed in reverse, I have seen
diodes that have had the band (cathode end) applied to the wrong end of the diode , even though the
diode works perfectly fine. If installed this way , it would be reversed and cause some havoc in the circuit.
Also , Check your resistors prior to soldering into the circuit. I have seen countless times when a builder
solders a wrong value resistor into the circuit. Take a second for each resistor and measure them before
soldering them into the circuit. Deal with each one individually not the whole batch. The extra seconds it takes to measure the resistor saves hours of painstaking troubleshooting down the road.
I remember my first Neve 1272 preamp 15 years ago using self etch PCB and various components including sowter transformers. I fired it up and was really disappointed because no sound came out of it , just white noise. Turned out I had almost all the BC184C transistors reversed. I was lucky enough to remove them from the PCB board and re-use them without any harm from the heat of de-soldering the components. Second time around , I was very happy with the preamp, sounded amazing.
Maybe I don't need to repeat this as I assume most builders put the needed quality control into their builds. However, Sometimes the excitement in building a new project can hinder the build process, causing anyone to overlook simple steps or component details which can effect the end result. This is why I always keep a DMM handy when I'm soldering components in my boards. Double check everything even if it costs a few minutes in time for each component.
The transistors are tested prior to shipping , but I always identify
pin leads and test for beta prior to soldering in the circuit. This eliminates
tiresome trouble shooting of dead or problematic components which can exist even in
a brand new batch of parts.
The 2N4898 & 2N4910 should not be lying against the PCB board and
insulators are required.
BC109 (NPN) - tab is closest to Emitter, middle pin is base , last pin is collector
BCY34 (PNP) - tab is closest to Emitter, middle is base, last pin is collector
BCY71 (PNP) - tab is closest to Emitter, middle is base, last pin is collector
Make sure the 2N4898 and 2N4910 have not been installed in the wrong PCB pad
One is PNP and the other NPN, and the pad orientation is the same footprint for both.
Check to make sure all diodes are good and none are installed in reverse, I have seen
diodes that have had the band (cathode end) applied to the wrong end of the diode , even though the
diode works perfectly fine. If installed this way , it would be reversed and cause some havoc in the circuit.
Also , Check your resistors prior to soldering into the circuit. I have seen countless times when a builder
solders a wrong value resistor into the circuit. Take a second for each resistor and measure them before
soldering them into the circuit. Deal with each one individually not the whole batch. The extra seconds it takes to measure the resistor saves hours of painstaking troubleshooting down the road.
I remember my first Neve 1272 preamp 15 years ago using self etch PCB and various components including sowter transformers. I fired it up and was really disappointed because no sound came out of it , just white noise. Turned out I had almost all the BC184C transistors reversed. I was lucky enough to remove them from the PCB board and re-use them without any harm from the heat of de-soldering the components. Second time around , I was very happy with the preamp, sounded amazing.
Maybe I don't need to repeat this as I assume most builders put the needed quality control into their builds. However, Sometimes the excitement in building a new project can hinder the build process, causing anyone to overlook simple steps or component details which can effect the end result. This is why I always keep a DMM handy when I'm soldering components in my boards. Double check everything even if it costs a few minutes in time for each component.
Thank you for the hints. It's a Fester Unlimited "TG-2".
I actually did check some transistors with a transistor checker before soldering in, but that was mainly to double-check on the orientation side of things. I'll check again however..
Is it possible to run the circuit without the output section? Because I might have fried the big transistors when I put them in wrong once (and without micas) so desoldering might have been a bit brutal to them at high temperatures.. They are insulated though with mica insulator but there are screws going through the far end holes to connect the transistor body to the pads on the PCB. I guess that's all OK right? Maybe I should test for continuity between body and each of the pins?
I'll check that, the rotation of each transistor and diode and come back. Thank you for the support guys, this really helps. If you have any other ideas based on the testpoint scopes, please let me know..
I actually did check some transistors with a transistor checker before soldering in, but that was mainly to double-check on the orientation side of things. I'll check again however..
