Hi,
I have a very nice sounding superscope R-1220 reciever.
Just now, the right channel lost allmost all it's volume and sounded distorted.
After all the regular checking an measuring, I decided to play it with the lid off.
There was an unfamiliar component glowing orange inside.
I marked it with a green dot on the attached pic.
Anybody knows what it is and if i can replace it?
Thanks a bunch!
I have a very nice sounding superscope R-1220 reciever.
Just now, the right channel lost allmost all it's volume and sounded distorted.
After all the regular checking an measuring, I decided to play it with the lid off.
There was an unfamiliar component glowing orange inside.
I marked it with a green dot on the attached pic.
Anybody knows what it is and if i can replace it?
Thanks a bunch!
Attachments
Hi beamnet,
I'm pretty sure that's a lamp. That is from memory as I have serviced many in the past. Not so many these days.
Your Superscope is a nice little receiver. They look nice when clean. They were a less expensive line to the Marantz line that Superscope distributed.
Anyway, on to repairing this. You have excessive current flowing through the lamp. Do not run the receiver any more. You need to repair the faults. I have never had to replace one of these lamps, so I can't help you with the type number. Probably a 40 mA bipin of some kind.
If you are not familiar with repairing equipment, proceed with extreme caution. It would be a shame to see this nice little set die needlessly. If you send it out for service, look for a tech who is familiar with Superscope. That tech will be 45 ~ 65 years old most likely and may work from home by now.
To service, test each and every transistor in that channel carefully. You need a good transistor checker, like a Heathkit IT-18 (measures both leakage modes). May as well replace the capacitors by now. Measure all the resistors in the output/driver section. Replace them even if they are only discoloured. Use a variable power supply or variac (variable AC transformer) to power it up for testing. This will prevent further damage. Don't even try to power it up until you have replaced the blown components.
-Chris
I'm pretty sure that's a lamp. That is from memory as I have serviced many in the past. Not so many these days.
Your Superscope is a nice little receiver. They look nice when clean. They were a less expensive line to the Marantz line that Superscope distributed.
Anyway, on to repairing this. You have excessive current flowing through the lamp. Do not run the receiver any more. You need to repair the faults. I have never had to replace one of these lamps, so I can't help you with the type number. Probably a 40 mA bipin of some kind.
If you are not familiar with repairing equipment, proceed with extreme caution. It would be a shame to see this nice little set die needlessly. If you send it out for service, look for a tech who is familiar with Superscope. That tech will be 45 ~ 65 years old most likely and may work from home by now.
To service, test each and every transistor in that channel carefully. You need a good transistor checker, like a Heathkit IT-18 (measures both leakage modes). May as well replace the capacitors by now. Measure all the resistors in the output/driver section. Replace them even if they are only discoloured. Use a variable power supply or variac (variable AC transformer) to power it up for testing. This will prevent further damage. Don't even try to power it up until you have replaced the blown components.
-Chris
Hi beamnet,
The lamps do not normally glow. An open filament is possible, but not glowing is normal for that circuit.
You need to either pick up a good tester (you will use it, believe me) or build some testing jigs. A bad tester is worse than not having one. The IT-18 goes for $10 ~ $silly money on Eeek Bay. The IT-18 is fast and accurate. There are others just as good, but they generally take much more time to use. Could be my prejudice here since I've used an IT-18 since they were new (in the 70's). I love mine and have a spare in case it breaks. I did buy mine new and it wasn't cheap. They only had factory wired ones left at the time. I did build an IT-121 about five years ago. My father found that unbuilt kit on Eeek Bay.
One of the more important tests are the leakage tests. A rough guide to beta is required, but the leakage tells you if the transistor is going bad before it fails. It does miss some, but catches most iffy parts. The missed ones are probably my fault for not heating each one up as I test it.
-Chris
The lamps do not normally glow. An open filament is possible, but not glowing is normal for that circuit.
You need to either pick up a good tester (you will use it, believe me) or build some testing jigs. A bad tester is worse than not having one. The IT-18 goes for $10 ~ $silly money on Eeek Bay. The IT-18 is fast and accurate. There are others just as good, but they generally take much more time to use. Could be my prejudice here since I've used an IT-18 since they were new (in the 70's). I love mine and have a spare in case it breaks. I did buy mine new and it wasn't cheap. They only had factory wired ones left at the time. I did build an IT-121 about five years ago. My father found that unbuilt kit on Eeek Bay.
One of the more important tests are the leakage tests. A rough guide to beta is required, but the leakage tells you if the transistor is going bad before it fails. It does miss some, but catches most iffy parts. The missed ones are probably my fault for not heating each one up as I test it.
