Kit or parts selection for Fisher 500B

Sam08861

Super Member
Hello All,

Getting ready for a parts order for a Fisher 500B install. ( Restarting thread, previous was here: http://audiokarma.org/forums/index....for-fisher-500b-restore-whats-missing.715883/ )

Photos of the unit:
IMG_0546.JPG

IMG_0544.JPG

Parts being labeled for replacement:

IMG_0545.JPG

And below is my 'draft' mouser order. Wanting to know if I'm on the right track with these parts as there are a lot of choices.

1. Not sure if I should go all metal film on all the resistors, or go carbon where the service manual lists composition?
2. For the mylar caps, should these be replaced with mica?
3. Looks like PIO caps are not available at mouser. Any recommendations for a source?
4. Assuming I should go aluminum electrolytic / nichicon for all the electrolytics?
5. Should the ceramics be replaced with polypropolines? Orange drops?

Mouser Order.jpg

There's a text cut and paste below if the above is difficult to read. Hoping to edit this so it's helpful for someone else with a 500b in the future. Also haven't decided if I want to go with the Hayseed cans yet or restuff them. Anyone with experience know if any of the 500B cans have tar in them?

Any help greatly appreciated!

Sam

Fisher Schematic Number Service Manual Part Qty. Part # Ea. Total

C91, C92 Molded, .01uf, 20%, 600V 2 594-2222-338-68105 1.45 $2.90

Safety Capacitor na 1 80-R413I2100DQ00K 0.74 $0.74

CL 89 Thermistors na 2 527-CL80A 2.01 $4.02

Grommets
na 4 187 P/N 534-730 0.18 $0.72

C210 Electrolytic, 1uf, 350V 1
647-TVX2V010MAD
0.9 $0.90

R106, R107, R108, R109 Compositon 1K Resistor 4
71-CMF551K0000FHEA
0.27 $1.08

C74 Electolytic, 8uf, 50V 1
594-2222-138-31109
2.52 $2.52

SR1 Selenium Rectifier, Bridge 1 512-GBPC3504W 2.69 $2.69

GL856 Diodes na 2
863-MR856G
0.45 $0.90

C79A & C79B Electrolytic, 2 section, 1000uf, 35V 2
647-UVY1H102MHD
0.49 $0.98

R128 Wirewound, 15, 5W 1
588-40F15RE
2.05 $2.05

Cathode Resistors na 4
71-CMF5510R000FHEB
0.35 $1.40

R 124, R129 Composition, 5.6K, 5% 2 660-MOS2CT52R562J 0.13 $0.26

C85 Electrolytic, 100uf, 25V 1
647-UVZ1V101MED
0.18 $0.18

R135 Dep. Carbon, 10K, 5%, 1/3 W 1 free- have them 0.3 $0.30

CR3, CR4 Silicon Diode 2
625-UF5408-E3
0.69 $1.38

C84A Electrolytic, 2 section, 40uf, 500V 1
647-UCY2H470MHD
4.13 $4.13

C78A, B, C Electrolytic, 3 Section: 20uf, 300V -- 40uf, 400V, 40uf, 450V 1
75-TVA1712
13.5 $40.50

C84B, C88 Electrolytic, 2 section: 200uf, 250V, 200uf 250V 2
647-LGN2G561MELC40
7.29 $14.58

R133 Glass, 1.2K, 7W 1
66-W221201JRLF
1.2 $1.20

R131 Composition, 1.2K, 1W 1
660-SPR2CT52R122J
0.46 $0.46

R126 Composition, 2.7K 1
594-5083NW2K700J
0.34 $0.34

R125 Dep. Carbon, 22K, 5%, 1/3 W 1
594-5083NW22K00J
0.34 $0.34

R123 Composition, 100K 1
594-5073NW100K0J
0.18 $0.18

C77A, B, C, D Electrolytic, 4 section: A 50uf, 250V B 50uf, 250V, C 50uf, 250V, D 50uf, 250V 1
647-UCY2V470MHD3
1.75 $7.00

