I've got my veteran SSE that has been running great for almost 8 years, but is presently having a problem that isn't obvious upon inspection. I've been running new issue Tung-Sol 6550's, 12AT7, and 5AR4 for at least 9 months without incident. I have the SS diodes installed but not presently in use (they have a switch to choose between them and the tube rectifier).
I have been through a few sets of tubes over the years, and the only component failure I've had is when a gassy tube caused a capacitor to pop.
The fuses in the IEC plug had blown, so I checked the tubes and since they all look fine, I replaced them. Unfortunately, they instantly blew again. There are 2A fuses in use, FWIW.
So I opened up the amp and so far aside from some minor heat marking on a few resistors, the only other thing I have found is one of the ceramic resistors has a piece that was cracked. Measuring it, however, shows the value to be nominal so I'm gathering this isn't what is causing the fault. Just an incidental discovery, and something I'll certainly replace before I close everything up.
I am curious if anyone has used some type of circuit breaker in lieu of the fuses on their amps. Over the years I've seen the fuses keep going up in price, and I cringe at the thought of wasting two of them every time I try a configuration change for troubleshooting.
At any rate, I'm all ears - but I'm wondering if either the diodes have failed or saving that if I have an IC failure, given that there are no other board indications of defect.
I have been through a few sets of tubes over the years, and the only component failure I've had is when a gassy tube caused a capacitor to pop.
The fuses in the IEC plug had blown, so I checked the tubes and since they all look fine, I replaced them. Unfortunately, they instantly blew again. There are 2A fuses in use, FWIW.
So I opened up the amp and so far aside from some minor heat marking on a few resistors, the only other thing I have found is one of the ceramic resistors has a piece that was cracked. Measuring it, however, shows the value to be nominal so I'm gathering this isn't what is causing the fault. Just an incidental discovery, and something I'll certainly replace before I close everything up.
I am curious if anyone has used some type of circuit breaker in lieu of the fuses on their amps. Over the years I've seen the fuses keep going up in price, and I cringe at the thought of wasting two of them every time I try a configuration change for troubleshooting.
At any rate, I'm all ears - but I'm wondering if either the diodes have failed or saving that if I have an IC failure, given that there are no other board indications of defect.
I've run the tube rectifier through my tube tester and it checks out OK - did yours test okay or do you not have a tester?
The IEC jack has a compartment that slides out with a fuse on each side (hot and neutral). Maybe I need to replace it with one without redundant fuses.
Win - I know that I had read about the diodes some time ago, but I've never had an incident over all these years, sometimes even using them instead of the tube rectifier. Has anyone come up with a better replacement part and/or circuit to avoid repeated failure? I presume removing them from the PCB will isolate the fault.
You don't even have to remove them from the board - just clip one lead of each diode to isolate them.
The best way to use a diode rectifer, imo, is to get one of the solid state devices that plugs into the rectifier tube socket, or make a plug in if you are using a non standard rectifer tube.
I've only used the on board diodes on my child resistant SSE - with dismal results. Two sets of diodes failed in about as many years, and they weren't even the fancy ones.
Win W5JAG
The best way to use a diode rectifer, imo, is to get one of the solid state devices that plugs into the rectifier tube socket, or make a plug in if you are using a non standard rectifer tube.
I've only used the on board diodes on my child resistant SSE - with dismal results. Two sets of diodes failed in about as many years, and they weren't even the fancy ones.
Win W5JAG
So would I. The early FREDs were prone to avalanche breakdown on turn off, especially with a Hammond power transformer. One shorts out when the amp is turned off, then the other is blown on the next power up. They don't always show a short on an ohm meter either. If you are not using the SS rectifier option, just remove the diodes.
I don't have a tube tester, I have two SSE's and when I tried the same tube rectifier in the
other one it blew the fuse in there too.
If the rectifier tests fine in your tube tester then the problem is elsewhere.
Several users have had problems with their SS diodes in the past and at least for some of
them it was due to fake diodes purchased on Ebay.
I've never had any problem with my SS diodes, but like you I use the tube rectifier most of
the time except when I'm using my lower voltage SSE, there I often switch over to SS when I want a higher B+
I'm returning to inspect the amp again - I've got the Edcor power transformer so maybe that is part of why it took 7-8 years before I had an incident. I mainly used the SS option when my original 5AR4 died and I had no replacement tube. I however, have noticed that the power transformer does seem to be less stressed (less hum) when using the SS rectifiers.
If I decide to replace the diodes at some point, is there a newer part (or circuit) that is being recommended in place of them?
Also, can anyone comment how long a pair of output tubes should last? I use the amp most days (it is connected to the TV as well as for listening to music).
Looks like I've found the following part numbers:
ISL9R8120P2 which was mentioned as no longer available (but is being sold at Sonic Craft, who posted that there is availability)
RHRP15120 which a few seem to be using
Anyone using either of these?
The amp has been working beautifully, but I figure if I'm going to get replacement resistors I could throw a few of the diodes on the order too.
ISL9R8120P2 which was mentioned as no longer available (but is being sold at Sonic Craft, who posted that there is availability)
RHRP15120 which a few seem to be using
Anyone using either of these?
The amp has been working beautifully, but I figure if I'm going to get replacement resistors I could throw a few of the diodes on the order too.
ISL9R8120P2 was what was originally recommended for the SSE but availability seems to be sketchy in recent years.
After another builder recommended RHRP15120 I got these for my second SSE and they've been working fine for almost two years.
Regarding output tubes longevity it depends on how many hours of use and how hard you drive them.
I would guess a a good pair of current production tubes on average should last two to three years before you start to hear any deterioration.
I've been using EH KT88 for over four years and they still sound as good as new but I sometimes interchange with other tubes such as EL34 and 6L6.
My Latino VTA ST-120 blew rectifier tubes several times. I then tried a Weber SS rectifier that plugged into the rectifier socket and all was fine until I moved the amp. After red plating one tube I discovered Latino missed a solder connection. I fixed that and all was well again.
Blake
I'd get rid of the diodes and switches and go with just the rectifier. My Bugle Boy 5AR4 has been in service for 8 years, not counting tomorrow
If you must have diodes, use the CL-150/180 inrush limiter George now specifies. I have'm in my SS rectified KT-88 mono blocks and you can do the Times Crossword waiting for the meters to register.
If you must have diodes, use the CL-150/180 inrush limiter George now specifies. I have'm in my SS rectified KT-88 mono blocks and you can do the Times Crossword waiting for the meters to register.
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Agreed, considering how many people have had problems with these I think I managed pretty well. Do you feel that the RHRP15120 is superior to the original part?
I can't say if it is superior as I'm not that technically knowledgeable.
I actually got it for my second SSE because the original one, ISL9R8120P2, was not available.
It was recommended by another builder who used it in his SSE.
I used the original ISL9R8120P2 diode in my first SSE for KT88 and other higher power tubes. I built this SSE
about four years ago (not as long as you
). I estimate it has over 5000 hours on it and no problems yet. About two years ago I built my second SSE for lower power tubes like 6V6, 6F6 and others. I used the
RHRP15120 diode in this one and after over 2000 hours it's still working fine.
I like to have both options in my SSE, the FRED's as well as the tube rectifier.
When I was ordering parts for my two SSE's I got spares of these and some other parts, just in case.
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