99 Problems.... The Revox kind.

[Hxt1]

Sigh.. The Pr99 is modded. Speed and eq mods done, tested etc.
I decided to really clean up the machine.
Painted the faceplates, removed that sticky gunk from the reel tables, and polished them, replaced all of the bulbs and so on.
Now it really looks amazing, my wife LOVES it (rare, very very rare)
And now, it won't play tapes.
Capstan motor non operational.
Doesn't make sense, as the board went in and worked fine prior to the cosmetic upgrades, of course I had lifted traces, etc, but weaseled my way around those.
Fuses are fine (the 3 that I can see)
I unseated the board and had a good look see. (Oh, the cussing' going on around here tonight)!
Tomorrow I will actually get a solen to pop in and chuck the two series caps.
Anyone have experience with this kind of problem?
I'm now back to square one. 9 machines (10 come Wednesday) and NO 2track 15ips!!!!
Eye twitch. Gin. Tonic.
eBay...?

 

[stellavox]

Do you have a scope so you can do some troubleshooting?

Charles

 

[flez007]

Might sound weird but...since it was working in the beginning...I would follow the AC path from the motors back to transformer just to check any loose cable. That usually happens after an internal clean-up whete air-preassure spray is applied .

 

[Hxt1]

Unfortunately I don't have a 'scope... I do have a multimeter, and I'm SO proficient with it, I managed to short the deck whilst taking 'readings'... Need a new fuse now.
I'm trying to figure out if there is a fuse for the capstan motor itself.
And since the servo board is the only thing I've fiddled with related to the capstan control, I'm thinking that must be where the problem lies.
Yes, tracing the AC to the trannies revealed no loose connections.
I'm stumped. Flustered. Taking a day off, I'll revisit it on Monday (my incessant swearing is upsetting my poor Mother in Law, she doesn't speak a word of English, but she knows the 'universal language'... Poor thing)

 

[Ki Choi]

As Charles suggested, you would need an O'scope to trace the servo enable signal. Since it was working before you made it pretty..., I would suggest you remove repainted face plate, make sure the tension sensors are good and try it again. I have seen a Studer with the top plate repainted but the increased in tickness prohibited some of the rollers in the tape path from turning properly - causing error. Before the capstan servo to work, in most cases, you need tension on both supply and take up sides.

 

[Hxt1]

As Charles suggested, you would need an O'scope to trace the servo enable signal. Since it was working before you made it pretty..., I would suggest you remove repainted face plate, make sure the tension sensors are good and try it again. I have seen a Studer with the top plate repainted but the increased in tickness prohibited some of the rollers in the tape path from turning properly - causing error. Before the capstan servo to work, in most cases, you need tension on both supply and take up sides.

Thanks, that's interesting, I will take a look, however, I only painted the very front of the faceplate, but there is a possibility I put the thing on improperly. Where is this 'sensor' located? I'll have to disassemble the works anyways, the counter mechanism squeals like the proverbial stuck pig, so that will need seeing to. This machine is going to be my mobile unit whether it likes it or not! (until I come a cross a lyrec, of course)
Gosh, I'm lOoking forward to the ampex, it's so rudimentary and straightforward in comparison!!!

 

[Ki Choi]

Do you have the service manual?

 

[Hxt1]

Yes, I have the full factory service manual that came with it.

 

[RogerD]

Here's a link on another forum about the PR99. Besides Ki here at WBF,AK has some RKI on Revox also. Hope you get your PR99 up and running.

http://www.audiokarma.org/forums/showthread.php?t=387722&highlight=pr99

 

[Hxt1]

As Charles suggested, you would need an O'scope to trace the servo enable signal. Since it was working before you made it pretty..., I would suggest you remove repainted face plate, make sure the tension sensors are good and try it again. I have seen a Studer with the top plate repainted but the increased in tickness prohibited some of the rollers in the tape path from turning properly - causing error. Before the capstan servo to work, in most cases, you need tension on both supply and take up sides.

Kim, I'm confused... Are you saying there are sensors that must be engaged in order for the capstan motor to work?
In my admittedly very limited experience, the capstan motor turns on and begins spinning the moment the power is turned on.
I was afraid there was no power going into-out of the board, I decided to feel the transistor/heat sink on the capstan control board, and while touching it with my right hand, reached around and touched the capstan with my right. Unmm. There is definitely power going to that board! Yes, I got a shock. I've replaced the caps, traced the circuit, laced things together where traces lifted, etc.
I'm at the end of my rope here... There doesn't seem to be power going to the capstan motor.

 

[CLEM]

You did have PR-99 or PR-99 MK II ?
To make sure motor runs well, put resistor of 20 ohm / 5 Watts between pin 1 (M3-1) and pin 2 ( TO-M3 ) on speed control pcb. If it's doesn't work, problem with motor or phase shift cap., or connectors. If it is OK then make a jump from Q2 body (collector) to test point " H " (emitter), you may use the 20 ohm resistor too. If the motor turnning, may be the C25 blown, if not, the D1 might be the culprit.
There is about 130 VAC around the control pcb and motor.

