Hi,
Could someone please help me again with this temperamental amp, probably not the easiest to work on for a beginner. Not sure but it probably better to open a new thread as its a new issue.
I had previous trouble with this amp, which was no power going to one side of the input selector switch, it turned out to be Q701, this issue as resolved.
Now its going into protection mode on power up, I have taken some voltage readings and these are the results:
IC502 P/N:SVI2004A
Pin1= -41.2
Pin2= +42.7
Pin3= -40.7
Pin4= -42.5
Pin5= -42.5
Pin6= -37
Pin7= -40.6
Pin8= 0
Pin9= 0
Pin10= -40.6
Pin11= -36.9
Pin12= -42
Pin13= -42
Pin14= -40.3
Pin15= +42.2
Pin16= -40.9
IC501 P/N:AN7062
Pin1= 0
Pin2= -8.19
Pin3= -16.5
Pin4= 41.4
Pin5= 40.6
Pin6= 42.4
Pin7= 42.4
Pin8= 42.4
Pin9= 42.4
Pin10= -15.9
Pin11= 42.3
Pin12= 42.3
Pin13=42.4
Pin14= 40.5
Pin15= 41.6
Pin16= -24.1
Pin17= -15.7
Pin18= -10.3
J6 connection cable (going towards IC501)
Pin1= -1
Pin2=0
pin3= -4.5
pin4 = -15.6
pin5 = + 16.2
Q501, Q 502, Q503 and Q 504 measured good out of circuit, no shorts. Tested in diode mode and hFE.
Likewise D501 & D502 both measured fine.
This is the voltage on Q606
Base = -40.0
Emitter = -41.6
Collector = - 0.6
Just hoping its not the SVI chip, after all the work put into this amp. Solder joints have all been reheated, old flux cleaned and inspected with magnifying glass.
Is it time to open up the SVI chip and inspect it?
Thanks so much in advance.
Could someone please help me again with this temperamental amp, probably not the easiest to work on for a beginner. Not sure but it probably better to open a new thread as its a new issue.
I had previous trouble with this amp, which was no power going to one side of the input selector switch, it turned out to be Q701, this issue as resolved.
Now its going into protection mode on power up, I have taken some voltage readings and these are the results:
IC502 P/N:SVI2004A
Pin1= -41.2
Pin2= +42.7
Pin3= -40.7
Pin4= -42.5
Pin5= -42.5
Pin6= -37
Pin7= -40.6
Pin8= 0
Pin9= 0
Pin10= -40.6
Pin11= -36.9
Pin12= -42
Pin13= -42
Pin14= -40.3
Pin15= +42.2
Pin16= -40.9
IC501 P/N:AN7062
Pin1= 0
Pin2= -8.19
Pin3= -16.5
Pin4= 41.4
Pin5= 40.6
Pin6= 42.4
Pin7= 42.4
Pin8= 42.4
Pin9= 42.4
Pin10= -15.9
Pin11= 42.3
Pin12= 42.3
Pin13=42.4
Pin14= 40.5
Pin15= 41.6
Pin16= -24.1
Pin17= -15.7
Pin18= -10.3
J6 connection cable (going towards IC501)
Pin1= -1
Pin2=0
pin3= -4.5
pin4 = -15.6
pin5 = + 16.2
Q501, Q 502, Q503 and Q 504 measured good out of circuit, no shorts. Tested in diode mode and hFE.
Likewise D501 & D502 both measured fine.
This is the voltage on Q606
Base = -40.0
Emitter = -41.6
Collector = - 0.6
Just hoping its not the SVI chip, after all the work put into this amp. Solder joints have all been reheated, old flux cleaned and inspected with magnifying glass.
Is it time to open up the SVI chip and inspect it?
Thanks so much in advance.
Pull out Q501~Q504
Connect collector point of Q501 & Q502 to ground via 3.9K resistors
Check voltages of SVI pins... () is right channel
1 (16)
3 (14)
5 (12)
Connect collector point of Q501 & Q502 to ground via 3.9K resistors
Check voltages of SVI pins... () is right channel
1 (16)
3 (14)
5 (12)
Hi,
First of all thank you again for responding so fast, I only got around to it tonight, did exactly as you requested and all pins are reading 0Volts now, does this sound correct?
Oh and its not going into protection mode anymore. Please tell me that its the transistors and not the SVI chip, as these are probably impossible to obtain at this stage.
Regards.
First of all thank you again for responding so fast, I only got around to it tonight, did exactly as you requested and all pins are reading 0Volts now, does this sound correct?
Oh and its not going into protection mode anymore. Please tell me that its the transistors and not the SVI chip, as these are probably impossible to obtain at this stage.
Regards.
