X202B time capsule
- Thread starter RS Steve
- Start date
Yeah, it's quite a nice piece of history. Hope to get a lot of use out of it down the road. Although, I enjoy my 1800 so much that it will be stressful just deciding which to use most. :scratch2:
After getting a full update, and restoration, my sweet X202B is about to be sent back my way. I have been afraid to use it much knowing it was stored for over 25 years, and it turns out the little I did use it was enough to make some parts get very close to failing. Now it will probably out live me, I can't wait to get it in use. :thmbsp:
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tube-a-lou
Addicted Member
That is Beautiful, enjoy it
Tube
Tube
And we know Dave had some FUN with it! Lucky Guy!!!
Boy did I ever! This is one of those units that's so perfect though that it just makes you want to take your toys and go home. I mean, how do you compete with it? As received, this unit was about as showroom perfect as it gets 50+ years later, complete with its original box, too.
But problems were already in play, so its good the restoration was done. Most of the small electrolytic caps were in the process of pushing out their rubber end caps, the DC Heater/Bias supply can cap had already started to vent, and two of the resistors in the power supply were operating at 108% and 161% of their rating. Fisher caught this in later units, although they never corrected the service manual to reflect the change.
For other X-202B owners, this would be R121 and R115 respectively for units with serial numbers between 50001 and 59999, which includes the subject at hand. For greatest dependability, these should be increased to 10 watt and 3 watt units respectively. In later units, Fisher increased these to 7 watt and 2 watt units to correct the design error. This unit had factory installed 5 and 1 watt units in place as specified in the service manual.
Finally, this unit was also populated with all those dark brown coupling caps, which aren't so prone to leaking, but are prone to becoming intermittent with time. So, besides the power supply resistors mentioned, all power supply and coupling caps were replaced, as were all the low voltage electrolytic caps and diodes. Screen Stability and individual cathode resistors were added to the output tubes, and a current limiter now provides a soft start at turn on. Along the way, the Aux 2/Tape Monitor bleed circuits were removed, and the headphone jack channel identity was corrected as well. It's now ready for another lifetime of Fisher service. It gets a post op checkup later this week end, but should be ready to go the first of the week.
It really was neat to work on such a pristine unit. Well, maybe not the phono preamp section, which is always a challenge in the X-202B. But it would have been a crime to have done everything else and not recapped that section as well, so that section was attended to as well. The pic shows the final result after all the work was finished.
Dave
But problems were already in play, so its good the restoration was done. Most of the small electrolytic caps were in the process of pushing out their rubber end caps, the DC Heater/Bias supply can cap had already started to vent, and two of the resistors in the power supply were operating at 108% and 161% of their rating. Fisher caught this in later units, although they never corrected the service manual to reflect the change.
For other X-202B owners, this would be R121 and R115 respectively for units with serial numbers between 50001 and 59999, which includes the subject at hand. For greatest dependability, these should be increased to 10 watt and 3 watt units respectively. In later units, Fisher increased these to 7 watt and 2 watt units to correct the design error. This unit had factory installed 5 and 1 watt units in place as specified in the service manual.
Finally, this unit was also populated with all those dark brown coupling caps, which aren't so prone to leaking, but are prone to becoming intermittent with time. So, besides the power supply resistors mentioned, all power supply and coupling caps were replaced, as were all the low voltage electrolytic caps and diodes. Screen Stability and individual cathode resistors were added to the output tubes, and a current limiter now provides a soft start at turn on. Along the way, the Aux 2/Tape Monitor bleed circuits were removed, and the headphone jack channel identity was corrected as well. It's now ready for another lifetime of Fisher service. It gets a post op checkup later this week end, but should be ready to go the first of the week.
It really was neat to work on such a pristine unit. Well, maybe not the phono preamp section, which is always a challenge in the X-202B. But it would have been a crime to have done everything else and not recapped that section as well, so that section was attended to as well. The pic shows the final result after all the work was finished.
Dave
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Beautiful X202B and restored by the best Fisher guy in the business congrats Steve! Yours is much nicer than mine! Al
Arghhhhh.......you hadda mention that!! I know when I worked on my own x-202-b I never got around to digging into the phono section for obvious reasons. Oh well, might as well get out the small tools and go for it :yes:
While I'm in there, I might as well replace the 2 diodes by the bias cap that I neglected to do. Suitable replacement???
And Steve, your receiver is now not only museum worthy, but will be confidently functional as well. Congrats to both you and Dave!! :thmbsp:
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Not -- I used 1N5402 diodes for the DC Heater/Bias power supply. These are 3A diodes that operate very conservatively at about 30% of both their forward current and PIV ratings. Should last multiple lifetimes at least!
Dave
Dave
Thanks D :thmbsp:
Another over the top rehab by Dave G, my X202B couldn't couldn't of been in better hands! :thmbsp:
Results are below.
1. Power Output and Distortion: 35.1/34.8 watts RMS @ .31% and .35% THD (at 1 kHz) respectively.
2. Frequency Response (through high level inputs, tone controls centered, filters off): +0/-.6 db (left) / +0/-.4 db (right) 20 Hz to 20 kHz.
3. Sensitivity: Hi Level inputs: .24 vac (both channels) for full power output. RIAA: .0033 vac (both channels) at 1 kHz for full power output.
4. Channel Balance (volume control up full, balance control centered): Within .25 db
5. Volume Control Tracking: Within 1 db at any setting.
6. Channel Separation (@ 1 kHz): > 65 db.
7. RIAA Accuracy: +/- .30 db (left) / +/- .35 db (right) 20 Hz to 20 kHz.
8. Hum and Noise (below 35 watts output): > 92 db (volume control at min), > 86 db (high level input, volume @ max), > 67 db (RIAA, volume @ max).
Results are below.
1. Power Output and Distortion: 35.1/34.8 watts RMS @ .31% and .35% THD (at 1 kHz) respectively.
2. Frequency Response (through high level inputs, tone controls centered, filters off): +0/-.6 db (left) / +0/-.4 db (right) 20 Hz to 20 kHz.
3. Sensitivity: Hi Level inputs: .24 vac (both channels) for full power output. RIAA: .0033 vac (both channels) at 1 kHz for full power output.
4. Channel Balance (volume control up full, balance control centered): Within .25 db
5. Volume Control Tracking: Within 1 db at any setting.
6. Channel Separation (@ 1 kHz): > 65 db.
7. RIAA Accuracy: +/- .30 db (left) / +/- .35 db (right) 20 Hz to 20 kHz.
8. Hum and Noise (below 35 watts output): > 92 db (volume control at min), > 86 db (high level input, volume @ max), > 67 db (RIAA, volume @ max).
The freshly restored X202B showed up today, and is proudly back in its place pushing my 4430's for now. It sure sounds special, and it's quite nice not having to worry about old caps failing. It might be the closest thing to buying a new one back in the day. 
Special thanks go out to Dave Gillespie, I can't even explain what it means to have someone this dedicated to these Fisher's, work his magic on my examples. :thmbsp:
Special thanks go out to Dave Gillespie, I can't even explain what it means to have someone this dedicated to these Fisher's, work his magic on my examples. :thmbsp:
