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Post by leonski on Jan 1, 2021 1:04:05 GMT -5
I recently rescued my ANCIENT Kenwood KA-7100 from the person who I loaned it to....which used it for a couple months than stored it. Power cord is in bad shape but the rest, while worn should still be fine...... PS caps appear Good. No bulges or split seams. They are ELNA 6800uf of 50v. A VERY common part. Amp is a dual PS design so has 2 diode bridges and 4 PS caps. But only 2 output devices per channel. It isn't all that high powered a rig! But reasonably well heat sinked. Output devices are a P/N pair of Toshiba per side. 4 total. I popped the TOP cover and removed my modification to PREAMP only which also allowed using the amplifier portion. I had run an amp off this for a time. A LONG time ago. This evening I removed the BOTTOM cover and saw it'll be easy to swap in a NEW power cord. I'll use 16-2 which is FINE for this application. Plug is NON-Polarized since this is before that became the norm. But the neat view was how EASY it would be to swap the PS caps. I wouldn't even increase the 'capacity'. Stock values are FINE, and available at commodity cheap prices. One neat feature is the SubSonic filter. If you've ever seen a woofer move back and forth, while playing a VINYL DISC, you were looking at either 'Rumble' or 'record warp'.......The subsonic cuts heavily at about 20hz DOWN and effectively saves your woofers from that particular kind of destruction.... Attachments:
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Post by lhracing on Jan 1, 2021 8:36:47 GMT -5
Nice looking amplifier, some of that older equipment sounded so sweet. Enjoy...
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Post by 405x5 on Jan 1, 2021 11:21:33 GMT -5
I recently rescued my ANCIENT Kenwood KA-7100 from the person who I loaned it to....which used it for a couple months than stored it. Power cord is in bad shape but the rest, while worn should still be fine...... PS caps appear Good. No bulges or split seams. They are ELNA 6800uf of 50v. A VERY common part. Amp is a dual PS design so has 2 diode bridges and 4 PS caps. But only 2 output devices per channel. It isn't all that high powered a rig! But reasonably well heat sinked. Output devices are a P/N pair of Toshiba per side. 4 total. I popped the TOP cover and removed my modification to PREAMP only which also allowed using the amplifier portion. I had run an amp off this for a time. A LONG time ago. This evening I removed the BOTTOM cover and saw it'll be easy to swap in a NEW power cord. I'll use 16-2 which is FINE for this application. Plug is NON-Polarized since this is before that became the norm. But the neat view was how EASY it would be to swap the PS caps. I wouldn't even increase the 'capacity'. Stock values are FINE, and available at commodity cheap prices. One neat feature is the SubSonic filter. If you've ever seen a woofer move back and forth, while playing a VINYL DISC, you were looking at either 'Rumble' or 'record warp'.......The subsonic cuts heavily at about 20hz DOWN and effectively saves your woofers from that particular kind of destruction.... Decades ago a fellow enthusiast had one of those Kenwoods 80 wpc. Integrated. I had the AR INTEGRATED. Both of us agreed the Kenwood was better. |
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Post by mountain on Jan 1, 2021 11:38:16 GMT -5
I had a rotel ra 1210 (60 watt/channel), mid 70”s model integrated amp. Loved it. A friend of mine still uses it. A couple of Friends at the time had a kenwood 40 watts/channel integrated amp about the same time period. It was also a very nice piece.  |
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Post by leonski on Jan 1, 2021 13:04:06 GMT -5
I want to RE-CORD my amp but have a problem I never encountered before. PLUG is non-polarized. BOITH blades are the same width so it'll plug in either way. NOT a 3-conductor cord. NO GROUND. Neither side of the power cord goes to ground. BUT when I turn the amp 'on' I cmeasure resistance between the 2 prongs. Transformer Primary, I guess. When I record? I have 2 choices. Wire up a duplicate of what I have. OR add a 3rd wire to chasis ground and get a grounded plug. ONE other thing. The Power Cord has ONE leg with a slight rib. In the old days, this would have meant something. But I don't know if it means Neutral or HOT. Anybody KNOW anything or have some Sage Advice.  ?? The World wants to know.... |
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DYohn
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Post by DYohn on Jan 1, 2021 14:32:52 GMT -5
Use a 2-wire cord same as OEM. The ribbed conductor is primary NEUTRAL. It will work either way, of course, wire is wire, but that's the old IEC code.
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Post by SteveH on Jan 1, 2021 15:50:24 GMT -5
Haha, I have a Kenwood KR-2090 from 1978, a whopping 16WPC/RMS. Just for the hell of it, I powered this up last week and it works fine.  |
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Post by leonski on Jan 1, 2021 20:28:00 GMT -5
Before the Kenwood, I had a PIONEER SX-626 Receiver. I grew to really HATE it. While it performed OK, (just) the FM tuner portion was Unstable.
It had a signal strength AND Center Channel meter. But after 20 minutes to 30 minutes on station? It'd 'twitch' and jump up or down enough to MUTE.
They denied a problem. Even the fix-it people probably gave it 5 minutes and called it good or overheated (it wasn't)
And THAT'S when I went with the Kenwood.
Later, I bought the 40$ or 50$ Tuner from RadioShack but it poor quieting and was unusable.
For an Early receiver? I'd look for a Marantz Gyro Touch.......I don't know from model numbers but the 'look' of that stuff makes me want one......
For an Integrated? SANSUI AU-9900 is on the short list.
Maybe I should try to find and restore a pair of the ORIGINAL ADVENT loudspeakers? That'd be appropriate for ANY of the gear anyone in this thread has mentioned.