Ok Figured it must not be the SVI chip
I have two a1123 pnp replacements, but no 2sc2631, does the emitter -collector and collector -base voltage really need to be 150V, since we are only using about 40volts. I have some new c1815 npn, collector dissipation is also a bit lower.
I have two a1123 pnp replacements, but no 2sc2631, does the emitter -collector and collector -base voltage really need to be 150V, since we are only using about 40volts. I have some new c1815 npn, collector dissipation is also a bit lower.
2SC2631 n-p-n transistor complementary pnp, replacement, pinout, pin configuration, substitute, marking C2631, equivalent, datasheet
Or have some of these, they look like a closer match
2N5551 n-p-n transistor complementary pnp, replacement, pinout, pin configuration, substitute, marking 2N 5551, equivalent smd, datasheet
Or have some of these, they look like a closer match
2N5551 n-p-n transistor complementary pnp, replacement, pinout, pin configuration, substitute, marking 2N 5551, equivalent smd, datasheet
It is not the SVI
I am interested in those voltages though
+ 40 with all inputs -40
Both ch.....
Iirc this happens when pin 2 of J6 is ungrounded
I am interested in those voltages though
+ 40 with all inputs -40
Both ch.....
Iirc this happens when pin 2 of J6 is ungrounded
Hi,
Thank god its not the chip anyway. (I have a spare an7062 at hand also if needed)
I will test pin 2 on J6 tonight again, it measured -1v when I checked it. I will do a continuity test on it to ground when i get home tonight.
Thanks.
Thank god its not the chip anyway. (I have a spare an7062 at hand also if needed)
I will test pin 2 on J6 tonight again, it measured -1v when I checked it. I will do a continuity test on it to ground when i get home tonight.
Thanks.
Ok I have checked pin 2 of J6 and it has continuity to ground, I should probably put the transistors back in to continue debug?
I will put in two new A1123, and two 2N5551 observing that I need to swap the base & collector on the 2N5551 as the pin layout is different. And then take some voltage readings again. I have also re-seated J6 on the main board.
I will put in two new A1123, and two 2N5551 observing that I need to swap the base & collector on the 2N5551 as the pin layout is different. And then take some voltage readings again. I have also re-seated J6 on the main board.
Hi,
Still stuck with this, what do you suggest next? do you think it could be the An7062?
Thanks in advance.
Still stuck with this, what do you suggest next? do you think it could be the An7062?
Thanks in advance.
I’m curious about voltages
Pins 1,5,12 & 16 at -40v with pins 3 and 14 at +40v
Check R513 R514 R519 & R520
Then I’d fit new Q501 & 502
A test mode
And in place of Q503 and 504 use 7.8K resistance from Collector to Emitter of them
See what voltages are there
Pins 1,5,12 & 16 at -40v with pins 3 and 14 at +40v
Check R513 R514 R519 & R520
Then I’d fit new Q501 & 502
A test mode
And in place of Q503 and 504 use 7.8K resistance from Collector to Emitter of them
See what voltages are there
I checked the resistors Check R513 R514 R519 & R520 all good.
Fitted new Q501 & 502, and installed a 7.5k resistor between collector & emitter (I did not have 7.8k)
Measure voltages again on the SVI chip and nothing has changed, all voltages are the same.
Fitted new Q501 & 502, and installed a 7.5k resistor between collector & emitter (I did not have 7.8k)
Measure voltages again on the SVI chip and nothing has changed, all voltages are the same.
voltages at J6 seem off pins 1 and 3
Disconnect J6 and connect pin 2 of J6 to ground- when cable removed from it it becomes ungrounded
If still no better I’d try new AN7062
Disconnect J6 and connect pin 2 of J6 to ground- when cable removed from it it becomes ungrounded
If still no better I’d try new AN7062
Ok will give that a good later tonight, Just making sure, connect pin 2 of the cable end or the amp socket to ground or both?
Hi,
Tried to ground pin2 on the main board to the chassis...solder wire came in handy, this did not fix the issue. Soldered in new 7062 and when I heard the relay click well that says it all. Now to put it all back together. Was given a nice kenwood ka 3020 yesterday by someone going to dump it, no sound on one channel, some switch cleaner in all the rotary switches and it was fixed. So now have two working amps.
Thanks again for all your help, hopefully the technics will last another 30 years now...😀
Tried to ground pin2 on the main board to the chassis...solder wire came in handy, this did not fix the issue. Soldered in new 7062 and when I heard the relay click well that says it all. Now to put it all back together. Was given a nice kenwood ka 3020 yesterday by someone going to dump it, no sound on one channel, some switch cleaner in all the rotary switches and it was fixed. So now have two working amps.
Thanks again for all your help, hopefully the technics will last another 30 years now...😀
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