R127, R132, R134 Glass, 180, 3W 3
594-5093NW180R0J
0.48 $1.44

C14, C15 Mylar, .022uf, 250V 2
505-MKP4O122204B00KS
0.69 $1.38

C8, C9 Ceramic, .01uf, 20%, 500V 2
505-M10.01/630/10P
0.62 $1.24

C43, C44 Mylar, .047uf, 400V 2
505-M10.047/1000/10
1.22 $2.44

C27, C30 Ceramic, 1000, 1000V 2
505-M101000/630/5
0.55 $1.10

C59, C62, C68, C69 Ceramic, 330, 1000V 4
598-CDV16FF331JO3F
1.93 $7.72

C57, C58, C60, C61 (c57, c60) Mylar, .047uf, 400V, (c58, c61) Mylar.047, 10%, 250V 4 PIO from tubestore $12 shipped $0.00

C63, C64 Ceramic, 18, N470 1000V 2
598-CDV19EF200JO3F
2.42 $4.84
 

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Questions answered in turn

1.) Carbon Film of Metal Film is ok. Your choice.

2.) NO. Mylars are usually left alone unless they are leaky. ERO-FOL's usually aren't leaky. Only replace the output couplers due to change in size (.047 to .1uf) You CAN change Mylars for other films or PIO's as you feel.

3.) E-Bay, AES (Antique electronics Supply) etc. for PIO's. Jim McShane has a limited stock also.

4.) Yes. UPW series for Power supply and try for UKL for signal path. These are proven low leakage and low noise.

5.)NO! FISHER used a high grade ceramic when used. No need to change any of them out in most cases unless leaky.

C210 replace with a 1uf 350v film cap. This will improve FM MPX operation. Any Electrolytic under 4.7uf can be replaced with a film. Above 4.7uf you run into sizing problems.

R133 change from 7W to 10W. These run very hot. A bit more dissipation capability will help with resistor life.
71-RS0101K200FE12

C59, 62, 68,69 you can leave alone as they are in the NFB loop. No need to change unless leaky. And replace with same type if you do change.

All Can Caps have a bit of tar used as an adhesive and vibration inhibitor in the top of them. All of the can's I've opened from FISHER's are all of the same construction.
 
Thanks again Larry! In the end I've decided to go with the full Jim McShane kit, since mouser had a several key parts out of stock and it's my first Fisher restore. While waiting I'm exploring the IBAM and other mods and will order those up and post follow-ups as I progress.

Sam
 
Ok, so I've installed the full Jim McShane kit. Haven't yet done the new screen resistors mod or IBAM. (looks like we lost a few posts, but I did get to see the great advice for Rockyhill and others)

Here's the unit cleaned up with new LED lights and new and restuffed cans (2 in back)... Only the short can was left alone with the caps underneath.

IMG_0575.JPG

Good news, we do have sound and all the controls seem to work, however...
BAD news is that the sound is scratchy and tinny and I think low volume as I have to the 3/4 mark to hear it clearly.

Checking the voltages from the schematic, I get the following:

voltages may 26.jpg

For those who can't read my chicken scratch/awesome hand made paint text above:

Point Expected Voltage Actual Voltage (All in DC)
------- ----------------------- --------------------
B 395 199.5 (measured where cr3 and c88 join. Also, I got negative values... -10 between the diodes cr3/cr4 and -222 on the ground side of cr4)
C 348 188.2 (measured where
E 320 179
F 290 165
D 165 -8

As you can see, these are way off!

Also, the 'stereo beam' isn't lighting up, but I also don't have an antenna hooked up. Finally, I get the same results (sound wise) on any of the inputs.

Any suggestions on what to check next?

ps... Please let me know what wiring photos you want to see and I'll be glad to post them as it's very possible I've made some mistakes along the way. Glad to take and post them all. Source is otari reel to reel and output is to just recapped wharfedale w70s, both of which work great on another receiver.
 
So I tried using just the ground side of cr4 as a ground point for the meter and got closer readings. Thinking that I had bad ground, I jumped from this point to the chassis and have MUCH clearer sound and now get a 392VDC reading at point B. While the sound is clearer, the volume is still at 2/3rd for a decent volume.

