I have 8 ceramics for the main amp. 4 per channel. I will replace them as your sugestion with G0G.
Hello Roger2,
I have a problem, i was looking at the power amp board and is different from the board and schematic from the service manual.
For example my amp board dont have ce23/24 capacitors...
maybe the schematics are for the 3400 amplifier i dont know..
I have a problem, i was looking at the power amp board and is different from the board and schematic from the service manual.
For example my amp board dont have ce23/24 capacitors...
maybe the schematics are for the 3400 amplifier i dont know..
Use the link I posted. Download the service manual from that site. It contains clean schematics of both the 2400 and 3400, as well as the parts list.
The site hifiengine is good. No spam and they won't send you anything you didn't ask for. It is the best free manuals site. Register there with no worries.
Compare 2400 and 3400 schematics looking for Ce23,24.
The site hifiengine is good. No spam and they won't send you anything you didn't ask for. It is the best free manuals site. Register there with no worries.
Compare 2400 and 3400 schematics looking for Ce23,24.
This site has a good picture of the 2400 main amp board (scroll down). Does it have Ce23,24?
Kenwood KR-2400 Receiver | iamthejeff
Does your board have De1-4?
Often when changes are made in a production run, those changes do not get updated in the service manuals. I do not know if that is the case here. Just offering that as one possibility.
I am not an amp circuit expert. Perhaps those two caps were not absolutely critical and Kenwood decided to omit them? I don't know. Maybe someone else reading this could offer an opinion.
Kenwood KR-2400 Receiver | iamthejeff
Does your board have De1-4?
Often when changes are made in a production run, those changes do not get updated in the service manuals. I do not know if that is the case here. Just offering that as one possibility.
I am not an amp circuit expert. Perhaps those two caps were not absolutely critical and Kenwood decided to omit them? I don't know. Maybe someone else reading this could offer an opinion.
Last edited:
Yes my board is equal to that one in the picture...
Does not have ce23,24 but has the de1-de4 if you zoom you can see them.
Does not have ce23,24 but has the de1-de4 if you zoom you can see them.
Assuming:
1) De1-4 are connected to ground, as Ce23,24 are shown in the schematic
2) there is no indication that Ce23,24 were ever installed in your amp (no evidence of empty through-holes with solder remnants on pads)
3) your amplifier section functions properly
...I would not be concerned about missing Ce23,24.
I would also not be concerned about some corrosion on those metal cans as long as the metal appears to be intact. This amp is 44 years old.
1) De1-4 are connected to ground, as Ce23,24 are shown in the schematic
2) there is no indication that Ce23,24 were ever installed in your amp (no evidence of empty through-holes with solder remnants on pads)
3) your amplifier section functions properly
...I would not be concerned about missing Ce23,24.
I would also not be concerned about some corrosion on those metal cans as long as the metal appears to be intact. This amp is 44 years old.
Just checked the schematic for KA-4006 which (I believe) is a couple years after KR-2400. This is an amp which I did a complete rebuild of.
On the KA-4006 schematic it shows De1-4 connected to ground. No bipolar caps involved.
On the KA-4006 schematic it shows De1-4 connected to ground. No bipolar caps involved.
What you think of the main filter caps?
They are 3300uf.
Should i stay with that value or increase for example to 6800uf or more....or paralell two 3300uf per rail?
They are 3300uf.
Should i stay with that value or increase for example to 6800uf or more....or paralell two 3300uf per rail?
1) If this is your first project like this, I would not change the main caps just yet. You have a lot of parts to be replaced already. In fact, you should do these parts replacements in stages, a few parts at a time, then testing the amp to verify that there are no mistakes or problems. It will also be good for you to hear what happens when refreshing parts in the amp and tone sections. Later, after you are familiar with the new sound, you can do the main caps and see what difference that makes.
Most likely, any audible improvements will come from replacing smaller caps and from upgrading any electrolytics to film (Wima). Smaller caps, especially those with lower voltage ratings, age and deteriorate more quickly than the large filter caps.
2) But yes, at some point you should replace those main filter caps. I would go up to 4700uF and no further. You will need to know the lead spacing. And verify that no weird pin configuration exists (for example, the leads of original caps on KA-8100 are off-center).
You might be able to find some Nichicon "audio grade" caps to fit (KG, KW, FW etc). If you find one of those go with it. If not, ripple current and ESR are the key parameters to compare by when looking at general purpose caps for this position. If cost is no object there are other options (Mundorf for example).
Most likely, any audible improvements will come from replacing smaller caps and from upgrading any electrolytics to film (Wima). Smaller caps, especially those with lower voltage ratings, age and deteriorate more quickly than the large filter caps.
2) But yes, at some point you should replace those main filter caps. I would go up to 4700uF and no further. You will need to know the lead spacing. And verify that no weird pin configuration exists (for example, the leads of original caps on KA-8100 are off-center).
You might be able to find some Nichicon "audio grade" caps to fit (KG, KW, FW etc). If you find one of those go with it. If not, ripple current and ESR are the key parameters to compare by when looking at general purpose caps for this position. If cost is no object there are other options (Mundorf for example).
Last edited:
Yes this is my first project of this type.
This amp has some sentimental connection with me. When i started listening to vinyl was with this amp and i was impressed by the sound of records compared to my expensive digital dac/powered speakers at the moment...
So this amp as been on the side line for 4 years.
Now i have more understanding of electronics and experience on soldering etc. I feel i can do it.
This amp has some sentimental connection with me. When i started listening to vinyl was with this amp and i was impressed by the sound of records compared to my expensive digital dac/powered speakers at the moment...
So this amp as been on the side line for 4 years.
Now i have more understanding of electronics and experience on soldering etc. I feel i can do it.
Last edited:
You can do it, no doubt. As with anything new, take your time and be certain of each step along the way.
Does the receiver work 100% now? All functions work properly? No cut-outs, scratchy pots or switches, weakness in one channel vs the other?
In vintage gear, pots and switches are the biggest and most frequent problem: corrosion on contact areas that are operating at low voltages. Doesn't take much to disrupt or impede a line level signal. In the case of this amp, there are also wires between different boards that are not soldered, but use removable (plug-in) connectors. The contact areas in those plug-in connectors are also vulnerable to corrosion related issues (this is addressed on that site I linked with the pic of the main amp board, good reading).
Does the receiver work 100% now? All functions work properly? No cut-outs, scratchy pots or switches, weakness in one channel vs the other?
In vintage gear, pots and switches are the biggest and most frequent problem: corrosion on contact areas that are operating at low voltages. Doesn't take much to disrupt or impede a line level signal. In the case of this amp, there are also wires between different boards that are not soldered, but use removable (plug-in) connectors. The contact areas in those plug-in connectors are also vulnerable to corrosion related issues (this is addressed on that site I linked with the pic of the main amp board, good reading).
Last edited:
Yes the amp is working fine, no problems on channels. The connectors from the wires between board are not tight as they should be.
I have deoxit to use on selectors, pots and switches.
I'm gonna bypass some selectors like the speaker selection one.
I have deoxit to use on selectors, pots and switches.
I'm gonna bypass some selectors like the speaker selection one.
- Status
- Not open for further replies.