Is it possible to run the circuit without the output section? Because I might have fried the big transistors when I put them in wrong once (and without micas) so desoldering might have been a bit brutal to them at high temperatures.. They are insulated though with mica insulator but there are screws going through the far end holes to connect the transistor body to the pads on the PCB. I guess that's all OK right? Maybe I should test for continuity between body and each of the pins?
I'll check that, the rotation of each transistor and diode and come back. Thank you for the support guys, this really helps. If you have any other ideas based on the testpoint scopes, please let me know..
electrochronic said:
maxwall
Well-known member
- Joined
- Nov 17, 2004
- Messages
- 1,137
You must run the output transistors for the amp to work properly.
It is posssible to check the output transistors with a DMM in Diode mode.
here is a short tutorial on how to check for open or shorted transistors
with TO-3, TO-66, TO-220 or TO-92 types.
Set your meter to the continuity / diode "bleep" test. Connect the red meter lead to the base of the transistor. Connect the black meter lead to the emitter. A good NPN transistor will read a junction drop voltage of between 0.45v and 0.9v. A good PNP transistor will read "OL". Leave the red meter lead on the base and move the black lead to the collector. The reading should be the same as the previous test. Reverse the meter leads in your hands and repeat the test.
Now connect the black meter lead to the base of the transistor. Connect the red meter lead to the emitter. A good PNP transistor will read a junction drop voltage of between 0.45v and 0.9v. A good NPN transistor will read "OL". Leave the black meter lead on the base and move the red lead to the collector. The reading should be the same as the previous test.
Finally place one meter lead on the collector, the other on the emitter. The meter should read "OL". Reverse your meter leads. The meter should read "OL". This is the same for both NPN and PNP transistors.
With the transistors on a pcb in circuit, you may not get an accurate reading, as other things in the circuit may affect it, so if you think a transistor is suspect from the readings you have got, remove it from the pcb and test it out of circuit, repeating the above procedure.
Note : Transistor that shows shorted juctions indicates a bad device, the meter will usually beep continuous.
OL = Open Line
You can check for beta which is the easiest, but the Beta tester sockets on most DMM's do not allow for the big TO-3 or TO-66 packages to fit. In this case you can build a test jig that plugs into the DMM sockets
and is wired to the transistor plug in socket, example TO-66.
It is posssible to check the output transistors with a DMM in Diode mode.
here is a short tutorial on how to check for open or shorted transistors
with TO-3, TO-66, TO-220 or TO-92 types.
Set your meter to the continuity / diode "bleep" test. Connect the red meter lead to the base of the transistor. Connect the black meter lead to the emitter. A good NPN transistor will read a junction drop voltage of between 0.45v and 0.9v. A good PNP transistor will read "OL". Leave the red meter lead on the base and move the black lead to the collector. The reading should be the same as the previous test. Reverse the meter leads in your hands and repeat the test.
Now connect the black meter lead to the base of the transistor. Connect the red meter lead to the emitter. A good PNP transistor will read a junction drop voltage of between 0.45v and 0.9v. A good NPN transistor will read "OL". Leave the black meter lead on the base and move the red lead to the collector. The reading should be the same as the previous test.
Finally place one meter lead on the collector, the other on the emitter. The meter should read "OL". Reverse your meter leads. The meter should read "OL". This is the same for both NPN and PNP transistors.
With the transistors on a pcb in circuit, you may not get an accurate reading, as other things in the circuit may affect it, so if you think a transistor is suspect from the readings you have got, remove it from the pcb and test it out of circuit, repeating the above procedure.
Note : Transistor that shows shorted juctions indicates a bad device, the meter will usually beep continuous.
OL = Open Line
You can check for beta which is the easiest, but the Beta tester sockets on most DMM's do not allow for the big TO-3 or TO-66 packages to fit. In this case you can build a test jig that plugs into the DMM sockets
and is wired to the transistor plug in socket, example TO-66.
Hi Guys
Having an issue with my TG build and would like some help trouble shooting.
The unit is set up EMI style and is compressing as you would expect with attack and release all functioning ok, but when I switch between clean and bypass the bypassed signal is considerably louder than the clean signal (even without any compression) also there is very little gain makeup. I have checked the bypass board and all is ok there, so it seems to be on the main board.
I have the same problem on both channels so I am guessing I have put the wrong values in somewhere.