However, point C is 64VDC. I am thinking on the can caps where these were replaced with non cans need the negative sides to ground. I will recheck everything per schematic and then post pics shortly and results shortly as I'm now certain there are some rookie errors here.
 
I love how good my 500B sounds. I would double check all your work, make sure your soldering was done well, etc and also check all your tubes (you have a tube testor?) Congrats on your 500B. Mine was also the first tube item I worked on and I bought the metal-bone kit off of ebay. I looked at the instructions he sent me just the other day after years and I was really impressed with how it was done. I've heard great things about Jim McShane and I bet his was as good or not better. Good luck figuring the rest out and hope you enjoy the music from yours as I have mine. What kind of speakers are you running btw?
 
Thanks NYListens,

I am powering a set of wharfedale w70s (original "mark I" w70 with all alnico 12" woofers, 4" tweeters and 8" ish midranges) that I just replaced the original Arrow brand oil capacitors with KBGs from thE bay. The crossover pots still need more cleaning but I've found spots where they work fine and produce good sound.

The 'McShane' kit only came with (beyond the parts) a parts list, one jpeg image of a schematic for adding the additional diodes to the rectifier and a PDF of service manual (same PDF that is available a lot of places) so one key difference is no instructions whatsoever with this kit. That said, everything but the diodes (and cathode resistors) are a replacement so finding and swapping out was straightforward, but it does take some time going back and forth between the unit and the schematic several times to ensure one is pulling the right parts and that things are wired correctly (polarity wise, where it matters).

There's a few 500B threads on this forum that were very helpful in getting the undocumented bits in place. Jims responsiveness to the couple of wrong parts sent and quick questions was immediate so am very happy with the customer service and he was quite clear on what to expect with this kit.

I popped the fuse yesterday when being a dummy and putting one of the jumpers in the wrong place with the unit on and so haven't gotten around to retesting with the jumpers, final soldering of the grounds or taking the photos just yet. Hoping to get replacement fuse(s) and do that this afternoon.

Sam
 
ps.. NYListens, I do have an EICO 625 tube tester, but have not tested the tubes yet as they all lit up, but will do that now.

Anybody know the right settings for the Fisher branded 12ax7 tubes? I've found a number of options in the documentation but seems the Eico 625 isn't the best for testing these types. I've never seen a reading past the 1st 1/3rd in the 'good' section (60-70%) with even new 12ax7 or 12at7 type tubes in the past but all the other types get to near the 90%-95% mark for known good/new tubes

Sam
 
After soldering in the ground, and am now getting pretty good sound:

Point Expected Voltage Actual Voltage (All in DC)
------- ----------------------- --------------------
B-------395------- 396.2
C-------348------- 363.4
E-------320------- 344.7
F-------290------- 316.3
D-------165------- 170.2

And here are the photos:

c84a attached to r131 and r133 and negative side to ground (arrow) and lead going to several other components.
c 84a2.JPG

c77 and resistors

c77.JPG

c78 (incidentally, reads 0v on the ground side of the r123 resistor, but 263V on the other side. Wonder if this is a bad part?
c78.JPG

c79 a and b along with resistors and c91, c85
c85 and c79ab.JPG

Cathode resistors and some nfb loop and r133
cathode resistors.JPG

coupling caps 1
coupling caps 1.JPG

c91 and c92, along with c88 and c c79a, c79b and cr3, cr4 diodes
diodes and caps.JPG

pios and other mica caps and resistors
pios.JPG

c63, c64 and r133 and others
r133 and loop.JPG
 

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Last edited:
ps... after hooking up an antenna, the stereo beam seems to be working. The bars are very faint, but the edges get bright and close together if a signal is strong and 'moves with the beat' a bit on less strong stations. The FM section seems to be a fair bit louder than the aux input I'm plugged into.

Do my voltage readings seem too high or are they within an acceptable level of tolerance?

Any advice on what other voltage measures and diagnostics I should be doing before moving on? (just for now; still have to put in screen resistors and relocate r133 as well as c210 and c74 and the thermistor to for current inrush protection)
Btw, the local homey deepo only had fast blow 3a fuses and they seem to be working fine.