-Chris
another, more accurate way of telling if a transistor is getting ready to fail is noise testing it. apparently transistors begin to get noisier as they get ready to fail. NASA has been using noise testing methods since the 70s. a transistor increases its noise production as it gets to the last 10% of its life. if you could build a noise test jig for transistors, you could compare a suspect part against an average of known good parts. somewhere here i have the article from a NASA engineer on how they discovered this, and their testing methods.
Hi unclejed613,
Heating and cooling the transistor package will show mechanical die defects or wire bond issues. Heat will cause much more leakage. Cold will cause moisture (or impurities) to become more conductive and increase leakage.
The wear out period for transistors operating well within their limits is so long that the wear out hours are not known very well. Nor is the end of life failure mode. If you read early GE or RCA documentation, they look at leakage as their indicators of transistor quality. The noise is a secondary effect. An oscilloscope may be the better tool as an indicator in that case anyway.
-Chris
They do get noisier, but I disagree that that test is more accurate. It is also more difficult to implement that test. The noise is due to leakage currents mostly. Measuring leakage is easier and allows you to put a number on it. That depends on how sensitive the test is, you may need to know what normal leakage is if you are measuring germanium transistors or your test is very sensitive.
Heating and cooling the transistor package will show mechanical die defects or wire bond issues. Heat will cause much more leakage. Cold will cause moisture (or impurities) to become more conductive and increase leakage.
The wear out period for transistors operating well within their limits is so long that the wear out hours are not known very well. Nor is the end of life failure mode. If you read early GE or RCA documentation, they look at leakage as their indicators of transistor quality. The noise is a secondary effect. An oscilloscope may be the better tool as an indicator in that case anyway.
-Chris
Hi Jacco,
Yes, those were reasonably hard to kill. They sounded okay and had some reserve power. Over here in Canada, in the Toronto area, Marantz were easily had. It was more difficult to find the Superscope product. Many people still had there Marantz receivers that they bought in university many years later. When I was doing warranty service on these, I was surprised to see my first Superscope under warranty.
Some Superscope models used older output assemblies from earlier Marantz models. That was cool to see. I think the R-1270 was one of those.
Hi Charles,
Thank you.
Hi unclejed613,
Now that the group that has Denon has the Marantz name, we have seen a return to some real quality units. I am no longer involved in warranty service, but would have welcomed the line back the way it is now.
-Chris
Yes, those were reasonably hard to kill. They sounded okay and had some reserve power. Over here in Canada, in the Toronto area, Marantz were easily had. It was more difficult to find the Superscope product. Many people still had there Marantz receivers that they bought in university many years later. When I was doing warranty service on these, I was surprised to see my first Superscope under warranty.
Some Superscope models used older output assemblies from earlier Marantz models. That was cool to see. I think the R-1270 was one of those.
Hi Charles,
Thank you.
Hi unclejed613,
I think that the confusion was over the fact that the original Sony importer were the same brothers that handled Marantz. Marantz was never a Sony product and the designs were completely different. Marantz designs were actually ahead of most other brands in technology. Later, the evil Philips people bought the rights to the line and trashed it in short order. They pulled the standard (for them) "no parts available" thing as they slam dunked the quality. I dropped the Marantz line after they went to TC Electronics in Canada. A truly useless group of individuals to deal with. Later, a company called "Lenbrook" picked up the line in Canada to finish the job. An example. A power transformer for a double cassette deck was priced at $180 CDN - my cost! This is something that would have retailed around $40 CDN. So the line was unserviceable in Canada.
Now that the group that has Denon has the Marantz name, we have seen a return to some real quality units. I am no longer involved in warranty service, but would have welcomed the line back the way it is now.
-Chris
i remember superscope products. i do remember ordering parts from the same distributor as sony, maybe that's why i thought they were made by sony.
on a very small rabbit trail.... has anybody ever noticed that sony has been using the same chassis stamping and circuit board footprint in their low end receivers for over 20 years? and because of this, the pc board still breaks in exactly the same place, except there's about 5 times as many traces routed through that corner of the board now........
on a very small rabbit trail.... has anybody ever noticed that sony has been using the same chassis stamping and circuit board footprint in their low end receivers for over 20 years? and because of this, the pc board still breaks in exactly the same place, except there's about 5 times as many traces routed through that corner of the board now........
The company actually goes back to the early 1950s and Superscope was the company that pioneered the cinema wide screen format of the same name. (Apparently a process to reduce wide screen film duplication costs.) Sony Superscope was originally created in the late 1950s to distribute Sony tape recorders in the USA, later they acquired Marantz (after the bankruptcy) and manufactured a line of Marantz branded products in Japan. The company still exists today in some form and is privately held, here is a link to their history: http://www.superscope-marantzpro.com/company/about/superscope.shtml
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