Does anyone have a list of voltages for the TPs and or ideas of where to start?
Having an issue with my TG build and would like some help trouble shooting.
The unit is set up EMI style and is compressing as you would expect with attack and release all functioning ok, but when I switch between clean and bypass the bypassed signal is considerably louder than the clean signal (even without any compression) also there is very little gain makeup. I have checked the bypass board and all is ok there, so it seems to be on the main board.
I have the same problem on both channels so I am guessing I have put the wrong values in somewhere.
Does anyone have a list of voltages for the TPs and or ideas of where to start?
simonsez
Well-known member
drask said:
I don't think so, that meter won't dance nicely in this circuit. You need 2.4ma meter, but it can work even without meter.
Hello,
I've just finish to build the TG.
I've 18,6v on T+20 and -18,6 on T-20.
And less 28v at the PSU out. So I think it's the PSU transfo, I use a 2x25v. So I'll change this.
But I want to know is what serves the jump 1-6.
And what is T_K and T_J.
And what value we do have at this point?
Thank's,
Jr
I've just finish to build the TG.
I've 18,6v on T+20 and -18,6 on T-20.
And less 28v at the PSU out. So I think it's the PSU transfo, I use a 2x25v. So I'll change this.
But I want to know is what serves the jump 1-6.
And what is T_K and T_J.
And what value we do have at this point?
Thank's,
Jr
I didn´t build this but from what I read jumpers 1-6 fine tune the voltage. I guess putting one or more jumpers at different positions will change +-V slightly...
but just guessing
Pachi
but just guessing
Pachi
One doubt about HOLD.
If you use a pot instead of switch (5k log with 5k resistor in series for +-15bd).
Is the attached drawing correct? Just cut the pcb, put 5k at R115, solder 5k pot to ATTACK pcb (are the pin numbers correct?) and short 2/3 at the I/O board INPUT/HOLD molex?
If this is correct it seems better to solder the pot before soldering the attack knob.
Just trying to figure it out before build. Thx
Pachi
If you use a pot instead of switch (5k log with 5k resistor in series for +-15bd).
Is the attached drawing correct? Just cut the pcb, put 5k at R115, solder 5k pot to ATTACK pcb (are the pin numbers correct?) and short 2/3 at the I/O board INPUT/HOLD molex?
If this is correct it seems better to solder the pot before soldering the attack knob.
Just trying to figure it out before build. Thx
Pachi
Attachments
lnk 1 is for stereo link.
I revised Fester's boards to 51X format, and found little, for most people irrelevant, buggie at current version of rack format boards.
IIRC, this fix was already posted; anyway.
Funny, this buggie wasn't present in old version boards. Gremlins? Dunno
Old version boards are very first ones without components values at silkscreening; there were 18 mono boards;
only me and some of first builders used them. First version boards had no transformer / bypass board.
If you plan to build it with HOLD or already have HOLD control at your unit, please refer to archive.
http://ij-audio.com/downloads/TG_FIX.rar
IF USED IN CH**R CONFIGURATION - J_CH*R SHORTED, NO HOLD CONTROL - THIS FIX IS NOT RELEVANT.
FOR USE WITH HOLD CONTROL ONLY!!!!
CUT TWO TRACES AND CONNECT 2 WIRES AS SHOWN AT PICTURES.
Fix takes 2 minutes exactly. Worst case, if you have to open/remove knobs at existing unit, 5 minutes.
I revised Fester's boards to 51X format, and found little, for most people irrelevant, buggie at current version of rack format boards.
IIRC, this fix was already posted; anyway.
Funny, this buggie wasn't present in old version boards. Gremlins? Dunno
Old version boards are very first ones without components values at silkscreening; there were 18 mono boards;
only me and some of first builders used them. First version boards had no transformer / bypass board.
If you plan to build it with HOLD or already have HOLD control at your unit, please refer to archive.
http://ij-audio.com/downloads/TG_FIX.rar
IF USED IN CH**R CONFIGURATION - J_CH*R SHORTED, NO HOLD CONTROL - THIS FIX IS NOT RELEVANT.
FOR USE WITH HOLD CONTROL ONLY!!!!