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Post by mountain on Jan 1, 2021 21:16:23 GMT -5
Before the Kenwood, I had a PIONEER SX-626 Receiver. I grew to really HATE it. While it performed OK, (just) the FM tuner portion was Unstable. It had a signal strength AND Center Channel meter. But after 20 minutes to 30 minutes on station? It'd 'twitch' and jump up or down enough to MUTE. They denied a problem. Even the fix-it people probably gave it 5 minutes and called it good or overheated (it wasn't) And THAT'S when I went with the Kenwood. Later, I bought the 40$ or 50$ Tuner from RadioShack but it poor quieting and was unusable. For an Early receiver? I'd look for a Marantz Gyro Touch.......I don't know from model numbers but the 'look' of that stuff makes me want one...... For an Integrated? SANSUI AU-9900 is on the short list. Maybe I should try to find and restore a pair of the ORIGINAL ADVENT loudspeakers? That'd be appropriate for ANY of the gear anyone in this thread has mentioned. I had the original advent loudspeakers, stacked. They are sill in use today (reconed) at a friends house. They matched well with my rotel integrated. |
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Post by leonski on Jan 1, 2021 23:23:29 GMT -5
STacked Was REAL popular for a while. Stack bottom speaker tweeter UP and top speaker tweeter DOWN.......
And what blows me away is that in the Utility Cabinet, they were maybe 135$ each or so. A real bargain.
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Post by Ex_Vintage on Jan 2, 2021 0:01:18 GMT -5
I have a Kenwood KA-7300 that I purchased new in 1975. Dual power systems with dual transformers (essentially a pair of monoblocks in 1 chassis). I recently recapped it and cleaned all switches and pots. Even by todays standards, this is an exceptional sounding amp. i'm thinking of picking up a TA-100 for more preamp capability (digital inputs) and still using the Kenwood for the power amp section.
I also recently acquired a Kenwood 600 integrated amp which was the grandad of all Kenwood amps. Re-capped it and ended up selling it for a fair value.
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Post by leonski on Jan 2, 2021 2:29:30 GMT -5
The 7100 was EASY to convert to a preamp. Jumpers from main board, on backside of front panel......to the amp board. so I just parallelled wires out...bought some RCA to bare 'shielde' and soldered up.
I just undid the work the other day.
The 7100 has a single transformer with 2x outputs feeding dual power supplies. So it has 2 bridge rectifer (4 big diodes each) and 2x6800uf filter caps, again with 2 per side. And 4 rail fuses. 2 per channel.
This amp successfully drove my 4ohm (some say 5 ohm) MG-1 Magnepans. VERY old school and certainly within a couple years age of the amp!
Where'd you get the caps? I'm having trouble locating 50v 6800uf Electolytics for the PS. Plenty of space to fit most any cap. Need radial leads ideally about 16mm apart. Stock are about 1"+ diameter and 2"+ tall.....
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Post by Ex_Vintage on Jan 2, 2021 8:46:57 GMT -5
Caps came from Digi-Key. They carry Elna for the audio path and I believe the main power caps were Nichicon Gold Tune series caps. If I remember correctly, the main power caps were clamp mounted and hard wired (not in a circuit board) so there was some flexibility there.
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Post by leonski on Jan 2, 2021 12:58:12 GMT -5
I'm having a heck of a time....and yes.....I'm a DigiKey Veteran. OEM was ELNA. No longer can find exact lead spacing, and indeed 6800uf @50v is not readily available.
I'd have thought these were EASY to source. Other first tier builders are also NOT making this value.
MIght have to resort to a parallel / series arrangement but at that point space becomes the limit.
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Post by Ex_Vintage on Jan 3, 2021 22:21:44 GMT -5
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DYohn
Emo VIPs
Posts: 18,494
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Post by DYohn on Jan 4, 2021 10:41:32 GMT -5
I'm having a heck of a time....and yes.....I'm a DigiKey Veteran. OEM was ELNA. No longer can find exact lead spacing, and indeed 6800uf @50v is not readily available. I'd have thought these were EASY to source. Other first tier builders are also NOT making this value. MIght have to resort to a parallel / series arrangement but at that point space becomes the limit. Don't know about lead spacing but Digikey shows that value available from Nichicon |
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Post by housetech on Jan 4, 2021 12:51:49 GMT -5
The old Kenwoods were not bad units at all for the money and were pretty clean sounding. We had a 30w/ch Kenwood receiver that lasted 40 years. I owned the Pioneer SA-9100 & TX-6100 tuner, mid 70's.
Were those old integrated amps class A?
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Post by leonski on Jan 4, 2021 15:39:34 GMT -5
I'm having a heck of a time....and yes.....I'm a DigiKey Veteran. OEM was ELNA. No longer can find exact lead spacing, and indeed 6800uf @50v is not readily available. I'd have thought these were EASY to source. Other first tier builders are also NOT making this value. MIght have to resort to a parallel / series arrangement but at that point space becomes the limit. Don't know about lead spacing but Digikey shows that value available from Nichicon After some research AND some help......I settled on Nichicon KW series. Avaialble in 6800uf / 50v in a size about the same as stock BUT 10mm lead spacing, which isn't the end of the world.... All of about 5$ each.....less, really. I'll use a tiny dab of Hot Glue to support part to board..... |
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Post by leonski on Mar 5, 2021 2:07:31 GMT -5
Replaced the power cord, too.
Went to 'The Despot' and bought a 16-2 extension cord. I cut off the plug with about 7 feet of wire and went to electronics supply house and got the appropriate straing relief.
It was the right one, for the wire.....which I can't offhand remember what they called it....like st-2 or something.....
Had to drill out hte mounting which required extensive masking than vacuuming before install. soldering went easy but the strain relief was a PIA to install. But now IN and secure.
Stock cord was 18-2 so this is my 'power cord improvement' project for the year.
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?? The World wants to know....