What adjustments should I be making to the phono level and phase inverter pots?

Please also let me know if I can take some better or more specific pictures.
 
Those voltages are OK, well within tolerance. I would check the voltages at pin 5 on each 7591 to see what cathode current each are drawing. And, the supply voltage to the preamp tubes' filaments from the bias supply - should be around -25v.
 
ps... after hooking up an antenna, the stereo beam seems to be working. The bars are very faint, but the edges get bright and close together if a signal is strong and 'moves with the beat' a bit on less strong stations. The FM section seems to be a fair bit louder than the aux input I'm plugged into.

Do my voltage readings seem too high or are they within an acceptable level of tolerance?

Any advice on what other voltage measures and diagnostics I should be doing before moving on? (just for now; still have to put in screen resistors and relocate r133 as well as c210 and c74 and the thermistor to for current inrush protection)
Btw, the local homey deepo only had fast blow 3a fuses and they seem to be working fine.

What adjustments should I be making to the phono level and phase inverter pots?

Please also let me know if I can take some better or more specific pictures.

This is the phase inverter sticky from the Fisher forum:

http://audiokarma.org/forums/index.php?threads/quick-and-easy-400-phase-inverter-adjust.559415/

MAKE SURE THE 500B IS UNPLUGGED AND CAPS DISCHARGED.
 
Thanks Rockyhill and Bruce,

Will measure those and go through the phase inverter adjustment tonight and report back the results.

Sam
 
Use the 625 Tube data sheets, @ http://bama.edebris.com/manuals/eico/625data/. 12ax7's on mine always read no higher than 62 on the scale, even new. Hickok's also have problems with 12a-7's in that they read somewhat low. On the 625 with 12ax7's, Anything below 40 I would consider weak and below 30 to 25 marginal to bad, but still usable for circuit testing. It's not the tubes, it's the actual circuits inside and how they read that type of tube.
 
Rockyhill, Thanks for the link and I just completed that. I was able to adjust the phase inverters to match the set pins to the 100th of an ohm. One tube/pot set was 47.06 ohms and the other 48.41 ohms.

For future reference for those with 500Bs, these measurements are taken where the 4 PIOs attach to the phase inverter tubes and the specific process for the 500B paraphrased from the link above is.

1.) Using an alligator clip lead, short C78C to ground. (where resistor 131 connects)
2.) Ground the common lead of ohm meter to chassis.
3.) Measure and record the resistance value that appears at pin #3 of the left and right phase inverter tubes.
4.) Connect your ohm meter to pin #1 of the left and right phase inverter tubes, and adjust their respective phase inverter control for the respective value noted in Step #3 above.
5.) Remove the alligator clip leads before powering up. .....You will get a bit of smoke from r131 if you don't.. Don't ask me how I know this :-o

Larry, thanks for confirming the low readings on the 12axxx tubes with the Eico 625. Will check these out shortly... sooooo many tubes, lol!

Bruce, thanks for the info and the voltages for Pin 5 of the 7591 output tubes read as follows:

tube-----voltage (DC)
v13------.3433
v14------.3134
v15------.1818
v16------.2527

Looks like a problem above? Shall I also go ahead and check the output tubes too or is this indicative of another issue?

One other naïve newbie question, where should I measure the voltages from the "preamp tubes' filaments from the bias supply?"
 
Thanks nondigital, after a long cool down and with 13/14 and 15/16 swapped I get the following after a 5 minute warmup:

tube-----voltage (DC)
v13------.3102
v14------.3858
v15------.2393
v16------.1693
 
Hope running it like this isn't a problem? FM Stereo (and mono for that matter) sounds pretty damn good through the wharfedales. With the loudness on the bass has to be set to the 9am-10am position or so. Plenty of thump, maybe even too much as the stations seem to broadcast with funky eq settings. Talk and music shows on NPR are very good too and seem to have more balanced sound and sound very "live."

Guessing the above is indicative of v15 and v16 tubes being bad or is there a power supply problem that should be feeding more voltage to v15/v16?

Can test the tubes to confirm if that's the right step.

Sam
 
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