CUT TWO TRACES AND CONNECT 2 WIRES AS SHOWN AT PICTURES.
Fix takes 2 minutes exactly. Worst case, if you have to open/remove knobs at existing unit, 5 minutes.
DonnieDarko
Well-known member
- Joined
- May 26, 2012
- Messages
- 125
Hey,
I´m in the midst of building this unit and have some problems. I went all vintage parts: Allen Bradley military resistors (even baked them 9 hours in the oven to ensure proper tolerance), vintage semi conductors from Electro Chonic and so on…
It would be great if you guys could help me out.
PSU PCB:
Some (a lot of) parts on the PSU Board are not mentioned in the BOM.
I guess the four big Diodes can be 1N4007 rated up to 1000V ore similar. The four smaller ones between the IC´s need to be IN4004 I guess. Is this right?
BYPASS PCB:
There is a Cap labeld "CZ" on the board near the power hook up. In the schematic, this seems to be a 3300uf cap. Didn´t find a 3300uf cap in that small size and put in a 3300pf which fits perfectly. Can this be right?
Also, there is a resistor "RZ" next to it, that has no known value.
MAINBOARD PCB:
Could´t find a 200uf cap and put in another 220uf. Fine?
SWITCHES PCB:
There is a rsistor "R115"- someone earlier in this thread asked what should be placed there but I didn´t find any answer. Does anybody have an idea?
Thanks guys!
I´m in the midst of building this unit and have some problems. I went all vintage parts: Allen Bradley military resistors (even baked them 9 hours in the oven to ensure proper tolerance), vintage semi conductors from Electro Chonic and so on…
It would be great if you guys could help me out.
PSU PCB:
Some (a lot of) parts on the PSU Board are not mentioned in the BOM.
I guess the four big Diodes can be 1N4007 rated up to 1000V ore similar. The four smaller ones between the IC´s need to be IN4004 I guess. Is this right?
BYPASS PCB:
There is a Cap labeld "CZ" on the board near the power hook up. In the schematic, this seems to be a 3300uf cap. Didn´t find a 3300uf cap in that small size and put in a 3300pf which fits perfectly. Can this be right?
Also, there is a resistor "RZ" next to it, that has no known value.
MAINBOARD PCB:
Could´t find a 200uf cap and put in another 220uf. Fine?
SWITCHES PCB:
There is a rsistor "R115"- someone earlier in this thread asked what should be placed there but I didn´t find any answer. Does anybody have an idea?
Thanks guys!
DonnieDarko
Well-known member
- Joined
- May 26, 2012
- Messages
- 125
Thanks, that helped me already!
bieckmusic
Well-known member
Hey everyone,
I'm putting together my bom and, have a question about the steppedswitches for the tg1 front panel. For attack do I install a 3k3 resistor, then a .6k, then a .8k and so on?(cumulative style) or do I actually install a 3k3, then 3k9, then 4k7…
I saw an earlier thread that said something about the values being cumulative, and got confused, because the schematic doesn't seem to indicate it being cumulative...
Does this same technique apply to the other stepped switches, it looks like it does not apply to the hpf switch. I'm guessing I just install the values exactly like on the schematic. c110 33n, c108 22n etc,,,
Also, is the recovery cumulative or do I install the values on the schematic?
thanks to anyone who can help clear this up. This project is a little scary for a newbie like me!!
bless,
greg
I'm putting together my bom and, have a question about the steppedswitches for the tg1 front panel. For attack do I install a 3k3 resistor, then a .6k, then a .8k and so on?(cumulative style) or do I actually install a 3k3, then 3k9, then 4k7…
I saw an earlier thread that said something about the values being cumulative, and got confused, because the schematic doesn't seem to indicate it being cumulative...
Does this same technique apply to the other stepped switches, it looks like it does not apply to the hpf switch. I'm guessing I just install the values exactly like on the schematic. c110 33n, c108 22n etc,,,
Also, is the recovery cumulative or do I install the values on the schematic?
thanks to anyone who can help clear this up. This project is a little scary for a newbie like me!!
bless,
greg
loopermc5
Well-known member
Just follow the bom and schematic and youll be fine.
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