 

[Hxt1]

You did have PR-99 or PR-99 MK II ?
To make sure motor runs well, put resistor of 20 ohm / 5 Watts between pin 1 (M3-1) and pin 2 ( TO-M3 ) on speed control pcb. If it's doesn't work, problem with motor or phase shift cap., or connectors. If it is OK then make a jump from Q2 body (collector) to test point " H " (emitter), you may use the 20 ohm resistor too. If the motor turnning, may be the C25 blown, if not, the D1 might be the culprit.
There is about 130 VAC around the control pcb and motor.

Thank you, I've walked away from the machine for the time being!
Now I know how to test the motor itself!
I just need to locate the sites you speak of...
I'm coming up to speed verry slowly!

 

[Hxt1]

CLEM, thanks for the tips.... I'm lost as far as the location of 'Q2' point 'H', C25, and D1... but I did manage to find pin 1 and pin2, by trial and error, as there are no markings or letters on my PCB, nor are there any corresponding labels on the schematic in my service manual.
I piut the resistor between pin 1 and 2, and viola! the motor turns..... I'm guessing C25, and D1 are fuses?
if so, where would I find them? I am only seeing F1 and F2 in my machine, and of course, they are both fine!
cheers!

 

[CLEMENS]

sir, I am so sorry that I dont relize my reply did not posted recently.
D1 is a bridge diode, a black round parts with marks + _ and ~ on it.
Also you can find the spec on a list around the pcb layout in the manual, it is a pitty that I am away from the red service manual. to make sure C 25
, just desolder it and without C25 should be running ok.
regards,
Clem

 

[stellavox]

x

 

[Hxt1]

x

"I'm getting confused - is What's Best a Revox service forum?

Charles"

Oops. My apologies. I titled the thread '99 problems' alluding to the fact that, well... I'm having problems with my revox pr99.
The only other online forum I've ever belonged to was 'Lenco Lovers' a group of hobbyists sharing tips an techniques for modding Lenco turntables, more of a collective atmosphere of laymen, enthusiasts, and hobbyists, as opposed to Industry folks and Professionals.
That said, I won't post anymore threads about my pr99,
If anyone would like to contact me off forum regarding services and rates, my email address is: h_thomison@hotmail.com
Cheers!

 

[stellavox]

No Problem - and I didn't mean to be a "pompous ass". There are a number of other tape forums - I know of one on yahoogroups.com - and there are probably many others where there is a LOT of combined knowledge on various brands of recorders. Suggestions??? There also may be a point where you need to consider finding a good (hopefully local) service technician.

Charles

 

[CLEMENS]

CLEM, thanks for the tips.... I'm lost as far as the location of 'Q2' point 'H', C25, and D1... but I did manage to find pin 1 and pin2, by trial and error, as there are no markings or letters on my PCB, nor are there any corresponding labels on the schematic in my service manual.
I piut the resistor between pin 1 and 2, and viola! the motor turns..... I'm guessing C25, and D1 are fuses?
if so, where would I find them? I am only seeing F1 and F2 in my machine, and of course, they are both fine!
cheers!

If there is no C25 then Your PR99 not the MK II, PR-99 MK II using digital counter, and also variable speed control implemented in MK II.
D1 located near by the P1 pin1, beside the 0.47 mFd C1.
Don't hesitate to ask me.

 

[Hxt1]

Charles, please don't take my post the wrong way!
I'm new here, I just wanted to lay out where I'm coming from, which is more like a 'room full of guys futzing around' with DIY, bouncing ideas off of each others heads.
I greatly appreciate all of the advice and help you guys have given me thus far, remember, I started with Arian's speed mod! The diagrams, pics, and step by step stuff made me feel a bit more capable than I actually am!
I've reached out as far as finding a tech goes, seems r2r is pretty specialized, so I've not had much luck, BUT... I've figured out (finally) how to read the schematic in my revox service manual, so hopefully I'll be able to handle this bit on my own.
Charles, your own help and experience has been invaluable, you've even gone so far as to email me personally with instruction and diagnosis!
CLEM, thank you for your help as well...
I hope to be starting a thread titled "She's so fine, my cherry red 99"!
I guess buying that $500 Studer B67 with a 'malfunctioning ic' is out of the question!!!
Lol! (I'm not kidding, I was about to go there.... I've got a serious problem guys)!!
Cheers, and thanks again!

 

[CLEMENS]

Remember under the name REVOX Willy Studer made consumer product, so the profesional product branded STUDER the high spec. tape rec. using rollers to minimize the tape friction and of course it should be constant tension tape recorder. B67 is a constant tension R2R, tape lifter using no rollers. If you going to play around with B67 make sure you have the red hard cover Service Manual. I still have some "transport" parts and electronic parts and also a lot of A77, B77, PR99 heads ( record & repro ).
Regards,
Clem.